ISS N 003 1-0204

Transactions and Proceedingsof thePalaeontological Society of Japan
N ew Series

No.

155

Pa laeon to log ica l Soc iety of Ja pa n
Se ptember 30,

1989

Co-Editors

Hisayoshi Igo, Hiroshi Noda and Kei Mori
Editorial Board

Yoshikazu Hasegawa (Yokohama National University), Itaru Hayami (University of Tokyo),
Hisayoshi Igo (University of Tsukuba), Makoto Kato (Hokkaido University), Itaru Koizumi(Hokkaido University), Yasumochi Matoba (Akita University), Kei Mori (Tohoku University),
Hiroshi Noda (University ofTsukuba), Kazushige Tanabe (University ofTokyo), Tsunemasa Saito(Yamagata University), Kazuhiko Uemura (National Science Museum), Akira Yao (Osaka City
University)

Officers for 1989-1990
President: Itaru Hayami
Honorary President: Teiichi Kobayashi
Councillors: Kiyotaka Chinzei, Takashi Hamada, Yoshikazu Hasegawa, Itaru Hayami,
Hiromichi Hirano, Hisayoshi Igo, Noriyuki Ikeya, Junji Itoigawa, Tadao
Kamei, Makoto Kato, Tatsuaki Kimura, Itaru Koizumi, Kei Mori, Hiroshi
Noda, Ikuwo Obata, Kenshiro Ogasawara, Tsunemasa Saito, Yokichi Takayanagi, Kazushige Tanabe, Hiroshi Ujiie
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Auditor: Sakae O'Hara
The fossil on the cover is Phillipsia ohmorensis Okubo, an Early Carboniferous trilobite
from the Hikoroichi Formation in the Higuchizawa valley, Ofuna to City, Iwate Prefecture, northeast Japan (Collected by A. Haga, PAt 5766, X 3.0; after Kobayashi and
Hamada, 1980, pI. 6, fig. 4).
All communication relating to this journal should be addressed to the

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Trans. Proc. Palaeont. Soc. Japan, N.S., No. 155, pp. 141-158, IO Figs., September 30, 1989

880.

NEW TAXA IN THE LATE TRIASSIC DAEDONG FLORA,
SOUTH KOREA. PART 2*
TATSUAKI KIMURA
Institute of Natural History, 24-14-3 Takada,Toshima-ku, Tokyo, 171 Japanand

BONG-KYUN KIM
c/o Department of Geology, Seoul National University,
Seoul, 151 Korea

Abstract. Continued from our previous issue (Part I), this paper deals with thedescription of the following newly recognized taxa in the Daedong Flora: Pterophyllum
cheondaeriense, sp. nov., Anthrophyopsis decurrens, sp. nov., Drepanozamites sp. A, Podozamites ex gr. schenki Heer, P. sp. A, Cycadocarpidium sp. cf. C. asaense Kon'no, C. sp.
cf. C. nagatoense Kon'no, C. sp. A, Taeniopteris cheondaeriensis, sp. nov. and T.
mungyeongensis, sp. nov.
Key words.

Daedong flora, Korea, Late Triassic.

typicum: Amisan Formation at Cheondaeri.
Locus typicus: Cheondae Coal-Mine,
Cheondaeri, Janggog-myeon, Hongseonggun, Chungcheongnam-do (see Kimura andKim, 1988, p.604). Derivatio nominis:
After the locality.
Diagnosis: Leaf more than 15 cm long,oblanceolate in outline, 8.4 cm wide at thewidest portion; rachis marked with threelongitudinal striations, up to 2 mm wide
below. Pinnae borne closely at an angle of
65-90 degrees, long and narrow, and nearlyparallel-sided for the most part; the longest
4.7 cm long and 4-5 mm wide above, but
shorter, elongate-triangular in form below.
Pinnae not expanding distally, but slightly
expanded at base. Pinna apex mostly acutely or sometimes obtusely pointed. Veins
weak, arising from the lateral sides of rachis,9-12 in n urn ber (10-12 per cm) at the base ofeach pinna, mostly simple, but one of them

Systematic description
Specimens described in this paper are kept
in the National Science Museum of Korea,
Daejeon City.
Bennettitales (continued from ourprevious paper)
Genus Pterophyllum Brongniart, 1828
Pterophyllum cheondaeriense
Kimura et Kim, sp. nov.
Figures IOa-f

Material: Holotype; Reg. no. T-0126A(Cheondaeri). Paratypes; Reg. nos. T-0109,
0110 0127 (Cheondari). Examined specimens: Reg. nos. T-0032, 35, 38, 57, 64, 74,
107, 113, 121, 122 and 126B-C. Stratum·Received July 9, 1987: revised manuscript accepted
July 30, 1989.
141

142

Tatsuaki Kimura and Bong-Kyun Kim

once forked at or near the base, parallel,
ending at the distal margin.
Distribution and occurrence: Pterophyllum
cheondaeriense is locally common, the broken leaves being often thickly massed, but isonly known from the Amisan Formation at
the Cheondaeri area.
Discussion and comparison: In our leaves
examined, cuticle is not preserved. The
petiole and reproductive organs are notknown.
This new species is characterized by its longand narrow pinnae above and elongatetriangular ones below, both having an acutely
or obtusely pointed apex and mostly simple
veins, 10-12 per cm in density.
There are many Pterophyllum species similar in form and size to ours as listed below,
but they are all distinguished from P. cheondaeriense on account of various features as
briefly mentioned below:
Pterophyllum astartense Harris: Harris,
1932b, Rhaetian of Greenland: Adjacent pinnae sometimes separated. Basalpinnae variable in form, with rounded or
truncated apex. Veins mostly forked at
all levels.
P. ctenoides Oishi: Oishi, 1932a, Upper
Triassic N ariwa Group: Rachis thick,nearly 1 cm wide at the base. Pinnae
more than 10 cm long. Veins 8 in number in each pinna, basiscopic veins decurrent.
P. jaegeri Brongniart: Brongniart, 1828
and others, e.g. Leuthardt, 1903. Mainly from the Upper Triassic of Europe:
Rachis thick. Pinna apex truncated.
P. longifolium Brongniart (non Jaeger):
Brongniart, 1828 and others. Mainly
from the Upper Triassic of Europe:

Pinnae expanded distally, with truncatedapex. Veins 4-5 in number in eachpinna.
P. subaequale Hartz: Hartz, 1896, Liassicof Greenland; Johansson, 1922 (identified as P. andraeanum): Rachis always
transversely wrinkled. Basal pinnaewith rounded or truncated apex.
P. thomasi Harris: Harris, 1952, 1969,
Middle Jurassic of Yorkshire: Rachis
thick, up to 8 mm wide. Veins 4 innumber in each pinna.
P. tietzei Schenk: Schenk, 1887; Zeiller,
1902-1903 and others, Upper Triassic of
Iran, North Viet Nam, China and elsewhere: Pinna apex rounded. Veins 1522 in number at the middle of eachpinna.
P. xiphipterum Harris: Harris, 1932b,
Rhaetian of Greenland: Rachis thick.
Pinnae attached to the upper sides ofrachis. Basal pinnae with truncatedapex. Veins forked at all levels, 50 per
cm in distal half of pinna.
Under the circumstances, we propose Pterophyllum cheondaeriense as a new species
herein.
Cycad ales
Genus Anthrophyopsis Nathorst, 1878
Anthrophyopsis decurrens
Kimura et Kim, sp. nov.
Figures 12a-b

Material: Holotype; Reg. no. 81-023T(Cheondaeri). Paratype; Reg. no. 81-038T(Cheondaeri). Stratum typicum: Amisan
Formation. Locus typicus: Cheondae
Coal-Mine, Cheondaeri, Janggog-myeon,~ Figures 10 (a-f)-l1. All natural size. 10. Pterophyllum cheondaeriense Kimura et Kim, sp. nov. :All from Cheondaeri (Cheondae Coal-Mine). lOa. Apical portion of a leaf (Reg. no. T-0126A, Holotype).
lOb. Showing the occurrence. Broken leaves are thickly massed (Reg. no. T-122). lOco Drawn from FigurelOa. lOd. Middle portion of a leaf (Reg. no T-0127, Paratype). 10e. Basal portion of leaf (Reg. no. T0127C, Paratype). lor. Proximal part of a leaf, with detailed venation (Reg. no. T-126B). 11. Drepanozamites sp. A : A part of a leaf, showing the mode of attachment of pinnae and venation (Reg. no T -0196).
Loc. Cheondaeri

880.

New Late Triassic plant-taxa from Korea 2

143

10d

11

3cm

Tatsuaki Kimura and Bong- Kyun Kim

144

Hongseong-gun , Chungcheongnam-do (seeKimura a nd Kim , 1988, p.604). Derivatio
nominis: From markedly decurrent late ra lvei ns.
Diagnosis : Leaf e longate-obovate in outline, more than 14.6 cm long and 6 cm wide a t
the widest portion. Margin s entire. Rachis
thick , 1.05 cm wide below and 0.25 cm a bove,
longitudin a ll y striated on its surface, giving

off lateral veins a t an a ngle of 40 degrees
below a nd 50- 60 degrees middle to above,a nd at interva ls of 1.5 mm (6.7 per cm inden sity). Lateral vei ns pa rall el, markedly
decurre nt nea r their origin , forming elongatereticul ate meshes. Meshes varied in length
according to their position , typica ll y 7- 8 mmlong and 1- 1.5 mm w ide.
Distribution and occurrence: Two leaves

12b

12a
3cm

'--_-'-_--L_--',

Figure 12. Anthrophyopsis declirrens Kimura et Kim , sp. nov.: Natura l size.
no. SI-023T). Lac. Cheo nda eri. 12b. Dra w n from Figure 12a.

12a. Holotype (Reg.

880.

New Late Triassic plant-taxa from Korea 2

were obtained from the Amisan Formation at
the Cheondaeri area.
Discussion and comparison: The present
leaves, though their both ends are missing,resemble those of Anthrophyopsis, Ctenis andGlossopteris because of their networked venation. We prefer to assign our leaves to
Anthrophyopsis, because Ctenis leaves areusually not entire but segmented and Glossopteris leaves have been known mostly fromthe Permian plant-beds in the Gondwana
Floristic Province. However, resemblance
between our leaves and some Glossopterisleaves is quite remarkable. We are of 'theopinion that A nthrophyopsis decurrens is aspurious imitation of some Glossopterisleaves.
Anthrophyopsis decurrens is distinguishedfrom the following hitherto known Anthrophyopsis species by its markedly decurrent
lateral veins:
Anthrophyopsis crassinervis Nathorst:
Upper Triassic of Sweden (N athorst,
1878a, 1886): Greenland (Harris, 1926,
1932a); Western Pamir (Vladimirovich,1958); South China (Sze and Hsli, 1954;
Sze et al., 1963; Feng et al., 1977;
Chen et al., 1978; Zhou, 1978).
A. leeiana (Sze) Florin: Upper Triassic ofSouth China (Sze, 1931 ; Sze and Hsli,
1954; Sze et al., 1963; Li, 1964).
A. miassica Viadimirovich: Upper Triassic of Eastern Ural (Vladimirovich,1958).
A. naruensis Doludenko et Svanidze:
Lower Jurassic? of Georgia (Doludenko
and Svanidze, 1970).
A tuberculata Chow et Yao and A.
venulosa Chow et Yao: Upper Triassicof South China (in Feng et al., 1977;
Chen et al., 1978; He et al., 1979).
Sagenopteris glossopteroides origi nally described by Hsli et al. (1974) from the Upper
Triassic Daqiaode Formation Yunnan,
China has leaflets similar in form and venation to our leaves, but it is distinguished fromours by its palmately compound leaf.

145

In our leaves cuticle is not preserved.
Unclassified Cycadopsida
Genus Drepanozamites Harris, 1932b
Drepanozamites sp. A
Figure II

Material: Reg. no. T-OI96 (Cheondaeri).
Description: Obtained specimen is a single
leaf-fragment, more than 8 cm long with 5
pairs of subopposite pinnae borne on thelateral sides of the slender rachis (2 mmwide). The pinnae are 2.4 cm long and 0.9
cm wide at the middle portion, broadest at
the base, with more or less auriculated acroscopic base, attached by a somewhat decurrent
basiscopic basal corner, and tapering to arounded apex usually pointing backwards;
margins are entire. The veins are slender,
diverging from the point of attachment of
pinna, mostly forked thrice freely, 14-15 in
number per cm at the middle of pinna.
Cuticle is not preserved.
Distribution and occurrence: Very rare.
Known only from the Amisan Formation at
the Cheondaeri area.
Remarks: Judging from its slender rachis,the present specimen appears to represent the
middle or upper part of a leaf, because in
Harris' type species, Drepanozamites nilssoni,basal rachis is fairly thick, being 3-4 mm
wide. If our specimen is indeed that part ofa leaf, our pinnae differ in size from those of
Drepanozamites nilssoni, because in the typespecies the pinnae on the middle to upperparts of a leaf are more elongated and about
twice as large as ours.
Drepanozamites p'ani originally describedby Sze (I956b) from the Upper Triassic
Yanchang Formation, North China is distinguished from ours by its thick rachis (5 mmwide) and by the presence of a vaguely
defined midrib in its pinnae.
According to Sze (l956b), Rhacopteris (?)
gothani originally described by Sze (I93~b)from the Upper Triassic Anyuan FormatIOn
in Jiangxi, which was later referred by Harris

146

Tatsuaki Kimura and Bong-Kyun Kim(1937) to Drepanozamites nilssoni, is different
from the type species despite the margin of
pinnae being more or less dissected distally,
crenated and occasionally even lobed.
Therefore, Sze ( 1956b) proposed to refer thoseleaves to Drepanozamites gothani in his discussion. In their later monograph (Sze etal., 1963), however, they regarded thoseleaves as Drepanozamites nilssoni together
with additional specimens from the Upper
Triassic Xujiahe Formation in Sichuan.
Our leaf is somewhat different from these
Chinese leaves in having less elongated pinnae which point backwards. Drepanozamites? sp. indet. from the Upper Triassic
Nariwa Group (Oishi and Huzioka, 1938)
differs from ours in its trapezoid pinna with asmall number of veins.
Coniferales
Genus Podozamites Braun in MUnster, 1843
Podozamites ex gr. schenki Heer
Figures 13a-c

Podozamites schenki Heer: Kawasaki, 1925, p.55,
pI. 41, figs. 112-113; pI. 45, fig. 120.

Material: Reg. no. 81-123 (Hanaeri) andmany other leaf-fragments.
Description: Figure 13a shows a broken
leafy shoot, 8 cm long. The axis is slender,
0.8 mm wide, traversed longitudinally by a
few ridges and furrows, and sends off spirally

arranged leaves which lack petiole. The
leaves are mostly long and slender, nearlyparallel-sided for the most part but narrowed
gradually towards both ends, being 4.3 cm
long and 2 mm wide (a leaf indicated by thearrow-A in Figure 13b); the apex is obtusely
pointed. A leaf shown by the arrow-B (Figure 13b) is elongate-oval in outline, 1.8 cm
long and 2.5 mm wide; its apex is rounded
and base is markedly decurrent and appressedto the axis; the ratio (LjW) of our leaves
ranges from 7.2 to 31.3, typical number being
21.5. The veins are dichotomously forked
near the base, parallel to each other, notconverging at apex, typical numbers being 78 (40-47 per cm) in each leaf; in a leaf indicated by the arrow-B (Figure 13b), the veins
number II but the vein-density is normal (44per cm). Cuticle is not preserved.
Distribution and occurrence: Podozamites
ex gr. schenki is locally common in the
Gimpo, Nampo and Bansong Groups.
Remarks: Our specimens are closely referable macroscopically to those of Podozamites
schenki known widely from the older Mesozoic plant-beds. At present we regard themas Podozamites ex gr. schenki, because ourleafy shoots occasionally bear such elongateoval leaves as shown in Figure 13a (anarrow-B in Figure 13b) which have not beenrecorded from other localities.
The leafy shoots described by Kawasaki(1925) from the Gimpo and Nampo Groups
as Podozamites schenki are indistinguishable~
Figures 13 (a-c)-17 (a-b). Natural size, unless otherwise indicated. 13. Podozamites ex gr. schenki
Heer: 13a. A typical leafy shoot (Reg. no. SI-123). 13b. Drawn from Figure 13a. 13c. Drawn from a leaf
indicated by an arrow-A in Figure 13b, showing the venation. Loc. Hanaeri. 14. Podozamites sp. A: 14a.
A broken leafy shoot with elongate leaves (Reg. no. SI-053). Loc. Hanaeri. 14b. A broken leafy shootwith 6 spirally arranged leaves (Reg. no. SI-03IT). Loc. Cheonndaeri. 14c. Drawn from Figure 14b.
14c'. Enlarged from a leaf indicated by an arrow-A in Fgiure 14c, showing the detailed venation. 14d.
Drawn from Figure 14a. 14d'. Enlarged from a leaf indicated by an arrow in Figure 14d, showing thedetailed venation. 15. Cycadocarpidium sp. cf. C. asaense Kon'no: ISa-b. Enlarged bracts withbiovuliferous scale-scars (Reg. no. SI-002T). Loc. Cheondaeri. ISc. Drawn from Figure 15b. ISd. A
bract with digitate and biovuliferous scales (Reg. no. S1-002T). Loc. Cheondaeri. 16. Cycadocarpidium
sp. cf. C. nagatoense Kon'no: 16a. Enlarged bract; ovuliferous scales are missing (Reg. no. S1-003T).
16b, d. Bracts with two scars of seeds (the other one is invisible) (Reg. no. S1-00ST). 16c. A bract with threescars of seeds (Reg. no. S2P-B). 16e. Drawn from Figure 16a (l6a, b, d; from Cheondaeri, 16c; from
Hanaeri). 17. Cycadocarpidium sp. A: 17a. An enlarged bract with two large-sized scale-lobes andovules. Loc. Cheondaeri. 17b. Drawn from Figure 17a.

880.

14c

New Late Triassic plant-taxa from Korea 2

14c'

147

13b
13c

lcm

15b

16e

16d

"\f 15c
2cm

I

5cm
L-....L..------'-------L------'-_,

15d

15a

148

Tatsuaki Kimura and Bong-Kyun Kim

from ours.
In Japan, it is noted that Podozamites leafy
shoots bearing such long and narrow leaves
are restricted to the Late Triassic floras. Our
Podozamites ex gr. schenki resembles externally P. gramineus originally described byHeer (1876) from Ust-Balei. Heer's original
specimen (P. gramineus) is a single detachedleaf and is distinguished from ours by its
more elongated leaf with four veins. However, leafy shoots regarded as Podozamites
gramineus by many authors (e.g. Vakhrameev, 1958; Vassilevskaja and Pavlov, 1963;
Prosviryakova, 1966) are externally indistinguishable from ours except for the elongateoval-shaped leaf.
Podozamites agardhianus (Brongniart)
Nathorst known from the Upper Triassic of
Sweden resembles in leaf-form P. ex gr. schenki, but it is distinguished by its leaves being
rather expanded near the base as shown by
Nathorst (1878c, pI. 3, fig. 14).

Podozamites sp. A
Figures 14a-d'

Material: Reg. nos. 81-031T (Cheondaeri), 81-020, 046, 053 (Hanaeri) and manyother broken leafy-shoots and detachedleaves.
Description: Many incomplete leafy-shoots
were obtained. The axis is slender, 0.9 mm
wide below and 0.7 mm above and gives off
spiraly arranged leaves. The leaves are sessile and varied in size and form. The leaves
on the distal part of a shoot are generally
longer than those on the proximal part of thesame shoot. The longer leaves are typicallyelongate-oval in form, up to 4 cm long and at
most 0.5 cm wide, with obtusely pointed orrounded apex, and they are attached to theaxis at a narrow angle as shown in Figure
14d. The leaves on the proximal part of ashoot are typically oblanceolate in form, andmeasure up to 3 cm long and at most 0.45 cm
wide, with rounded apex and they areattached to the axis at a wide angle as shownin Figure 14c. The veins are dichotomously
forked at or near the base, then runningparallel to each other, ending at distal andlateral margins, and not converging at apex,
and their numbers range from 13 to 15 in eachleaf. Cuticle is not preserved.
Distribution and occurrence: Podozamites
sp. A is locally common in the Mungyeong
and Chungnam Coal-Fields, especially so at
the Cheondaeri and Hanaeri localities.
Remarks: Podozamites sp. A is characterized by its small-sized leafy-shoots, and it isdistinguished from P. ex gr. distans (Presl)
Braun and P. ex gr. schenki Heer (both arecommon elements in the Daedong Flora) by
its small-sized leaves and its leaf-form, respectively. Our Podozamites sp. A resembles
somewhat some detached leaves described as
P. lanceolatus var. (or forma) eichwaldi Heerfrom China by Schenk (1883, pI. 50, figs.2?,
3; pI. 51, fig. 3; pI. 52, fig. 8), Krasser (1905,
pI. 4, fig. 4), Sze (1933b, pI. 8, fig. 7), Sze et al.
(1963, pI. 99, fig. 5= Krasser's specimen) In
leaf-form and venation.
Podozamites sp. A also resembles in its
leaf-size P. agardhianus (Brongniart) Nathorst var. acuminatus proposed by Kon'no(1961) from the Carnian Momonoki Formation, but P. sp. A is distinguished by having
leaves whose apex is obtusely pointed orrounded instead of being acuminate, and bypossessing 13-15 veins in each leaf comparedwith 8-10 in the latter.
The leaves of Podozamites agardhianus
known from the Upper Triassic of Sweden(Nathorst, 1878c) are longer, twice as long as
those of P. sp. A and bear smaller number ofveins (9 at middle).
Seed-bearing fructifications
Genus Cycadocarpidium Nathorst, 1886

Cycadocarpidium organs are rather abundant in Upper Triassic formations of Yamaguchi Prefecture, Japan. They were described by Kon'no (1961) together with Pod-

880.

New Late Triassic plant-taxa from Korea 2

ozamites leafy-shoots. In his paper, Kon'no
distinguished seven Cycadocarpidium species
or forms and four Podozamites species orvanetles. However, until now no Cycadocarpidium species has been described from
Korea in spite of its common occurrence fromthe Amisan Formation at Cheondaeri and the
Bongmyeongri Formation at Hanaeri. Thus,
we made here the first record of this genus anddistinguished four forms, including a questionably identified one (C. ? sp. B).
Florin (1951, 1953) stated that the conescale was not a compound carpellary leaf
carrying ovuliferous pinnae at its base but
one composed of a bract with an axillary
fertile shoot or seed-scale complex. In thisstudy, we could not confirm this statement by
Florin.
Key to the species or forms (excluding C. ?
sp. B)
1. Bract narrowly lanceolate, veins 10 innumber .............. · C. sp. cf. C. asaense
2. Bract ovate or elongate-ovate, veins 7-12.................. C. sp. cf. C. nagatoense
3. Bract possibly elongated, velns 16.......................................... C. sp. A

Cycadocarpidium sp.
cf. C. asaense Kon'no
Figures 15a-d
Compared: Cycadocarpidium asaense
Kon'no, 1961, p. 202, pI. 24, figs. 2-4.

Kon'no:Material: Reg. nos. 81-002T, OIlT, 030T
(Cheondaeri), 82-PA, 81-127G (Hanaeri) andmany other bract-fragments.
Description: Cone-scale consists of bractand ovu1iferous scales. The bract is lanceolate in outline, being 2.6 cm long and 0.35
cm wide (Figure 15b) and more than 2 cm
long and 0.45 cm wide (Figure 15a), and hasan acutely pointed apex. The veins fork
dichotomously near the base or simply, runparallel to each other and to the lateral

149

margins of bract. They number 10 at the
middle and are not converging at apex. The
ovuliferous scale is bidigitate and biovuliferous; the lobe of ovuliferous scale is nearly
triangular or oblong, measures 0.35 cm longand 1.5 mm wide and bears a pointed apex.
The ovule is ovate in form, 3.5 mm long and
2 mm wide, and directed downwards. The
pedicel of cone-scale is well defined, morethan 7.5 mm long, and up to 0.8 mm wide.
Cuticle is not preserved.
Distribution and occurrence: Common in
the Amisan Formation at Cheondaeri and in
the Bongmyeongri Formation at Hanaeri.
Associated Podozamites species include P. ex
gr. distans and P. sp. A at Cheondaeri, andP. ex gr. schenki and P. sp. A at Hanaeri.
Remarks: The present specimens are identifiable, in their form and venation of bract
and biovuliferous scale, with Cycadocarpidium asaense originally described by
Kon'no (1961) from the Ladino-Carnian
Hiramatsu Formation. In our specimens,
however, the ovules are shorter (3.5 mm) thanthose of the original specimens (6 mm) andthe bracts are slender (3.5-4.5 mm wide) thanthose of original ones (6.5-7 mm wide) .
Thus, we herein refrain from making a full
identity of our specimens with Kon'no's
species.
Cycadocarpidium sp. cf. C. asaense isclearly distinguishable from C. sp. cf. C.
nagatoense and C. sp. A both of which aredescribed together because of its slender habitof bract.
Some specimens of Cycadocarpidium
swabii illustrated by Harris (1935) are similar
in form and size of cone-scale to ours, butthey are distinguished in having smaller numbers of veins converging at apex and indistinct ovuliferous lobes. Cycadocarpidium
swabii described by Oishi (1932c) from theMomonoki Formation is similar in form ofbract, but it is distinct in its veins converging
at apex and possessing longer ovules (6 cm
long and 2 mm wide).
Biovuliferous Cycadocarpidium issykkul-

150

Tatsuaki Kimura and Bong-Kyun Kim

ense, C. insignis and C. dzerganense all
described by Genkina (1963, 1966) from theUpper Triassic Issyk-Kul Basin are distinguished from ours by their large-sized bracts
and in the last mentioned species by its
small-sized circular ovules (1 mm in diameter).
Cycadocarpidium erdmanni Nathorst(sensu lato) is aI.so similar to ours in form ofbract and ovuliferous scale and size of ovule,but it is clearly distinguishable by its small
number of veins (4-6).
Kon'no (1961) mentioned that Cycadocarpidium asaense was associated with Podozamites sp. cf. P. astartensis Harris whichbears large-sized and oblong-ovate leaves.
In Korea, there found are no such large-sized
Podozamites leaves as those referable to P. sp.
cf. P. astartensis, except for P. ex gr. distans.
Cycadocarpidium sp.
cf. C. nagatoense Kon'no
Figures 16a-e
Compared: Cycadocarpidium nagatoense Kon'no:
Kon'no, 1961, p.203, pI. 23, figs. 7-8.

Material: Reg. nos.81-003T, 008T
(Cheondaeri), 81-092, 82-PB (Hanaeri) andmany other fragments of sterile bracts.
Description: Among the collection, there
are three complete bracts; their dimensions
excluding short pedicel are 1.85 cm long and7.5 mm wide, 2 cm long and 6 mm wide, and2 cm long and 8 mm wide. The pedicel is 34 mm long and 1 mm wide, but it expands
abruptly at its upper end into the broad baseof bract. The bract is ovate or elongateovate in outline, with an obtusely pointed orrounded apex. The veins fork dichotomously once or twice near the base, then runningparallel to each other and to the margins, anddo not converge at apex; they number 7-12
at the middle of bract. No interstitial veinhas been observed. The ovules shed to leave
their scars; the largest ovule is 3.5 mm longand 2.5 mm wide. The ovules are three in
number (triovuliferous) (Figure 16c). No
trace of ovuliferous lobe has been recognized.
Cuticle is not preserved.
Distribution and occurrence: Common in
the Amisan Formation at Cheondaeri and in
the Bongmyeongri Formation at Hanaeri.
Associated Podozamites species are P. ex gr.
distans and P. sp. A at Cheondaeri, and P. ex
gr. schenki and P. sp. A at Hanaeri.
Remarks: The present specimens are, inform of bract, venation and size of ovules,
most close to Cycadocarpidium nagatoense
originally described by Kon'no (1961) fromthe Carnian Momonoki Formation. However, we were unable to identify fully our
specimens to Kon'no's species because of theindistinctness of our ovuliferous scales.
Harris (1935) showed the form-variation ofcone-scales of Cycadocarpidium swabii Nathorst (sensu lato). Cycadocarpidium swabii
differs from C. nagatoense in its biovuliferous scale. Some of Harris' specimens agreewith ours in form of bract but our bracts arefurther distinguished from those of Cyadocarpidium swabii by the veins not converging at
apex.
Cycadocarpidium swabii descri bed by
Oishi (1932c) from the Momonoki Formation
is not triovuliferous but apparently biovuliferous, and differs from the present specimens in its veins converging at apex.
Cycadocarpidium swabii described by Sun(1979) from the Upper Triassic Malugou
Formation, Jilin, Northeast China is comparable with ours in venation, but it is distinguished from ours by its biovuliferous habit
and its obovate or elongate-oval bracts.
Some specimens regarded as Cycadocarpidium tricarpum Prynada by Stanislavsky(1976) from the Upper Triassic of the Donetz
Basin are similar in form of bract to thepresent specimens, but they are distinguishedby a small number of veins (4-8 in eachbract).
Kon'no (1961) mentioned that Cycadocarpidium nagatoense and Podozamites distans

880.

New Late Triassic plant-taxa from Korea 2

var. nagatoensis Kon'no bearing small-sized
ovate leaves might belong to the same plant.
However, no such small-sized Podozamites
leaves have been found in association withthe present C. sp. cf. C. nagatoense in Korea.

151

Unclassified plants
Form-genus Taeniopteris Brongniart, IS2S
Taeniopteris cheondaeriensis
Kimura et Kim, sp. nov.
Figures ISa-g

Cycadocarpidium sp. A
Figures 17a-b

Material: Reg. no. Sl-03JT (Cheondaeri).
Description: There obtained was a single
broken cone-scale characterized by its
multinerved bract, bidigitate and biovuliferous scales and large-sized ovules. The bractis 9 mm wide but its whole shape is notacertained. Pedicel is thick, being 2 mm
wide. The veins fork dichotomously once or
twice near the base, then run parallel to eachother, number 16 at the middle, and possibly
do not converge at apex, judging by the right
one ending the lateral margin of bract asshown in Figure 17b. The ovuliferous lobe
is possibly triangular in form and is 6 mm
long. The still-preserved ovule is oval inform, 5 mm long and 3 mm wide, and arranged perpendicularly to the pedicel.
Distribution and occurrence: Only a single
specimen was obtained at Cheondaeri in close
association with Podozamites sp. A.
Remarks: Cycadocarpidium sp. A is comparable with C. giganteum originally described by Sun (1979) from the Upper Triassic Malugou Formation, Jilin, Northeast
China in its large-sized and multi-nerved
bract and also large-sized ovules. According
to Sun (1979), his biovuliferous Cycadocarpidium giganteum is characterized by abroadly lanceolate bract, typically 5.5-6 cm
long (the largest Scm) and 1.3-1.4 cm wide,
14-17 veins traversing the middle of bract,and large-sized oval ovules which are 6-7 mmlong and 4-5.5 mm wide. Thus Cycadocarpidium sp. A resembles closely C. giganteum,
but we at present reserve to make its specificidentity later, because of our cone-scale being
represented only by a single broken one.

Material: Holotype; Reg. no. Sl-007TA(Cheondaeri). Paratypes; Reg. nos.
SI-007TB-E (Cheondaeri). Examined specimens; Reg. nos. T -00S2, SI-003T -035T(Cheondaeri), SI-113A, I27D, 240A (Hanaeri). Stratum typicum: Amisan Formation
at Cheondaeri. Locus typicus: Cheondae
Coal-Mine, Cheondaeri, Janggog-myeon,
Hongseong-gun, Chungcheongnam-do (seeKimura and Kim, 19S5, p.604). Derivatio
nominis: From the locality.
Diagnosis: Taeniopteroid leaves variablein form and size, shortly petioled, typicallyelongate-oblanceolate to elongate-oblong inoutline. The longest one more than 11 cm
width variable depending on leaves, rangin~from I cm to 2.2 cm at the widest portion.
Lamina attached to the lateral sides of slenderrachis up to I mm wide, gradually narrowed
to the well-defined petiole. Margins entire
or broadly wavy. Lateral veins originatingfrom rachis at an angle of 75 degrees; angle
reduced towards the base of lamina; usuallyforked once at their origin; density 20-33 per
cm, but in those unusually elongated laminae
veins sometimes simple and sparse.
Distribution and occurrence: The present
new species is common in the Amisan Formation at Cheondaeri and in the Bongmyeongri
Formation at Hanaeri.
Discussion and comparison: The present
new species is characterized by its elongatedleaves usually with veins forked once at theirongm. In some unusually elogated laminae(e.g. Figure 1St), however, they show unusual
venation, either simple or forked once andrather sparsely distributed. Figure lSg also
shows a cuneate base of lamina which unusually has simple and sparse veins. Unfortunately, in our specimens cuticle is not preser-

Tatsuaki Kimura and Bong - Ky un Kim

152

\
)

I~

18f
18a

18d

(

1ge

)

)
~

)
\

!

18e

18c

18g

19k
5cm
' - - - - ' - - - - - ' - - - - ' - - - - - - ' - - - - - - '1

19h

19j

880.

New Late Triassic plant-taxa from Korea 2

ved and their apices are all missing.
The following species are similar in sizeand form to our Taeniopteris cheondaeriensis,
but they are distinguished from ours by thosefeatures which are briefly mentioned below:
Taeniopteris mcclellandi (Oldham et Morris) Feistmantel, 1876, p. 36; Zeiller,
1902-1903, p. 61, pI. 9, figs. 3-5: Larger
in size with stout rachis. Kawasaki's
specimens (1925, p. 34, pI. 20, figs. 6263), regarded by him as T. mcclellandi,
are referable to T. richthofeni as mentioned by Oishi (1940, p. 141, 149).
T. minensis Oishi (Oishi, 1932c, p. 60, pI. 2,
figs. 1-5): Lateral veins are simple orforked once at variable distance fromtheir origin; the veins are somewhat
coarser (20-25 per cm) than ours.
T. shitakensis Oishi (Oishi, 1932b, p. 10,
pI. 3, fig. 8): This species was defined on
the basis ofa single leaf with stout rachis.
Lateral veins are simple or forked oncenear their origin, and are somewhat coarser (25-30 per cm) than ours.
T. stenophylla Kryshtofovich (Kryshtofovich, 1910, p. 11, pI. 2 fig. 1): Lateralveins are forked once or twice at variable
distances from their origin, and are coarser (20-25 per cm) than ours.
T. tenuinervis Brauns (N athorst, 1878b, p.
47, pI. 7, fig. 6; pI. 8, figs. 8, 11-12, 1416; pI. 10, figs.2-5; 1879, p.59, pI. 11,
fig. 9): Lateral veins are mostly simple.

153

Taeniopteris mungyeongensis
Kimura et Kim, sp. nov.
Figures 19a-k

Material: Holotype; Reg. no.81-163B(Hanaeri). Paratypes; Reg. nos.81-163A,
C, 0 (Hanaeri). Examined specimens: Reg.
nos. 81-052, 063, 073, lOlA, B, C, 113, 127,
151, 0240 (Hanaeri). Stratum typicum:
Bongmyeongri Formation, Bansong Group.
Locus typic us : Hanaeri (East side), Maseong-myeon, Mungyeong-gun, Gyeongsangbuk-do (see Kimura and Kim, 1988, p.
604). Derivatio nominis: From the name of
Mungyeong Coal-Field.
Diagnosis: Leaf oblanceolate-obovate inoutline, shortly petioled, apex broadly
rounded, lamina attached to the upper sidesof rachis, with markedly cuneate or rarely
rounded base, more than 15 cm long, widthvariable according to leaves, up to 3 cm at thewidest portion. Rachis rather slender, 1.2
mm wide at base, giving off numerous veins at
a wide angle. Margins entire or irregularly
undulated. On the most part of lamina,
veins usually forked twice, the first forked at
the base, the second near the base; density
20-42 per cm at the margin; often bending
downwards near the base. On the cuneatepart of lamina, a half of veins forked twice
and the rest once, the first forked at the base,the second on the midway; density 21 per cm
at the margin. In some of the leaves, veins
either simple or forked once irregularly.
Distribution and occurrence: The present~
Figures 18 (a-g)-19 (a-k). All natural size. 18. Taeniopleris cheondaeriensis Kimura et Kim, sp.
nov.: 18a. (Reg. no. SI-007TA, Holotype). 18b. One of para types (Reg. no. SI-007T8). 18c. The widest
leaf (2 cm wide) with rounded apex (Reg. no. SI-035T). ISd. The longest leaf (more than 11 cm); veindensity 2S per cm (Reg. no. Sl-240A). 18e. A leaf with waved margins; vein-density 20 per cm (Reg. no.
T-00S2). 18f. An unusually cuneate leaf-base with disordered veins (Reg. no. SI-127D). 18g. A cuneatebase with simple and sparse veins (Reg. no. SI-003T). Loc. Cheondaeri (ISa-c, e. g) and Hanaeri (lSd, f).
19. Taeniopleris mungyeongensis Kimura et Kim, sp. nov.: 19a. Holotype (Reg. no. SI-1638). 19b. A
slightly distorted leaf; vein-density 35 per cm (Reg. no. SI-1278). 19c. A distorted leaf; vein-density 30
per cm (Reg. no. Sl-127A). 19d-e. Cuneate bases with distorted veins (Reg. nos. Sl-2408, SI-IOlA). 19f,
g, h, i. Leaves with once or twice forked veins (l9f; vein-density 42 per cm, 199; 40 per cm). Reg. nos.
Sl-0738 (19f, g), Sl-127C (19h, i). 19j. An unusual leaf with disordered veins (Reg. no. Sl-151). 19k. An
unusually small-sized leaf with oblong lamina (Reg. no. SI-0240C). Loc. Hanaeri.

154

Tatsuaki Kimura and Bong-Kyun Kim

new species is common but only known fromthe Bongmyeongri Formation at Hanaeri.
Discussion and comparison: The present
new species is characterized by its oblanceolate-obovate leaves with regularly twice
forked veins except for the basal cuneate part,and it differs in venation from any known
Mesozoic taeniopteroid species from East
Asia. According to our present knowledge,
Mesozoic taeniopteroid leaves with twice
forked veins are rather rare.
A leaf shown in Figure 19k displays unusual venation, either simple or forked once
irregularly. However, we consider it to berare example and it indeed belongs to thisspecies, because that leaf occurred among
other normal leaves of Taeniopteris mungyeongensis.
Taeniopteris mungyeongensis, sp. nov. resembles T. nabaensis, a little known species
first described by Oishi (l932a) from theNorian Nariwa Group in its leaf-size andvenation, but in Oishi's species, the second
vein-forking occurs in their mid-course ofextent unlike ours with forking regularly
occurring close to their origin.
Taeniopteris lanceolata also first describedby Oishi (1932a) from the Nariwa Group has
once or twice forked veins. However, theirforking occurs at variable distances from thebase.

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New Late Triassic plant-taxa from Korea 2

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- - , 1878b-1886: Om floran i Skanes kolfdrande
Bildningar. I. Floran vid Bjuf. Svergig. geol.
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- - , 1878c: Ditto. II. Floran vid Hoganas och
Helsingborg. Ibid., 29, p. I-53, pis. 1-8.
- - , 1906: Ober Dictyophyllum und Camptopteris
spiralis. K. svensk. Vet.-Aad. Handl., 41 (5),p. 1-24, pis. 1-7.
Ngo, C.K. (Ao, Z.K.), 1956: Preliminary notes on
the Rhaetic flora from Siaoping Coal-Series of
Kwangtung. J. Cent. South Inst. Min. Met.,
no. I, p. 18-32, pis. 1-7 (in Chinese).
Oishi, S., 1930: Notes on some fossil plants from theUpper Triassic beds of Nariwa, Provo Bitchu,
Japan. Jap. Journ. Geol. Geogr., 7 (2), p.4958, pI. 7.
- - , 1932a: The Rh:letic plants from the Nariwa
District, Provo Bitchu (Okayama Prefecture),
Japan. Journ. Fac. Sci., Hokkaido Imp. Univ.,(4),1 (3-4), p. 257-380, pis. 19-53.
- - , 1932b: The Jurassic plants from Shitaka (theMaizuru Coal-Field), Provo Tango (Kyoto Prefecture), Japan. Ibid., 2 (I), p. 1-13, pis. 1-3.
- - , 1932c: Rhaetic plants from Province Nagato(Yamaguchi Prefecture), Japan. Ibid., 2 (I), p.
51-67, pis. 9-10.
- - , 1935: Notes on some fossil plants from Tungning, Provo Pinchiang, Manchoukuo. Ibid., 3(I), p. 79-95, pis. 6-8.
- - , 1940: The Mesozoic floras of Japan. Ibid., 5(2-4), p. 123-480, pis. 1-48.
- - and Huzioka, K., 1938: Fossil plants from
Nariwa. A supplement. Ibid., 4 (1-2), p.69101, pis. 7-12.
- - and Takahasi, E., 1936: The Rhaetic plantsfrom Province Nagata. A supplement. Ibid., 3(2), p. 113-133, pI. 10.
- - and Yamasita, K., 1936: On the fossil Dipteridaceae. Ibid., 3 (2), p. 135-184.
Prosvirjakova, Z.P., 1966: Jurassic flora from Mangwishlak and its significance for stratigraphy.
172 pp., 35 pis. VSEG EI, Acad. Sci. USSR,
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Schenk, A., 1864: Beitrage zur Flora des Keupers
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Bamberg Ber., 7, p. 51-142, pis. 1-8.

880.

New Late Triassic plant-taxa from Korea 2- - , 1883: Pflanzen aus der Steinkohlen Formation.
In Richthofen, F. von: China. IV. Palaeontologischer Theil (288pp., 54 pis.). p.211-244,
pis. 30-45.
- - , 1884: Die wahrend der Reise des Grafen Bela
Szechenyi in China gesammelten fossilen
Pflanzen. Palaeontographica, 31 (3), p. 164181, pis. 13-15.
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Bibl. bot., Stuttgart, 6, p. 1-12, pis. 1-9.
Schimper, W.P., 1869: Traite de Paleontologie
Vegetale, ou la Flora du Monde primitij dansses raports avec les formations geologiques et laFlore du Monde actuel. Premiere Partie. 738
pp., 53 pis. Paris.
Seward, A.C., 1903: Fossil floras of Cape Colony.
Ann. South Afr. Mus., 4, p. 1-122, pis. 1-14.
Sixtel, T.A., Sabitskaja, L.I., Khudaiberdyev, R. Kh.,
Loseva, N.M., Burakova, A.T. and Iminov, J.
Kh., 1971: Jurassic plants from the standard
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164-206, pis. 1-27 (in Russian).
Stanislavsky, F.A., 197 I: Fossil flora and stratigraphy of the Upper Triassic of Donbass. 139
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Sun, G., 1979: On the discovery of Cycadocarpidium
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I -33, pis. 1-6.
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Natn. Res. Inst. Geol., A cad. Sinica, no. 13, p.
77-86, pis. 8-10.
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abstract).
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157

Sinica, N.S., (A) 5, I - I I I (Chinese part), p. I 13217 (English part), pis. I-56.
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Rep., Inst. Arct. Geol., Leningrad. p.73-96,
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Anthrophyopsis from the Upper Triassic of
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Triassic and Lower and Middle Jurassic plantsfrom the Hsiangchi Group, Western Hubei.
Mem. Nanjing Inst. Geol. Palaeont., Acad.
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Yabe, H., 1922: Notes on some Mesozoic plants fromJapan, Korea and China, in the collection of theInstitue of Geology and Palaeontology of the
Tohoku Imperial University. Sci. Rep., Tohoku Imp. Univ., 2nd. Ser., 7 (I), p. I -28, pis. 14.

- - and Koiwai, K., 1928: Remarks on the genera
Annulariopsis, Lobatannularia and Annularites.
Proc. Imp. Acad., Japan. 4 (9), p. 537-540.
- - and Oishi, S., 1929: Notes on some fossil plantsfrom Korea and China belonging to the genera
Nilssonia and Pterophyllum. Jap. Journ. Geol.
Geogr., 6(3-4), p. 85-101, pis. 18-20.
Yokoyama, M., 1905: Mesozoic plants from Nagato
and Bitchu. Journ. Coli. Sci., Imp. Univ.
Tokyo, 20 (5), p. I - I 3, pis. 1-3.
Zeiller, M.R., 1886: Note sur les empreintes vegetales
recueillies par M. Sarran dans les couches decombustible du Tonkin. Bull. Soc. Geol. France, (5), 14, p. 575-58 I.

Tatsuaki Kimura and Bong-Kyun Kim

158- - , 1902-1903: Flore fossile des gftes de Charbon
du Tonkin (Etudes de gftes minlraux de laFrance). 328 pp., 56 pis. Paris.
Zhang, J.H., 1978: Plant. In Stratigr. Geol. Working Team, Guizhou Provo ed.: Fossil atlas ofSouthwest China. Guizhou volume I. p.662663, 797, pI. 140. Geol. Publ. House, Beijing(in Chinese).
Zhang, W., Zhang, Z.e. and Zheng, S.L., 1980:

Plant. In Palaeontological atlas of Northeast
China. (2) Mesozoic and Cenozoic volume. p.
221-239, pis. 103-210. Geol. Publ. House, Beijing (in Chinese).
Zhou, T.S., 1978: On the Mesozoic coal-bearing
strata and fossil plants from Fujian Province.
Prof. Pap. Stratigr. Palaeont., no. 4, p.88-134,
pis. 15-30. Geol. Publ. House, Beijing (inChinese).

Korea: Amisan ~~ill, Baegunsa B~~, Bansong 1Ai~, Bongmyeongri Il.q~.lIL
Cheondaeri ::R-Ei'.lIL Chungcheongnam-do Ji!;',~m~, Chungnam
Daedong *IPJ, Dangi Jf*c., Danyang f}1llI;, Dobung ti5:\!, Gimpo (Kimpo) ~rm. Gobangsan
ji1ij:tJjill. Gyeongsangbuk-do !l[;!ij:ft~. Hajo ""f,lll;. Hanaeri ""f7?J.lI!.. Jogaegog: Having
Pyeongyang 1'-!i. Samcheog
no Chinese characters. Mungyeong ~!l. Nampo-=~. Seongjuri ~{t.llL China: Anhui :tell. Anyuan :telt. Chengzihe ~T7PJ.
Dakeng *:I1L. Daqiaode *ll!if:l:1!!. Fujian m~. Fuxian ~W<. Gansu ttll. Guangdong JA~. Guizhou ili:1'li. Hebei 7PJ:ft. Heilongjiang ;W;~iI. Hubei f/jJj:ft. Jiangxi
iIl19. Jilin
Junggaer ~lIim. Keramayi %1.ll.~{t(. Liaoning ~•• Linjia*. Malugou .~IIE~. Qinghai Nita. Shanxi ill 119. Shihezi :O!kT. Sichuan 1Z9)11.
Sunjiawan 1**~. Wenbinshan JtJlill. Xiangxi 'ilf~. Xiangyun r-f~. Xiaoping'N;;i'. Xingjiang ~5.lI. Xizang 119il:. Xujiahe ~*7PJ. Yanchang ~~. Yingchen -g~. Yipinglang -:>jZrJt Yunnan ~m. Zieza *Ei;t:L. Japan: Hiramatsu 1'-~. Momonoki ti5;f\.. Nariwa nJ(;3f1. Ryoseki ~:O. Yamaguchi ill Q. (Detailed seats of Korean
localities. see Kimura and Kim, 1984a, p.204),'!',m,

erm.

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Trans. Proc. Palaeonl. Soc. Japan, N.S., No. 155, pp. 159-168, 6 Figs., September 30, 1989

881.

AN EARLY MIDDLE PLEISTOCENE MURID RODENTMOLAR FROM THE KOBIWAKO GROUP, JAPAN*
YOSHINARI KAWAMURA
Department of Earth Sciences, Aichi University of Education,
Kariya,448
and

KAZUAKIIIDA
Satte Senior High School,
Satte, Saitama Prefecture, 340-01

Abstract. A murid M' obtained from the Hiraen Clay Member of the Kobiwako
Group is the oldest record of the family in the Japanese Islands. The molar is assigned tothe small Japanese field mouse, Apodemus argenteus, an endemic species living in the islands
today. It indicates that this species originated by the early Middle Pleistocene (0.65-0.7
Ma). Moreover, the molar contributes to reconstructing the Quaternary mammalian faunal
succession in Japan, because the faunal content of mammalian biozone QM3 (0.5 to 0.73 Ma)
is poorly known.
Key words.
central Japan.

Murid, Apodemus argenteus, early Middle Pleistocene, Kobiwako Group,

present specimen provides the important information on micro-mammals of this period.
The main purpose of this paper is to present a detailed systematic description of thespecimen. Furthermore, we briefly describe
the stratigraphic sequence of the Kobiwako
Group around the fossil locality, and discuss
the biostratigraphic problems.

In troduction

Until recently, murid remains from theJapanese Islands were known only from sediments younger than the early Middle Pleistocene. They were mostly obtained fromcave and fissures, and their ages were ambiguous. A murid molar described here wascollected from a lacustrine clay bed of theKobiwako Group, which is dated with confidence as the early Middle Pleistocene.
Therefore this find is very important frombiostratigraphic view, and is now regarded as
the oldest record of murids in the islands.
Mammalian remains of the early Middle
Pleistocene are extremely rare in Japan(Kamei et al., 1988). Only a few forms oflarge mammals are known. Therefore theGeological setting

The Kisen River is a small stream that runs
from west to east through the northern part of
the Katata Hills into Lake Biwa (Figure I).
A branch of the river flowing down from thesouthern outskirts of Kurihara cuts a small
gorge. The murid molar was found by oneof us (lida) in a clay block lying on theriverbed of the branch in October 1986. The
block had undoubtedly fallen down from a'Received August 30, 1988; revised manuscript
accepted July I, 1989.
159

Yoshinari Kawamura and Kazuaki Iida

160

A

300m

c

200

100

above sealevel...........

eb "V 'l~"!~~-.:'!~~~-.: 7a vv

c -v : : : : : : : : : : : 7b::::::::::: 7C
7da"\1''' --

19o~S;~ 4

afHfHHls

8O·..•...•...... ···•. 13'-""'==""'"
Figure 1. Map showing the location of the fossil locality (A), geological map of the same area (B) andsection along X-X' (C). 1-13: lithologic units (5-12: members of the Kobiwako Group). I: alluvium.
2: lower terrace deposits. 3: middle terrace deposits. 4: higher terrace deposits. 5: Ryuge Sand andGravel. 6: Sakawa Clay. 7: Kurihara Alternation of Sand and Clay (7a: upper part, 7b: middle part,7c: lower part, 7d: lowest part). 8: Hiraen Clay. 9: Takashiro Alternation of Sand and Clay. 10 :Kisen Clay. II: Kitahama Sand. 12: Nijigaoka Clay. 13: basement rocks (Pre-Tertiary). a-g: volcanic ash layers. a: Sakawa II. b: Kurihara III. c: Kurihara II. d: Kurihara I. e: Biotite II. f:
Biotite I. g: Kisen.

881.

Mudd molar from the Kobiwako Group

Biotite II Volcanic Ash Layer"'r

CLAY BED YIELDINGTHE PRESENT FOSS I L

~

....~

III
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CLAY

["

SILT
ALTERNATI NG
BEDS OF SILTAND SAND
SAND

Figure 2. Columnar section of the Kobiwako
Group observed along the gorge wall of the fossil
locality.

clay bed exposed on the northern wall of thegorge. This bed is 5.6 m in thickness, andconsists of bluish gray massive clay withremains of plants and freshwater shells (Figure 2). Teeth and bones of freshwater fishes
are also contained but rare. They show thesame state of preservation as that of the murid
molar.
After finding the molar, 161 kg of sedimentwere collected from the clay bed, and washedthrough screen (0.5 mm mesh). Althoughremains of freshwater fishes and shells wereobtained, no other mammalian fossils were
found.
On the basis of the stratigraphy of the gorge

161

wall, the clay bed is assigned to the lowest
part of the Hiraen Clay Member. This member is the fifth lithologic unit of the Katata
Formation, Kobiwako Group (Hayashi,
1974; Figure 3). Around the fossil locality,
westward dipping beds allow the ascending
stratigraphy of the formation to be observed
from east to west (Figure 1).
!ida (1988, MS) inferred from thesedimentological analyses that the Hiraen
Clay Member was deposited in a shallow
lake. On the other hand, the ResearchGroup for Natural History of Lake Biwa
(1986) studied green algae, diatoms, protozoans, molluscs and insects from the lower
part of the Katata Formation including theHiraen Clay, and considered that it was deposited in the littoral zone of a shallow lake.
Eighteen volcanic ash layers intercalated in
the Katata Formation play an important roleas marker beds (Figure 3). Among them, theKisen and B Volcanic Ash Layers in the
Kisen Clay Member, and the E Volcanic Ash
Layer in the Ryuge Sand and Gravel Member
are correlated with the Azuki, Sayama andKasuri Volcanic Ash Layers in the Osaka
Group, respectively (Ishida and Yokoyama,
1969; Hayashi, 1974; Yoshikawa, 1983).
The Azuki and Kasuri Volcanic Ash Layers
were dated at 0.87±0.07 Ma and 0.37±0.04(or 0.38±0.03) Ma, respectively by fission
track (Nishimura and Sasajima, 1970). On
the other hand, Suzuki (1988) determined theages of the Sayama and Kasuri Volcanic Ash
Layers as 0.77±0.31 Ma and 0.42±0.08 Ma,
respectively by the same method. Additionally, a fission track age of 0.7±0.14 Ma was
obtained from the Biotite I Volcanic Ash
Layer in the Kisen Clay Member by Nishimura and Yokoyama (1975). On the other
hand, Hayashida et al. (1976) designated theBrunhes-Matuyama geomagnetic boundary to
the horizon about 10 m above the Biotite I
Volcanic Ash Layer in the section of theKisen River. On the basis of these chronological data, the horizon of the murid molar
is estimated as about 0.65 to 0.7 Ma in age.

Yoshinari Kawamura and Kazuaki !ida

162

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Figure 3. Generalized sequence of the Katata Formation and stratigraphic distribution of fossil mammals.
The fission track ages in parentheses indicate those of the correlative volcanic ash layers in the Osaka Group. I:
Nijigaoka Clay Member. 2: Kitahama Sand Member. 3: Kisen Clay Member. 4: Takashiro Alternation
Member. 5: Hiraen Clay Member. 6: Kurihara Alternation Member. 7: Sakawa Clay Member. 8, 9: Ryuge
Sand and Gravel Member, and Yamashita Alternation Member.

Biostra tigraphic consideration
Proboscideans and artiodactyls are reported from the Katata Formation in the Katata
Hills (Naumann, 1881; Hiki, 1915; Matsumoto and Ozaki, 19S9; Ikebe et al., 1966;
Kamei, 1966; Okazaki and Matsuoka, 1979;
Tamura et al., 1982; Taruno et al., 1983;
Kamei, 1984 etc.). The murid specimen is
the first record of micro-mammal in the formation. The stratigraphic position of thesemammalian remains is summarized in Figure
3. The murid specimen occurs at the lowest
horizon among them.
Kamei et al. (1988) proposed a mammalian biozonation of the Late Neogene andQuaternary sediments in the Japanese Islands.
They divided the Middle Pleistocene into
three biozones, QM3 (0.73 to O.S Ma), QM4(O.S to 0.3 Ma) and QMS (0.3 to 0.12 Ma).
The faunal contents of QM4 and QMS areabundant, but that of QM3 is almost un-881.

Mudd molar from the Kobiwako Groupknown. Only two forms, Mammuthus cf.
armeniacus and Bison sp., were reported from
QM3. Accordingly the present specimen is
an important addition to the mammalianfauna of this biozone.

Systematic description

163

anteri or
lingUal-.J

,,

,,

1-

W-----:, precingulum,
enteroconul e l i ngua 1 anteroconepres tyl eanterostylelabial anterocone

Descriptive terminology and method of
measurements are given in Figure 4. The
specimen described here is stored in the
Department of Geology and Mineralogy,
Faculty of Science, Kyoto University.
Order Rodentia Bowdich, 1821
Family Muridae Gray, 1821
Genus Apodemus Kaup, 1829
Apodemus argenteus (Temminck, 1844)
Figure 5

Mus argenteus Temminck, 1844, p. 51, pI. 15, fig. I.
Other synonyms are given in Kawamura (1989).

Material.- 1 isolated left MI (KUJC 1(0718).
Locality.- Kurihara, Shiga-cho, Shigagun, Shiga Prefecture (135'54' 13"E; 35"9' 37"
N).

Horizon.- Hiraen Clay Member, Katata
Formation, Kobiwako Group.
Age.- Early Middle Pleistocene (ca. 0.65
to 0.7 Ma).
Description.- The' crown is as high as
those of the living species of Apodemus, butsomewhat higher than those of Micromys (Band C of Figure 5). In occlusal view, it has
an oval outline, and comprises three chevronshaped cusp rows (anterior, middle and posterior chevrons), which are the basic pattern ofmurid MI. The buccal cusps (labial anterocone, paracone, metacone and posterior
cingulum) and central cusps (lingual anterocone, protocone and hypocone) are inclined
to the front, while the lingual cusps (anterostyle, enterostyle and posterostyle) are almost
erect. The central cusps are larger than othercusps.
The dentine fields of the three cusps of theposterior spur of
1abi a 1 anterocone

protoconeLenterostyle --+-T--\-'~~.-rct--paracone,.j7--metacone
posterostyle

posterior cingulum
hypocone

Figure 4. Terminology and method of measurements of murid MI. The terminology is based
mainly on Jacobs (1978).

anterior chevron are well confluent with eachother. Neither precingulum nor prestyle arerecognized. The occlusal surface of thelabial anterocone is considerably anterior tothat of the anterosty Ie. The posterior spur ofthe former cusp is well defined, while that of
the latter cusp is indistinct. The anteriorchevron is clearly separated from the middle
chevron by a deep transverse valley. No
accessory cusps are observed at the lingual or
buccal entrance of the valley.
The dentine fields of the three cusps of the
middle chevron are also confluent. Moreover, that of the paracone is continuous withthat of the metacone in the posterior chevron.
The occlusal surfaces of the paracone andenterostyle are approximately set in the sametransverse line. The transverse valley between the middle and posterior chevrons is
deep, but opens only lingually.
The dentine fields of the four cusps of theposterior chevron are confluent with eachother. The morphology of this chevron is ofthe" argenteus type" as discussed by Kawamura (1989). Namely, the posterior cingulum is well developed and strongly connectedto the metacone and hypocone. Furthermore, the hypocone is directly connected toYoshinari Kawamura and Kazuaki !ida

164

c.

o

1mm

Figure S. Apodemus argenteus (Temminck , 1844). Left M' from(KUJCI00718) . A: occlusal view. B : lingual view. C : buccal view .

the metacone. The valley between the
hypocone and posterior cingulum is distinct,
but becomes a slender closed pit. The posterostyle is well developed and elongate
antero-posteriorly.
A root below the lingual anterocone ispreserved. It extends antero-superiorly. It
is thick and has an antero-posteriorly elliptical cross section .
Measurement.- The specimen was measured by a profile projector (Nikon V-12)
with an electric digital counter (Nikon CM65). The measurements of the comparative
living materials (Figure 6) were also obtainedby the same instrument.
Length of crown (L)·· .. ··I.77 mm
Width of crown (W)·· .. · ·1.08 mm
Comparison and discussion .- The present

the Hiraen

Cl ay Member

specimen was compared with the actual
molars of six living murid genera known fromJapan (Apodemus, Diplothrix, Micromys,
Mus, Rattus and Tokudaia), and with thedescriptions and illustrations of the molars of
46 living murid genera (Abditomys , Ano-nymomys, Archboldomys, Bandicota,
Batomys, Berylmys, Bullimus, Bunomys,
Carpomys, Celaenomys, Chiromyscus , Chiropodomys, Chrotomys, Crateromys, Cremnomys, Crunomys , Dacnomys, Diomys ,Echiothrix, Eropeplus, Golunda , Hadromys,
Haeromys , Hapalomys , Kadarsanomys,
Lenomys, Lenothrix , Leopoldamys, Limnomys , Margartamys, Maxomys, Melasmothrix, Millardia, Nesokia, Niviventer, Palawanomys, Paruromys , Phloeomys, Pithecheir, Rhynchomys , Srilankamys, Sun-

881.

Murid molar from the Kobiwako Groupdamys, Taeromys, Tateomys, Tryphomys,
Vandeleuria) given by Misonne (1969), Mus-

A. mystacinus (Danford et Alston)A. jeanteti MichauxA. flavicollis (Melchior)
A. sylvaticus (Linnaeus)
A. dominans Kretzoi
A. microps Kratochvil et Rosicky
A. argenteus (Temminck)
A. speciosus (Temminck)
A. peninsulae (Thomas)
A. giliacus (Thomas)
A. draco (Barrett-Hamilton)
A. latronum Thomas
A. semotus Thomas
A. agrarius (Pallas)ser (1981, 1982a, b), and Musser and Newcomb (1983). Additional comparisons werecarried out on the basis of the descriptions
and ill ustrations of the molars of 15 fossil
murid genera (Antemus, Anthracomys, Cas-

tillomys, Chardinomys, Karnimata, Occitanomys, Orientalomys, Paraethomys, Parapelomys, Parapodemus, Progonomys,
Rhagamys, Rhagapodemus, Stephanomys,
Valerymys) given by Schaub (1938), Michaux(1969), Bruijn and Meulen (1975), Weerd(1976), Jacobs (1978), and Jacobs and Li(1982).
As the result, it is strongly suggested thatthe morpological characters of the specimen
are best coincident with those of Apodemus,
to which the specimen is undoubtedly assigned.
The genus Apodemus comprises many living and fossil species. The following species
are representatives of the genus:

W) :
(m
m:

:
I

165

Kawamura (1989) distinguished three morphotypes in the posterior chevrons of Ml andM2 of Apodemus. In the "speciosus type",
the posterior cingulum is absent, or forms aweak projection of the hypocone. In thelatter case, it is never connected to the metacone, but the hypocone is connected to themetacone by a strong ridge, which is separated from the posterior cingulum. In the

1 . ,.:i -;1--..
.,•.. ....',.:,•. ·:r
..
.
.
•
....
: .

4

1 .40 - - -- - - - - -: - - - -- - -- -- - - - - - - -~ - - - -- - - - -- - - - - - -;- - - - - -- ~• •~- - - - -:,

-

+

,,

•••••

,

.

+ ,
,
+
:.
:
--------~- --- ------ ---- + ~--_Q_-+j-- - - ----~- -- ---- - --------:- -------

008+~ cEo 0

Cbl ° 00
eg °00 ~(X)

o
°

S

0

o08
en • ..,..:
J'l O,Qtj 0 0•~'tY 0<0Present specimen

Apodemus argenteus,0CO:+ Apodemus giliacusI
0 ,• Apodemus speciosuso',-- - - - - - - ~- 0--- - - - - - - - - - - - -~ - - - - - - - - - - - - - - - ~- - - - - - - - - - - - - - -~ - - - - - --

00

1. 00

,

01

1

1. 20

+

0

,,
I

1.60

1.80

I

I

,:

2.00

2.20

L(mm)

Figure 6. Scatter diagram showing the relationship between the length and width of crown for thepresent specimen and M' of the Japanese living Apodemus.

166

Yoshinari Kawamura and Kazuaki lida

"giliacus type", the posterior cingulum issituated on the ridge between the metacone
and hypocone. The "argenteus type" ischaracterized by a well-developed posterior
cingulum which is connected to the hypocone
and metacone, but separated from the ridge
between the last two cusps.
Among the above-listed species, A.
mystacinus, A. jeanteti, A. flavicollis, A.
sylvaticus, A. dominans, A. microps, A.
speciosus, A. pen insulae, A. giliacus, A.
semotus and A. agratius are different fromthe present specimen in having Ml with theposterior chevron of the speciosus or giliacus
type. Moreover, Ml of these species except
A. microps are larger than the present specimen. Although available information on
the dental morphology of A. drcrco and A.
latronum is poor, Ml of these two species
seem to be larger than the specimen.
Ml of the remaining species, A. argenteus,strongly resembles the specimen in outline
and height of. crown, arrangement and morphology of each cusp (especially the posteriorchevron with the pattern of the argenteustype) and size. As shown in Figure 6, thelength and width of the specimen plot in thecenter of the cluster of the living A. argenteus. Because no significant differences arefound between the specimen and Ml of A.
argenteus, the specimen can be referred to A.
argenteus.
Kawamura (1989) described many specimens of A. argenteus from middle Middle
Pleistocene to Holocene localities in theJapanese Islands. These are very similar tothe present specimen in the morphology ofcrown and size. He also pointed out that A.
argenteus remained almost unchanged inthese characters from the middle Middle
Pleistocene to Holocene. The present specimen indicates that such an unchanged condition can be traced back to the early Middle
Pleistocene. Therefore, it is inferred that A.
argenteus originated from its ancestral species
in or prior to the Early Pleistocene.
The Early Pleistocene fossil records of

Apodemus in China are very important forconsidering the ancestry of A. argenteus.
Unfortunately, they are very few. A. cf.
sylvaticus from Huaiyu (Teilhard, 1940) is the
only comparable form. However, this form
is considerably different from A. argenteus(Kawamura, 1989). Furthermore, as rri:!ntioned above, the Early Pleistocene andPliocene fossil species from Europe such as A.
jeanteti and A. dominans also differ from A.
argenteus. Consequently, the ancestry of A.
argenteus remains unknown. As pointed
out by Kawamura (1989), this species seems
to have evolved along an independent lineage
from the other known species of Apodemus.
Conclusion
The murid molar found in the Hiraen Clay
Member of the Kobiwako Group is undoubtedly referred to Ml of Apodemus. The comparisons with many species of the genus showthat the morphology and size of the molar are
best compared with those of A. argenteus, anendemic species of the present Japanese Islands. Because the geological age of themolar is estimated to be 0.65 to 0.7 Ma, it isconcluded that the biostratigraphic range of
A. argenteus extends back to QM3, and thisspecies already inhabited in the islands in theearly Middle Pleistocene. The occurrence ofthe molar strongly supports the opinion of
Kawamura (1989) that A. argenteus arosefrom its ancestral species in or prior to the
Early Pleistocene.
Acknowledgment
We are deeply indebted to Professor T.
Kamei (Shinshu University) and Associate
Professor L.L. Jacobs (Southern Methodist
University) for critical reading of the draft ofthis paper, and to Associate Professor T.
Kosaka (Shinshu University) for discussing
and encouraging us in numerous ways.
Thanks are also due to Dr. K. Takemura(Kyoto University), Mr. H. Taruno (Osaka881.

Murid molar from the Kobiwako Group

Museum of Natural History), Dr. Y. Tomoda,
Dr. F. Kumon (Shinshu University) and Mr.
T. Hayashi (Nishiura Senior High School)for providing us valuable suggestions. We
are grateful to Mr. K. Hayashi (Yayoi Primary School) and Miss Y. Asano (Yutakagaoka Primary School) for helping us in thescreening of the sediments, and to Mr. F.
Iguchi and Mrs. C. Iguchi for giving us facilities in our field survey.

References cited
Bruijn, H. de and Meulen, A.J. van der, 1975: The
Early Pleistocene rodents from Tourkobounia-I(Athens, Greece). Proc. Kon. Ned. Akad.
Wetensch., Ser. B, vol. 78, no. 4, p. 314-338.
Hayashi, T., 1974: The Kobiwako Group in the
Katata Hills, Shiga Prefecture, Japan. Jour.
Geol. Soc. Japan, vol. 80, no. 6, p. 261-276. (inJapanese with English abstract)
Hayashida, A., Yokoyama, T., Takemura, K., Danhara, T. and Sasajima, S., 1976: Preliminary
report on magnetostratigraphy of the Kobiwako
Group on the west coast of Lake Biwa, Central
Japan. In Horie, S. ed., Paleolimnology ofLake Biwa and the Japanese Pleistocene, vol. 4,
p.96-108.
Hiki, T., 1915: Bubalina remains from the Provinceof Omi. Mem. Coli. Engineer. Kyoto Imp.
Univ., vol. I, no. 5, p. 245-247, pis. 1-3.
Iida, K., 1988, MS: The Kobiwako Group of the
Katata Hills, Shiga Prefecture, especially on the
paleoenvironments induced from sedimentary
facies and fossil fish fauna. 193p., Master
Thesis of Shinshu Univ. (in Japanese withEnglish abstract)
Ikebe, N., Chiji, M. and Ishida, S., 1966: Catalogueof the Late Cenozoic Proboscidea in the Kinki
District, Japan. Jour. Geosci. Osaka City
Univ., vol. 9, article 3, p.47-56, pis. 1-8.
Ishida, S. and Yokoyama, T., 1969: Tephrochronology, paleogeography and tectonic development of Plio-Pleistocene in Kinki andTokai Districts, Japan. Quat. Res. (DaiyonkiKenkyu), vol. 8, no. 2, p. 31-43. (in Japanesewith English abstract)
Jacobs, L.L., 1978: Fossil rodents (Rhizomyidae &Muridae) from Neogene Siwalik Deposits, Pakistan. Mus. Northern Arizona Press Bull., Ser.
52, p. i-xi + p. 1-103.
- - and Li C.K., 1982: A new genus (Chardinomys) ofmurid rodent (Mammalia, Rodentia)
from the Neogene of China, and comments on its

167

biostratigraphy. Geobios, no. 15, fasc.2, p.255259.
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Univ., Ser. Geol. Min., vol. 32, no. 4, p. 381-394,
pis. 12-14.
- - , 1984: Fossil mammals: Lake Biwa and fossil
mammals: Faunal change since the Pliocene
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Dr. W. Junk Publ., Dordrecht, Boston and Lancaster.
- - , Kawamura, Y. and Taruno, H., 1988: Mammalian stratigraphy of the Late Neogene andQuaternary in the Japanese Islands. Mem.
Geol. Soc. Japan, no. 30, p.181-204. (inJapanese with English abstract).Kawamura, Y., 1989: Quaternary rodent faunas in
the Japanese Islands (Part 2). Mem. Fac. Sci.
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1-235.
Matsumoto, H. and Ozaki, H., 1959: On a new geological subspecies of Archidiskodon paramammonteus Matsumoto discovered at Ono, Shiga
Town, Province of Omi. Bull. Nat. Sci. Mus.,vol. 4, no. 4, p. 355-357, pis. 55-57.
Michaux, J., 1969: Muridae (Rodentia) du Pliocene
superieur d'Espagne et du Midi de la France.
Paleo vertebrata, vol. 3, no. I, p. 1-25, pis. 1-2.
Misonne, X., 1969: African and Indo-Australian
Muridae, evolutionary trends. Ann. Mus. Roy.
de I'Afrique Centrale, Ser. In-Bo, Zool., no. 172,
p. 1-219, pis. 1-27.
Musser, G.G., 1981 : Results of the Archbold Expeditions. No. 105. Notes on systematics of IndoMalayan murid rodents, and descriptions of new
genera and species from Ceylon, Sulawesi and thePhilippines. Bull. Amer. Mus. Nat Hist., vol.
168, article 3, p. 225- 334.
- - , 1982a: Results of the Archbold Expeditions.
No. 107. A new genus of arboreal rat from
Luzon Island in the Philippines. Amer. Mus.
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No. 110. Crunomys and the small-bodied shrew
rats native to the Philippine Islands and Sulawesi(Celebes). Bull. Amer. Mus., Nat. Hist., vol.
174, article I, p. 1-95.
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4, p. 327-598.
Naumann, E., 1881: Ueber japanische Elephanten
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Nishimura, S. and Sasajima, S., 1970: Fission track
age of volcanic ash-layers of the Plio-Pleistocene
Series in Kinki District, Japan. Earth Sci., vol.

Yoshinari Kawamura and Kazuaki lida

168

24, no. 6, p. 222-224. (in Japanese with English

abstract)- - and Yokoyama, T., 1975: Fission track ages of
volcanic ashes of core samples of Lake Biwa andthe Kobiwako Group (2). In Horie, S. ed.,

Paleolimnology of Lake Biwa and the Japanese
Pleistocene, vol. 3, p. 138-142.
Okazaki, Y. and Matsuoka, C., 1979: A review ofmammalian fossils in Shiga Prefecture. In

Land and Life in Shiga,' Separate Volume for
Geomorphology and Geology and Geologic Mapof Shiga Prefecture 1,' 100,000 in Scale, p.
391-467, Foundation of Nature Conservation in
Shiga Prefecture. (in Japanese with English

summary)
Research Group of Natural History of Lake Biwa,
1986: Freshwater fossil assemblages from the
Pleistocene Kobiwako Group on the southwestside of Lake Biwa. Bull. Mizunami FossilMus., no. 13, p. 57-103, pis. 9-20. (in Japanesewith English abstract)
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Teilhard de Chardin, P., 1940: The fossils from
Locality 18 near Peking. Palaeont. Sinica, New
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Japon et les iles que en dependent. In Siebold
P.F. de, Temminck, J.e. and Schlegel, H., Fauna
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Bull., Spec. Publ. 2, p. 1-217.
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Kinki District, Japan. Monogr. Assoc. Geol.
Collab. Japan, no. 25, p.45-61. (in Japanesewith Engish abstract)

Tamura, M., Okamura,Y. and Matsuoka, e., 1982:

Hiraen .lt~liI. Huaiyu W<:rut't. Kamiogi J:{!P*. Katata IJi£EB. Kisen JH~, Kitahama
Kurihara ~JJ.ii:. Nijigaoka!III 'T fr, Otani
Ryuge ~*,
Sakawa -ftc) II, Sayama ~i1I. Shiga-cho ;tr-~IBJ. Shiga-gun ~~m. Takashiro i\1ij:!/iJZ, Yamashita Llf"f.

*:fr.

~t~, Kobiwako tlfEf.!¥IiIl.

tlfEf.!¥IiIlJlffii' I?£:±l ~ t-:t:pMj~JrfTi!tllUMO)~t!l!i § ;f.;;( ~ f40) St!l!i{~E: tlfEf.!¥IiIlJlff
O).f;t~liIf~±Jlii' I?£:±l ~ k~t!l!iMO)J:~~ 1 *St!l!ilt. ;f.;;( ~ #O){~E C ~ -C It B*11J!1l;JltlO)to)-C~7.Jo ':'O){~Elt. mtEO)B*11J!1l;0)~1'iti-C~7.J 1:::.;I;f.;;( ~ Apodemus
argenteus 1:::.i'lJ:lE ~.h 7.J~ -C ~ ,t-:.:.

*

0

.:.

c :a:-lf- ~ -C ~'7.J0

It. *tiii~t:pMJ!!~i!tllUMO) 0.65-0.7 Ma i -Z::·I:::.ti7t{~~ I? I:::. B*-Clt, t:pMJ!!~i!tllUMI:::.;f§~"t 7.J Pflj~LiIJ¥J.J{~E1II'0)':' C

(0.5 Ma ii' I? 0.73 Ma) O)ilJ4'JJJ;j:§O)[73~ii~mtEli c ~ c'~ I?.h -C \" t.n'.:. c ii,
I?, 4'@]O){~Elt B *11J!1l;O)Pflj~LilJ4'JJJ;j:§0)~JI~:a:-~ *-7.JJ:-z::'m:~-C ~ 7.J o0) QM3

ftiJ;fi~-m'~EBfp~

Trans. Proc. Palaeont. Soc. Japan, N.S., No. 155, pp. 169-177, 4 Figs., September 30, 1989

882. DENTICULOPSIS PRAEHYALINA, SP. NOV.:AN EARLY MIDDLE MIOCENE PENNATE DIATOM FROMDOGO, OKI ISLANDS, SOUTHWEST JAPAN*
YOSHIHIRO T ANIMURA
Department of Geology, National Science Museum,
Hyakunin-cho, Shinjuku-ku, Tokyo, 169

Abstract. A new pennate diatom, Denliculopsis praehyalina, from the early Middle
Miocene diatomite of the Oki Islands is described. This species has many affinities to
Denliculopsis hyalina but differs from it by having areolation on valve face. The new
species combines morphological features of two Denticulopsis species, D. hyalin a and D.
laula. A predominance or acme of D. praehyalina is restricted to the uppermost part of
Middle Miocene D. hyalin a Zone in the Northwest Pacific, and it is a good maker for thehorizon.
Key words.

Denliculopsis, diatom, Middle Miocene, Oki Islands.

and granitic rocks, exposed in the central partof the island. It is divided into the Tokibariyama, Kori, Kumi, Tsuma and Yui Formations in ascending order, with unconformities
separating each of the formations (Tomita,
1936; Okubo, 1984; Yamazaki, 1984). The
Tokibariyama and Kori Formations consist
mostly of acidic to intermediate lava andpyroclastic rocks, but contain some intercalated conglomerate, sandstone and mudstone.
The Kumi Formation, from the base upward,
is composed of sandstone, shale and thickmassive diatomite (Yamazaki, 1984). The
formation ranges from a few meters to about
200 meters in thickness. The Tsuma Formation is mainly composed of sandstone andsandy mudstone. The Yui Formation ischaracterized by basic lava and pyroclastic
rocks with some intercalated clastic rocks.
The massive diatomite of the Kumi Formation is early Middle Miocene in age on thebasis of diatom-based correlations (Yokota,
1984; Okubo and Yokota, 1984).
All the samples for this study were collected from the diatomite bed of the Kumi

Introduction
Early Middle Miocene diatomite collectedfrom Dogo, Oki Islands contains a new
Denticulopsis species which has morphological characteristics similar to those reported for Denticulopsis hyalin a (Schrader)
Simonsen (Schrader, 1973a; Simonsen,1979).
Denticulopsis hyalina is characterized by
the double-layered perforation of mantle andhyaline valve surface. The new species also
has the same mantle structure. Distinct
areolation, however, is found on valve face ofthe new species.
This paper will present a description of the
new species, and its biostratigraphical andevolutional implication.

Geological notes
The Neogene in Dogo, Oki Islands crops
out around the basement complex, gneisses'Received November, 29, 1988; accepted July I,
1989.
169

Yoshihiro Tanimura

170

Formation.
Outcrops and material
Thirty-six samples were collected for thisstudy from three outcrops of the Kumi Formation (Figures I, 2). The Iinoyama outcrop is a working diatomite mine located on
the south side of Saigo-wan. This outcrop,from the base upward, contains dark graystratified siliceous shale and yellowish whitemassive diatomite. The siliceous shale
grades upward into diatomite which is unconformably overlain by a thick stratified
carbonaceous sandstone of the Tsuma Formation. The thickness of the diatomite
reaches more than 40 meters at the thickest
part. The uppermost part of the diatomite is
tuffaceous with large quantity of glauconitic
minerals and sponge spicules. Fourteen
samples were collected from the stratigraphic
section of the mine at one to ten meters intervals.
At Minoura, the formation consists of dark

Figure 1.

gray siliceous shale and yellowish whitemassive diatomite, as in the Iinoyama outcrop, but it contains some intercalated paleorange fine-grained sandstone in the lowermost part. The diatomite is estimated to be
26 meters thick. Nodules of opaline cristbalite, IO to 30 centimeters thick, is commonly found in the diatomite. Three layers ofglauconitic minerals are also found in theupper part.
The Tsuma outcrop is composed of threesmall roadside cliffs. The formation contains dark gray siliceous shale and yellowish
white massive diatomite about 13 meters
thick. Twenty-two samples were collectedfrom the Minoura and Tsuma outcrops at one
to five meters stratigraphic intervals.
Methods
Twenty-five samples were selected for thisstudy. A preparation of slide was done asfollows; about one gram of dried sample wasplaced in a 200 ml beaker with a boiled solution of hydrogen peroxide (H 2 0 2 , 15%) for
disaggregation of rocks. After boiling forabout 20 minutes, the beaker was filled with
distilled water, and kept at room temperature
for about 7 hours. Then fine material in

Location of outcrops.

882.
TSUMA

A new Miocene diatom

MINOURA171

IINOYAMA

II

~

..

!

-; II
= a.-;
~.:

.: .:

~

.c .c

~

...

Cl

.........

.c

c:i

.. .
.. ....

!

c:i"~ c:i
a.

~<lDh

c:i

.
.

"'OK ..
t8A

.~

...
...

.
..
.......

t:

N

0:

c:i

0'115 to

o

"o

·e

...

G>
C

co
co

~

Q.

o

.-""
~

0:
G>

Q

Q

sandstone, siltstoneG>~ conglomerate

50 sand pipe
B glauconite

E:J tuffaceous

C

o

..

N

§!tUflD diatomite

§

.."

~

to

0'115 to5c:i...............

siliceous shale

Om

Figure 2. Stratigraphic occurrences of Denticu/opsis species in the upper part of the Kumi Formation.
Dh; first common occurrence of Denticu/opsis hustedtii.

suspension was carefully removed by decantation, and the beaker was filled again with
distilled water. This procedure was repeatedat three times. A 0.1 to 0.5 ml of the final
residue was diluted by distilled water toobtain a suspension of proper density. For
slide preparation, 0.5 ml of the suspension
was taken with an automatic micropipettewith disposable plastic tips, and was placedon a square cover glass, 18 X 18 mm in size.
After drying, it was mounted on slide glasswith Pleurux.

Observation and identification of diatoms
were made at X 1,250 magnification withdirect transmitted light and Nomarskii
differential interference contrast. For scanning electron microscopic observation,
diatom valves were collected by filteration of
the suspension within 0.8 J.lm milipore filter.
Relative abundance of each Denticu/opsis
species in a flora was estimated by counting
over 200 valves while traversing a slide undera LM.

Yoshihiro Tanimura

172

Observations

Denticulopsis praehyalina Tanimura, sp. nov.
Figures 3-1--9; 4-1--7
Synonym: Denliclilopsis lauta (Bailey) Simonsen;
Schrader, 1973a, pI. 2, figs. 21-22; Schrader, 1973b,
pI. I, fig. 20.

Description.- Valves heavily silicified, elliptical to linear-elliptical with bluntly
rounded ends, 10-40,um long, 5-9 ,um wide.
Valve face slightly convex or almost flat.
Primary pseudosepta about 3 in 10 ,um.
Marginal ribs short and thick. Secondary
pseudo septa absent, but one or two apicalpseudosepta present at each apex of most
specimens. Apical pseudosepta usually
oblique to transapical axis. The punctae
arrangement on valve face is fairly variable.
Valve face sporadically or densely punctated,
12-24 punctae in 10 ,um. Transapical striaeof densely punctated specimens about 15-20
in lO,um; punctae more or less decussate
arrangement. In some sporadically punctated specimens, only one or two lines of transapical striae found near each pseudosepta.
In many sporadically punctated specimens,
clusters of puncta are arranged in a line along
the raphe-bearing valve margin. Under a
LM observation, each cluster looks like arounded triangle to hexagonal large pore,
about 0.5-0.7,um wide, 6-8 in 10 ,um.
Round large depression, about 1.5,um indiameter, present in two apically arranged
rows. Small spinule form a line along theboth sides of valve face edges, about 10-13 in
10 ,um. Raphe situated on the upper part ofvalve mantle. Mantle is high and perforated.
The pore of mantle consists of an outer fineperforation, 32-38 in 10 ,um, and an innerround to hexagonal large pore, 7-10 in 10,um. Foramen of septum oval to elliptical,
about 3 in 10 ,um. Thickening between each
two foramens 2-4,um long, about 0.5-1.5,um
wide.
Holotype.- MPC (Micropaleontology collection, National Science Museum, Tokyo)
slide 04231 (sample OKI 3-8), illustrated in
Figures 3-2a, b.
Paratype.- MPC slide 04232 (sample
OKM 18A), illustrated in Figures 3-3a, b.
Type locality.- Minoura outcrop, Dogo,Oki Islands, Shimane Prefecture.
Stratigraphic range.- Rare to common inearly Middle Miocene.
Remarks.- This new species is close to
Denticulopsis hyalin a and D. miocenica(Schrader) Simonsen (Schrader, 1973a;
Simonsen, 1979). The most striking featureof the new species is the double-layered areolation of mantle (Figures 4-3,4). This characteristic structure is also found in D. hyalin a
and D. miocenica. A definite difference
between D. hyalina and this species is theabsence of valve face punctae of the former.
This species also differs from D. miocenica by
the rhombic valve shape, well-developed
broad septum deck and small round septum
foramen of the latter.
Some densely punctated specimens (Figures
3-5; 4-4) of this species closely resemble
Denticulopsis lauta (Bailey) Simonsen,(Simonsen et Kanaya, 1961 ; Simonsen, 1979)
in valve view under a LM observation. In
the specimens from the Kumi Formation,
however, they can be distinguished from thelatter by their broad valve shape and coarse
punctae of valve face. In addition, the mantle structure is an easily discernible diagnostic
structure under a SEM observation.
Three forms described and illustrated by
Schrader (Schrader, 1973a, pI. 2, figs. 21-22 ;1973b, pI. I, fig. 20) as Denticula laula are~
Figure 3. 1--9. Denliculopsis praehyalina, n. sp.; 2--4,6--9, Sporadically punctated specimen; 1,5,Densely punctated specimen; 2a, 2b, Holotype; 3a, 3b, Paratype. 10--14, Denliculopsis hyalina, Kumi
Formation. 15, Denliclilopsis husledlii (Simonsen et Kanaya) Simonsen, Kumi Formation. 16--17,
Denliclilopsis laula (Bailey) Simonsen, Kumi Formation. 18, 19, Denliclilopsis miocenica (Schrader)
Simonsen, Kumi Formation. (Scale bar= 10 JIm)

10

16a

882.

A new Miocene diatom

17b

18a

173

11

16b

17a

18b

19a

19b

174

Yoshihiro Tanimura

identical with the new species. These show
the common features in heavily silicified
valves, sporadically arranged puncta and theline of rounded triangle to hexagonal large
pores on valve face.
Okuno (1964) described the two varieties of
Denticula (= Denticulopsis) lauta from thediatomite of the Kumi Formation, Minoura
outcrop; D. lauta var. punctata Okuno(Ok uno, 1964, pI. 504, fig. b) and D. lauta
var. valida (Pedicino) Okuno (Okuno, 1964,
pI. 505, bottom figs.). Some sporadicallypunctated types of the new species (Figures 31; 4-1) are possibly identical with D. lauta
var. punctata. Definite identification, however, are difficult. Because, the mantle structure, the most distinctive feature of the new
species, is not shown in Okuno's description
and illustration of the variety. In addition,
the repository of type material is uncertain, so
the re-examination of the type slides is impossible (Ok uno, per. com., 1988).
The figured specimens of D. lauta var.
valida (Okuno, 1964, pI. 505) consist of two
different forms. Secondary pseudo septa arepresent in the top figures and absent in thebottom. The former is assignable to be
Denticulopsis hustedtii (Simonsen et Kanaya)
Simonsen (Simonsen and Kanaya, 1961;
Simonsen, 1979) or its allied species, and thelatter corresponds to his description (Ok uno,1965) about the variety.
Denticula elegans var. valida Pedicino
which was described from the hot springs of
Ischia Island, the Gulf of Napoli (Pedicino,1867), was raised to the specific rank, D.
valida, by Grunow (van Heurck, 1881).
Denticula valida is recombined with D. lauta
as its variety, D. lauta var. valida, by Okuno(1964).

Denticula lauta var. valida is not thesame form as D. elegans var. valida or D.
valida. The valve outline of D. elegans var.
valida (Pedicino, 1867, pI. 1, figs. 42-45) andD. valida (van Heurck, 1881, pI. 49, fig. 5;
H ustedt, 1928, pI. 3, figs. 6, 8) are more lanceolate with elongated apices, while the polesof D. lauta var. valida (Ok uno, 1964, pI. 505,
bottom left fig.; Okuno, 1965, pI. 2, fig. h) are
broadly rounded and the valve sides are moreor less linear. Therefore, it is highly probable that Okuno's recombination is not
appropriate.
The bottom left figure of plate 505 (Ok uno,1964) resembles some morphological types(Figures 3-5; 4-4) of the new species.
These show the common features in heavily
silicified valves and densely arranged puncta,
so the specimen (Ok uno, 1964, pI. 505, bottom left fig.; not Okuno, 1964, pI. 505, reconstruction diagram and Ok uno, 1965, pI. 2, figs.
f, g) probably is a densely punctated type ofthe new species.
Stratigraphic distribution
Figure 2 shows the stratigraphic distri bution of Denticulopsis species in the threeoutcrops investigated. At the Iinoyama andMinoura outcrops, D. praehyalina is sparse in
the lower part of the diatomite sections. The
species occupies 0.5 to 2.5% of the flora. An
increase in abundance appears in the upper oruppermost part of the sections. Here, D.
praehyalina accounts for more than 3% (up to7%) of the flora. Abundant to common specimens of D. lauta are also found at andaround the same horizons.
Denticulopsis hyalina is present III the~
Figure 4. 1-7. Denticu/opsis praehyalina. n. sp. 1, Sporadically punctated specimen, oblique exteriorview of valve; Arrows with letter symbols d and s indicate large depression and small spinule, respectively;
Outer fine perforation of mantle is dissolved; 2, Oblique girdle view of broken valve; 3, Sporadicallypunctated specimen; a) Valve exterior, note clusters ofpunctae along valve margin; b) Oblique girdle view
showing double-layered perforation of mantle ; 4, Densely punctated specimen, a) Valve exterior, b) Oblique
girdle view showing double-layered perforation of mantle; Arrows with letter symbols d and s indicate large
depression and small spinule, respectively; 5, Sporadically punctated specimen, oblique view of valve
exterior; Valve is thickened by silica overgrowth; 6, Sporadically punctated specimen, valve interior, note
apical pseudo septa ; 7, Oblique internal view of valve. (Scale bar=5 jim)

882.

A new Miocene diatom

175

Yoshihiro Tanimura176

middle to upper part of the diatomite sections. In the middle part it comprises 0.52.5% of the flora, and increases upward. In
the uppermost part of the sections, there is asudden drop in abundance of D. hyalina, and
it is followed by the first common occurrenceof D. hustedtii (open triangle with letter
symbol Dh). The characteristic distributionsof these species are not found in the section of
the Tsuma outcrop, for the reason that thediatomite section of the Tsuma outcrop represents only the lower to middle part of thewhole diatomite bed of the Kumi Formation.
These biostratigraphical data show that theoccurrence of D. praehyalina ranges from theupper part of the D. lauta Zone (Koizumi,1973) to the horizon just above the D. hyalin a
Zone (Maruyama, 1984).
The stratigraphic occurrence of D. hyalina
and D. hustedtii have been documented inseveral localities of Japanese Islands andadjacent seas, for example Matsushima,Northeast Honshu (Akiba et al., 1982),
Pacific side sections of Honshu (Maruyama,
1984) and DSDP Hole 438A (Maruyama,
1984). In these localities the predominanceor acme of D. hyalina is reported to be in theuppermost part of the D. hyalina Zone, andto be just below the first common occurrenceof D. hustedtii. The absolute age of thehorizon of this predominance or acme wasestimated to be 15-14 Ma on the basis ofradioisotopic dating- and paleomagnetic
stratigraphy-based correlations (Koizumi,1985). An abundant occurrence of D. praehyalina at and around the same horizon IS
also a good marker of the horizon.

Notes on evolutionary trends
In as much as Denticulopsis praehyalina, D.
hyalina and D. miocenica share a doublelayered perforation of mantle, the most characteristic morphological feature of these
species, it may be inferred that these three
species are on the same evolutionary line.
The fact that intermediate forms occur fairly

commonly among these three species supports
this inference.
The stratigraphic occurrence of Denticulopsis species have been well documented inmany localities of North Pacific (Simonsen
and Kanaya, 1961 ; Schrader, 1973a, b; Barron, 1980; Koizumi, 1985; Akiba andYanagisawa, 1986). In these works, it has
been generally accepted that D. hyalina
evolves from D. lauta. Two abrupt morphological changes, however, were involvedin the evolution; a formation of doublelayered perforation of valve mantle and complete reduction of areolae on valve face. By
the introduction of D. praehyalina, the gradual evolution from D. lauta to D. hyalina canbe understood easily.
Denticulopsis praehyalina occurs in thelowermost part of diatomite bed of the Kumi
Formation. The species probably evolves
from D. lauta or its variety. Denticulopsis
hyalina is a descendant of the species. This
group shows tendency to create hyaline surface structure. This evolutionary line seems
to go on into Denticulopsis katayamae Maruyama (Maruyama, 1984) which possesses secondary pseudo septa, shallower valve mantle
and valve face edge punctae. The doublelayered mantle pore are also found in D.
katayamae valve by SEM observation(Akiba and Yanagisawa, 1985, p.489, pI. 20,
figs. 4, 5, 7).
Acknowledgments

I am grateful to Drs. Itaru Koizumi of
Hokkaido University, John A. Barron of the
U.S. Geological Survey (Menlo Park), Fumio
Akiba of Japan Petroleum Exploration Company and Kazuhiko Uemura of National
Science Museum for kindly reviewing themanuscript and for many valuable suggestions. I also thank Drs. Haruo Okuno ofProfessor Emeritus of Kyoto Institute ofTechnology, Yasuji Saito of National Science
Museum, Yukio Yanagisawa of Geological
Survey of Japan and Toshiaki Maruyama of882.

A new Miocene diatom

Tohoku University for their helpful advice.
Four samples marked Mu were collected by
Dr. Yasuji Saito and Mr. Takashi Mitsuokaof the same Museum.
References cited
Akiba, F., 1986: Middle Miocene to Quaternary
diatom biostratigraphy in the Nankai trough andJapan trench, and modified Lower Miocene
through Quaternary diatom zones for middle-tohigh latitudes of the North Pacific. In:
Kagami, H., el al. eds., Init. Repts. DSDP, vol.
87, p.393-481, pis. I-30. U.S. Gevernment
Printing Office, Washington.
- - and Yanagisawa, Y., 1986: Taxonomy, morphology and phylogeny of the Neogene diatom
zonal marker species in the middle-to-high latitudes of the North Pacific. In: Kagami, H., etal. eds., Ibid., vol. 87, p. 483-554, pis. I-53. U.
S. Government Printing Office, Washington.
- - , - - , and Ishii, T., 1982: Neogene diatom
biostratigraphy of the Matsushima Area and its
environs, Miyagi Prefecture, northeast Japan.
Bull. Geol. Surv. Japan, vol. 33, no. 5, p.215239, pis. 1-3.
Heurck, H. van, 1881: Synopsis des diatomees deBelgique. Atlas, pis. 31- 77, Anvers.
Hustedt, F., 1928: Untersuchungen uber den Bau derDiatomeen, IV. Ber. Deutsch. Bot. Ges., vol.
46, p. 148-164, pI. 3.
Koizumi, I., 1983: The Late Cenozoic diatoms ofsites 183-193, Leg 19, Deep Sea Drilling Project.
In: Creager, J.S., et al., eds., Init. Repts. DSDP,
vol. 19, p. 805-855, pis. 1-8. U.S. Government
Printing Office, Washington.
- - , 1985: Diatom biochronology for Late Cenozoic Northwest Pacific. Jour. Geol. Soc. Japan,
vol. 91, p. 195-211.
Maruyama, T., 1984: Miocene diatom biostratigraphy of onshore sequences on the Pacific side ofNortheast Japan, with reference to DSDP hole

177

438A (part 2). Sci. Repts., Tohoku Univ., Ser.
2 (Geol.), vol. 55, p. 77-140, pis. 11-15.
Okubo, M., 1984: Outline of geology of Oki Islands.
Geol. Rep. Shimane Univ., vol. 3, p. 75-86.
- - and Yokota, M., 1984: On the fossil assemblages of diatoms in Dogo, Oki Islands. Jour.
Geol. Soc. Japan, vol. 90, no. 6, p.411-414.
Okuno, H., 1964: Fossil diatoms. In: Helmcke
J.-G. and Krieger, W., eds., Diatomeenschalen i~elektronenmikroskopischen Bild V, pis. 504-505.
Cramer, Weinheim.
- - , 1965: Diatomaceous earth in Oki Island (2).
Jour. Japanese Bot., vol. 40, no. I, p. 7-11, pis.
1-2.
Pedicino, N.A., 1867: Pochi studj sulle diatomee
viventi presso alcune terme dell'isola d'Ischia.
Atti Accad. Sci. Fis. Napol., vol. 3, no. 20, p. 117, pis. 1-2.
Schrader, H.-J., 1973a: Cenozoic diatoms from theNortheast Pacific, Leg 18. In: Klum, L.D., etal., eds., Init. Repts. DSDP, vol. 18, p. 673-797,
pis. 1-26. U.S. Government Printing Office,Washington.
- - , 1973b: Stratigraphic distribution of marine
species of the Denticula in Neogene North Pacificsediments. Micropaleontology, vol. 19, p.417430, pI. I.
Simonsen, R., 1979: The diatom system: Ideas on
phylogeny. Bacillaria, vol. 2, p. 7-91.
- - and Kanaya, T., 1961: Notes on the marine
species of the diatom genus Denticula Klitz.
Internal. Rev. Hydrobiol., vol. 46, no. 4, p.498513.
Tomita, T., 1936: Geology of Dogo, Oki Islands, in
the Japan Sea. Jour. Shanghai Sci. Inst., Sec.
2, no. 2, p. 37-146.
Yamazaki, H., 1984: Geological study of the
Miocene Series of Dogo, Oki Islands. Geol.
Rep. Shimane Univ., no. 3, p.87-97.
Yokota, M., 1984: Diatomaceous earth in Dogo, Oki
Islands. Ibid., no. 3, p. 139-144, pis. 1-2.

Iinoyama WiU-!, Kamaya ~;fr, Kori :1m, Kumi ~Jt Minoura
Tokibariyama 1lifiJ!U-!, Tsuma 'ifill], Yui ¥Ill*".

~i'ffi,

Saigo

gg~,

Trans. Proc. Palaeont. Soc. Japan, N.S., No. ISS,. pp. 178-196,32 Figs., September 30, 1989

883.

CENOMANIAN (CRETACEOUS) INOCERAMIDS (BIVALVIA)
FROM HOKKAIDO AND SAKHALIN - I
Birostrina nipponica (Nagao et Matsumoto)*
T A TSURO MATSUMOTO
c/o Department of Geology, Kyushu University 33, Fukuoka 812
and

AKITO ASAI
Division of Geology, Department of Mineral Industry, Schoolof Science and Engineering, Waseda University, Tokyo 160

Abstract. In this paper Birostrina nipponica (Nagao et Matsumoto, 1939) is redefinedand fully described. It is markedly inequivalve, with very small or scarcely discernible
posterior wing; left valve is very convex, with much incurved umbo; ornament is fine andweak. This species is very variable and includes at least three forms, viz. (a) slender form
with a strongly projected left umbo, (13) form with subrounded main part of valve whichshows a uniform convexity and (y) narrowly convex form with a summit along the growthaxis. The three forms seem to intergrade. None of them is identical to any of the variable
forms of Albian B. concentrica (Parkinson) nor to Middle Cenomanian B. tamurai which
has a posterior radial groove and develops irregular ribs in late growth-stage.
Some of the specimens hitherto called Inoceramus concentric us var. nipponicus aretransferred to certain other species. For instance, those from the Zone of Mantelliceras
japonicum (Lower Cenomanian) should be mostly referred to I. tenuis Mantell; a few are
to be referred to a Turonian species allied to I. inaequivalvis Schliiter. B. nipponica in arevised sense occurs so far from the high Middle to low Upper Cenomanian of Hokkaido and
Sakhalin. A form represented by several specimens is allied to but different from thisspecies and described tentatively under B. aff. nipponica.
Key words.

Birostrina. Inoceramus, Albian, Cenomanian, Hokkaido, Sakhalin.

from South Sakhalin (mainly the Naibuchi
and northeasterly adjacent Aikawa areas) inaddition to those from selected areas of
Hokkaido. The results are to be publishedin a series of numbered papers, which may be
written by a variety of different authors.
In this paper (Part I) we give a revised
description of Birostrina nipponica (Nagao etMatsumoto, 1939), and clarify both its taxonomic status and geological age. The material for the restudy of B. nipponica consists
primarily of the specimens obtained by one ofus (Matsumoto, 1942-43), sometimes with aIntroduction

Twelve species of the Inoceramidae which
occur in the Cenomanian of Japan have been
recently described in five successive papers (Ito V) (Matsumoto and Noda, 1986; Matsumoto et al., 1987, 1988; Matsumoto andTanaka, 1988; Matsumoto, 1989).
There are still more specimens to be described and illustrated. As the major title
shows, we now include the older collections·Received December 5, 1988; revised manuscript
accepted June 20, 1989.
178

883.

Cenomanian inoceramids - I

coworker (Matsumoto and Okada, 1973), andthose recently acquired by the other (A.A.)
through field works in the Ashibetsu andObirashibe (simply called Obira) areas. The
syntypes of Nagao and Matsumoto (1939) andhypotypes ofIkegami and Omori (1957), withprefix OM, have been examined, so far as they
are accessible.
T~e repositories of the described and/or
discussed specimens are as follows, withabbreviations in parentheses:
British Museum (Natural History), London (BM)
Geological Collections, Kyushu University (GK)Collections of Geology and Mineralogy,
Hokkaido University, Sapporo(GMH)
Institute of Geology and Palenotology,
Tohoku University, Sendai (lGPS)
School of Education, Waseda University,
Tokyo (WE)
Sedgwick Museum, University of Cambridge (SM)
University Museum, University of Tokyo(UMUT)As to the technical terms and their abbreviations, we follow those defined and used in
the aforementioned five papers, especially
Matsumoto and N oda (1986, p. 410-411) andMatsumoto et al. (1987, p. 147). In addition
to them we propose to measure the length ofthe curved line along the axis of growth,which is abbreviated to G. In a highly convex valve, with a much incurved umbo, theratio G /H is a useful parameter. A curvimeter is used for the measurement of G.
For the locality records and stratigraphy
readers may refer to Matsumoto (1942-1943),
Ikegami and Omori (1957), Matsumoto andOkada (1973) and Sekine et al. (1985). Asaiis preparing a paper on the Upper Cretaceous
stratigraphy of the Ashibetsu area.

179

Palaeontological description
Family Inoceramidae Zittel, 1881
Genus Birostrina J. Sowerby, 1821

Birostrina nipponica(Nagao et Matsumoto, 1939)
Figures 1-28, 32

1939.

1957.
1966.
1976.

Inoceramus concentricus Parkinson var.
nipponicus Nagao et Matsumoto, p.267, pI.
25 (3) figs. 1,3,6 (non pI. 24 (2), fig. 2; pI. 25(3), figs. 2, 4, 5).
Inoceramus concentricus var. nipponicus Nagao et Matsumoto; Ikegami and Omori, pI. 5,
fig. 1 ; pI. 6, figs. 1, 2.
Inoceramus nipponicus (Nagao et Matsumoto); Pergament, p. 32, pI. 2, figs. 1-4.
Inoceramus concentricus nipponicus Nagao etMatsumoto; Noda and Matsumoto, pI. Cr31, fig. 1 (non fig. 2).

Lectotype.- IGPS specimen (BV) figured
by Nagao and Matsumoto (1939, pI. 25, fig.
I), from the U gui-zawa (sometimes called
Ugoi-zawa), a tributary to the River Naibuchi(= Naibuti or Naibu), South Sakhalin,designated by Pergament (1966, p. 32).
Material.- Fairly well preserved specimens in our collections, i.e. (1) GK. H440
(BV, compo into m. with inner shell layer
partly preserved and outer shell layer on theumbonal part of LV) (Figure 1) collected by
T.M. from loc. Y216p, in the Shiyubari area,
northeast ofOyubari; (2-6) GK. H8262 (BV)
(Figure 2), H8263 (BV) (Figure 3), H8264(Figure 4), H8265 (LV) and H8266 Uuvenile
L V) (Figure 5) compo int. m. with alteredinner shell layer partly preserved, and also
ext. m. of LV of H8262, all in one and thesame nodule collected by H. Okada and T.M.
with assistance ofT. Nishida, from loc. RlOl,
about 900 m west of Kiritachi Pass on Highway 239 between Soueushinai and Kotanbetsu.
(7-33) Numerous specimens from one andthe same nodule collected by T.M. from loc.
N67-68p of the Birin-zawa, a branch of the180

Tatsuro Matsumoto and A kito Asai

Figure 1. Biroslrina nipponica (N agao et Ma tsum o to ). G K . H440 (BV) (fo rm a) fr o m loco Y 2 l 6p,
Shi yub a ri a rea (T. M. Co ll.) . Left (a ) and ri ght (b) late ra l, a nteri o r (c) a nd posterior (d) views, X I.
Duplica te fi gures (a' b' d' ) in di ss imil a r li ghts a re co mplement ary to show min o r deta ils o f th e o rn amentati o n. Th e very apex o f th e bea k in LV is des troyed. A tiny juve nil e cro ps o ut fr o m th e rock ma tri x o n th eve ntral marg in of LV . Pho tos (Fi gures 1- 20 ) by M. No da a nd S. T oshimitsu.

Ri ver N a ibuchi , deri ved fro m the sa nd y siltstone o f the fossiliferous uppermost pa rt o f
the K awa kita Group (m arked as Mh-K z), o fwhich the numbered spec imen s are GK .
H244A (LV) a nd B (RV) ; GK . H245A , B(both LV) (Figures 7, 8), C (LV) (Figure 6)
a nd 0 (LV) ; GK . H 246A (Figure 9), B, C ,0 , and E (a ll LV) ; GK . H247A a nd B (bothBV) (Fi gures 14- 16), C (RV) a nd 0 (LV)
(Figure 17), E a nd F (bo th RV) (Figures 18,19) ; GK . H 248A (LV) (Fi gure 20) , B (LV) ,C (RV) , O-G (LV) a nd H (BV) ; GK. H249A(RV) (Figure 13), B (LV) a nd C (RY) ; GK .
H 250A (LV) (Fi gure 10), B (RV) (Figure II),C (RV) (Figure 12) and 0 (LV) ; GK .
H25 1A (BV) . These are mo stly compo site
intern a l moulds, with inner shell layer partly
attached. There is a n extern a l mo uld (B' ) for
H2 50B.
In the WE Co ll ection s the fo ll ow in g ,speci-

883.

Cenomanian inoceramids - I

mens are selected: (34-36) WE. P025A (LV
and displaced RV with incomplete umbonalpart) (Figure 21), WE P026A (LV) (Figure22) and WE. P027 A (BV) (Figure 23) these three internal moulds, with a prominent
altered, dark green inner shell layer are fromloc. As 1065, the Poroko-ashibetsu, a tributary to the upper reaches of the River Ashibetsu, central Hokkaido (A. Asai Coll.); (3739) WE. P028T (LV) (Figure 24), WE
P030T (LV) (Figure 25) and WE. P031T(RV) (Figure 26) - these three composite
internal moulds, with inner shell layers adhered to some portions, are from loc. T6082a86,
Member Mh on the River Obirashibe, northwestern Hokkaido (A. Asai Coll.); (40-41)
WE. P041A (LV) (Figure 27) and WE
P042A (LV) (Figure 28), both compo into m.,with an altered, dark green inner shell layer
adhered to a considerable area, from a driftedboulder on the Tsukimi-zawa, a western tributary to the River Ashibetsu, central Hokkaido (A. Asai Coll.).
(42),GMH. 7167 (LV) (Nagao and Matsumoto, 1939, pI. 25, fig. 6), from Hakkin-zawa,
Oyubari area; (43) GMH. 7163 (LV) (Ditto,
pI. 25, fig. 3), from the Naibuchi area, South
Sakhalin (now missing); (44-46) OM. II476 (BV) (lkegami and Omori, 1957, pI. 5, fig.
1), compo int. m., covered with inner shelllayer for the major part, from loc. IK B-6(ColI. Yoshimi Yamaguchi), OM. II-478(L V) (Ditto, pI. 6, fig. 1), compo into m. with
inner shell layer partly adhered, from loc. IK
B-5 (Coil. Satosi Ikuno) and OM. II-479 (BV)
(Ditto, pI. 6, fig. 2) compo int. m. from loc IK
R-19 (Coil. T. Omori) (read anterior view for
posterior view in their explanation of pI. 6),
the above three from the lower part of Member IIc (=Mk2 of Ikegami and Omori),
Mikasa Formation of the Ikushumbets Valley, central Hokkaido. They were obtained
during the construction of the water way
tunnel from the Katsura-zawa dam to theelectric power station.
Diagnosis.- Shell small, highly inequivalve. Left valve very convex and muchlSI

elongated along the axis of growth; its umbonal part prominent, exceeding greatly thehinge line, and curving markedly inward to
somewhat prosocline beak. Right valve lessconvex than the left, with simple prosocline
beak.
Outline of shell inequilateral and considerably variable. The umbonal part of left
valve more or less narrow; the main disk
oblong to suboval or rather subround, withthe axis of growth nearly straight or gently
concave forward. Hinge line short; anterior
margin nearly straight and somewhat concave
below the umbonal part; ventral margin
more or less narrowly rounded and somewhat
asymmetric, passing to a long, arcuate posterior margin. Posterior wing very narrow or
scarcely discernible.
Surface of shell typically nearly smooth,
only with fine concentric lirae at juvenilestage which develop to concentric rings later;in addition to them, concentric subcostae
and/or major concentric undulations or weakribs may sometimes occur, with or without
somewhat deeper interspaces, at middle tolate growth-stages.
Dimensions.- See Table 1.
Observation.- This species is so variable
that at least three forms are distinguished asfollows:(a) - The slender, oval form, represented
by GMH. 7167 (one of the synthypes of
Nagao and Matsumoto, 1939, pI. 25, fig. 6)
and GK. H440 (Figure 1) from the OyubariShiyubari area, OM. 11-476 (lkegami andOmori, 1957, pI. 5, fig. 1) (Figure 32 in thispaper) from the Ikushumbets area, WE.
P041A (Figure 27) and WE. P042A (Figure28) from the Ashibetsu area. The left valve
is slender and greatly elongated along the
growth-axis. Its narrow umbilical part
broadens gradually to the suboval main partof the disk. The outline of the right valve issubtrapezoid-oblong. The shell is ornamented with fine concentric lirae on the surface orrings on some parts and later faint concentric
undulation may appear, with subcostae on

Tatsuro Matsumoto and Akito Asai

182
Table I.
Specimens
Lectotype
OK. H440/I

WE. P041A
OK. H8262/I

OK. H8263/I

WE. P026A
WE. P028T
OK. H247B/I
A
WE. P025A
WE. P030T

Measurements of Birostrina nipponica on selected specimens.

V

form

H

L

L/H

0

O/H OIL

b

b/H

-50
64.0
54.4
56.6

-34
41.2
41.2
36.1

.68
.64
.76
.64

-70
-92
-62

1.40

2.06

-17

.34

-90

1.44
1.14
1.59

2.23
1.50
2.49

20.5
-12
-21

.32
.22
.37

33.8
29.3
32.8

.70
.81
.73
.86

-53
-34
-52

1.57
1.16
1.58

2.23
1.43
2.17

27.5
30.2
41.8

23.8
23.8
24.0
23.7
21.2
-28

-33
-42

1.39
1.98
2.29

.39
.27
.38
.31

11.5
15.8

.38

-64

1.20
1.39
1.53

13.3
7.8
12.5
8.6

37.0
29.7
33.0
34.0

20.0
16.6
-17
18.4

.54
.56
.52
.54

-55
-37
-52
-60

1.49
1.25
1.58
1.76

2.75
2.23
3.06
3.26

16.3

.44

9.3
15.0

.31
.45
.50

LV

a(f3)

LV
RV
LV

a

LV
RV
LV
RV
LV

f3

f3(a)

LV

f3(a)

LV
RV
LV
LV

'Y

a
a

f3
f3
f3

'Y
'Y
'Y

.70
.67

some of their summits.
The lectotype is referable to this Ot form,
with respect to its nearly smooth shell with
faint undulations at late stage; however its
shell form is not so slender as WE. P04IA,
being intermediate between Ot and f3 forms.
As it had no register number, it is not traced
with certainty at IGPS, but we cannot statethat it is lost. It may be deposited in the oldbuilding of the IGPS at Katahira-cho. Pergament designated it as the lectotype without
inspecting the actual specimen.
(f3) - The tumid, suboval form, represented by GK. H8262 (Figure 2) and GK. H8263(Figure 3) from loco RIOI, Kotanbetsu route.
This is smaller, less high and broader, withlarger LjH, and more inflated than the form
Ot; however GjH or GjL is not very different
between the two forms. It shows rather uniform convexity on the main part of the valve.
The umbonal part of its left valve is not sonarrow as that of the form Ot and gradually~

Figures 2-5.

17.0

s

slL

a

16.0

.39

100'

'Y

0

115'

65-70'

f3 =58'f3= -60'

10.2

.43

105'

10.6

.45

105'

-100'

63'

-7.8

.47

-90'

127'

68'

65-75'

f3= -63'.38

broadens to the main part. The ventral
margin is well rounded, though somewhat
asymmetrical. The fine concentric lirae on
the shell or fine rings on the composite internal mould are as characteristic as thos~ in theform Ot. They may be better shown on theothrwise smooth young part (see Figure 5).
Concentric subcostae or narrow ribs develop
at the middle to late stages. Some of them
are accompanied by constriction-like deeper
in terspaces.
WE. P026A (Figure 22), from the Porokoashibets, and WE. P028T (Figure 24), fromthe Obirashibe, are referable to form f3 withrespect to the shell-form, but their subcostae
are weaker and the constriction is almost
undeveloped as in the form Ot. Incidentally,
the very apex of the beak is missing in these
two specimens. S. Toshimitsu (personalcommunication) has suggested that the incurved apical portion of the beak must have been
in a hollow state, while the main part of theBirostrina nipponica (Nagao et Matsumoto).

Four specimens, respresenting the form

f3, all from loc. RI01 on Highway 239 (Kotanbetsu-Soeushinai) (CoIl. T. M. and H. Okada, assisted by T.

Nishida). 2: GK. H8262; 3: GK. H8263; 4: GK. H8264; 5: GK. H8266 Uuvenile}. Different viewsof the same specimen are connected by dotted lines. The views (left lateral, right lateral, anterior, posterior
and dorsal) are self-explanatory and not repeated. The same way of illustration is kept also for Figures 6-32. Magnification for 2-4: X 1.5, 5: X 2.

883.

Cenomanian inoceramids -

I

183

184

Tatsuro Matsumoto and Akito Asai

valve was filled with mud. In one example(WE. P026A) there is a trace of later calcification in the hollowed apical portion.
(y) - The oblong form, with highly convex left valve, is represented by GK H247A, B(Figures 14-16) and many others (Figures 610) in the population of the Birin-zawa,
Naibuchi area. WE. P025A (Figure 21),
which came from the same locality as theaforementioned, WE. P026A, is also an example of the form y.
This form is small, being less than 35 mm
in H of LV. Its left valve is highly convex
not only from the beak to the ventral margin
but also from the anterior margin to theposterior, forming a summit along the majorpart of the growth-axis, which itself is nearlystraight. Thus, the left valve is narrow, erect,
highly convex and very oblong. The rightvalve is also erect, less convex and more orless oblong (elongate-subelliptical), showing
an asymmetric curvature of the ventral toposterior margin. The surface of the shell ismainly smooth, with only fine concentriclirae and rings. At more or less late growthstages, a few narrow ribs or subcostae appear
on both valves, normally with associated deep
interspaces or narrow constrictions.
Smaller examples, e.g. GK. H245C (Figure6) and WE. P027 A (Figure 23), which do notshow the distinct ribs or constrictions, asmentioned above are probably juveniles ofthis form. GK. H245A (Figures 7, S), GK.
H246A (Figure 9) and GK. H250A (Figure10), which are slightly larger than the above
two show a constriction with or without
associated riblet at or near the preserved
ventral margin. WE. P030T (Figure 25)(internal mould of LV) is certainly assigned
to the form y in view of its diagnostic shell-

form, but its ornament is very weak ascompared with GK. H247 A and B of nearly
equal size. It shows faint concentric undulations and weak, partial subcostae, like thoseof the form a. It should be noted further
that this specimen was obtained at the same
locality as WE. P031T (RV of rather a type)(Figure 26) and WE. P02ST (LV of rather {Jtype) (Figure 24) mentioned above.
On the other hand, GK. H24SA (Figure 20)
and GK. H247C and 0 (Figure 17) and probably H247E and F (Figures IS, 19) are intermediated between the forms {J and y. Incidentally GK. H247A, B and some others fromthe same locality show a particular posture ofembedding (see Figures 14, 15), which may betaphonomically explained (S. Toshimitsu,
pers. comm.).
To sum up, the three forms, which we
designate a, {J and y for convenience, do notdeserve to be ranked as subspecies, because
they occur sometimes in the same place or in
the same fossiliferous zone and because we see
occasionally intermediate or transitional
forms and also forms with mixed characters.
Comparison and discussion.- Inoceramus
concentricus Parkinson var. nipponicus
Nagao et Matsumoto, 1939 (p. 267) was evidently a mixture of several species. Birostrina nipponica (Nagao et Matsumoto) in arevised definition is described above andsome of the syntypes described and illustrated
40 years ago should be excluded from thisspecies. For example, GMH. 5965 and
GMH. 5971, figured by Nagao and Matsumoto (1939, pI. 25, figs. 2, 5), were collectedby the late Dr. Kenichiro Otatume from
Nutapomanai of Kami-hobetsu in the upper
reaches of the River Hobetsu. By courtesy ofProfessor T. Kato, one of us (T.M.) had an~
Figures 6-13. Birostrina nipponica (Nagao et Matsumoto). All the specimens from a large nodule
at loc. N67-68p, Birin-zawa, a branch of the River Naibuchi, derived from the fossiliferous Zone Mh-Kz,
South Sakhalin (T.M. Coll.), mostly representing the form y unless otherwise stated. All X 1.5, except
6: X 2 and 8': X I. 6: GK. H245C (LV); 7: GK. H245A (LV); 8: GK. H245A (above) and GK.
H245B (LV) (below); 8' : same as 8 with some other incompletely exposed specimens; 9: GK. H246A(L V); 10: GK. H250A (LV); 11: GK. H250B (RV); 12: GK. H250C (RV); 13: GK. H249 (RV), oneof the abundantly assembled specimens.

883.

Cenomanian inoceramids _ I
185

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Tatsuro Matsumoto and Akito Asai

opportunity to read Otatume's unpublishedthesis in the Institute of GMH to compare hisroute map with a result of T.M.'s field work
(Matsumoto, 1981, fig. 2). It is now evident
that the above two specimens came from theTuronian part of the section. They have a
triangular postero-dorsal wing or ear, which
is well demarcated from the inflated umbonal
part of the left valve, being clearly shown by
the actual specimen of GMH. 5971 and partly
concealed by the rock matrix in GMH. 5965.
Nagao and Matsumoto failed to sh0w the
wing in the illustration. This form is allied
to, if not identical with, Inoceramus inaequivalvis Schliiter (1877, p. 265) (= I. striatus
of Goldfuss, 1836, pI. 112, fig. 2; nonMantell, 1822).
Another example which should now be
excluded from B. nipponica is UMUT.
MM6478 (=Tk. 1-687), a syntype of Nagao
and Matsumoto (1939, pI. 24, fig. 2). It wascollected in 190 I by the late Professor Hisakatsu Yabe, when he was a graduate student.
Its locality on the label by Yabe's handwriting is "the middle course of the River
Obirashibets" (now shortend to Obirashibe or
Obira), but its provenance is not exactly
known. As small ammonites referable to
Desmoceras (Pseudouhligella) cf. japonicum
Yabe are in the rock matrix, a Cenomanianage may be suggested. The left valve has aflat postero-dorsal wing; the inflated umbonal part inclines abruptly and steeply tothe flat wing but the fine concentric rings
continue from the main part of the disk to thewing. The umbo is somewhat (but notstrongly) incurved and the apex of the beak isacutely pointed. The ornament on the composite internal mould consists of numerous,
fine and even, concentric rings which are at

middle to late growth-stages combined withregular, weak to moderate concentric ribs.
The hinge line is nearly a half of the shelllength and the valve is moderately (notstrongly) convex. This specimen is referable
to Inoceramus pictus minus Matsumoto(1989, p.19) (see also Kauffman, 1977, p.
174).
Birostrina nipponica of the Cenomanian
age is certainly similar to B. concentrica(Parkinson) of the Albian, but how these two
species are related has yet to be worked out.
Kauffman (l978a, p. iv.2-iv03) wrote his preliminary observation on the British material,
expecting successive change with stratigraphic
sequence from the upper Lower Albian to thehighest Upper Albian. The earliest form
which he called B. concentrica, n. subsp. A,
from the upper part of the Zone of Douvillieiceras mammilla tum (uppermost Lower
Albian) is described as "a small, highly convex, narrow and very elongated along theheight axis (nearly tear-drop shaped)" andseems to be similar to the form ex of B.
nipponica in shell-form. According to
Kauffman, it has "an anterior sulcus and a
few coarse, widely and unevenly spaced, concentric rugae". Therefore, it seems to bequite dissimilar to our form ex with respect tothe ornamentation. Anyhow, it is difficult tofully understand the subspecies A, B, C, D
and subsp. brasiliensis (White) from England,
without full descriptions and adequate illustrations.
Pending the issue of Kauffman's monograph, we should compare B. nipponica withthe typical form of B. concentrica, that is B.
concentrica concentrica in the sense ofKauffman (l978a, p. iv03). Although Parkinson's (1819, p. 59, pI. 1, fig. 5) holotype~
Figures 14-20. Birostrina nipponica (Nagao et Matsumoto). Some other specimens from a large
nodule at loco N67-68p, Birin-zawa of Naibuchi area, Zone Mh-Kz, South Sakhalin (T. M. ColI.)(continued from Figs. 6-13), all X 1.5. 14: GK. H247A (BV) (above) and B (BV) (below), showing thelateral view of RV and posterior view of LV; 15: Ditto, lateral view of LV of H24 7A and dorso-Iateral viewof LV of H247B; 16: GK.H247B, normal lateral view; 17: GK. H247C (RV) (above) and D (LV)(below), both somewhat distorted secondarily; 18: GK.H247E(R V) (above) and F (RV) (below), the latter
somewhat inclined to the posterior; 19: GK.H247F, normal lateral view; 20: GK: H248A (L V), intermediate form between f3 and y.

883.

Cenomanian inoceramids -

I

187

188

Tatsuro Matsumoto and Akito Asaicannot be traced (Woods, 1911, p. 267), thespecimens from the Gault at Folkestone illustrated by Woods (1911, pI. 46, figs. 1-7) are
regarded as representing the typical form of
B. concentrica, which is said to range fromthe upper half of Middle Albian to the basal
Upper Albian (cristatum nodule bed)
(Kauffman, 1978a, p. iv.3). One of us (T.
M.) once looked at these specimens of Woods
at Sedgwick Museum and British Museum(Natural History). This typical form of B.
concentrica has a rather evenly convex androunded main part of the valves, and is somewhat similar to the form f3 of B. nipponica,
but there are some differences. In the left
valve of the former the umbonal part is narrow and broadens abruptly to the main part,
whereas in that of the latter the umbonal part
gradually broadens to the main flank. Generally the former is more oblique than thelatter. In both forms the young part is nearlysmooth, showing only fine and dense concentric rings. On the middle to late part, weak
subcostae may appear occasionally and irregularly in the former, whereas subcostae
develop more frequently in the latter, some ofwhich are raised to narrow ribs and accompanied by constrictions of deep interspaces. The forms a and y of B. nipponica
are undoubtedly different from the typicalform of B. concentrica.
Pergament (l966, p. 32, pI. 2, figs. 1-4) described some examples of B. nipponica fromthe Cenomanian of the Koryak-Kamchatka
region, Far East of the USSR. They seem tobe generally referable to the form f3 in thispaper, although some inclination towards theform a is shown by those with weak ornamentation (pI. 2, figs. 1,2) and that towards
the form y by another (pI. 2, fig. 3). However, without inspecting the actual specimens,
we cannot confirm these identifications. The
same remarks are applied to the incompletely
preserved specimens from the Cenomanian of
the Naibu (Naibuchi) area of Sakhalin,
which Pergament (l966, p. 30, pI. 1, figs. 1- 4)
described under "Inoceramus cf. concentricus".
On numerous but often incompletely
preserved specimens from the Albian of the
Antarctic Peninsula region, Crame (1980,1985) has fully describd Birostrina concentrica. The outline of the left valve is sovariable that he distinguished at least threemain types. The first of these (represented byfigs. 5, 6 in Crame, 1985, pI. 59) may be similar to the slender form (a) of B. nipponica,
but the former is more oblique and has an
expanded, postero-dorsal, wing-like flat area.
The second, pear-shaped type (Crame, 1985,
pI. 59, figs. I, 7, 8) may be somewhat similar
to the form f3 of B. nipponica in the convex,
subrounded main part of the valve, but theleft umbonal part of the latter is not sonarrow as that of the former, showing gradualbroadening (i.e. increase of LjH) toward themain part. The third, squatter type of Crame(l985, pI. 59, fig. 10) has no counterpart in B.
nipponica, but some variety of our form f3
could be similar to it, at least superficially.

~
Figures 21-28. Biros/rina nipponica (Nagao et Matsumoto). Examples of various forms in the WE
Collections. 21: WE. P025A (form y) (LV; with a deficient RV attached in perpendicular to LV), fromloco As 1065 of the Poroko-ashibetsu, tributary on the west side of the Ashibetsu Valley (A. A. Coll.), X 1.2.
22: WE. P026A (LV) (form /3 with some inclination to a), from the same locality as above (A. A. Coll.), X
1.2. Note that the apex of the incurved beak was destroyed away. 23: WE. P027 A (BV) Uuvenile,
probably intermediate form between /3 and y), from the same locality as above (A.A. Coll.), X 1.2. 24:
WE. P028T (LV) (from /3 somewhat inclined to a) from loco T6082a86, left bank of the upper main courseof the River Obirashibe (A.A. Coll.), X I. The figure on the left side above is in normal lateral view, thaton the left side below in dorsal-lateral view. The apex of the beak was again destroyed away. 25: WE.
P030T (LV) (form y), from the same locality as above (A.A Coll.), X I. 26: WE. P031T (RV) (form a or/3), from the same locality as above, X I. 27: WE. P04lA (LV) (form a), from a boulder at loco As3028 on
the Tsukimi-zawa, Ashibetsu Valley (A.A. Coll.), X I. 28: WE. P042A (LV)Uuvenile of form a), from thesame locality as above (A.A. Coll.), xO.9. Photos (21-23) by M. Noda; others by A. Asai.

883.

23

Cenomanian inoceramids -

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190

Tatsuro Matsumoto and Akito Asai

There is no example in the specimens illustrated by Crame which is comparable withthe form y of B. nipponica, although an
example of the right valve (Crame, 1985, pI.
59, fig. 13) seems to be somewhat similar to,
but not quite identical with, some right valves(e.g. RV of GK. H247A, Figure 14 above;
GK. H250A, Figure 12 of this paper) of theform y.
According to Crame (1985, p. 508) "norigid morphologic or stratigraphic divisions
can be placed between the three types and it isalmost certain that they intergrade". The
same statement can be applied to the threeforms in our material. There is, however, noidentical forms between the populations of
the Antarctic Albian and those of theJapanese Cenomanian (precisely speaking
Middle to Upper Cenomanian). Likewise,
there are no similarities between the populations of the British Albian and those of theJapanese Cenomanian.
Birostrina concentrica itself is long ranging.
According to Dhondt and Dieni (1988, p. 24),that species ranges from the Douvilleiceras
mammilla tum Zone (upper Lower Albian) to
the Upper Albian (Hysteroceras varicosum
Subzone included) and shows world-wide
distribution.
Taking all the characters into consideration, as well as the separation in geologicaloccurrences, we are inclined to distinguish B.
nipponica as a species independent of B.
concentrica, although the phylogenetic relationship between the two species has yet to beworked out.
Birostrina tamurai Matsumoto et N oda(1986, p. 411, pI. 81, figs. 1-6; pI. 82, figs.l3; pI. 83, figs. 1-3; pI. 85, figs. 4-5), from theMiddle Cenomanian of Kyushu and Hokkaido, is similar to B. nipponica in shell-form
but distinguished in having a radial sulcus on
the posterior part and stronger but often irregular ribs at more less late growth-stages. On
the average B. nipponica is less oblique thanB. tamurai, although the variations of thetwo species in this regard may overlap tosome extent and the secondarily deformed
specimens should be excluded from thiscomparison.
Inoceramus concentricus var. costatus
Nagao et Matsumoto (1939, p. 270) needs
careful restudy. Its lectotype was designatedby Tamura and Matsumura (1974, p.49) as
UMUT. MM6480 (= Tk. 1-690) (Nagao andMatsumoto, pI. 24, fig. I). It was obtained in1935 by T.M. at loco Ikl2 (precisely 12-12,
southern one of the two points at 12 on theroute map of fig. I in Nagao et al., 1938),
from the middle part of Member lId, i.e. theupper part of the tripartite Mikasa Formationon the eastern wing of the Ikushumbets anticline. The bed at Ik 12-2 is one of thesandstone beds with intercalated layers ofconglomerate rich in Glycymeris and slightly
below the zone characterized by Inoceramus
hobetsensis Nagao et Matsumoto. It is somewhat above the predominant tuffite, a key
marker of the Lower Turonian Zone of
Mytiloides mytiloides in central Hokkaido.
Therefore, the type locality (Ik-12) is evidently assigned to the Turonian, probably
rather low in the Middle Turonian.
The lectotype of var. costatus itself is somewhat inequivalve, but its left umbo is not soprominent and not so strongly incurved asthat of B. nipponica and its right valve ismoderately convex. It is ornamented withconcentric rings and subcostae which areclearly coarser than those of B. nipponica.
Thus it represents, together with similar specimens from various areas of Hokkaido, adistinct species, Inoceramus costatus Nagao
et Matsumoto, which is independent of B.
nipponica and B. concentrica. A faint posterior radial depression is descernible on theleft valve of the lectotype, although it is not
so distinct as that of B. tamurai. The left
umbo of I. costatus is not so prominent andincurved as that of B. tamurai and the subcostae of I. costatus is more uniform and notso irregularly strong as those on the late partof B. tamurai. One of us (T.M.) presumes
that I. mametensis Pergament (1971, p. 44, pI.

883.

Cenomanian inoceramids - I

4, figs. 2, 3; pI. 5, figs. 2~5; pI. 7, figs. 2, 3)
could be a junior synonym or a subspecies ofI. costatus. More precise description of I.
costatus based on a large number of specimens from Japan is now in preparation by M.
Noda.
Matsumoto (1977, fig. I,; also fig. I in
Takayanagi and Matsumoto, 1981) once set
the Zone of Inoceramus nipponicus in theupper Lower Cenomanian in parallel with
the Zone of Mentelliceras japonicum, but thiswas a mistake. It is now evident that I.
nipponicus in those charts is mostly I. tenuis
Mantell, which has a less prominent andmuch less incurved left umbo and less narrowly rounded ventral margin than B. nipponica(see Matsumoto et al., 1987).
Occurrence.- The lectotype was collectedfrom the Ugui-zawa, a tributary to the River
Naibuchi. This stream runs maily along
Zone Mh2 (i.e. the Turonian Zone of Inoceramus hobetsensis; see geological map by
Matsumoto, 1942, pI. 5), but several small
branches come from the ridge formed bysandstones of the upper part of the Kawakita
Group across the Cenomanian fossiliferous
zones of Kz-Mh and Mho. As this specimen
belongs to the old collections of IGPS, its
exact provenance is hardly decided, but thelabel indicates No. II Group, which is the late
Dr. Shimizu's (1935, p. 169) division andCenomanian on the evidence of ammonites.
From the position.in the stratigraphic section,
Mho is probably referable to the upper Cenomanian and Kz-Mh the lower Upper or upper
Middle Cenomanian.
GMH. 7167, an example of the form awhich was called the typical form by Nagao
and Matsumoto (1939), came from the upper
reaches of the Hakkin-zawa, where Cenomanian strata are extensively exposed, butwhat part of the Cenomanian is not precisely
recorded.
OM. II-476, figured by Ikegami and Omori(1957), is one of the best specimens of theform a. This and two other specimens werecollected from the lower part of Member lIc

191

of the Mikasa Formation in the Ikushumbets
valley, i.e. the lower Upper Cenomanian on
the evidence of Eucalycoceras pentagonum(Jukes-Browne) described by Matsumoto( 1975).
WE. P041A and WE. P042A (both form a)were in a drifted nodule at loc. As 3029 in the
Tsukimi-zawa of the Ashibetsu valley.
From the lithological character and the location of As 3029, their provenance is inferredas the middle part (silty fine-grained sandstone to sandy siltstone) of the Mikasa Formation, i.e. upper part of the Cenomanian(For the stratigraphic section across the western wing of the Ashibetsu syncline, see Matsumoto and Okada, 1973, fig. 10, although it isalong the Hachigatsu-zawa, north of the
Tsukimi-zawa.). The loc. As 3029 is stratigraphically about 50 m higher than the loc.
As 3211 ofTsukimi-zawa, where several specimens of Calycoceras (Newboldiceras) sp. wereobtained along with Desmoceras (Pseudouhligel/a) japonicum.
GK. H8262-H8266, which represent theform 13, were in a nodule from the mudstoneof loc. R 10 1. on highway 239 (between
Kotanbetsu and Soeushinai), which is stratigraphically somewhat (about 60 m) higher
than the loc. R100, where Calycoceras (Newboldiceras) sp. was found, and is assigned
tentatively to the lower part of the Upper
Cenomanian (see Matsumoto and Okada,
1973, fig. 8).
Loc. As. 1065 of the Poroko-ashibetsu in
the Ashibetsu valley, where WE. P025A.
P027A (both y-form) and WE. P026A (rather
f3-form) were obtained, is referable to somewhere in the middle to upper part of the
Cenomanian, for it is slightly higher than thelayer where Desmoceras (Pseudouhligel/a)japonicum occurs commonly and considerably below the layer with Mytiloides
mytiloides (Mantell), although the minor
gelogic structures are somewhat complicatedin the outcrops along this stream.
Loc. T6082a86, where WE. P028T (form 13
with some inclination to a), WE. P030T

Tatsuro Matsumoto and Akito Asai

192

(form y) and WE. P031T (RV of form a?)were obtained, is a cliff on the left side of themeandering main course of the River Obirashibe, 100 m west of loco MH390 of Tanaka(1963, map II), mudstone of the Member Mh,
Upper Cenomanian.
Loc. N67-68p, a large nodule in the Birinzawa, a branch of the River Naibuchi (South
Sakhalin), in which numerous specimens of
the form y and some of form f3 were
contained, must have been derived from thefossiliferous, silty sandstone, marked Mh-Kz(Matsumoto, 1942) at the top of the Kawakita
Group. This is either the upper part of the
Middle Cenomanian or lower part of theUpper Cenomanian, from its stratigraphic
position (no acanthocerati-d ammonite has
been found there).
To sum up, B. nipponica is early Late
Cenomanian and possibly also late Middle
Cenomanian in age, on the evidence of therepresentative specimens described in thispaper. To know the true range, further
material from more sections in various areas
should be investigated.
The three forms, called a, f3 and y, occur
predominantly in particular lithofacies ofdifferent places, although there may be intermingling to a minor degree. This fact suggests that each of them may have adapted to aparticular type of environment (S. Toshimitsu, personal discussion with T.M.). To
confirm this idea satisfactorily, further analyses will be necessary.

Birostrina aff. nipponica(Nagao et Matsumoto, 1939)
Figures 29-3\

Material.- GK. H22l (Figure 29) (LVwith shell adhering to major part) from loco
N309h, left bank of the River Naibuchi immediately south of the entrance to the Yunosawa, Zone Mho of Matsumoto (1942) (T.
M. Coll.); GK. H8276A, B (Figure 30) (LV)and C (BV but half concealed by rock matrix)(comp. int. m., with inner shell layer adhering
to some portions), from loco Ik2020e, gorge of
the River Pombets a tributary to the River
Ikushumbets, central Hokkaido (T.M. ColI.) ;WE. P029T (Figure 31) (LV, compo into m.,with inner shell layer adhering partly), fromloco T6054a84, right side of the River Obirashibe (see Sekine et al., 1985, fig. 3.2), northwestern Hokkaido (ColI. by Y. Tanaka, S.
Ago and A. Matsuzawa).
Description.- Shell small and inequivalve.
Left valve highly convex, with much incurved
and prosocline umbo and beak; axis of
growth sigmoidal, with forward convex curvature on the main or late part of the valve;
outline obliquely suboval, with somewhat
expanded postero-ventral part which tends tobe flattened; anterior margin slightly concave blow the beak and very broadly convex
in the main part, passing to the asymmetrically rounded ventral margin; posterodorsal margin gently concave, forming an
obtuse angle with the postero-ventral margin.
Right valve less convex than the left andsubtrapezoid-suboval in outline.
Surface of the shell marked by fine concentric striae. The internal mould at firstsmooth and then ornamented with concentricrings which correspond to the interspaces ofthe striae on the shell surface. Concentric
subcostae or narrow and weak ribs may
develop at more or less late growth-stage. A
very faint radial depression may be discernible in some specimens (GK. H8276 A andC).
Comparison. - Although B. nipponica isconsiderably variable and includes several
forms as described above, we exclude thisparticular form from that species. It isindeed somewhat similar to the form f3 of B.
nipponica, but clearly distinguished by its
sinuous growth-axis which curves obliquely
to the posterior with growth, forming anteriorly convex curvature on the main part of thevalve.
This form looks somewhat similar to B.
concentrica brasiliensis (White) (1887, p.56,

883.

Cenomanian inoceramids -

I

193

29

c
Figures 29-31. Biroslrina aff. nipponica (Nagao et Matsumoto). 29 : GK. H221 (LV), from loc. N309h, Zone
Mho, Naibuchi valley (T.M. Coll.), x 1.3. 30 : WE. P029T (LV), from loc. T6054a84, Member Mh, Obirashibevalley (collected by Y. Tanaka, S. Ago and A. Matsuzawa), X 1.5. 31: GK. H 8276A and B (both LV), from loc.
IK2020e, Pombets Gorge, lower part of Mikasa Formation, lkushunbets valley (T.M. Coll.), x 1.2. a: lateral viewof H8276A and posterior view of H8276B ; b: lateral view of partly concealed H8276B, with a postero-dorsal portionof H8267A at the right corner; c : anterior view of H8276A ; d : anterior view of H8276B on the left and dorsallateral view of H8276A. Photos (21-23) by M. Noda.

Tatsuro Matsumoto and Akito Asai

194

Figure 32. Birostrina nipponica (Nagao et Matsumoto). OM. 11 - 476 (BV) (form a) , collected by
Yoshimi Yamaguchi from loc. IK 8 - 6 of the water-way tunnel from the Katsura-zawa dam to the station of
the electric power, Ikushumbets valley (reproduced from Ikegami and Omori, 1957, by permission) . Scalebar: 10 mm.
Table 2.
Specimens
GK. H221

Measurements of Biros/rina aff. nipponica on selected specimens.
V

H

L

Lj H

G

Gj H

Gj L

b

bj H

LV

32.0

24.0

.75

52.0

1.63

2.2

13.4

.42

GK. H8276A

LV

36.0

25.6

.71

53.0

1.47

2.1

16.0

.44

WE. P029T

LV

36.5

- 26

.71

55 .0

1.51

2.1

16.5

.45

pI. 3, figs . 11,12; Maury, 1937, pI. 8, figs . 9,
10, 13; Kauffman, 1978b, pI. I, figs. II , 16),from the Middle Albian of Brazil , South
Africa and elsewhere, but its left beak is not
so strongly prosogyrous as in that subspecies
and its occurrence is much separated in geological age. Therefore, the similarity may be
due to a homeomorphy .
Dimensions.- See Table 2.
Occurrence.- Loc. N309h, Zone Mho,
sandy siltstone in the lower part of the Miho
Group, upper part of the Cenomanian.
Loc. Ik2020e, calcareous nodule in thegreenish grey fine to medium-grained sand-stone in the lower part of the Mikasa Formation on the western wing of the Ikushumbets
anticline. It is slightly above the layer inwhich fragmentary pieces of Calycoceras(Newboldiceras) sp. are intermingled with
abundant trigon ian shells, probably upper
part of the Middle Cenomanian.
Loc. T6054a84, mudstone of the Member
Mh (Tanaka, 1963) of the Obirashibe valley,
upper part of the Cenomanian .
The stratigraphic range of this form has yet
to be worked out by the study of morematerial from various sections.

883.

Cenomanian inoceramids - I

Acknowledgements

We wish to thank Professor Hiromichi
Hirano for his pertinent supervision to one ofus (A.A.) and for generous help in various
ways to both of us; also Drs. Masayuki N oda
and Seiichi Toshimitsu for fruitful discussions and for kind help in taking photographsof the GK and some of WE specimens.
We owe much to the persons who assisted
us in the field works. Their names are indicated in the item Material. Thanks areextended to Dr. J.A. Crame who has kindy
read our first draft, giving valuable suggestion
and information, and also to the late Dr. J.B.
Reeside, Jr. and Dr. Peter Bengtson who supplied to one of us (T.M.) with Brazilian
papers which were inaccessible in Fukuoka.
Miss Saiko Nitani assisted us in preparing thetypescri pt.
References cited
Crame, J.A., 1980: The occurrence of the bivalve
Inoceramus concentricus on Dundee Island,
Joinville Island Group. Bull. Br. Antarct.
Surv., no. 49, p. 283-286.
- - , 1985: Lower Cretaceous inoceramid bivalvesfrom the Antarctic Peninsula region.
Palaeontology, vol. 28, part. 3, p.475-525, pis.
54-61.
Dhondt, A.V. and Dieni, I., 1988: Early Cretaceous
bivalves of eastern Sardinia. Mem. Sci. Geol.,
Univ. Padova, vol. 40, p. 1-97, pis. 1-13.
Goldfuss, A., 1836: Petrefacta Germaniae. pt. 2, p.
106-118, pis. 108-115, DUsseldorf.
Ikegami, S. and Omori, T., 1957: On the Mikasa
Formation in the Katsurazawa dam site area of
the Ikushumbetsu River, Mikasa, Hokkaido.
Jour. Hokkaido Gakugei Univ., Sec. lIB, vol. 8,
no. I, p. 70-89, pis. 1-14 (1).
Kauffman, E.G., 1977: Middle Cretaceous Euramerican and North Pacific Inoceramidae.
Palaeont. Soc. Japan, Spec. Pap., no. 21, p. 169212 ..
- - , 1978a: British Middle . Cretaceous inoceramid
biostratigraphy. Ann. Mus. d'Hist. Nat. Nice,vol. 4 (for 1976), p. ivol-iv oI2.
- - , 1978b: South African middle Cretaceous
Inoceramidae. Ibid., xvii oI-xvii 6.
Mantell, G., 1822: Fossils of the South Downs; orillustrations of the geology of Sussex. 320 p.,
0195

42 pis., London.
Matsumoto, T., 1942: Fundamentals in the
Cretaceous stratigraphy of Japan. Part I.
Mem. Fac. Sci., Kyushu Imp. Univ., Ser. D,
Geol., vol. I, p. 130-280.
- - , 1943: Ditto. Parts II and III. Ibid., vol. 2,
no. I, p. 97-237.
- - , 1975: Additional acanthoceratids from Hokkaido (Studies of the Cretaceous Ammonites
from Hokkaido and Saghalien-XXVIII). Ibid.,
vol. 22, no. 2, p. 99-163, figs. 1-18, pis. 11-23.
- - , 1977: Zonal correlation of the Upper
Cretaceous in Japan. Palaeont. Soc. Japan,
Spec. Pap., no. 21, p.63-74.
- - , 1981: The specimens of Inoceramus (Bivalvia)
donated to the Kitakyushu Museum of Natural
History. Bull. Kitakyushu Mus., Nat. Hist.,
vol. 3, p. 15-26, pis. 2-5 (J).
- - , 1989: Some inoceramids (Bivalvia) from the
Cenomanian (Cretaceous) of Japan.- V. A
world-wide species Inoceramus pictus Sowerby
from Japan. Trans. Proc. Palaeont. Soc.
Japan., N.S., no. 153, p. 12-24, 10 figs.
- - , Asai, A. and Hirano, H., 1987: Ditto. - II.
Three species from Hokkaido, well known
abroad but hitherto undescribed in Japan.
Ibid., no. 147, p. 146-164, 8 figs.
- - , - - , - - and Noda, M., 1988: Dillo. III. Three species occurring commonly in the
North-west Pacific region. Ibid., no. 149, p.
378-395, 9 figs.
- - and Noda, M., 1986: Ditto. - I. New or little
known four species from Hokkaido and Kyushu.
Ibid., no. 143, p. 409-421, pis. 81-85.
- - and Okada, H., 1973: Saku Formation of the
Yezo geosyncline. Sci. Repts., Dept. Geol.,
Kyushu Univ., vol. II, no. 2, p. 275-309 (J).
- - and Tanaka, K., 1988: Some inoceramids(Bivalvia) from the Cenomanian (Cretaceous) ofJapan. - IV. An interesting new species from
Hokkaido. Trans. Proc. Palaeont. Soc. Japan,
N.S., no. 151, p. 570-581, 15 figs.
Maury, c.J., 1937: 0 Cretaceo de Sergipe.
Monografia Servo Geol. Min. Brasil, no. II (for1936), 283+xxxv pp., 28 pis.
Nagao, T. and Matsumoto, T., 1939: A monographof the Cretaceous Inocramus of Japan. Part I.
Jour. Fac. Sci., Hokkaido Imp. Univ., Ser. 4,
vol. 4, nos. 3-4, p. 241-299, pis. 23-34.
- - and - - , 1940: Ditto. Part II. Ibid., vol. 6,
no. I, p. 1-64, pis. 1-20.
- - , Saito, R. and Matsumoto, T., 1938: Preliminary note on the succession of Cretaceous strata
along the course of the Ikushumbets, Hokkaido.
Jour. Geol. Soc. Japan, vol. 45, no. 533, p.259263.
Noda, M. and Matsumoto, T., 1976: Mesozoic mol-

Tatsuro Matsumoto and Akito Asai

196

Takayanagi, Y. and Matsumoto, T., 1981: Recent
advances in the Cretaceous biostratigraphy ofJapan coordinating mega- and micro-fossils.
Recent Progress Nat. Sci. Japan, no. 6, p. 125138.
Tamura, M. and Matsumura, M., 1974: On the age ofthe Mifune Group, central Kyushu, Japan.
Mem. Fac. Educ., Kumamoto Univ., no. 23, Sec.
1 (Nat. Sci.), p.47-56, pI. 1.
Tanaka, K., 1963: A study on the Cretaceous sedimentation in Hokkaido, Japan. Rept. Geol.
Surv. Japan, no. 197, 122 pp., 2 maps, 3 pis.
White, C.A., 1887: Contributions to the paleontology of Brazil; comprising descriptions ofCretaceous invertebrate fossils, mainly from theProvinces of Sergipe, Pernembuco, Para andBahia. Archiv. Mus. Nac. Rio. de Janeiro, vol.
7, v + 273 pp., 27 pIs. (originally published in
1887; reprinted in 1888).
Woods, H., 1911 : A monograph of the Cretaceous
Lamellibranchia of England. vol. 2, part. 7,
Palaeontogr. Soc. Monogr. for 1910, p.261284, pIs. 45-50.
(J): in Japanese with English abstract or brief
explanation. (R): in Russian.

luscan fossils of Japan 4 (Cretaceous Inoceramus). Atlas of Japanese Fossils, no. 45, Cr.
3I-Cr.36, Tsukiji-Shokan, Tokyo (1).
Parkinson, J., 18 I 9: Remarks on the fossils collectedby Mr. Phillips near Dover and Folkestone.
Trans. Geol. Soc. London, vol. 5, p. 53-59.
Pergament, M.A., 1966: Zonal stratigraphy andInoceramus of the lowermost Upper Cretaceousof the Pacific coast of the USSR. Trans. Acad.
Sci. USSR, Geol. Inst., vol. 146, 83 pp., 36 pIs.
(R).

- - , 197 I : Biostratigraphy and Inoceramus of Turonian-Coniacian deposits of the Pacific regionsof the USSR. Ibid., vol. 212, 202 pp., 73 pis.
(R).

SchlUter, c., 1877: Kreide-Bivalven zur Gattung
Inoceramus. Palaeontographica, vol. 24, p.
249-288, pis. 36-39.
Sekine, H., Takagi, A. and Hirano, H., 1985: Biostratigraphical study of the Upper Cretaceous of
the north-east part of the Obira area, Hokkaido.
Fossils (Palaeont. Soc. Japan), no. 38, p. 1-15 (J).
Shimizu, S., 1935: The Upper Cretaceous cephalopods of Japan, Part I. Jour. Shanghai
Sci. Inst., Sec. 2, vol. I, p. 159-226.

Aikawa ffiJ II , Ashibetsu P"lJlJ, Birin-zawa ViIi 1* iR, Hachigatsu-zawa j\}j iR, Hakkinzawa s~iR, Hobetsu m~lj, Ikushumbets (Ikushunbetsu) ~*~Ij, Kami-hobetsu J:
m~lj, Katahira Jt:>f, Katsura-zawa i'iiR, Kawakita JII:Jt, Kiritachi ~:l1:, Kotanbetsu~ft~lj, Miho ~~, Mikasa .:::1't, Naibuchi (= Naibuti or Naibu) P'lmJI, Nutapomanai
3< !J ;f,...,. T -1, Obira,J\f, Obirashibe (Obirashibetsu) 'J\f~, Oyubari *5~.It Pombets (Ponbetsu) ~~Ij, Poroko-ashibetsu 1I!!\\.y p"~Ij, Sakhalin -1j- /\ ~ /', Shiyubari :/.::z.
'7 /~ ~ (:±.55N), Soeushinili ;mtt-P'l, Tsukimi-zawa }j Je.iR, Ugui-zawa (Ugoi-zawa) ?
(' l 'iR, Yu-no-sawa i'YiO)iR.
:Jtw~· -1j-/\ ~ /'i£s:E!Uc-tc /...,. =-7 /'MO)-1 / -tc '7 A A~ - I. Birostrina nipponica(Nagao et Matsumoto): Inoceramus concentricus var. nipponicus Nagao et Matsumoto,I 939 fi!E~b:TIj.l§l!i-C, -to):l!!!'l!l:ffif~O)gcfiJlv::' {, ~b:~ -:,[':0 4-@]~~M (, 110:Z. "'CIlJ~W
L t.:o altlEfi fi Birostrina v::'~ -t 91.1:, 7 Iv e: 7 /,0) B. concentrica (Parkinson), *flM'tj:t{fll0) B. tamurai Matsumoto et Noda c fi~~1j ~.:h 9 m:J\.b~~ L <, 1l!1!:J: 3 ~ (a, (3,y) v::' 5t vt-c 1} '" O)%'l!l:~gC L ko L 1.1' L 3 ~fiW~-C'itJi1jt-t 9 v 51 r !J -1 7°fi a ~t":b~(3 ~v::.1jtITO)m«i]~~-t 0 ~W L t.:~*fiJ:{fll-tc / ...,. =- 7 /' O)r{fllo)b~~H 'b~, -{flli"U~~tj:t{fllO)J:{fllv::.bt.: 9 'iiJ1l~i1:b~~ 9 3 ~O)i£t±lffif~v::'~fHn 'b~, 1=.,~,~~v::'::6''fO)~b:~",:>
t.:O) 1.1, (, L.:h tJ:lvOI<:O) l. concentricus nipponicus tj:t v::.fi I. tenuis Mantell, I. pictus
minus Matsumoto, B. aff. nipponica (*)cl<:~v::'~c)Zn ~ o v::. 7- = - p =- 7 /'0) I. inaequivalvis SchlUter v::.)liJ~O){'O)~:Z.-2;i.:h-Cl't.:of0*ji~~ ·l:lt#Ij.I§A
0

0

0

0

'0

Trans. Proc. Palaeont. Soc. Japan, N.S., No. 155, pp. 197-21 1,7 Figs., September 30, 1989

884. DINOFLAGELLATE CYST ANALYSIS OF HOLOCENE SEDIMENTS
FROM LAKE HAMANA IN CENTRAL JAPAN*
NATSUHIKO KOJIMA
Department of Biology, Faculty of Science
Osaka City University, Osaka 558

Abstract. Dinoflagellate cysts occur in the Holocene sediments of Lake Hamana,
Central Japan. The cyst assemblages are dominated by Brigantedinium spp., Selenopemphix quanta and Seleno. hamanaensis of the Peridinioid Lineage, and Polykrikos schwartzii, Poly. kofoidii and Pheopolykrikos hartmannii of the Gymnodinioid Lineage. A few
cysts of the Gonyaulacoid and Tuberculodinioid Lineages are also present in the samples.
Six dinoflagellate cyst assemblage zones are established based on differences of species
composition. From the cores of central Lake Hamana, environmental changes from stableinner bay to brackish-water lake and then to freshwater lake and finally to brackish-waterlake were recorded in the cyst composition. One new species, Selenopemphix hamanaensis,
and four cysts are described.
Key words.

Dinoflagellate cyst, Holocene, paleoenvironment, Lake Hamana.

the New Kansai International Airport in
Osaka Bay. These has been only one workon cysts in Holocene sediments. Matsuoka(l987a) discussed the Holocene paleoenvironment based on dinoflagellate cyst assemblages
in core samples from Kawasaki City.
This paper describes the Holocene dinoflagellate cyst assemblage and discusses paleoenvironmental changes in Lake Hamana.

Introduction

Studies of Quaternary dinoflagellate cysts
have been carried out mainly in the North
Atlantic region since the 1960's. Initially,
the majority of these studies were descriptive
works (e.g., Rossignol, 1961, 1962); later
studies focused on comparisons of the Quaternary assemblages with modern cyst distributions (e.g., Harland, 1977; Reid and Harland, 1977). More recently, dinoflagellate
cysts have been useful in paleoenviromental
studies (e.g., Dale 1985; Long et 01., 1986)
and Harland (1988) suggested the possibilityof paleoclimatic analysis using such cysts.
In Japan, there have been only a few works
on Quaternary cysts. Matsuoka (1976) described palynomorphs including dinoflagellate cysts from the Pleistocene Osaka
Group. Harada (1984) carried out apaleoenvironmental study based on
dinoflagellates in the samples obtained from

Samples
Samples were collected from two locations
as shown in Figure I. These core samples
were taken to investigate environmental changes by a research team from Shizuoka University (Representative: N.Ikeya). Thesesamples were taken with a thin-walled sampler and triple-tube sampler.
85H-I (Location: 34°45'59"N, 137°35'31"
E)

This site is situated in the northern part ofLake Hamana and has the deepest water(about -12 m) (Figure I). The core samples"Received December 26, 1988; revised manuscript
accepted August I, 1989.
197

Natsuhiko Kojima

198

Pacific Ocean
Figure 1.

Location of coring sites, 85H-l and 85H-2.

were obtained from a depth of 1.45-16.75 mfrom the bottom of the lake.
The sediments in this core mainly consist of
homogeneous gray silt and the geologic ages
were confirmed by tephra intercalated at threehorizons (Figure 2). These tephra were Os awa scoria (-6.49- -6.55 m, ca. 3,000 y.B.P.),
Kawagodaira pumice (- 6.56 - - 6.58 m, ca.
3,000 y.B.P.) and Kikai-Akahoya tephra (14.18- -14.32 m, ca. 6300 y.B.P.) in descend-

ing order (Ikeya et al., 1987). The sedimentation rate at this site is calculated to beapproximately 0.22 cm/year based on theseages.
85H-IB (Location: about I m north of
85H-l)
These samples correspond to the loss in theupper part of core 85H-1. The supplementary core ranges -0.32- - 1.22 m from thebottom of the lake. They consist mainly of

884.

Om

85H-2

85H-I

Holocene dinoflagellate cysts

85H-18

10

199

3.09
5500± 160
Gastropoda
4.125190± 110
Gastropoda
4.385780± 120 Phytoclast
29.84
7470± 130
Gastropoda
36.61
9720± 130
Pelecypoda
Only one tephra bed was recognized as
Kikai-Akahoya tephra ( - 8.98 m, ca. 6,300 y.
B.P.) in this core (Ikeya et al., 1987).

20

Methods30

s i 1tsandy sillsand
40c. sandalternating layersof si It and sand

LEGEND

Figure 2. Columnar section of the samplingsites. Os: Osawa scoria, Kgp: Kawagodaira pumice, Ah: Kikai-Akahoya tephra (adapted from Ikeya
et al. 1987).

dark greenish-gray silt laminated with blackand light gray silt. They contain shell fragments and give off a hydrogen sulfide (Ikeya
et al., 1987).
85H-2 (Location: 34°45'03"N, 137"35'31"
E)

This site is situated at the edge of a troughin the lake (Figure I). The water depth isapproximately 5 m. The recovered core material ranges in depth from 0 to -41.64 m andis composed of alternating beds of silt andsand. The sediments are more sandy thanthose of 85H-I and the sedimentary facies
changes frequently.
The 14C ages measured for eight horizons(Figure 2) are as follows (Ikeya et al.,1987):
SampleDepth (m) Age (y.B.P.)
Gastropoda
0.86
790± 100
Gastropoda
3980± 120
1.90
Gastropoda
2.80
5240± 100

All the samples were processed using
palynological preparation techniques (Shimazaki, 1979). However, they were not treatedwith in order to avoid damaging the cysts(Matsuoka, 1984b). An outline of the process used follows:(1) An approximately 10% solution ofhydrochloric acid is added to the sample(1 cc) to dissolve the calcium carbonate
particles.
(2) The remains are treated with anapproximately 50% solution of hydrofluoric acid to remove silicate particles.
(3) The organic remnants are sieved
through a 150-mesh screen to exclude
large grains.
(4) The residue is sieved through a 635mesh screen to trap cysts, and the refinedmaterial is examined microscopically.
The refined samples (with water) mixed
with a solution of polyvinyl alcohol are
spread over cover glasses (18 mmx24 mm)
and dried on a hot plate at about 40°C.
Each cover glass with the specimen is mounted in polyester resin.
Forty three samples of 85H-l and 85H-IB,and forty-six samples of 85H-2 were examinedby palynological analysis. The absolute
number of cysts per three slides was calculated for 85H-I and 85H-IB, and the absolute
number of cysts per 0.1 cc of refined sample
was counted for 85H-2.
Dinoflagellates often have two scientificnames, one for the vegetative stage, and theother for the resting cyst stage. Some cystswith no cyst-based name are referred to by

Natsuhiko Kojima

200

their vegetative cell names in this paper.
Although there are disagreements over thetaxonomic classification of the genus Polykrikos (Fuk uyo, 1982; Harland, 1981;
Matsuoka, 1984a), Matsuoka's (1985b) criterion for Poly. schwartzii, the network structure on the periphragm is followed here.
Table 1.

~
Species

GONYAOLACOID LI NEAGE
Spiniferites aff. S. berel ius
S. bulloideus
S. cf. hyperacanthus
S. ramosus
S. spp.
Operculod in i um centrocarpum
O. aff. craS5um
O. cf. israelianum
O. sPp.
L i ngu lod i n i um machaerophorum
PERIDINIOID LINEAGE
Brigante<iinium cf.assymetricum
B. cariacoense
B. aff. irregurale
B. majusculum
B. simplex
B. spp.
Stelladinium abei
Stellad. reidi i
Selenopemphix al ticincutum
Seleno. quantaSeleno. hamanaens is
Trinovantedinium capi tatum
T. sp.
Votadinium carvum
V. spinosulD
Lejeunecys ta concre ta
L. falJax

Dinoflagellate cyst assemblage zone
Investigation of dinoflagellate cysts revealed six assemblage zones in cores 85H-I and
85H-2 (Tables 1-3, Figures 3-6).
Assemblage zone A (85H-I, [IJ-[3J; 85H2, [I J)

List of dinoflagellate cysis in core 85H-l.

-"" ;; -..,. ;;; "", -"" ;; -..,."" ;; -..,. ;;;1 ""- ""- ;;<-= -..,.'7'"...: ...:'"""~.; c 1
'"
..,.
'" ""
'" "" -<-=
""
""
'"
""
""
.n
...: ...:
sln
'"
'"
ci

'"

t-

tt-

ci

ci

N

t-

N

~

0

N

~

~

~

o

0

N

N

~

~

M

N

M

~

~

-i

M

N

0

0

M

-i

_-i

~

0

d

<ri

0

0

0

~

~u?

~

0

~tO

-

0
0

~u:i

I

I
I
I
I

~

~r..:

I
I

I

I
I

2

I
2

I
2

4

6

3

I

I
2

I

I

6
I

4

I

3

3

L. spp.
i'laltispinula? minuta
Protoperidinium type C
Cyst of Proto. lattisimum
Cys t of Pro to.

3
2
2

I
2

2

GYIINODINIOID LINEAGE
Polykricos kofoidii
Poly. schwartzi i
Pheopolykricos hartmannii

29
42

I
2

2
65

2
39

I

8

2
16

2

19

12

11

TUBERCULODINIOID LINEAGE
Tuberculodinium vancampoae

TOTAL

86

9

71

0

0

0

I

4
8

10

CHLOROPHYCEAE
Pediastrum sp.
Straustrum sp.

INCERTAE SEDIS
P. rubina

I

0

0

40

0

I

2

3

0

3

3
43

884.

Holocene dinoflagellate cysts

This zone is characterized by an abundanceof Polykrikos cysts. Poly. schwarztii makes
up 40-92% of samples 8SH-l, [IJ and [3].
Poly. kojoidii increases suddenly at the top of
this zone, sample 8SH-l, [1]. Pseudoschizaea
rubina, with unidentified microfossils, occurs
in this zone.
Table 1.

co '" ;;;
'"
~ 1 1
<:>
<:>
co
'"
'" _00'"..: _00
!!

~

'"<:>

..,.

''"", '..,."
<:>

0

c::;
~,

co
c?
<:>

<:>

'"

co

co

;;

d

...:

:;;:
...:

<:>

<:>
<:>

<:>
..,.

,

'"
d

2
3

1

1
1

1
1
1
1

1
1
3
1

Continued.
c::;

...;

<:>

...:

-'" 1=::: ~- -:::-'" -'"~5 ~1(1

N

<:>

,

co

Assemblage zone B (8SH-l, [4J - [ISJ ; 8SH2, [2J?)
There are a few cysts in this zone. Poly.
schwartzii is very abundant in sample 8SH-l,[11 J. Gonyaulacoid cysts are recorded insamples 8SH-I, [7J and [13]. Peridinioid
cysts are found in samples 8SH-I, [IOJ and-, '" '"'" ,

co

<:>
<:>

6
'"
...;

;;

;;;

...;

~

..;

'"
...;

<:>
<:>

,

<:>

'6"'

..;

M

,

1
2

co

..;
<:>

co

;;

;;;

...
""
..,.

...'"
M

..;

,
<:>
'"
..;

<:>

..;

~

1

1

;;;

.;,

....

co..,.

<:>

0

;;;

,

.n

on

<:>
<:>

co

'"

;;;

0

,

""

--...; I;;- 13 '" ~ ..; --'" --'" ~- § -- --..,. --.... --..,. -.n '".n
g

~

201

1
1

1
1

1
2
3
2
1

1
2
3

~

:l!.

2
3
2
1

M

N

M

~

1

1

1
2
2
3

1
1
3
1

1

4

1

2
2

1
2

1

1

3
3

1

3

5

2

1

8
1

10

46

2

4
33
7
1

34

22

1
1
7
23

1
49
19

17
109

1
33
84

4
31
13

3
1
9

4
1
2

2
1
2

3
1
8

4

5

16

1

5
7

1

49

60
3

11

21

58
21

12
54

1
27
73

6

10

11

1

3
1
9

8

1

49

16

9

21

50
1

2
19

2

5
2
1

5
74

3
71

7
38

2
27
16

1
58
8

1
38
49
1

5

18
1
53

1
26
8

5

2
1
1

1
3
40
2
9
102

3
17

37

9
14
29

18
8

1
65
12

4
2

9
1
4

1
8

1

1
13
24

6
18
10

3
8
159 138

31
18

6
7

4

2

4

35

5

10

1
3
2
3

1

2

1
31
13

5
13
95

3
30
24

6
3
200 2001
214

1
201 200

4

3·

36

16

1
2
68
59

17
26

3

5

5
1

2
1
1

2
4
21

1
74

2
17

7
29
3

2

2
1
1

1
2
15

2

2
4

1
1

2

3

2

2
4

2

1
6

5

1

2

1
3

5
9

17
13

5
46

1
5
20

1
63

10
3
10

5
20

3
-8

170

1
4
153

70

3
145 206

1
205

3
153

1
200

1
198

4
249

200

1
2
244 216

11
67
2

5

1
44

1
14
1
2
1
6

1
4

1
2

25
1

16

3
11

2

6

1

5
1

50

1
6

1
4

12

1
200

34

14

1
89

N

o
N

List of dinoflagellate cysts in core 8SH-2.

Table 2.

~~~~NCCM~~~~~~~~
Depth {m} ~~~~~~~~~~~~~d~_m~~~M~MN~~~~~~. 'N~~~~~~~~~~~~~~~~~~~~~~~~~~~g~
CC-NM~~~~~OOOO~.

ccccccoccc~ccocccccoccccccc~ccc=m~~~~~~~=ccccC~_==~~~~~N~N~~~~~~~~_NCC~_C~~_N~N

Om~~C'.lCOC'L~~-.:::I"'C:V:CCOc.c

.

~

.

~

.

•••••••••••••••••••••••••••••••••

.
. . .
. .
. . C _ _ NM_~~~~=-N~_~~~~=C-~~_~=~~OO=CcC-~~ _ _ ~~~~~R~~=~~~~====~~~~~~~~~~~~~~~~~~~~~~

Species

.

.

0

_

N

M

~

~

~

~

~

~

0

_

N

M

~

~

~

~

~

~

0

N

M

~

~

~

~

~

~

C

-

N

~

~

~

~

=e~~~~~~e--===-=-=-~NNNNN~~~e~~~~~~~~~~~~~~-'~~GONYAULACOID LINEAGE
Spiniferites blJlloideus

S. mmoslJs
S. spp.
T. i ngu Tod ill i /lm machaerophoruu,

211
4Operculodinium centrocarplJm
O.? sp.

I II

I I

PERIDINIOID LINEAGE
Briganteliinium cariacoense I 1
B. irrelfUrale
B. simplex
12
B. ma.jusculum
H. spp.
I6
Selenopemphix alticinclJtum
Seleno. quanta
11
Seleno. hamanaensis
Votadinium carvum
spi nosum11
LejelJnecysta concreta
Cyst of Proto. oblonlfUm
Multispinula? minuta
Trinovantedinium sp.A
Cyst of Pro top.

v.

GYMNODINIOID LINEAGE
Pol.Ykricos kofoidi i
Poly. schwartzi i
Pheopolykricos hartmanni i

16
17

I 11

1
1

1
1
12
2 I 21 11 212 1 5 1 2 513
1
III
114
5 4
12
11111 i II
2 1 1I
1I I I I I 1
1
1
I 11

~

1;;-

112 III

15111114111

215

I1
2 1201 I 1 I 5 I 1

<::l

>::

~.

112

11

~

~

112

1
4

2

::::

1I I
1 I 1I I I I I I 1

11117121414
65
2
TUBERCULODINIOID LINEAGE
TuberclJ 1od i n i IJm vancampoae
11213124
INCERTAE SEDIS
Dino. ? cyst type A
Dino.? cyst type D
2
Dino.? Cyst type E
21681 15TOTAL 12410111131312111217112141151261318114121010 11161210 10 181112175141011212141241511341411221518101010101010
TOTAL: except INCERTAE SED IS

§.
I::)

884.

Holocene dinoflagellate cysts

203

•
H1B

Os-Kgp"10

Ah"

Number of cysts/O. lee
100

200

Number of cysts
Figure 3. Vertical distributions
flagellate cysts in core 8SH-l.

of dino-[15]. The samples in this zone incude freshwater planktonic algae, Pediastrum andStaurastrum.
Assemblage zone C (85H-l, [16J-[27J;
85H-2, [3J-[38J?)
Brigantedinium spp., Selenopemphix
hamanaensis, Poly. kofoidii, Poly. schwartzii
and Pheopolykrikos hartmannii are continuTable 3.
Assemblage
zone

Figure 4. Vertical distributions
flagellate cysts in core 8SH-2.

of dino-ous throughout this zone. Gonyaulacoid
cysts are present at less than 3%. Brigantedinium spp. are observed abundantly fromsample 85H-l, [21J to [24]. Seleno.
hamanaensis is found plentifully in the upper
part of this zone. Polykrikos cysts are foundevenly throughout these samples. Votadinium carvum and Lejeunecysta concreta are
restricted to the samples from the middle toupper parts and their occurrence correspondswith cyst abundance. The number of cysts

Dinoflagellate cyst assemblage zone for cores 85H-I and 85H-2.

Age (y.B.P.)

Sample No.

Depth (m)Sample No.

Depth (m)A

168- 536

85H-I-[ IJ - [ 3J

0.37- l.18

85H-2- [I J

0.05-0.06

B

727-2800[ 4 J - [15J1.60- 6.16

C

3000-5005[16J - [27J

6.60-11.01[3JD

5182-5368[28J - [29J

11.40-1l.81~

E5455-6641[30J - [40J

12.00-14.61~

F

6727-7095[4IJ-[43J

14.80-15.61

[38J

1.65-

-34.30[39J - [40J ? 35.10-36.01

Natsuhiko Kojima

204

decreases higher in the zone.
Assemblage zone D (85H-I, [28J - [29J ;85H-2, [3J - [38J?)
This zone is distinct in 85H-I but indistinct
in core 85H-2. The number of cysts, especially Gymnodinioid cysts, decreases in thiszone. Brigantedinium spp. and Seleno.
quanta are frequent and Lejeunecysta concreta is found in constant numbers, but
Seleno. hamanaensis is rarely found.
Assemblage zone E (85H-I, [30J-[40J;85H-2, [3J - [38J?)
This zone is marked by the cyst dominance.
Brigantedinium spp., Seleno. quanta andPheo. hartmannii are also recorded throughout the samples, and Seleno. hamanaensis isalso present except sample 85H-I, [39J.
These four cysts make up a high percentage in
the assemblage. Tuberculodinium vancampoae also occurs throughout the samples, but
is not as abundant. Gonyaulacoid cysts areconcentrated around the middle part of thiszone. Samples 85H-I, [38J and [39J arecharacterized by a dominance of Pheo. hartmannii. These two samples may correspondto 85H-2, [13J and [28J which also have ahigh percentage of Pheo. hartmannii.
Assemblage zone F (85H-l, [41J - [43J ;85H-2, [39J - [40J?)
The samples in this zone are characterized bya continuous occurrence of Brigantedinium
spp., Seleno. quanta and Pheo. hartmannii,
and the amounts of cysts decrease higher inthe zone. The assemblage zone for the samples of 85H-2, [39J and [40J is unclear
because there are a few cysts.

Paleoenvironment
Using cyst assemblages, geographical distribution data on modern dinoflagellate cysts
provide important information for environmental analysis. A relationship between
environmental inclinations and cyst distribution in surface sediments has been recognizedsince William's report (l971a, b).
Wall et al. (1977) and Harland (1983)
described modern cyst distribution in the
North Atlantic Ocean. The former authors
examined the relationship between cyst assemblage types and their oceanographic environments. Similar investigations have been carried out since the 1970's (e.g., Williams
1971 a, b; Davey and Rogers, 1975), although
there are still insufficient data on the environmental information derived from cysts. Harland (1983) compiled the data as accumulated
results and they have since proved valuable,
although more detailed information on cyst
distribution is needed.
Paleoenvironmental research in Japan ismainly based on local information on cyst
distribution (Harada, 1974; Kobayashi etal., 1986; Matsuoka, 1976, 1982, 1985a, b,
1987b) and the use of cyst studies forpaleoenvironmental analysis data (Harada,
1984; Matsuoka, 1987a). Dinoflagellate
cyst distribution shows distinct provincialIsm.

In Nagasaki Bay southwestern Japan, thepercentage of cyst species of the Peridinioidgroup is 40.3% in the outer part of the bay andthe average number of species is 7.5. The
corresponding values for the inner area of thebay are 32.3% and 5.7, respectively. The
species number of the Peridinioid group,~
Figure 5. All photographs X 600. 1,2. Selenopemphix hamanaensis, sp. nov. 1; holotype, polar
view. 2; holotype, polar view showing archeopyle (arrow), slide 85H-I 10.60-10.61 m CD (97.1/33.2 L).
3. Selenopemphix hamanaensis, sp. nov., paratype, polar view, slide 85H-I 10.60-10.61 m @ (99.9/36. OL).
4. Selenopemphix hamanaensis, sp. nov., paratype, polar view, slide 85H-I 10.60-10.61 m@ (100.2/38.6 L).
5. Selenopemphix hamanaensis, sp. nov., polar view, slide 85H-I 13.80-13.81 m@ (99.0/23.2 L). 6.
? Selenopemphix hamanaensis, polar view, short-spined type?, slide 85H-2 31.20-31.21 m @ (101.0/38.2
L). 7. Selenopemphix quanta (Bradford) Matsuoka, polar view, slide 85H-I 10.60-10.61 m@(89.0/22.
3L). 8. Selenopemphix quanta (Bradford) Matsuoka, polar view, slide 85H-I 14.20-14.21 m CD (99.5/40.2

L).

884.

Holocene dinoflagellate cysts

205

206

Natsuhiko Kojima

1

2

. .3

4

9

884.

Holocene dinoflagellate cysts

Aasscmblap,czone

D a.7..
B <l.7..

C a.7..

~

E a.z.

~. a.7..

%lr__--------__--------~--~--~ 100
o

-""

85H-l
o

c..
~

0

50

~

=

"'

"u

~

~

o

5
core depth

%
~ 100
0

.-...,
-""

85H-2

~

0

c..
~

0

50

~

=
"'

;;;
~
~

'"

/

c..

0

10

20

30

40 m

core depth

Figure 7. Polykrikos cyst percentages in the
cores 85H-I and 85H-2.

therefore, generally decreases toward theinner bay (Matsuoka, 1985a).
Akkeshi Bay and Lake Saroma are situatedin eastern Hokkaido, which is in northern
Japan. In Akkeshi Bay, which is open to the
inflow of oceanic water, the percentage of cyst
species of the Peridinioid group is 53% andthe average number of species is 10.8. On theother hand, Lake Saroma, which has a narrow lake mouth, has corresponding values of

207

34.7% and 5.2, respectively. The average rateand species number are smaller than those in
Akkeshi Bay (Matsuoka, 1987a). The number of cyst species of the Peridinioid grouptends to decrease in the presence of fresh
water.
The decrease in the number of cyst speciesof the Peridinioid group in Lake Hamana atapproximately 5,000 y.B.P. indicates the presence of oceanic water untill that time. The
cysts of the genus Polykrikos are distributed
in inner bay areas around Japan (Matsuoka,
1985b). The period, ca. 4,000 y.B.P.-ca. 3,000 y.B.P., of this species coincides with theperiod offreshwater diatoms (Kashima, 1987)
and the occurrence of planktonic algae livingin fresh to brackish water. The high ratio in
the occurrence of Polykrikos cysts indicates aperiod of desalination of the environment ofa decrease in the amount of oceanic water.
Figure 7 illustrates these environmental oscillations. The relative ratio of Polykrikos cyst
in 85H-I clearly shows the environmental
history at this site. Especially, obvious environmental changes appear to have occurred atthe - 8 m and - II m horizons. The same
standardized graph of 85H-2 is discontinuous
because of the unstable sedimentary conditions at this site. The upper part of this coreshows a high percentage of Polykrikos andthis is in accord with the trend in 85H-1.
The changing aspects of the assemblages
and data on an absolute age scale obtained byradiocarbon dating, tephra and sedimentation
rate revealed the paleoenvironmental history
in the northern and central area of Lake
Hamana.
Ca. 9,700 y.B.P.-ca. 7,500 y.B.P. (85H-2,[34J - [38J : 85H-l, not observed): Many+- Figure 6. All photographs X 600. 1. Lejeunecysta concreta (Reid) Matsuoka, dorso-ventral view,
slide 85H-I 13.80-13.81 m@ (95.2/39.4L). 2. Cyst of Protoperidinium oblongum. dorsal view, slide 85H-I
10.60-10.61 m @. 3. Cyst of Protoperidinium sp., ventral view, slide 85H-I 13.80-13.81 m CD (95.7/25.
3L). 4. Polykrikos schwartzii Blitschli, dorso-ventral view, slide 85H-I 11.00-11.01 mCD (93.3/45.6 L). 5.
Votadinium spinosum Reid, dorso-ventral view, slide 85H-I 11.00-11.01 m CD (87.5/36.7 L). 6.
Brigantedinium simplex (Wall) Reid, slide 85H-I 9.40-9.41 m@(94.1/29.9L). 7. Pheopolykrikos
hartmannii (Zimmermann) Matsuoka and Fukuyo, slide 85H-I 10.60-10.61 m CD. 8. Dinoflagellate cyst?
type E, slide 85H-2 32.00-32.01 m CD (100.2/27.8 L). 9. Dinoflagellate cyst? type A, slide 85H-I 7.60-7.
61 m CD (98.5/29.3 L). 10. Dinoflagellate cyst? type D, slide 85H-2 29.50-29.51 m CD (91.0/43.8).

208

Natsuhiko Kojima

cyst species are found and Tuberculodinium
vancampoae occurs throughout this interval.
This species has been observed in bay areas
around Japan (Matsuoka 1985b). This evidence may indicate inner bay conditions
during this period.
Ca. 7,500 y.B.P.-ca. 6,400 y.B.P. (assemblage zone F): There are a few species. Thiscondition indicates lake obstruction or inflow
of marine water.
Ca. 6,400 y.B.P.-ca. 5,400 y.B.P. (assemblage zone E): Many species occur throughthis interval. A large number of cysts is also
observed. The ratio of Polykrikos decreases
in comparison in the upper part of this core
and the occurrence of Operculodinium centrocarpum is frequent. Species of Gonyaulacoid cysts increases in the middle part of thisinterval. The distribution of Polykrikos
cysts is known to be inner bay areas and o.
centrocarpum increases from the inner bay tothe bay mouth (Matsuoka, 1985a, Kobayashi
et al., 1986). These observations indicatethat oceanic water invaded the bay in large
quantities.
Ca. 5,400 y.B.P.-ca. 5,200 y.B.P. (assemblage zone D): An abrupt reduction of cyst
number suggests closing of the bay mouth.
Ca. 5,200 y.B.P.-ca. 3,000 y.B.P. (assemblage zone C): Cysts increase again, but theratio of Polykrikos rises to more than the levelin the period before ca. 5,400 y.B.P. The
environment returned to a stable inner bay,
but obstruction to sea water is greater than
before. This is reflected in a decreased number of Peridinioid cysts. These conditions
indicate that the flow of marine water isblocked. Thereafter, the number of cyst
gradually decreased and the relative ratio of
Polykrikos increased further. At this time,planktonic freshwater algae occurred andbrackish water diatoms increased (Kashima,1987). These data suggest that desalinationof the lake progressed slowly.
Ca. 3,000 y.B.P.-ca. 536 y.B.P. (assemblage
zone B): Occurrence of cysts is scarce, but a
lot of Polykrikos cysts are regularly foundduring this period. The lake was almost
completely filled with fresh water but was
periodically invaded with marine water.
Ca. 536 y.B.P.-present (assemblage zone
A): This interval yields a stable number ofcysts again. The cyst assemblage resembles
that of surface sediments (Kojima, unpublished data). Therefore the conditions of
this lake became similar to the present conditions which were formed by a tsunami in 1498
(Nonaka 1977).
This paper describes paleoenvironment
based on the distribution of cysts, but thistype of research has just started in Japan.
Taxonomy
There are two systems used for the classification of dinoflagellate cysts and motile
forms, but at the present the two systems have
not yet been unified. Because the relationship between motile and cyst forms is not wellunderstood and some dinoflagellates do not
produce cysts. Furthermore, we cannot estimate motile forms of fossil species.
Although the systems have been improved, in
this paper the criterion set forth by Matsuoka(1985a, 1987b) are followed.
All specimens are stored in the Laboratoryof Paleobotany at Osaka City University(OCU).
Class Dinophyceae Fritsch, 1929
Family Peridiniaceae Ehrenberg, 1832
Cyst-genus Selenopemphix Benedek, 1972
emend. Bujak 1980
Type species; Selenopemphix
Benedek, 1972

nephroides

Selenopemphix hamanaensis, sp. nov.
Figures 5-1-6

Derivation of name: From its occurrencein Lake Hamana.

884.

Holocene dinoflagellate cysts

Holotype: Core 85H-l, interval 10.6010.61 m, slide 85H-l 10.60-10.61 m CD (97.1/
33.2 L) (OCU-l). Holocene, Lake Hamana,
Shizuoka Pref., Central Japan.
Diagnosis: Intermedia pentagonia cysta
brunneola in coloris compressaque in directionis polaris. Murus cum lubrica pagina
ornatus flexibilis angustis aciculatis spinis,
aequaliter distributis supra testam. Archeopyla intercalata 2a.
Diagnosis: The intermediate pentagonal
cyst is compressed in the polar direction andis pale brown in color. The wall has asmooth surface and is ornamented with flexible slender acicular spines uniformly distributed on the test. Archeopyle intercalary
2a.
Descriptions: The test is peridinioid fromthe equatorial view and nearly circular fromthe polar view. The cyst wall consists of an
autophragm only. The epicyst has domelike or conical structure and the hypocyst may
have a slightly antapical lobe. The paracingulum is confirmed by faint ridges but eachadcingular border may be marked by rows ofspines. The paras ulcus is occasionally recognized by a slight indentation.
Dimensions: Width 74-54 p'm, Thickness
72-48 p'm, Length of spine 4-24 p'm (20specimens measured).
Remarks: Seleno. hamanaensis is similar
to Seleno. armata and Seleno. quanta, but
the former differs from the latter in being
more completely circular from the polar viewand having more slender spines. This
species has a relatively constant width but thespines show various lengths, ranging from 4
p'm to 24 p.m. The cyst is mostly observed
from the polar view because the morphological characteristics cause the cyst to beoriented in the same direction. No motile
form of this cyst is known, but it probably
belongs to Protoperidinium.
Genus Protoperidinium Bergh, 1882

209

Cyst of Protoperidinium sp.
Figure 6-3

Description: A medium-sized, brown cyst
made up of two layers. The periphragum
forms a membranous structure. The external
form from the dorso-ventral view is pentagonal. The epicyst is conical to dome-like inshape, and the hypocyst is trapezoidal fromthe equatorial view. Both the apical andantapical parts have no prominent projections. The paracingulum is obviously
distinguished by a membranous ridge. The
parasulcus is obscure. Archeopyle intercalary, formed by the loss of plate 2a (?).
Dimensions: Length 50-60 p'm, Breadth
58 p.m, Breadth of cingulum 6-7 p'm (2 specimens measured) (OCU-2).
Incertae sedis
Dinoflagellate cyst? type A
Figure 6-9

Description: This small spherical cyst isdark brown in color. The test is covered
with spines but there are not many. The
spines are short (about I p.m) and conical inshape. The shell is approximately 30 p'm indiameter except for the spines. The archeopyle is chasmic.
Occurrence: 85H-2, -9.60- -9.61 m.
(OCU-3)
Dinoflagellate cyst? type D
Figure 6-10

Descriptive remarks: Type D is small,
spherical and pale brown. Its test is coveredby spines but there are only a few. Spines
are each about 4 p'm in length. The central
body is approximately 30 p'm in diameter.
This acritarchous cyst is similar to"Dinoflagellate cyst? type A", but differs inhaving longer processes and a lighter-coloredwall.
Occurrence: 85H-2, -6.40- -6.41 m, -Natsuhiko Kojima

210

8.80- -8.81 m, -12.60- -12.61 m, -24.70- -24.71 m, -29.50- -29.51 m.(OCU-4)
Dinoflagellate cyst ? type E
Figure 6-8

Descriptive remarks: Like type A, type E
is small spherical and dark brown. Its test isoverlaid by spines, but the spine density ishigher than in types A and D. Spines areeach 1-3 Jim in length. The test is 20-30
Jim in diameter, except for the spines.
Occurrence: 85H-2, -31.20--31.21m, -32.00- -32.01 m, -34.30- -34.31 m.
(OCU-5)
Acknowledgments
I am much indebted to Drs. S. Kokawa and
S. Tsuji of Osaka City University for theiruseful suggestions and encouragement.
Thanks are also due to Dr. K. Matsuoka of
Nagasaki University for helpful advice on
dinoflagellate cysts, critical reading of themanuscript and providing the samples. I
would like to thank Dr. S. Nishida of Nara
University of Education for his helpful criticism of the manuscript. I wish to thank Drs.
H. Morimoto of Osaka City University and
M. Yoshida of Nagasaki University for their
help with Latin translations. I am also
grateful to all my colleagues of Osaka City
University for their help and support.
References
Dale, B., 1985: Dinoflagellate cyst analysis of Upper
Quaternary sediments in core GIK 15530-4 fromthe Skagerrak. Norsk Geologisk Tidsskrift., vol.
65, p. 97 -102.
Davey, R.J. and Rogers, J., 1975: Palynomorph distribution in Recent offshore sediments along two
traverses off south west Africa. Mar. Geol., vol.
18, p. 213-225.
Fukuyo, Y., 1982: Cysts of naked dinoflagellates.
In "Fundamental studies of the effects of marine
environment of the outbreaks of red tides", p.
205-214, Rep. Enviro. Sci., BI48-RI4-8, Monbusho. (in Japanese)

Harland, R., 1977: Recent and late Quaternary (Flandrian and Devensian) dinoflagellate cysts frommarine continental shelf sediments around theBritish Isles. Palaeontographica, Abt. B. 164, p.
87-126.
- - , 1981 : Cysts of the colonial dinoflagellate Polykrikos schwartzii Biitschli 1873, (Gymnodiniales), from Recent sediments, Firth of Forth,
Scotland. Palynology, vol. 5, p.65-79.
- - , 1983: Distribution maps of Recent dinoflagellate cysts in bottom sediments from theNorth Atlantic Ocean and adjacent seas.
Palaeontology, vol. 36, p.321-387.
- - , 1988: Dinoflagellate, their cysts and Quaternary stratigraphy. The new phytologist., vol.
108, p. 111-120.
Harada, K., 1974: Distribution of fossil microplankton in surface sediments on the continental
margin on the Pacific off Japan. Master thesis.
Kyoto Univ., Japan (MS).
- - , 1984: Study of dinoflagellates from the submarine strata at the Kansai International Airport
in Osaka Bay off Senshu, Central Japan. In
Nakaseko, K (ed.) Geological survey of thesubmarine strata at the Kansai International
Airport in Osaka Bay, Central Japan. Rep.
Ca/am. Sci. Inst. (in Japanese)
Ikeya, N., Wada, H. and Ohmori, M., 1987: On theboring core sediments from Hamana Lake.
Geosci. Rep. Shizuoka Univ., vol. 13, p.67-111.
(in Japanese whth English abstract)
Kashima, K., 1987: Holocene paleoenvironment in
the Lake Hamana, presumed by diatom analysis.
In "Abstracts of Japan Association for Quaternary Research IT', p.66-67, Kobe. (inJapanese)
Kobayashi, S., Matsuoka, K. and Iizuka, S., 1986:
Distribution of dinoflagellate cysts in surface
sediments of Japanese coastal waters. I. Omura
bay, Kyushu. Bull. Plankton Soc. Jap., vol. 33,
no. 2, p. 81-93. (in Japanese with English
abstract)Long, D., Bent, A., Harland, R., Gregory, D.M.,
Graham, D.K. and Morton, A.C. 1986: Late
Quaternary paleontology, sedimentology andgeochemistry of a vibrocore from the Witch
Ground Basin, central North Sea. Mar. Geol.,
vol. 73, p. 109-123.
Matsuoka, K., 1976: Paleoenvironmental study of the
Saho and the Saidaiji Formations from a view
point of palynology. Bull. Mizunami FossilMus., no. 3, p. 99-117.
- - , 1982: Dinoflagellate cysts in surface sedimentsof Omura Bay, West Kyushu, Japan. In "Fundamental studies of the effects of marine environment of the outbreaks of red tides", p. 197-204,
Rep. Environ. Sci., BI48-RI4-8, Monbusho. (in884.

Holocene dinoflagellate cysts

Japanese)- - , 1984a: List of synonyms of late Pleistocene-toHolocene dinoflagellate cysts II. Peridinium
and Gymnodinium groups. News Osaka Micropal., 12, p. 1-15. (in Japanese with English
abstract)- - , 1984b: Preparation method of dinoflagellate
cyst. In "Akashiwo manual V" Study methodsof red-tide organisms. In Adachi, R. and Irie,
H. (eds.), p.49-54, The Working Party on
Taxonomy in the Akashiwo Kenkyukai. (inJapanese)- - , 1985a: Organic-walled dinoflagellate cysts fromsurface sediments of Nagasaki Bay and Senzaki
Bay, West Japan. Bull. Fac. Lib. Arts Nagasaki Univ., Nat. Sci., vol. 25, no. 2, p. 21-115.
- - , 1985b: Distribution of the dinoflagellate cyst in
surface sediments of the Tsushima Warm Current. Quat. Res. (Daiyonki-kenkyu), vol. 24,
no. I, p. 1-12. (in Japanese with English
abstract)- - , 1987a: Dinoflagellate cyst assemblages of the
alluvial deposits in the Tama River Lowland(Loc. 3). In Matsushima, Y. (ed.). The
geological studies on the alluvial deposits in theTama and Tsurumi Rivers Lowland, Kawasaki.,p. 83-88, Collection Commitee for the Kawasaki
Museum. (in Japanese)- - , 1987b: Organic-walled dinoflagellate cysts
from surface sediments of Akkeshi Bay and Lake
Saroma, north Japan. Bull. Fac. Lib. Arts,
Nagasaki Univ., Nat. Sci., vol. 28, no. I, p.35-

211

123.
Nonaka, T., 1977: Transition of Lake Hamana.
Hamana, no. 190, p.2-3. Shizuoka Pref. Fish.
Exp. Stn. (in Japanese)Reid, P.e. and Harland, R., 1977: Studies of Quaternary dinoflagellate cysts from the North Atlantic.
Cont. Ser. Amer. Ass. Stra. Paly., 5A, p. 147169.
Rossignol, M., 1961: Analyse pollinique de sediments marins Quaternaries en Israel. I. Sediments Recent. Pollen et Spores, vol. 3, p.303324.
- - , 1962: Analyse pollinique de sediments marins
Quaternaires en Israel. II. Sediments Pleistocenes. Ibid., vol. 4, p.121-148.
Shimazaki, T., 1979: Introduction of palynologicalprocessing technique using screens. Jap. Jour.
Paly., no. 23. p. 33-45. (in Japanese with English
summary)Wall, D., Dale, B., Lohman, G. P. and Smith, W.K.,
1977: The environmental and climatic distribution of dinoflagellate cysts in modern marine
sediments from regions in the North and South
Atlantic Ocean and adjacent seas. Mar. Micropal., vol. 2, p. 121-200.
Williams, D.B., 1971a: The distribution of marine
dinoflagellates in relation to physical and chemical conditions. p.91-96, In Funnel, B.M. andRiedel, W. R., (eds.) The micropaleontology ofoceans. Cambridge. Univ. Press.
- - , 1971b: The occurrence of dinoflagellates inmarine sediments. Ibid., p.231-243.

~~mJt7)7'G~~tJ, I?£llii" Q1iBJ~;g.:/ 7-. I- t7)5j-;tJf: ~~mJt7)7'G~~::2 7~MtJ, 1?1iBJ~;g~:/7-.I-~.lliLk.£lliLk:/7-.I-W.~~~~Uf4=~AY~-~~~i"Q=

Brigantedinium spp., Selenopemphix quanta. Seleno. hamanaensis, =¥ A / f 1 ~ A Y
Iv - 7'~.:.~i" Q Polykrikos schwartzii. Poly. kofoidii. Pheopolykrikos hartmannii tJ, I? tJ:. IJ,::2" = =*" =j 'Y 1/ 7-. Y Iv-7', T "" /~ 1/ '" f 1 = ~ A 1/' Iv-7·~.:.~i"Q:/ 7-. I- ~j;':S:.lli Lt.: •.:..h 1?t7):/ 7-. HI:. 6 ":)t7)W.*~.:.btJ,.h, .RJ(;fit7)3£{U IJ *~P3~~tJ, l?f't7.KmJ, ~ I?
~.:.ffR:7.KmJa-"" -C 1'}LFf(:7.KmJ c ~, ? :J'jJt3£{r.tJ~Jt~ ~.h t.:. tJ:. -Jo, I ~fi (Selenopemphix
hamanaensis) a-~ts 5 fia-gc.~ L k.
'Nl1;;1~

Trans. Proc. Palaeont. Soc. Japan, N.S., No. 155, pp. 212-217,2 Figs., September 30,1989

885.

FOORDICERAS AND DOMATOCERAS (NAUTILOID
CEPHALOPODS) FROM THE UPPER PERMIAN
TOYOMA FORMATION, SOUTHERN KITAKAMIMASSIF, NORTHEAST JAPAN*
MASA YUKI EHIRO
Department of Earth Sciences, College of General Education,
Tohoku University, Sendai 980
and

FUMINORI T AKIZA W A
Kinki and Chubu Center, Geological Survey of Japan, Osaka 540

Abstract. Two specimens of nautiloids, identified as Foordiceras cf. F. wynnei and
Domatoceras ogatsuense, n. sp., are described from the Lower Toyoman Series (Upper
Permian, Dzhulfian) in the Southern Kitakami Massif. The genus Foordiceras is firstdescribed from the Dzhulfian in Japan, and the genus Domatoceras is also first recorded fromJapan in this paper. These nautiloids are closely related to those from the Dzhulfian bedsof the Central Tethys.
Key words.
Northeast Japan.

Foordiceras. Domatoceras, nautiloid, Permian. Southern Kitakami.

manuscript.

Introduction
During his geological studies in the Ogatsu
district, Southern Kitakami Massif, one of theauthors (F.T.) collected two specimens of
nautiloids, referable to Foordiceras andDomatoceras, from the Upper Permian(Dzhulfian) Toyoma Formation. They warrant description because the occurrence of
cephalopods is quite limited in the younger
Paleozoic formations of Japan. Additionally, the present specimen of Domatoceras
represents a new species.
The authors express their appreciation toProfessor Brian F. Glenister of University of
Iowa and Professor Kei Mori of Tohoku
University for their critical reading of theGeological and paleontological note
The specimens described here as Foordiceras cf. F. wynnei (Waagen) and Domatoceras
ogatsuense, n. sp., were discovered in 1985
and in 1987, respectively, from sandy shale ofthe basal part of the Toyoma Formation
exposed on a river-bed, about 500 m northeast
of Myojin, Ogatsu-cho, Monoo-gun, Miyagi
Prefecture (Figure 1). The Permian of the
Ogatsu district is composed of the Oyakejima
Formation and the overlying Toyoma Formation. The latter is unconformably overlain
by the Triassic (Upper Scythian) Hiraiso
Formation. Some cephalopods, such as
Stacheoceras sp. and Timorites intermedium
have been reported from the Oyakejima For-

"Received January 23, 1989; revised manuscript
accepted August 1, 1989.
212

885.

Foordiceras and Domatoceras from Kitakami

NaburiBay

141·30'~~+Figure 1.

Map showing the fossil locality.

mation (Hayasaka, 1940; Ehiro et al., 1986),
and Cycloceras nov. sp. (= Protocycloceras cf.
P. cyclophorum), Stacheoceras otomoi and S.
sp. from the Toyoma Formation (Hayasaka,
1924; Shimizu and Obata, 1936; Ehiro etal., 1986). Murata and Shimoyama (1979)
divided the Toyoman Series into three zones
based on molluscan fossils and they recognized the lower two zones in the Ogatsu
district. The present specimens wereobtained from the lowest zone i.e. Lower
Toyoman Series. The Lower-Middle Toyoman Series corresponds to the Araxoceras
Zone of Ehiro (1987) and is correlated to the
Dzhulfian of Transcaucasia and Iran, and to
the Wujapingian of South China (Ehiro andBando, 1985; Ehiro, 1987).
Species of Foordiceras have already beenreported in the Japanese Islands from theformations slightly older than the Toyoma
Formation, i.e., the Kanokura Formation(Guadalupian-Abadehian) or its correlatives.
They are Foordiceras wynneiforme from the213

Oguradani beds of Central Japan (Hayasaka
and Ozaki, 1955) and from the Kanokuran
Series in the Southern Kitakami Massif (Koizumi, 1975), F. gregarium from the Kashiwadaira Formation in the Abukuma Massif,
Northeast Japan (Yanagisawa, 1967), and F.
akiyamai and F. ? sp. from the Kanokuran
Series in the Southern Kitakami Massif(Hayasaka, 1960, 1962). The present study isthe first description of Domatoceras fromJapan.
The species Foordiceras wynnei, to which
the Ogatsu specimen is compared, is only
known as a single specimen collected fromthe Upper Productus Limestone (Chhidru
Formation) in the Salt Range of Pakistan(Waagen, 1879). The Chhidru Formation is
now correlated to the Upper Dzhulfian, basedon paleontological evidence (PakistaniJapanese Research Group, 1985). Domatoceras ogatsuense, n. sp., is closely related toD. hunicum, originally described by Diener(1903) from a limestone of Chitichun in the
Tibetan Himalayas in association with ammonoids such as Cyclolobus walkeri Diener
and Xenodiscus carbonarius Waagen. It isalso known from the Dzhulfian Araxoceras
beds of Soviet Dzhulfa (Ruzhentsev and Sarycheva, 1965) and those of Iranian Julfa (Teichert and Kummel, 1973).

Systematic description
Family Tainoceratidae Hyatt, 1883
Genus Foordiceras Hyatt, 1893
Type species: - Nautilus goliatus
Waagen, 1879

Foordiceras cf. F. wynnei (Waagen)Figures 2-1 a, I b
cf. Nautilus wynnei Waagen, 1879, p.55, pI. 3, figs.
la-b.

Material: - A single internal mold,obtained by F. Takizawa in 1985, from Myo-214

Masayuki Ehiro and Fuminori Takizawa

jin, Ogatsu. GSJ. (Geol. Surv. Japan) F.
12866.
Description: - The specimen is deformed
into an ellipse and only its right side ispreserved. It is fairly large, thickly discoidal, evolute, with a wide umbilicus.
Measurements at the preserved end, in the
deformed state, are as follows (in mm) :116
Diameter (D)Umbilical diameter (U) 44 (U 100.38)
Height (H)
38 (HID 0.33)
The whorl section is rectangular to trapezoidal, with an apparently broadly arched
venter, and flat side that converge dorsally.
Ventral shoulders are narrowly rounded, andumbilical shoulders more broadly rounded.
Prominent transverse ribs extend from theventral shoulders to the umbilical shoulders.
They are nodose on the ventral margin anddiminish gradually toward the umbilicalshoulder. The number of ribs is estimated tobe nineteen on the last whorl. Suture is
unknown.
Comparison: - With respect to the general shell-form and shell ornamentation, theOgatsu specimen is comparable with Foordiceras wynnei (Waagen, 1879), from theUpper Productus Limestone of the Salt
Range, Pakistan. Our specimen has less sinuous ribs, however, than those of the latter.
The present specimen somewhat resembles
another Salt Range species Nautilus flemingianus Koninck (Waagen, 1879, p.48, pI. 3,
figs. 2a, b) in the general shell form, but it isdistinguished from the latter in having prominent nodes at the ventro-Iateral shoulders.
The Japanese species Foordiceras wynneiforme Hayasaka and Ozaki (1955, p. 183, pI. 1,
fig. 1) is closely allied to F. wynnei andconsequently to the present specimen. However, the former differs from the last two in its
less conspicuous nodes (Hayasaka and Ozaki,
1955, p. 184).

Occurrence: - Dark gray sandy shale ofthe basal part of the Toyoma Formation, NE
of Myojin, Ogatsu-cho, Monoo-gun, Miyagi
Prefecture, Northeast Japan.
Family Grypoceratidae Hyatt,in Zittel, 1900
Genus Domatoceras Hyatt, 1891
Type species: - Domatoceras umbilicatum
Hyatt, 1891

Domatoceras ogatsuense Ehiro andTakizawa, n. sp.
Figures 2-2a-2d

Material: - A single fragmental internalmold, obtained by F. Takizawa, in 1987, from
Myojin, Ogatsu. Holotype, GSJ. F. 12867.
Diagnosis: - Domatoceras with nodose
ribs on the lateral zone and a subcircularcross section in early stage; at maturity, theflanks are smooth and the cross section subquadrate.
Description: - The specimen is elliptically
deformed, with parts of two volutions. The
conch is fairly large, thickly discoidal,
evolute, with a wide and deep umbilicus.
Fine biconvex growth lines are preserved on
the umbilical wall and on a part of the lateralzone of the inner whorl. The outer whorl isof subquadrate section, with smooth surface.
The venter is slightly convex and the flanks
are flat, converging slightly toward the venter.
The whorl height near the ada pica I end of theouter volution is about 35 mm, and the corresponding greatest width, near the umbilicalshoulder, measures about 35 mm. The
ventrolateral and umbilical shoulder, measures about 35 mm. The ventrolateral andumbilical shoulders are rounded. The inner
whorl is of subcircular section, with prominent ribs on the lateral zone. They are~ Figure 2. la-lb, Foordiceras cf. F. wynnei (Waagen), GSJ. F. 12866, la, lateral view; Ib, crosssection, thin line shows the cross section through rib, xO.8. 2, Domatoceras ogatsuense, n. sp., Holotype,
GSJ. F. 12867, 2a, lateral view; 2b, 2c, cross sections; 211, suture line xO.8.
Arrows (b, c) mark the position of the cross sections.

885.

Foordiceras and Domatoceras from Kitakami

2 15

1b

......

..........-

J
2c

2d

216

Masayuki Ehiro and Fuminori Takizawa

nodose at the ventrolateral margin and diminish toward the umbilical shoulder. Height
and width at the adoral end of the inner
whorl are 16 and 15 mm, respectively, in the
deformed state.
The suture (Figure 2-2d) has a ventral lobe
that occupies most of the venter and a moderately deep lateral lobe that occupies nearly allof the flank.
Comparison: -In the general shape of thewhorl section and in the form of the suture,
the present new species is comparable toDomatoceras hunicum (Diener, 1903, p. 5, pI.
1, figs. la-c; Shimansky, in Ruzhentsev andSarycheva, 1965, p.4l, pI. 15, figs. 12a-b;
Teichert and K ummel, 1973, p. 421, pI. I, figs.
7-8, pI. 2, figs. 3-4), but it differs from thelatter in having convex venter in the outerwhorl, deeper umbilicus and prominent ribsin the inner whorl.
Upper Permian species, Domatoceras parallelum (A bich, 1878, p. 17, pI. 3, fig. 2; Arthaber, 1900, p. 213, pI. 18, figs. 2a-2c; Shimansky, in Ruzhentsev and Sarycheva, 1965, p. 41,
pI. 15, fig. lO; Teichert and Kummel, 1973, p.
421, pI. 2, figs. 1-2, 9-10) and D. gracile
Shimansky (Shimansky, in Ruzhentsev andSarycheva, 1965, p. 160, pI. 16, fig. 1), areclearly distinguished from the present specimen in the compressed whorl section.
Occurrence: - Dark gray sandy shale ofthe basal part of the Toyoma Formation, NE
of Myojin, Ogatsu-cho, Monoo-gun, Miyagi
Prefecture, Northeast Japan.

References
Abich, H.W., 1878: Geologische Forschungen in den
kaukasischen Liindern. Th. 1, Eine Bergkalkfauna aus der Araxesenge bei Djoulfa in Armenien. 126 p., Alfred Holder, Wien.
Arthaber, G., 1900: Das jungere PaHiozoicum aus derAraxes-Enge bei Djulfa. In, Frech, F. andArthaber, G., Das PaHiozoicum in Hocharmenien
und Persien. Beitr. Paliiont. Geol. Osterr.Ungarns Orients, Band 12, p. 209-308.
Diener, c., 1903: Permian fossils of the Central
Himalayas. Paleont. Indica, Ser. 15, vol. I, pt.
5, p. 1-204.

Ehiro, M., 1987: Permian ammonoids of the southern
Kitakami Massif, Northeast Japan - Their stratigraphic distribution and zonation of the Permian. Jour. Geol. Soc. Japan, vol. 93, p.823832 (in Japanese with English abstract).
- - and Bando, Y., 1985: Late Permian ammonoids
from the southern Kitakami Massif, Northeast
Japan. Trans. Proc. Palaeont. Soc. Japan, N.
S., no. 137, p. 25-49.
- - , Shimoyama, S. and Murata, M., 1986: Some
Permian cyc1olobaceae from the southern Kitakami Massif, Northeast Japan. Ibid., no. 142, p.
400-408.
Hayasaka, 1., 1924: Fossils in the roofing slate ofOgachi, Provo Rikuzen. Japanese Jour. Geol.
Geogr., vol. 3, p.45-53.
- - , 1940: On two Permian ammonoids from the
Kitakami Mountains, north Japan. Jour. Geol.
Soc. Japan, vol. 47, p.422-427.
- - , 1960: A new Permian species of Foordiceras
from the Kitakami Mountains. Bull. Nat. Sci.
Mus., vol. 5, p. 86-94.
- - , 1962: Two species of Tainoceras from thePermian of the Kitakami Mountains. Ibid., vol.
6,137-143.
- - and Ozaki, K., 1955: A Foordiceras from thePermian Formation of Central Japan. Sci. Rep.
Kanazawa Univ., vol. 3, p. 183-186.
Koizumi, H., 1975: Palaeozoic Cephalopods ofJapan. 149 p. Teiseki Bunko, Chiba (inJapanese).
Murata, M. and Shimoyama, S., 1979: Stratigraphynear the Permian-Triassic boundary and the
Pre-Triassic unconformity in the Kitakami Massif, Northeast Japan. Kumamoto Jour. Sci.,
Geol., vol. II, p. 11-31 (in Japanese with English
abstract).
Pakistani-Japanese Research Group, 1985: Permain
and Triassic Systems in the Salt Range andSurghar Range, Pakistan. In Nakazawa, K. andDickins. J.M., eds., The Tethys. Her paleogeography and paleobiogeography from Paleozoic
to Mesozoic, p. 219-312, Tokai University Press,
Tokyo.
Ruzhentsev, V.E. and Sarycheva, T.G., 1965: Development and change of marine organisms at the
Paleozoic-Mesozoic boundary. Trudy Paleont.
Inst. Acad. Nauk, SSSR, vol. 108, p. 1-431 (inRussian).
Shimizu, S. and Obata, T., 1936: Remarks on
Hayasaka's Protocycloceras cfr. cyclophorum and
the Permian and Carboniferous orthoconic
nautiloids of Asia. Jour. Geol. Soc. Japan, vol.
43, p. 11-29 (in Japanese with English abstract).
Teichert, C. and Kummel, B, 1973: Nautiloid cephalopods from the Julfa beds, Upper Permian,
Northwest Iran. Bull. Mus. Camp. Zool., vol.

885.

Foordiceras and Domatoceras from Kitakami

144, p.409-434.
Waagen, W., 1879: Salt Range fossils: Productus
Limestone fossils. Mem. Geol. Surv. India,
Palaeont. Indica, Ser. 13, vol. I, pt. I, p. 1-72.

217

Yanagisawa, 1., 1967: Geology and paleontology of
the Takakurayama-Yaguki area, Yotsukura-cho,
Fukushima Prefecture. Sci. Rep., Tohoku
Univ., Ser. 2, vol. 39, p.63-112.

Hiraiso :>jL~, Kanokura pt~, Kashiwadaira *s:>jL, Monoo-gun :j;j~1:.l!I5, Myojin:pfI, Ogatsu 1*Jm, Oguradani 'N'ffi;fr, Oyakejima *J\J:~, Toyoma ~*.

Ijijl¥i-ll'B~tl:Lil:f:t!!O)l:-ll'B-""'lvA*~*JI£: / -7- p -1 J-' Foordiceras:to J: '(f Domatoceras:l¥i-ll'B~tl:Lil:f:t!!O)T-ll'B~**1t Cl:-ll'B-""'lvA*X'lv7 7 -!If) £:0) I ~fi~~tr/ -7- p -1 J-'
2 fi, Foordiceras cf. F. wynnei :to J: '(f Domatoceras ogatsuense, n. sp. ~~JIll(; L- ko Foordiceras ItbtJ,OOO) X'lv 7 7 -!lftJ' I?, Domatoceras ItbtJ'OOtJ, I? 11. CIlb"C¥IH!:r ~ .ht.:o .::.h I? It.:t .h.:f.h9='-ll'B7' 7- A:f:t!!~O) X'lv 7 7 -~t\'tJ'I?£:i'::' 16 0) t;:'J!I~-c-;b::,o7k1Af§z.·j'(g7R)C~Trans. Proc. Palaeont. Soc. Japan, N.S., No. ISS, pp. 218-251, 18 Figs., September 30, 1989

886. TAXONOMY AND MORPHOLOGIC DIVERSITY OF MANDARINA(PULMONATA) IN THE BONIN ISLANDS*SA TOSHI CHIBA
Geological Institute, University of Tokyo,
Hongo 7-3-1, Tokyo 113

Abstract. Fifteen fossil and extant species including seven new species of the Pleistocene. Recent land snail genus Mandarina (Pulmonata; Camaenidae) of the Bonin
Islands are described, and their morphologic and possible interspecific relationships are
considered. Mandarina has undergone remarkable adaptive radiation in this small, isolated archiperago. The diversified shell morphology of these snails is characterized by complex allometric trends generated by the interplay of juvenile shell form and later shell growth
patterns. Morphologic features in the juvenile stage are little influenced by habitat conditions, and the classification of species based on juvenile shells matches well with that basedon genitalia. In contrast, adult shell characters are strongly influenced by environmental
conditions, suggesting that they are useful to consider habitats of fossil species.
Phylogenetic relationships of these species were preliminarily reconstructed from quantitative
analysis of juvenile shell and penial morphology. It is assumed that not only distinct
diversification of shell morphology in the same stock but also convergence of adult shellfeatures between the two species of different stocks has been occurred.
Key words.

Mandarina, adaptive radiation, island biogeography, Bonin Islands.

cosm of the seemingly infinite complexity ofcontinental and oceanic biogeography"(MacArthur and Wilson, 1967, p.3). I
regard that land snails are one of the bestmaterials to study the island life from theviewpoint of evolution because of their low
dispersal ability and diverse life habits as wellas their rich fossil records. Indeed, Gould(1969a) recognized in his study on Bermudian
land snails that extinction and speciation as
well as very rapid morphological change frequently occurred during the Pleistocene.
Similar events can be expected well in thefossil record of Mandarina in Bonin, and thisis the main reason why I treat the land snail
in this study. The final object is to understand the tempo and mode of evolution fromvarious paleontological and neontological
viewpoints. But there are two problems to
be conquered. First, the taxonomy of Man-

Introduction

Mandarina, a peculiar land snail genus
belonging to the pulmonata Camaenidae, has
undergone adaptive radiation in the Bonin
Islands in northwesteJ,"n Pacific, as Darwin
finches have done in Galapagos. Indeed, theBonin Islands have been entirely isolated
from other regions, and most animals andplants are indigenous.
The biota in small isolated islands has
attracted many biologists' attention, and theirworks have much contributed to establish
theories on biogeography and evolution.
"In the science of biogeography, the island is
the first unit that the mind can pick out andbegin to comprehend. By studying clusters
of islands, biologists view a simpler micro*Received January 25, 1989; revised manuscript
accepted August 10, 1989.
218

886.

Morphologic diversity of Mandarina

darina has not yet been studied sufficiently.
Two Holocene fossil species M. luhuana(Sowerby, 1839), and M. pal/asiana (Pfeiffer,1850), which were formerly regarded as Pleistocene fossil species (Iwasaki and Aoshima,
1970, Habe, 1973), and six living species. M.
mandarina (Sowerby, 1839), M. hirasei Pilsbry, 1902, M. hahajimana Pilsbry, 1902, M.
ponderosa Pilsbry, 1901, M. exoptata Pilsbry,
1902, and M. suenoae Minato, 1978, were
hitherto described (Sowerby 1839, Pfeiffer
1850; Pilsbry 1901, 1902a, b, c, d; Minato1978). The descriptions of these species by
previous authors are mostly too insufficient torealize the exact taxonomic relationshipbecause they are based on the external morphology of adult shells and genitalia in small
samples. Second, no paleontologicaldescription was made on Mandarina except
for the Holocene species, and abundantoccurrence of fossil from the Pleistocene
deposits has never been recorded in the Bonin
Islands before this work. Thus the main
purpose of this paper is (1) to revise theprevious descriptions, (2) to describe fossil
forms, and (3) even if preliminarily, to reconstruct the phylogenetic relationships of theseliving and fossil species.
The genus Mandarina was proposed by
Pilsbry (1894), designating M. mandarina as
the type species. Pilsbry (1894, 1928) regarded the genus as indigenous to Bonin. Subsequently, Emura (1943) and Minato (1978)
supported Pilsbry's view from the observationof genitalia.
Mandarina is strikingly diversified in the
Bonin Islands, occupying various habitats
such as tree, ground, mountain forest andcoastal bush. This is probably because noother large land snails could reach this archipelago. The adaptive radiation produced
unusually wide inter- and intraspecific variation in adult shell size and form (e.g., apertural shape, presence or absence of umbilicus
and keel) and shell coloration. For thisreason, it is difficult to classify Mandarina
species simply only from adult shell charac-

219

ters. In this paper I evaluate taxonomic
significance of various morphologic characters of the shell and genitalia in living samples, and the results are applied to the classification of fossil samples.

Material
The present study is based on 43 living
samples belonging to 10 species and 27 fossil
samples belonging to 11 species (6 extant and5 extinct species). The symbol, number ofindividuals and age of each samples are indicated in Table 1, and the exact locality isshown in Figure 1. Though the number ofindividuals is not always sufficiently large forstatistical treatment, these living samples seemto represent local populations. Fossils werecollected from the Holocene dunes and Pleistocene cave or fissure deposits. All of thespecimens are deposited in the University
Museum, University of Tokyo (UMUT).
Because the cave and fissure deposits arecommonly poorly stratified, it is often difficult to recognize fossil populations on thebasis of these samples. They may represent
some mixtures of allochronic living populations. Therefore, I determined the absolute
age of selected individuals of fossil specimens
by electron spin resonance (ESR) method.
As shown in Table 2, the result of ESR datingsuggests considerably long time spans forsuch fossil samples. For instance, the ESR
age for a sample from the fissure deposit of
Minamizaki (Loc. 14) ranges from 16,000 yr
B.P. to 53,500 yr B.P., suggesting a mixture of
allochronic individuals. The result, however, is coincident with the 14C age (32,400±
700 yr B.P.) which was obtained about a bulkof 50 gram individuals. Because the present
results of ESR and 14C datings must be further cross-checked by other method, they areapplied in this paper only to the preliminary
estimation and discrimination of sample ages.

Satoshi Chiba

220

Table 1. Sample list of Mandarina. L: Living, H: Holocene, P: Pleistocene.
Species (forma)

SampleLoc. N Age

Species (forma)

SampleLoc. N Age

M. aureola

AI8

18

25

L

14

14

P

18

24

P

FI

I

2

L

A24
A24(H)

24 20

L

M. hayamii
M. sp.
M. mandarina

Y 14(P)

AI8(P)

M3

3

24

7

M4

4

19
12

L

H

A25

25

M5

5

26

30
25

L

A26

L

M6

6

A27
A27(H)

27

25

L

10
II
4
15

H

M8
NI4(P)8
14

Ca3
CaI4(P)

3
14

Cb7

7

10
10
18
12
30
52
8

L

Cb8

8

7

L

Cb9
CblO(H)

9

7

L

L

10

18
2

H
L

M. polita

M. ponderosa (A)M. ponderosa (8)M. ponderosa (C)M. hahajimana

M. nolaM. chichijimana (A)

L
L
L
P
L

A28(H)

28

017

17

020

20

021

21

022

22

6
19

023

23

23

023(P)

23

25

P

Cbll

II

Pa26

26

16

L

Cbl2

12

Pa27
Pa27(H)

27

25

L

Cbl3

13

17
24

27

14

H

Cbl4

14

25

L

Pa28(H)

28

I

H

CbI4(H)

14

32

H

Pa29

29

9

L

CbI5(H)

15

H

Pa30

30
18

7
4

L

CbI4(P)

14

30
16

Cc2

2

14

L

Pbl8
PbI8(P)

H
L
L

L

M. chichijimana (8)M. chichijimana (C)M. hirasei

18

12

P

Pbl9

19

24

L

Pb20
Pc23(P)

20

9

L

23

4

P

118

18

4

L

HI3
HI4(H)JI9

19

L

HI5(H)

120

20

10
10

L

123

23
26

8
I

L
L

27
20

6

L

10
3
10

L
L

126
127

M. exoptata
M. suenoae

27

L

E20
S6
S8

6
8

L

Methods

Genital apparatus: Genital morphology,
which seems to be important for the systematics of Mandarina, has previously been
examined only to a little extent (Emura 1943;

P
L
L

L
L

P

H2

2

4

L

H5
HIO(H)

5

18

L

10
13
14
15
14
14
15
14
10
10
15

10
4
22
10
16

H

30

H
H

M. io
M. luhuana (A)II4(P)

M. luhuana (8)M. luhuana (C)M. luhuana (D)M. titan

LbI4(P)

LaI4(H)
LaI5(H)
LclO(H)
LdlO(H)
TI5(P)

30

L
H
H
P

P

30
8

H

I

H

4

P

Minato 1978). In the present study, not only
the external but also the internal morphologyof penis was examined under an optical
microscope about five to ten specimens foreach living species.
Shell form: I examined various shell char-

886.

Morphologic diversity of Mandarina

221

Mukojima

2~~~ ---

3km

18

•

·n

Izu Islands

30'

23

Bonin Islands
Mukojima '-,Nakodojima

Ototojima.r!' ,~'m
5

25
26

~ ~90

Chichijima - ,

,

26'

~

!.

28

Hahajima'/

4

~~.

27

0

"

~

30
29

~

i.5/

Meijima

~

•

11

10
12

14

Imotojima

Chichijima

AnejimaFigure 1. Sample localities of fossil and living population of Mandarina.
I: Byobuyama, 2: Hironeyama, 3: Anijima (Central part of plateau area), 4; Mansakuhama,
5: Mikazukiyama, 6: Yoakeyama 7: Sakaiura, 8: Hatsuneyama, 9: Kohiyama, 10: Kominato,
II : Higashikaigan, 12: Nishikaigan, 13: Takayama, 14: Minamizaki (John Beach), 15: Minamijima, 16: Higashiyama, 17: Nagahama 18: Sekimon, 19: Sakaigatake, 20: Chibusayama, 21:
Kensakiyama, 22: Nishiura, 23: Okimura, 24: Nankinhama, 25: Nakanodaira, 26: Houraine,
27: Minamizaki, 28: Hirashima, 29: Imotojima, 30: Meijima. Contour interval: 100 m.
Tab'le 2.

Cross check between 14C and ESR ages of fossil samples.
Data y.BP

Locality

FaciesCarbon 14

ESR

Chichijima
Minamijima
Minamizaki
Minamijima
Minamizaki
Hahajima
Minamizaki
SekimonOkimura(Loc. 15)
(Loc.14)(Loc. 15)
(Loc. 14)Dune
Red soil
Brown soil
Fissure deposits

32400±700(Loc.27)(Loc. 18)
(Loc.23)

Red soilCave deposits
Cave deposits

1990±609140± 11013300± 130

acters at different growth stages. For thispurpose, each shell was cut along the coilingaxis and various portions were measured withan aid of a digital micrometer (accuracy, I,urn) attached to a profile projector (Nikon,
VI6D). Basic morphology and measure-960±501550±60

1500-2500
5000-13000
16800-53500

ments of a Mandarina specimen in crosssection are diagrammatically shown in Figure
2. Geometric parameters explaining theshape of spire and aperture analyzed are listed
in Table 3. Adult shell can be easily recognized by their thickened and reflected outerSatoshi Chiba

222

Table 3. Linear measurements and indicesused in this paper. Peripheral angularity wasprovided at the 1/2 whorl before the adult
aperture by the rank from 0 (rounded periphery)to 5 (periphery with distinctly sharp keel). IP A
was measured at the 1/2 whorl before the adult
aperture. Juvenile umbilicus was measured at
the second whorl.
WH : number of whorls
H: shell height
HI: shell height of the first whorl- - AW
D

Figure 2. Linear measurements on a cross section of shell. For abbreviation of measurements see
Table 3.

lip.
Color pattern: Longitudinal reddish
bands are visible on the shells of some
Mandarina species. Although the number
and state of development of color bands are
considerably variable even in a single population sample, their position on the whorls isinvariable in many species: two bands
appear on the upper part of whorls and one
band on the lower part. In addition, theumbilical portion is sometimes tinged withreddish color.
I adopted a coding method to describe thecolor banding patterns in the samples
examined; I for the 'uppermost band, 2 forthe band just below the periphery, 3 for theband between periphery and umbilicus, and 4
for the band near the umbilicus (Figure 3).
In the case of a very narrow band comparedwith the light colored ground, the code is
described as "n". If a band is perfectly
absent, the code is described as O. In the caseof fused bands, the code number is enclosed
by parentheses.
Classification: Discrimination of living
species is based on the following criteria.
I. If the specimens from a given locality
or area can be classified into two groups on
the basis of disjunct difference of .genital

D
DI
AH

: shell diameter: shell diameter of the first whorl
apertural heightAH I : apertural height of the first whorl
AW : apertural width
AWI: apertural width of the first whorl
IH: height of inner lip
IW : width of inner lip
PA : length of aperture from top to periphery
IP A : index of peripheral position (P A/ AH)
PI
U
UM
UI
UJ
KE

: value of PA in the first whorl: width of umbilicus: relative width of umbilicus (U/D): juvenile umbilicus width: relative width of juvenile umbilicus: index of peripheral angularity

morphology (especially penial internal ornamentation), the two groups are regarded as
different species.
2. If the two samples from the two geographically separated areas are concho logically differentiated but have the same or only
slightly different genital morphology, they are
judged as belonging to different subspecies
here treated as formae of the same species.
3. If the two samples with similar genitalmorphology occur at the same locality but
inhabit different habitats, they are judged as
different species.
By use of these criteria, more objective andbiological classification was attempted.
However, it is not easy to apply rigid biological species concept. For instance, a complex
hybridization may occur between popula-

886.

Morphologic diversity of Mandarina

Figure 3. The coding system for banding patterns. Uppermost band: I, band above the lower
periphery: 2, subperipheral band: 3, band aroundumbilicus: 4.

tions. Populations having similar genitalmorphology may be sometimes reproductively isolated from one another, as reviewed by Emberton (1988). In the case of fossil
samples, species discrimination is based mainlyon the disjunct difference of shell morphology in the early growth stage and its comparison with intra populational variation of shellmorphology in living species.
Comparative morphology

Genital apparatus: External and internal
penial morphology in Mandarina is diagram-

223

matically shown in Figure 4. The penialtube is long in every species, extremely narrow at the middle portion in some species(M. aureola, M.ponderosa, M.polita). The
basal penis is thick in these three species. A
collar-like muscular sheath attaches to thebasal penis. External morphology of penis
in each species is illustrated in Figure 5. Theinternal ornamentation of penis consisits
basically of several columns of equal-sizedpilasters. In some species they show markedly longitudinal outgrowth. They vary bothin size and shape among species. At theuppermost portion of penis, conical shapedor relatively flat verge is present surrounding
the ejaculatory pore. Its shape, sculptureand size are different among species. Internal wall of basal penis is smooth without
pilasters. It has longitudinally arrangedsmooth regular folds. Atrium, which is the
portion between the genital pore and vaginal
opening, has a smooth wall covering randomly arranged folds.
Seasonal variation in the size and shape ofhermaphroditic duct, albumen gland andvagina are significant. Also, variation of
Genital pore

VaginaOviduct

Basal penis

Pilaster

Lower penis

PilasterUpper peniS

Verge
Flagellum
Eplphallus
Retractor muscle of penis
Buraa copulatrlx sac

Figure 4.

Diagrammatic genital morphology and terminology of Mandarina.

Satoshi Chiba
224

2

1

3

4

7

8

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

886.

Morphologic diversity of Mandarina

penis length, sheath length, retractor-muscle
length, and shape of folds in the basal penis
within a given population is wide because of
the difference of the contractile condition of
the organ. The use of these characters for
systematics therefore should be cautious. On
the other hand, intra- and inter-populationalvariation of sculptural details within a species
is insignificant. For example, the internal
penial morphology of two populations of M.
chichijimana is essentially similar, though
they can be apparently discriminated by shellfeatures as forma A and forma B (Figures 6a1, 6a-2). Because of the genital mor-

225

phological stability, each species seems to be
defined adequately by the penial sculpture.
Shell morphology and color pattern: The
shell shape of Mandarina changes remarkably with growth. The ontogenetic change is
explained by plotting the ratio of height toshell diameter versus whorl number for atypical specimen of each species (Figure 7).
Some species having mutually similar shapein the juvenile stage show extremely different
shape in the adult stage. On the other handsome other species having mutally different
shape in the juvenile stage show similar shapein the adult stage. In addition, color pattern. . ..

~.<~

~~'.

~~
~.

1

4

2

3

Internal penial morphology in Mandarina species: I: M. chichijimana (B), Cb14; 2:
M. chichijimana (A), Ca3; 3: M. mandarina, M3; 4: M. hirasei, H5. Scale bar indicates I cm.
Figure 6a.

~ Figure S. External penial morphology in Mandarina species: I: M. chichijimana (B), Cb14; 2:
M. chichijimana (A), Ca3; 3: M. hirasei. H5; 4: M. mandarina, M3; 5: M. aureola, A18; 6: M.
aureola, A25; 7: M. polila, 022; 8: M. ponderosa (A), Pa27; 9: M. hahajimana, 120; 10: M.
suenoae, S8. Each scale bar represents I cm.

sato shi Chiba

'2J.6

3

4

,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
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,
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,
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,
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,
,
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,
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,
,
,

886.

Morphologic diversity of Mandarina

227

1.3

o
o

M. luhuene (A)M. chlchilimene (B)" M. hlresel® M. ponderosa (A)® M. aureola

1.1

e M. hahallmana.. M. suenoae• M. e"optata

0.9

o

)(
Q)

0.7

"C

c:

0.5

2

3

4

5

6

Who'rl number
Figure 7. Ontogenetical change of shell hegiht index versus whorl number in typical specimens of eightspecies of Mandarina. This indicates that the characters of juvenile shell in Mandarina species are
overcome by the later shell growth pattern.

is often different between juvenile and adultstage. The variation of adult shell morphology in living and fossil species are summarized in Table 4. The variation of juvenile
shell morphology among species are presented in Table 5.

Systematic description
Order Stylommatophora
Family Camaenidae
Genus Mandarina Pilsbry, 1894

1894. Mandarina· Pilsbry, Man. of Conch., (2), 9:2141901. Boninia Pilsbry, Ann. Mag. Natural History,
7,8: 4

Type species: Helix mandarina Sowerby,
1839 by original designation.
Diagnosis. Shell solid, quite variable inshape. Shell diameter from 20 mm to 72
mm. Spire from high to low. Some species
with umbilicus or sharp peripheral angle.
Coloration variable within each species, butcommonly with 2 - 4 reddish brown bands~ Figure 6b.
1: M. ponderosa (A), Pa27; 2: M. aureola, A25; 3: M. polita, 022; 4: M. hahajimana, ]20; 5: M. suenoae, S8. Scale bar indicates 1 cm.

Satoshi Chiba

228

Table 4. Linear measurements in mm, ratios and indices of adult shells. x: mean, s : standard deviation.
Sample sizes are given in Table l.
Samples

WH

x

(s)

5.67(.16)
M3
M4
5.54(.14)
5.66(.14)
M6
M8
5.86(.17)
NI4(P)
5.10(.08)
Ca3
5.15(.17)
CaI4(P) 4.80(.18)
5.80(.22)
Cb7
5.85(.09)
Cb8
CblO
5.80(.21)
Cb12
5.73(.12)
5.72(.15)
Cb13
Cb14
5.61(.16)
CbI4(H) 5.61(.16)
CbI4(H) 5.52(.13)
CbI4(P) 5.83(.16)
Cc2
5.51(.08)
H2
5.03(.045)
H5
4.78(.16)
HIO(H)
4.63(.10)
HI4(H)
4.84(.18)
II4(P)
4.96(.14)
LaI4(H) 5.94(.19)
LaI5(H) 5.95(.12)
LbI4(P) 5.76(.19)
LclO(H) 5.70(.15)
LdlO(H) 5.50( - )6.10(-)
TI5(P)
A18
5.56(.15)
AI8(P)
5.41(.21)
A24
5.67(.16)
A25
5.65(.19)
A27
5.58(.19)
A28(H)
5.81(.21)017
5.75(.05)
5.32(.18)020022
5.50(.19)023
5.51(.16)023(P)
5.24(.18)
5.85(.16)
Pa27
Pa27(H) 6.10(.11)
Pa29
6.00(.25)
6.13(.19)
Pa30
PbI8(P) 5.89(.12)
Pb19
5.64(.15)
Pc23(P)
5.93(.03)
Jl9
4.86(.19)
4.93(.23)
120
123
4.60(.12)
127
4.90(.17)
E20
4.51(.08)
S8
5.52(.23)
YI4(P)
4.88(.14)
F1
6.10(-)

H

D

x

(s)

25.6(1.2)
22.5(1.3)
27.3(l.l)26.6(1.2)
22.0(.69)
23.8(1.2)
29.4( 1.6)
25.6(.46)
26.0(.77)
25.3(1.5)
24.6(1.2)
24.0(.75)
23.9(1.1)
23.7(.98)
23.8(.75)
28.3(1.0)
25.4( l.l)22.9(.64)
21.9(.90)
20.0(.95)
21.7(l.l)29.2(1.2)
42.0(1.6)
42.7(2.0)
47.3(2.4)
40.6(2.4)42.0(-)
72.0(-)
26.5(1.3)
29.2(1.2)
24.7(1.2)
24.4(.97)
23.7(1.1)
22.3(.75)
22.3(.56)
23.3(.76)
23.8(1.2)
21.4(.68)
27.2(.86)
22.1(.72)
24.2(1.2)
2l.l(1.5)
21.0(1.0)
26.5(.49)
23.8(.57)
26.4(.40)
19.5(1.0)
20.2(.74)
19.9(.64)
21.5(.94)
21.2(1.6)
19.5( l.l)27.4( 1.4)
20.5(-)x(s)

20.1(1.0)
18.2(1.1)
21.7(1.7)
21.7(1.3)
17.7(.43)
18.0(1.2)
19.8(1.0)
21.5(l.l)21.0(.65)
2 1.3 ( 1.2)
21.3(.70)
20.1(.83)
19.2(.98)
18.4(.85)
19.1(.72)
22.9(1.5)
20.7(.94)
15.4(.34)
14.5(.89)
12.5(.73)
13.3(.90)
20.0(1.0)
21.7(1.5)
23.2(.76)
25.0(1.5)
24.5(1.1)
21.2(-)
33.1(-)
19.9(1.3)
21.1(1.3)
19.8(.81)
20.0(.94)
18.4(.86)
19.0(.99)
18.5(.41)
17.6(.75)
18.4(1.7)
18.4( l.l)
18.9(.98)
21.0(.87)
22.6(.42)
20.1(1.7)
19.4(1.2)
21.4(.92)
18.7(.85)
20.5(.29)
15.0(1.1)
15.7(.63)
13.0(.90)
15.8(.21)
12.9( l.l)17.0(1.0)
17.8(1.0)
18.8(-)

H/D
it

(s)

.788(.027).808(.013).794(.051).814(.026).805(.031).756(.029).674(.037).840(.037).810(.010).852(.042).865(.032).835(.038).805(.035).777(.029).803(.025).806(.035).816(.033).674(.021).662(.030).626(.029).614(.026).686(.030).516(.035).545(.024).528(.025).603(.017).505( - ).520( - ).752(.030).723(.041).800(.029).823(.039).777(.024).851(.034).831(.006).755(.024).776(.074).862(.041).728(.029).947(.046).939(.054).952(.051).922(.023).809(.038).788(.030).775(.025).769(.048).779(.039).650(6030).738(.035).609(.022).878(.062).652(.033).917(-)

AH/AW

IW/AW

IH/AH

(s)

x (s)

X

it

.940(.030).941(.025).935(.043).943(.032)
l.l0(.027).956(.031).961(.039).933(.024).960(.050).978(.038).964(.026).959(.019).964(.029).993(.057).973(.040).976(.052).933(.032).930(.090).952(.041).939(.043).943(.018).957(.022).975(.042).968(.045)
1.02(.042).900(.014).837( - ).862( - ).974(.030).958(.031 ).955(.024).990(.046).986(.034).977(.038).960(.041).954(.041).990(.057).990(.050).980(.023)
1.00(.041).985(.041)
1.01(.027).980(.037).940(.025).944(.025).990(.050).934(.057).894(.013).936(.028).946(.037).895(.032).937(.027).894(.029)
1.01(-).628(.030).616(.008).578(.027).595(.040).508(.065).529(.046).458(.037).587(.029).581(.047).591(.034).564(.035).611(.043).600(.038).594(.051).604(.050).607(.029).497(.021).440(.031).432(.048).458(.038).442(.035).486(.035).276(.026).323(.044).416(.038).532(.029).420( - ).386( - ).550(.028).580(.039).601(.022).577(.050).569(.034).590(.034).608(.033).553(.026).589(.036).600(.038).596(.038).570(.024).587(.044).580(.029).592(.027).587(.054).610(.031).610(.031).570(.041).587(.023).448(.056).561(.037).514(.026).565(.038).559(.032).597(-)(s).542(.057).564(.027).580(.053).520(.034).476(.024).465(.029).469(.032).531(.038).563(.043).554(.041).537(.034).532(.033).533(.027).520(.025).484(.020).508(.024).480(.010).449(.026).418(.048).476(.019).420(.043).452(.026).520(.023).497(.029).538(.052).496(.034).519( - ).416( - ).491(.024).509(.024).501(.024).489(.033).483(.045).511(.025).488(.003).516(.032).494(.036).489(.024).511(.027).488(.035).472(.026).530(.021 ).491(.008).518(.039).495(.030).518(.034).479(.036).462(.028).468(.016).512(.066).418(.043).474(.028).487(.029).477 ( - )

IPA

x

(s)

.434(.033).431(.025).428(.039).454(.040).431(.025).462(.030).395(.034).449(.043).439(.024).441(.029).443(.032).425(.033).440(.020).437(.027).466(.033).427(.039).471(.039).427(.015).425(.030).431(.023).419(.032).423(.030).231(.032).213(.029).214(.056).371(.017).392( - ).337( - ).426(.003).426(.024).448(.028).465(.034).444(.018).465(.024).451(.025).456(.031).459(.036).474(.035).438(.025).490(.041 ).497(.022).507(.030).500(.020).446(.022).417(.014).465(.017).497(.030).514(.008).446(.016).452(.043).420(.015).527(.029).472(.031 ).424(-)

UM
it

(s)

.092(.101).078(.014).103(.010).100(.010).110(.014).104(.008).092(.009).208(.015).210(.017).140(.009).127(.007).129( - ).192( - ).068(.016).104(.003).065(.038).107(.007).035(.037)

KE
Min.

Max.

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
3
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
2
3
0
0
0
0
0
4

0
0
0
0
0

4
0

4
0
0
0
0
0
0
0
0
0
0
2
1
0
2
2
5
0
1
0
0
0
0
0
0
0
0
0
0
2
0
0
5
5
4
0
0
I
0
I
5
2
5
0

886.
Table 5.

Morphologic diversity of Mandarina

Linear measurements (in mm) and ratios of juvenile shell. x: mean, s: standard deviation.
01

Samples

229

HI

HI/DI

AHI/AWI

PI/HI

UJ

N
x

(s)

x

(s)

X

(s)

X

(s)

X

(s)

X

(5)

M3

10

2.14(.18)

2.69(.22)

1.26(.041)

2.02(.11 ).099(.018).096(.010)

M8

14

2.00(.12)

2.55(.13)

1.27(.049)

2.00(.11).103(.020).080(.010)

NI4(P)

5

2.61(.04)

3.13(.12)

1.20(.030)

1.91(.11 ).103(.0[2).107(.0[4)

Ca3

10

2.[8(.17)

2.72(.[8)1.25(.076)

2.[2(.[8).090(.02[).[20(.009)

Ca[4(P)

2.43(.18)

3.1 [(.16)

1.28(.07[)

2.09(.14).084(.0[9).170(.020)

Cb[3

25
[3

1.98(.14)

2.50(.20)

1.26(.064)

2.0[(.14).098(.01 [).IOO(.O[ [)

Cbl4

[7

2.02(.[4)2.60(.[7)1.28(.057)

2.06(.[7)0.94(.0[8).1 [3(.029)

CbI4(P)

9

2.[6(.[ I)2.63(. [6)

1.23(.073)

2.02(.[8).085(.024).1[3(.02[)

H5

10
[4

1.92(.22)

2.35(.09)

1.24(.130)

1.94(.10). [10(.020).[49(.010)

HI4(H)

1.85(.21)

2.3[(.13)

1.26(. [10)1.99(.10).[20(.015).137(.013)

I14(p)[2

2.[4(.[6)2.67(.[ [)1.26(.070)

2.05(.[4).072(.020).164(.025)

La[4(H)[5

2.33(.[4)2.96(.2[)

1.28(.086)

2.02(.12).082(.0[8).2[4(.03[)

La[4(P)[5

2.49(.[8)2.98(. [7)1.19(.050)

1.95(.[2).076(.0[ 7).[76(.022)

A[8

[2

1.95(. [5)2.[6(.[ [)1.12(.079)

1.80(.[4).l2l(.022).094(.0 [ 7)

A27

[4

2.02(.10)

2.36(.29)

1.14(.046)

1.86( .12).[46(.020).093(.0[0)A28(H)

5

2.13(.09)

2.47(.06)

I. [6(.046)

1.8 [(.10).[32(.0[6).107(.01 [)

020

3
[5

1.89(.11)

2.08(.[ [)1.12(.03[)

1.78(.09).[ [2(.0[4).040(.012)

2.05(.[4)2.27(.[ [)1.[ [(.050)

1.8[(.[0).[50(.020).054(.010)

8[2

1.98(.14)

2.26(.2[)

I. [3(.038)

1.76(.09).102(.0[5).043(.0[4)Pa27

2.08(.10)

2.45(.14)

1.15(.[OO)

1.82(. [ [).[ [9(.023).I19(.0[ [)023
023(P)
Pbl9[2

1.84(.20)

2.[9(.[7)1.19(.060)

177(.[ [).106(.0[7).[ [6(.0[6)J207

1.85(.17)

2.00(.[7)1.08(.0[ 7)1.66(. [3).[53(.0[8).108(.0[6)

J27

[[

1.97(.15)

2.[9(.[4)1.l0(.040)

1.7[(.08).147(.021).1 [8(.0[5)E20

6

1.83(.28)

1.87(. [9)1.03(.060)

1.56(.[2).[58(.025).[ [2(.005)

S8
Y[4(P)

6

1.78(.24)

1.94(.16)

1.l0(.066)

1.6[(.[2).220(.020)

077(.0[5)62.[5(.22)

2.34(.[5)1.05(.041)

1.55(.18).[85(.0[9).088(.0[4)or without color bands. Penis cylindrical inshape, with thick sheath and without penial
appendix. Internal part of uppermost penis
with verge. Internal penial wall ornamented
with some numbers of strongly or weakly
folding pilasters.

Mandarina mandarina (Sowerby, IS39)
Figures 5-4, 6a-3, 8-1, 15-1

1839. Helix mandarina Gray, MS.; Sowerby, in
Richardson et al. p. 143, pI. 34, fig. 2; pI. 38,
fig. 3.

1894. Helix mandarina Gray; Pi1sbry, p.124-125,

pI. 31, fig. 32.

1930. Mandarina mandarina (Sowerby); Kuroda,p. 206-207, pI. 14, fig. I.

1978. Mandarina mandarina (Sowerby); Minato,
p. 38, 39, 48, 49, pI. 3 fig. 4.

Material. RMlS400 (N = 19, sample M3),
RMlS401 (N = 12, sample M4), RMlS402(N = 10, sample M5), RMlS403 (N =4, sampleM6); RMlS404 (N = IS, sample MS).
Diagnosis. Medium-sized species of Mandarina characterized by color pattern 1(23)0
in both juvenile and adult stages and upper
penis sculptured by columns of weekly,

Satoshi Chiba

230

2

3

1

4

5

6

9

7

8

10

Figure 8. 1 : M . mandarina, RM IS403-a from Loc. 6 ; 2 : M. no/a , C M IS405-a (h o lotype) from Loc.
14 (P leistocene) ; 3: M . hirasei, RMI S42 1-a from Loc. 5 ; 4 : M . io , C MI S426-a (h o lo type) fr o m Loc. 14(Plei stoce ne ); 5: M . chichijimana (8), RM IS415-a (ho lotype) from Loc. 14 ; 6: M . chichijimana (8) ,CM IS4I S-a fr om Loc. 14 (Pleistocene) ; 7 : M . chichijimana(A) RM IS406-a from Loc. 3 ; 8 : M. chichijimana (A), CMI S407-a fro m Loc. 14 (Pleistocene) ; 9 : M. chichijimana (C), RMI S419 fr o m Loc. 2 ; 10 :M . chichijimana (A), C M IS407-b from Loc. 14 (Pleistocene). All in natural size.

irregularly fo lded , merged pilasters.

Description .
Genital morphology: Externall y, fl age ll um
uniform ly slender with a sharp and slendertip. Epiph allu s invariab ly thick. Peni s
unifo rmly thick a nd covered by sheath at thebasa l portion . The thickness o f peni s alm ost
the same as th at o f vagina. Intern a lly, lo wer

886.

Morphologic diversity of Mandarina

penis covered with 7-8 columns of regularlyand equilaterally folded, unmerging, equalsized pilasters. Center of the column slightly
ridged. Upper penis covered with many randomly complex merging column of irregularly and weekly folded pilasters. Verge
large, longer than wide, with a ventrally
subterminal pore and sculptured with slightly
folded cords continued from upper penial
wall.
Shell morphology: Shell medium in sizefor the genus and solid. Spire rather highand domed. Body whorl inflated. Umbilicus closed. Base circular and convex.
Aperture rather oblique, semicircular inshape. Periostome slightly thickened,
expanded and reflected. Whorls S.3-6.0 in
number.
Measurements (mm).
Specimen
RMI8400-a:

WH D
H AH A W
5.6 26.8 21.5 14.2 15.6

IPA
0.45

Observation and comparison. Some geographical variation in shell size can be found;
specimens from coastal area of Anijima (Loc.
4) have smaller shell than that from otherareas, and specimens from mountain area of
Chichijima (Loc.6) have very large shell.
However, geographical variation in shell
shape is insignificant for the genus.
Several specimens from Sakaiura samples(Loc. 6) have intermediate features between
M. mandarina and M. chichijimana. These
intermediates are assumed to be hybrids
between the two species.
Distribution. The distribution area of M.
mandarina is restricted to Anijima and thenortheastern part of Chichijima (Locs. 3,4, S,
6,8).
Mandarina nola, n. sp.
Figures 8-2, 15-2

Material. Holotype: CM1840S-a selectedfrom sample N14 (P). Paratypes: CMI840S[N=l1, sample NI4 (P)J.
Diagnosis. Small sized species of Mandarina. Shell with distinctly high aperture231

and clear umbilicus. Color pattern I (23) inboth adult stage and juvenile stage.
Description. Shell solid and conical inshape. Umbilicus clear and deep. Spirehigh and strongly domed. The number ofwhorls in adult shell from S.O to S.2. Aperture oblique in shape and high for the genus.
Base circular and convex. Periostome thickened and reflected.
Measurements (mm).
Specimen
Holotype(CMI8405-a):

WH D

H AH AWIPA U

5.1 23.217.513.112.40.41 2.1

Observation and comparison. This species
has similar color pattern to M. mandarina.
However, the new species is distinguishedfrom M. mandarina in having distinctly
higher aperture, smaller shell, narrower color
bands and clear umbilicus.
Distribution. This species occurs in theJohn beach fissure deposits (Loc. 14) of
before 33,000 yr B.P.
Mandarina chichijimana, n. sp.
Figures 5-1-2, 6a-I-2, 8-5-10,15-3-5

1969. Mandarina mandarina (Sowerby); Habe, p.
21, pI. 2, figs. 5-7.
1973. Mandarina mandarina (Sowerby); Habe, p.
5 I, pI. 4, figs. 6-8.
1978. Mandarina mandarina (Sowerby); Minato,
p. 38,41,49, figs. I, 6-7.

Material. Holotype (forma A): RM
1841S-a selected from sample Cb14. Paratypes: RMI8406 (N=30, sample Ca3)
CMI8407 [N=S2, sample Cal4 (P)J,
RMI8408 (N=8, sample Cb7), RMI8409(N =7, sample Cb8), RMI8410 (N =7, sample
Cb9), RMI8411 [N = 18, sample CblO (H)],
RMI8412 (N =2, sample Cbll), RMI8413(N = 17, sample CbI2), RM18414 (N =24,
sample CbI3), RMI841S (N =24, sample
CbI4), CMI8416 [N=32, sample Cbl4 (H)],
CMI8417 [N=30, sample CbIS(H)J,CM18418 [N=16, sample CbI4(P)J,
RMI8419 (N = 14, sample Cc2).

Satoshi Chiba
232

4

3

1

2

5

886.

Morphologic diversity of Mandarina

Diagnosis. Medium-sized species of Mandarina characterized by color pattern In34,
nnn4, On04, 0000 in adult shell, On04 or 0000
in juvenile shell, and internal penial wall
uniformly sculptured by longitudinal columns with regularly, equilateraly folded
pilasters.
Description.
Genital morphology: Externally, flagellum
slender with a sharp and slender tip. Epiphallus uniformly thin. Penis uniformly
thin and covered by sheath at the basal portion. Usually, penis far thinner than vagina.
Internally, middle and upper penial wall
uniformly covered with 7-8 rows of columnsof regularly, equilaterally folded, unmerging,equal-sized pilasters. Verge large, longer
than wide, sculptured with longitudinal andlateral regular cords.
Shell morphology: Three forms, formae A,
Band C, are distinguishable in this species.
The holotype belongs to forma B.
Forma A: Shell of medium-size for the
genus and solid. Spire low or medium inheight. Umbilicus clearly open. Body
whorl rounded or with weak to strong peripheral angle. Aperture circular in shape.
Periostome moderately thick and slightly reflected. Base rounded and convex. Whorls
4.6-5.5 in number. Color pattern In34, nnn4(band 1,3,4 sometimes incomplete andflamed) On04, 0000 in adult shell, and On04,
0000 in juvenile shell.
Forma B: Shell medium-sized for the
genus and solid. Spire rather high and strongly domed. Body whorl inflated. Umbilicus closed. Base rounded, convex.
Aperture rather oblique, semicircular inshape. Periostome slightly thickened,
expanded and reflected. Whorls 5.2-6.1 in
number. Color pattern 1n34 band sometimes incomplete and flamed in adult shell,
and On04 in juvenile shell.

233

Forma C: Shell morphology almost thesame as forma B except for having shorter
inner-lip. Color pattern In34 (band sometimes incomplete and flamed) in adult shell,
and On04 in juvenile shell.

Measurements. (mm)Specimens
WH D
H AH A W IP A
Holotype(RMI841S-a): S.6 24.0 19.5 13.0 13.6 0.43

U

Paratype
S.6 27.0 21.6 14.S 14.S 0.43
(CMI8418-a) :Paratype
4.6 28.9 18.7 14.3 IS.2 0.38 2.9(CMI8407-a) :Paratype
S.I 23.8 17.2 12.2 13.1 0.47 2.0(RMI8406-a) :Observation and comparison. Forma A
and forma B are apparently different in shell
shape but the difference of genital morphology is almost negligible. They are regarded
as subspecific status. Though the genitalia
of forma C could not examined in this study,
it may be regarded as another subspecies ofM. chichijimana, because of its similarity incolor patterns and shell shape with forma B.
Forma A shows a significant change ofshell morphology in the fossil record; most
specimens before 40,000 yr B.P. and somespecimens of 25,000-30,000 yr B.P. both havea sharp peripheral angle on the last whorl anda shallow suture on the spire. However,specimens of 30,000-40,000 yr B.P. and living
specimens both show no or only a weak
peripheral angulation on the whorl and havea deep suture on the spire. In addition, fossil
specimens are generally larger and wider thanliving specimens.
Remarks. Previous authors (Pilsbry
1894; Habe 1969, 1973; Minato 1978) regarded this species as belonging to M. mandarina. For instance, Minato (1978) attributed
the difference between M. chichijimana andM. mandarina to the geographic variation
within the same species. The former, how-

~ Figure 9. 1: M. luhuana (A), CM18428-a from Loc. IS (Holocene); 2: M. luhuana (8),CM 18429-a from Loc. IS (Pleistocene); 3: M. luhuana (C) , CM 18430-a from Loc. 10 (Holocene); 4: M.
luhuana (D) CM18431 from Loc. 10 (Holocene); 5: M. titan, CM18432-a (holotype) from Loc. IS (Pleistocene). All in natural size.

Satoshi Chiba

234

ever, can be distinguished from the latterbecause of the difference of sculpture on
upper penial wall and existence of the two
species at the same locality.
Distribution. In the deposits before 25,000
yr B.P., forma A is abundant. About 25,000
yr B.P., however, forma A seems to have been
replaced by forma B in the southern part ofChichijima. Now, forma B is distributed in
the southern part of Chichijima (Locs. 7-15).
Forma A already became extinct in Chichijima, and its distribution area is now
restricted to Anijima (Loc. 3). Forma C is
now distributed in Ototojima (Loc. 2), and its
fossil occurrence has not yet been confirmed.

Mandarina hirasei Pilsbry, 1902
Figures 5-3, 6a-4, 8-3, 15-6

1902. Mandarina hirasei Pilsbry, p. 141.
1973. Mandarina hirasei; Pi1sbry; Habe, p.52, pI.
4, figs. 9-11.
1978. Mandarina hirasei Pi1sbry; Minato, p. 41, 42,
48, 49, fig. 4, pI. 4, figs. 1, 2.

Material.

RM18420 (N=4, sample H2),

:Ii,

0

RM18421 (N = 18, sample H5), CMl8422
eN = 10, sample HlO (H)J, RMl8423 (N =4,
sample HI3), CMI8424 eN =22, sample Hl4(H)J, RMI8425 eN = 10, sample Hl5 (H)J.
Diagnosis. Small-sized species of Mandarina characterized by low spire, smoothsurface without color bands, clear umbilicus
and thin shell. Penial wall covered by columns of regularly, equilaterally folded,
equal-sized pilasters.
Description.
Genital morphology: Externally, flagellum
long with a slender tip. Epiphallus regularly
slender. Penis uniformly narrow and covered by sheath at the position of basal penis.
Internally, lower penial walls uniformly covered with 5-7 columns of regularly, equilaterally folded pilasters. Middle penial wallcovered with 6-7 columns of straight orslightly meandering pilasters. Upper penial
wall covered with 10-13 numbers of slightly
meandering pilasters. Verge large and longer than wide.
Shell morphology: Shell small, flat andthin for the genus. Umbilicus wide. Surface smooth. Aperture relatively large andoval in shape. Body whorl inflated with

~ :ormaA

La14(H) )

I/l

c:

Q)

E
o
Q)

:LI:~---LCJ~---L~--~,--------~~CJ-L__-F-o-rm--a-A--(--La-l-5-(_H~)_)C.

Forma 8

I/l

....o
...

:1\ r==CS

Q)

.0

E
:l

Z

:LI:__

Lb14(P) )0------------~--------------__-F-o-rm--a~~==(~L-CL~=(-H+)-):Lr~------------~--------------__-F-o-rm--a-D--(--L-d-l0~~=H~)-)
0.1

0.2

0.3

0.4

IPA value
Figure 10. Histograms of index of peripheral position (IPA) in five samples of M. luhuana. This
indicates that the present species can be divided into two groups; one is forma A and forma B and the otheris forma C and forma D.

886.

Morphologic diversity of Mandarina

obtuse peripheral angle. Periostome slightly
colored, thickened and reflected. Color pattern usually 0000, but sometimes 1030 or
0200.
Measurennents. (mm)Specimen
RM 18421-a

WH D
H AH AW IPA U
5.0 21.1 13.4 11.0 11.5 0.49 1.9Distribution. This species is usually foundin the basal portion of the leaves of Livistonaand Pandanus.
Living and Holocene specimens can befound in coastal area of Chichijima (Locs. S,
10, 13, 14, IS) and Ototojima (Loc.2). The
occurrence of M. hirasei was recorded also in
Nakodojima (Loc. I) (Habe 1969). This
species is abundant in Holocene dunes,
although there is no fossil record in thedeposits older than S,OOO yr. B.P.
Mandarina io, n. sp.
Figures 8-4,15-7

Material. Holotype: CM18426-a selectedfrom sample 114(P). Paratype: CMI8426[N = 14, sample 114 (P)J.
Diagnosis. Medium-sized species of Mandarina. Shell thin. Spire flat. Body
whorl markedly inflated. Color pattern
0000.
Description. Shell thin and medium-sized
for the genus. Body whorl remarkably
inflated and periphery rounded. Umbilicus
wide in juvenile shells but closed in adultshells. Surface smooth. Most specimenslack color band. Spire flat and weakly doming. Aperture oblique and semicircular inshape. Periostome thickened and reflected.
Base rounded and convex. Suture distinctly
deep. Whorls 4.S-S.0 in number. Colorpattern 0000.
Measurennents. (mm)Specimens

WH

D

H

AH AW IP A

Holotype(CMI8426-a) 4.9

29.1 18.1 15.5 16.4 0.41

Paratype(CMI8426-b) 4.7

29.9 19.9 16.9 17.5 0.43

235

Observation and connparison. This species
is similar to M. chichijinnana forma A of 30,
000-40,000 yr. B.P. in having a deep suture
and a round periphery on the body whorl.
The former however differs from the latter inhaving thinner shell, smoother surface, relatively larger and more inflated body whorl,
oblique shape of aperture, and closed umbilicus in adult stage.
Distribution. This species occurs in theJohn beach fissure deposits (Loc. 14) of about
22,000-32,000 yr. B.P.
Mandarina luhuana (Sowerby, 1839)
Figures 9-1--4, 15-8--9

1839. Helix luhuana Sowerby, p. 143. pI. 35, fig. 4.
1850. Helix pallasiana Pfeiffer, p. 67.
1886. Helix pallasiana Pfeiffer; Tryon, p.131, pI.
44, figs. 49, 50.
1890. Euhadra luhuana Sowerby; Pilsbry, p. 305.
1890. Nanina ruschenbergeri Pi1sbry, p. 186, text-fig.
3.
1902. Mandarina ruschenbergeri Pi1sbry; Pi1sbry, p.
141.
1930. Mandarina luhuana (Sowerby); Kuroda, p.
206, pI. 14, figs. 3,4.
1930. Mandarina pallasiana (Pfeiffer); Kuroda, p.
206, pI. 14, fig. 2.
1969. Mandarina luhuana (Sowerby); Habe, p. 19,
23, pI. I, figs. 3, 4.
1969. Mandarina pallasiana (Pfeiffer); Habe, p. 19,
23, pI. 1, figs. 1,2.
1973. Mandarina luhuana (Sowerby); Habe, p.51,
pI. 4, figs. 1-3.
1973. Mandarina pallasiana (Pfeiffer); Habe, p.51,
pI. 4, fig. 4.
1978. Mandarina luhuana (Sowerby); Minato, p.
43, 50, pI. 4, figs. 7, 8.
1978. Mandarina pallasiana (Pfeiffer); Minato, p.
44, 50, pI. 4, figs. 9, 10.

Material. CMI8427 [N = 30, sample Lal4(H)J, CMI8428 [N =30, sample LalS (H)J,CM18429 [N = 30, Lbl4 (P)J, CM18430 [N=4, LclO (H)J, CM18431 [N = 1, LdlO (H)J.
Diagnosis. Large species of Mandarina
characterized by flat spire and wide umbilicus.
Description. Four forms, i.e. formae A, B,

Satoshi Chiba

236

3
1

5

2

6

11

8

7

12

13

9

14

10

15

16

886.

Morphologic diversity of Mandarina

C and D are distinguishable in this species.
Forma A: Shell large, solid, heavy for the
genus. Spire very low but domed. Suture
deep. Umbilicus distinctly wide. Body
whorl with obtuse peripheral angle. Aperture oblique in shape. Base rounded andconvex. Periostome reflected and thickened.
Whorls 5.6-6.5 in number. Color pattern ofjuvenile shell On04. The basic color patternof adult shell ln34, On04, 0(23)4, 1(23)4 or(123)4, but sometimes the band incomplete
and flamed.
Forma B: Shell large, solid, heavy for the
genus. Spire very low and slightly domed.
Suture shallow. Umbilicus wide for the
genus, but narrower than that of forma A.
Surface sculptured by many numbers of spirallines. Body whorl with sharp peripheral
angle. Aperture oblique in shape and higher
than forma A. Periostome thinner and more
weakly reflected than that of forma A.
Whorls 5.4-6.0 in number. The color pattern of juvenile shell On04. Basic color pattern of adult shell (123)4. The band sometimes incomplete and flamed.
Forma C: The basic features of forma C issimilar to forma B. But forma C has lower
peripheral position than forma B (Figure 10).
Forma D: The basic features of forma D issimilar to forma A. But forma D has lower
peripheral angle and narrower umbilicus thanforma A (Figure 10). Forma B and forma C
are easily discriminated from forma D in
having sharply angulated periphery.

Measurements (mm).
Specimens WH D
H AH A W IP A U KE
CMIS42S-a 5.S 42.0 19.0 IS.O 19.5 0.22 9.90
CMIS429-a 5.S 51.0 27.3 25.0 25.5 0.21 7.21 5

CMIS430-a
CMIS431-a

237

5.7 3S.0 23.1 17.9 19.5 0.38 4.90 4
5.5 42.0 21.2 IS.5 22.1 0.39 5.46 0

Remarks. All the specimens described as
M. luhuana by previous authors belong toforma A. Forma C was described as M.
pallasiana (Pfeiffer, 1850) but is regarded here
as one of the formae of M. luhuana. No
intermediate specimen between pairs of thesefour formae could be found in the Holocene
specimens. However, in Pleistocene sample[Lb14 (P)J, a few intermediate specimens
between forma A and forma B, and forma B
and forma C can be found.
Distribution. The occurrence of M. luhuana is limited to the southern part ofChichijima. Forma A mainly occurs in the
Holocene dune deposits at Minamizaki (Loc.
14) and Minamijima (Loc. 15). Forma B
and a few intermediate specimens between
forma A and forma B occur from the Pleistocene fissure deposits at John beach (Loc.
14). Forma C occurs in the Holocene dune
deposits of Kominato (Loc. 10). Forma D
also occurs in the Holocene dune deposits ofKominato (Loc. 10).
Mandarina titan, n. sp.
Figures 9-5, 15-10

Material. Holotype: CM18432-a selectedfrom sample Tl5 (P). Paratytes: CM18432(N=3, sample TI5(P)J.
Diagnosis. Remarkably large species of
Mandarina characterized by low spire, thickand reflected periostome, and wide umbilicus.
Description. Shell remarkably large, solid,
heavy, exceeding 70 mm in diameter. Spirevery low and weakly domed. Aperture~ Figure 11. 1: M. aureola, RM1844S-a from Loc.25 (holotype); 2: M. aureola, CMIS445 from
Loc. 18 (Pleistocene); 3: M. aureola, CMIS452-a from Loc.28 (Holocene); 4: M. polita, RMIS457-a(holotype) from Loc. 23; 5: M. polita, CM IS45S-a from Loc.23 (Pleistocene); 6: M. ponderosa (8),RMIS439-a from Loc. 19; 7: M. ponderosa (A), RMIS434-a from Loc. 27; 8: M. ponderosa (A),RM18437-a from Loc.29; 9: M. ponderosa (A), RMIS43S-a from Loc.30; 10: M. ponderosa (C),CMIS443-a from Loc.23 (Pleistocene); 11: M. suenoae, RMIS467-a from Loc. S: 12: M. hayamii,
CMIS46S-a (holotype) from Loc.14 (Pleistocene); 13: M. exoptata, RMIS465-a from Loc.20; 14: M.
hahajimana, RMIS461-a from Loc. 20; 15: M. hahajimana, RMIS460-a from Loc.19, 16: M. sp.,
RM IS469-a from Loc. I All in natural size.

Satoshi Chiba

238

oblique, semicircular in shape. Periostome
thickened, markedly expanded and reflected.
Base rounded and convex. Body whorl withweakly angular periphery. Whorls about 6
in number. Color pattern (123)4.
Measurements. (mm)Specimen

WH D

H

AH AW IPAU KE

Holotype
6.1 72.0 33.1 33.2 37.2 0.34 13.8 1(CMI8432-a)

Observation and comparison. M. titan is
the largest species of Mandarina. It is morphologically distinct from M. luhuana in themuch larger shell size, low spire and markedly expanded, reflected periostome.
Distribution. The present species occurs
from the fissure deposits of Minamijima (Loc.
15). It appeared about 13,000 yr. B.P. andpossibly became extinct before 8,000 yr B.P.
M andarina ponderosa Pilsbry, 190 I
Figures 5-8, 6b-l, 11-6-10, 15-13-14

1901. Mandarina mandarina var. ponderosa Pilsbry,
p.402-403.
1902. Mandarina mandarina var. conus Pilsbry, p.
6.
1969. Mandarina ponderosa Pilsbry; Habe, p.21,
pI. 2, fig. 8.
1969. Mandarina conus Pilsbry; Habe, p. 21, pI. 2,
fig. I.
1978. Mandarina ponderosa Pilsbry; Minato, p. 39,
49, pI. 3, figs. 8,9.
1978. Mandarina mandarina (Sowerby); Minato,
p.49, pI. 3, fig. 3.
1987. Mandarina ponderosa Pilsbry; Maeda et al.,p. 68, pI. 20, figs. 288a-c.
1987. Mandarina mandarina (Sowerby); Maeda etal., p. 68, pI. 20. fig. 283.

Material. RM18433 (N= 16, samplePa26), RMI8434 (N =25, sample Pa27),
CMI8435 [N= 14, sample Pa27 (H)J,
CMI8436 [N=l, sample Pa28 (H)J,
RMI8437 (N =4, sample Pa29), RMI8438(N =6, sample Pa30), RMI8439 (N =4, sample PbI8), CMI8440 [N = 12, sample Pbl8(P)J, RMI8441 (N= 19, sample PbI9),
RM 18442 (N = 9, sample Pb20), CM 18443[N =4, sample Pc23 (P)J.

Diagnosis. Medium-sized species of Mandarina characterized by upper penial wall
sculptured with columns of slightly meandering zig-zag fold and lower penial wall sculptured with tightly folded pustules. Colorpattern n(23)0 in juvenile shell, and 1(23)0 or(123)0 in adult shells.
Description.
Genital morphology: Externally, flagellum
distinctly large, occupying one-third of total
penial portion in length, and curved near thetip. Epiphallus short and uniformly thick.
Penis relatively thick at the uppermost portion, distinctly narrowed at the middle portion. Penis distinctly thickened, cylindricalin shape in the middle to basal region andcovered with sheath at the basal portion.
Internally, upper penial wall sculptured withcolumns of irregularly meandering fold.
Middle and upper basal portions the wall
sculptured with 7 or 8 columns of tightly,
equilaterally folded pilasters. The center of
each column ridgec,
Shell morphology: Three forms (formae A,
B and C) are distinguishable in this species,
although they are all moderate in size.
Forma A: Shell conical in shape. Spirehigh and domed. Body whorl rounded orbarely angulated at the periphery. Umbilicus closed in the adult stage. Aperturerounded and high. Periostome markedly
thickened and slightly reflected. Baserounded, convex. Whorls 5.3 to 6.2 in number. Color pattern n(23)0 in juvenile shells,and 1(23)0 or (123)0 in adult shells. The
bands sometimes flamed. Usually, groundcolor dark, but the specimens from Meijima
reveal light ground color with flamed bands.
Forma B: Spire from low to high andweakly or strongly domed. Suture shallow.
Surface rough with clear spiral lines. Body
whorl with a strong peripheral angle. Aperture rounded in shape and relatively wide.
Periostome markedly thickened and reflected.
Base flattened. Whorls 5.4 to 6.0 in number.
Color pattern n(23)0 in juvenile shell; I (23)o or (123)0 in adult shells. Ground color

886.

Morphologic diversity of Mandarina

sometimes dark as well as color bands.
Forma C: Shell distinctly domed. Suture
shallow. Body whorl with angular periphery. Aperture round and high. Periostome
markedly thickened. Whorls about 6 innumber. Color pattern 1(23)0.
Measurements (mm).
Specimens

WH

D

H

AH AW IPA

KE0

RM 18434-a

5.7 22.5 20.9 13.0 13.1 0.50

RM18441-a

5.7 23.8 18.0 12.5 13.0 0.41

4CM18443-a

5.9 26.8 20.1

4

15.2 15.0 0.45

Remarks. The type specimen of M. ponderosa seems to belong to forma B. Some
specimens of forma A were described as M.
mandarina conus by Pilsbry (1902). Minato(1978) regarded forma A as a variant of M.
mandarina. The present species is, however,distinguishable from M. mandarina by thedifference of external and internal morphology of penis and color pattern in juvenile
shells.
Distribution. Living populations of forma
A are distributed in the coastal area of thesouthern part of Hahajima (Locs. 26, 27),
Meijima (Loc. 30), and Imotojima (Loc. 29).
Forma B is found in mountain area of Hahajima (Locs. 18-20). Pleistocene fossils
belonging to forma A occur in the cave
deposits of Sekimon (Loc. 18). Forma C
occurs in the Pleistocene deposits of Okimuracave (Loc. 23). Specimens of forma A werealso obtained from the Holocene dune
deposits of Minamizaki (Loc.27) and Hirasima (Loc. 28), and their shell morphology isquite similar to that of living specimens of thesame forma.
Mandarina aureola, n. sp.
Figures 5-5-6, 6b-2, 11-1-3, 15-11

1978. Mandarina mandarina (Sowerby); Minato,
p. 41, fig. 2.
1987. Mandarina mandarina (Sowerby); Maeda etal., p. 68, pI. 20, fig. 287b.

Material.

Holotype: RM 18448-a

from

239

sample A25). Paratypes: RM 18444 (N = 25,
sample A 18), CM 18445 [N = 24, sample A 18(P)], RMI8446 (N =20, sample A24),
CM18447 [N=7, A24 (H), RM18448 (N=29,
sample A25], RMI8449 (N =25, sample A26),
RM18450 (N=25, sample A27), CM18451
eN = 10, sample A27 (H)J, CMI8452 eN = II,sample A28 (H)J.
Diagnosis. Medium-sized species of Mandarina characterized by pilastral pustules oflower penis and lower penial wall sculptured
by columns of regularly and tightly folding
large pilasters, and upper penial wall sculptured by columns of regularly meandering
zig-zag pilasters.
Description.
Genital morphology: Externally, flagellum
short with a sharp tip. Epiphallus uniformly
long and narrow. Penis relatively thick at
the upper part, but distinctly narrow at the
middle part. Middle and base penis distinctly thickened and the shape cylindrical, slightly bent. Basal penis covered with sheath.
Internally, upper penis sculptured with columns of irregularly folding pilasters. Middle and upper basal portions of the penis
sculptured with 5-8 numbers of columns oftightly, equilaterally folded pilasters. The
pilasters are remarkably developed at theupper half. Verge small and wider thanlong.
Shell morphology: Shell medium-sized forthe genus. Spire moderate in height.
Suture deep. Body whorl inflated withrounded periphery. Umbilicus closed in
adult shells. Base rounded and convex.
Aperture rounded. Periostome thickened
and reflected. Whorls 5.1-6.1 in number.
Color pattern 0200, I n30 in juvenile stage;
basically 1230, (band I and band 3 sometimes
narrowed, fused or lacked) and sometimes
In30, 1030, (123)0 in adult stage.

Mesurements (mm).
Specimens
Holotype (RMI8448-a)Paratype (CMI8445-a)

WH D H AH AW IPA
5.8 25.821.0 14.8 14.4 0.49
5.4 30.822.6 16.8 17.8 0.46

Satoshi Chiba

240

- 020
• 023

H. polita'" 023(P)o A18
H. aureola'" A27o A28(H)

2.5

•
'"
01

2

.",

o

•

•

0

'" ~'Offi:,. ~ ~ "'4bo ~'".-'" 8 '"
0>

00

'" '"

0
0

0

1.5 L -_ _ _-'-_ _ _---'_ _ _- - - '

o

0.05

0.1

0.15

UJ
Figure 12. Scatter diagram showing the relationship between the diameter of the first whorl (Dl)and juvenile umbilicus width (UJ) for samples of M.
polila and M. aureola. The two species is clearly
distinguished by the difference of UJ.
Paratype (RM I 8452-a)

6.1 22.1 19.9 12.5 12.3 0.47

Observation and comparison. This species
shows slight geographic variation in the
penial morphology. For instance, the specimens from Sekimon (Loc. 18) and Nankinhama (Loc. 24) both have the similar features as those from Minamizaki (Loc.27),
although the former have longer flagellum
than the latter. The shape of flagell urn of the
Sekimon and Nankinhama specimens are
similar to that of M. polita. Concho logically, geographic variation is conspicuous;
Sekimon specimens (Loc. 18) have relatively
large, flat, reddish colored shells, while N akanodaira specimens (Loc. 25) have relatively
small, high, yellowish colored shells.
Furthermore, Minamizaki (Loc. 27) specimens have relatively wide, light colored shell.
Hirashima specimens (Loc. 28) are small witha high spire.
The Pleistocene fossil specimens (about
10,000 yr B.P.) occur from the deposits ofSekimon cave. These specimens have flatterand larger shell than living specimens. The
Holocene fossil specimens (about 2,000 yr B.

P.) occurs at Minamizaki. Basic features ofthem are the same as living specimens.
Remarks. The present Hahajima species
was regarded as inclusive in the geographic
variation of M. mandarina by previous
authors (Habe 1969; Minato 1978). However, the new species is distinguished from M.
mandarina from Chichijima in having distinctly thicker basal penis, narrower middle
penis and the larger pilaster. The discrepancy of penial morphology between M.
mandarina and this species is more significant than the difference between M. mandarina and M. chichijimana. Conchologically, this species is somewhat similar to
M. chichijimana, but differs from the latter inthe lower shell, wider aperture and absence ofband 4 in the juvenile stage.
Distrbution. This species is distributed
only in Hahajima islands. Living populations are found in Sekimon (Loc. 18) andMinamizaki-Nankinhama (Locs. 24-28) areasof Hahajima, Imotojima and Meijima.
Holocene fossils occur in dune deposits of
Nankinhama (Loc. 24), Minamizaki (Loc. 27)
and Hirasima (Loc. 28).

Mandarina polita, n. sp.
Figures 5-7, 6b-3, 11-4-5, 15-12

Material. Holotype: RM18457-a selectedfrom sample 023. Paratypes: RM 18453(N =6, sample 017), RMI8454 (N = 15, sample 020), RM 18455 (N = 6, sample 021),
RMl8456 (N= 19, sample 022), RMI8457(N=22, sample 023), CMI8458 [N=25, sample 023 (P)J.
Diagnosis, Medi urn-sized species characterized by markedly thick basal penis and smallumbilicus in juvenile shell.
Description.
Genital morphology: Flagellum long andslender. Epiphallus uniformly long. Penis
narrowed at the middle position. Basalpenis covered with sheath and distinctly
thickened, knob-like in shape. Internally,

886.

Morphologic diversity of Mandarina

uppermost penial wall sculptured with irregularly folding pilasters. Middle and upper
penial walls ornamented with 5 to 7 columnsof tightly, equilaterally folding pilasters.
Middle and lower penial walls sculptured
with about 5 columns of tightly folding anddistinctly developed pilasters. Verge small
and wider than long.
Shell morphology: Shell medium in size,
usually not exceeding 30 mm in diameter,
solid for the genus. Spire domed. Last
whorl with rounded periphery. Umbilicus
almost closed in juvenile stage and neveropen in adult stage. Aperture rounded.
Periostome thickened and reflected. Baserounded and convex. Whorls 5.0-5.8 in
number. Color pattern basically I n30, but itis sometimes variable among specimens fromthe same locality. Ground color usually
reddish.

Measurements (mm).
Specimens

WH D

241

ally large shells (mean val ue of diameter is27.2 mm) with a relatively low spire (meanvalue of HID is 0.775).
Remarks. M. poUt a was previously
regarded as inclusive in the geographic variation of M. mandarina by Habe (1969) and
Minato (1978). However, the former differsfrom the latter in having thicker basal penis
and narrower middle penis. The discrepancy of penial morphology between M.
mandarina and this species is moresignificant than that between M. mandarina
and M. chichijimana.
Distribution. Living populations are distributed in the central and northern parts ofHahaj ima (Locs. 16, 17, 20, 21, 22, 23). The
Pleistocene fossil specimens occur in the cave
deposits at Okimura (Loc. 23).

Mandarina hahajimana Pilsbry, 1902
Figures 5-9, 6b-4, 11-14-15, 15-15

H AH AW IPA

Holotype (RMI8457-a) 5.8 21.5 19.3 12.2 12.5 0.48
Paratype (CMI8458-a) 5.4 27.920.715.8 16.8 0.44

Observation and comparison. In the genital features M. poUta is similar to M. aureolaand M. chichijimana.
M. aureola differsfrom this species in having wider umbilicus in
the juvenile stage and with yellowish groundcolor (Figure 13) and apparently different
shape of penis. M. chichijimana is distinguished from this species in having higher
aperture in juvenile stage and the presence ofband 4.
The present species shows a significant
geographic variation in shell shape, size andcoloration. For instance, color pattern inboth living and fossil samples from Locs. 17,
21,22 and 23 is invariably In30, but such
patterns as 12nO, 1nnO, 1020, 1n30 are foundin the sample from Loc. 20. Specimens from
Loc.20 possess a very low spire (mean valueof HID is 0.755), while those from Loc.23
mostly have a remarkably high spire (meanvalue of HID is 0.862). The Pleistocene
fossil sample from Loc.23 consists of unusu-

1902. Mandarina mandarina var. hahajimana Pilsbry, p. 29.
1969. Mandarina hahajimana Pilsbry; Habe, p. 21,
pI. 2, fig. 4.
1978. Mandarina hahajimana Pilsbry; Minato, p.
40, 41, 50, pI. 4, figs. 3, 4.
1987. Mandarina hahajimana Pilsbry; Maeda elal., p. 68, pI. 20, figs. 285a, b.

Material. RMI8459 (N=4, sample 118),
RM18460 (N = 10, sample 119), RM18461(N = 10, sample 120), RM 18462 (N = 8, sample
123), RM 18463 (N = 1, sample 126), RM 18464(N = 6, sample 127).
Diagnosis. Small-sized species of M andarina characterized by upper penial wall
ornamented with separate columns of irregularly and slightly folded pilasters.
Description.
Genital morphology: Flagell um short witha sharp tip. Epiphallus of uniform thickness
and relatively short. Penis uniformly longand covered with sheath near the basal penis.
Middle penial wall ornamented with 7 or 8
columns of zig-zag, fold-like pilasters. Up-

Satoshi Chiba242

per penial wall ornamented with 10 or II
columns of slightly meandering, fold-likepilasters. Vorge conical in shpe and longer
than wide.
Shell morphology: Shell small, thin withsmooth surface. Spire weakly domed. Last
whorl with rounded or barely angulated
periphery. Umbilicus closed or open.
Aperture oblique in shape, wider than highand narrowed at the basal position. Peri ostome rather thick and slightly reflected. Baserounded and convex. Whorls 4.5-5.2 in
number. Color pattern 1030, nOnO, nnnO,
0000.
Measurements (mm).
H AH AW IPA U
Specimens WH D
RM18461-a 5.1 22.5 16.0 12.0 13.0 0.458
RMI8464-a 5.0 21.3 15.9 12.1 13.1 0.389 1.9Observation and comparison. All individuals of the sample collected from Loc. 19 havea relatively high spire and a closed umbilicus.
In contrast, a clear umbilicus can be seen insome specimens from Loc.20 and Loc.27.
The sample from Loc. 23 consists of specimens with a low spire and a clear and wide
umbilicus.
Distribution. This species is found on
leaves or trunks of trees in Hahajima (Locs.
17,18,19,20,23,25,26,27). Fossils are unknown.
Mandarina exoptata Pilsbry, 1902
Figures 11-13,15-16

1902. Mandarina exoptata Pilsbry, p. 117.
1969. Mandarina exoptata Pilsbry; Habe, p. 21, pI.
2, fig. 3.
1978. Mandarina exoptata Pilsbry; Minato, p.43,
49, pI. 3, figs. 1,2.
1987. Mandarina exoptata Pilsbry; Maeda et at., p.
68, pI. 20, fig. 284.

Material. RMI8465 (N = 10, sample E20).
Diagnosis. Small-sized species of Mandarina characterized by angular peripheryand clear umbilicus.
Description. Shell small for the genus.
Spire low and weakly domed. Suture shal-low. Body whorl relatively large with strong
peripheral angle. Umbilicus widely open.
Aperture oblique in shape. Periostomeslightly thickened and reflected. Whorls
about 4.5 in number. Color pattern 0000.
Measurements (mm).
Specimen WH D
H AH AW IPA U KE
RM18465-a 4.5 21.5 13.0 10.8 12.5 0.43 2.3 4

Distribution. Central mountain area of
Hahajima (Locs. 19,20). Fossils are unknown.
Mandarina suenoae Minato, 1978
Figures 5-10, 6b-5, 11-11, 15-17

1978. Mandarina suenoae Minato, p.40, 41,50, pI.
3, figs. 5, 6.

Material. RM 18466 (N = 3, sample S6),
RM 18467 (N = 10, sample S8).
Diagnosis. Small-sized species of Mandarina characterized by upper penial wall
ornamented with separate columns of weakly
folded pilasters.
Description.
Genital morphology: Flagellum short witha sharp tip. Epiphallus slender and relatively long. Penis uniformly long, covered withsheath at the basal position. Upper penial
wall ornamented with 10 or II separate columns of weakly meandering, fold-like pilasters. Middle penial wall ornamented withstraight columns of pilasters. Verge longer
than wide.
Shell morphology: Shell small, thin, olive
in color and conical in shape with a pointed
apex. Spire high but weakly domed. Surface smooth. Suture shallow. Last whorlwith an obtuse peripheral angle. Umbilicus
closed or small but sometimes clearly open.
Aperture oblique in shape. Periostome
thickened and reflected. Whorls 5.2-5.8 in
number. Color pattern usually 0000 andsometimes 1020.
Measurements (mm).
Specimen WH D
H AH AW IPA KE
RM I 8467-a 5.6 21.5 17.1 11.6 12.6 0.53

886.

Morphologic diversity of Mandarina

243,\1. r~;andar i na
H. nolaN. chichijimana (A)N. chichijimana (B)N. 1 uhuana.'1. hirasei
M. 10

H. aureola

N. polica
t ,\f.
• N.
• H.
... N.

ponderosa

hahajimana
exoptata
sueno<J('• .'1. hayami i

2

,...

'£--If j
I

I--1-~~lJl

I'·
I

1.5

0.05

0.15

0.1

0.2

P11AH1Figure 13. Scatter diagram showing the relation between the apertural height-breadth ratio (AH //A W /) and the flank height-whorl height ratio (P / / A H /) of the first whorl in thirteen of Mandarina species.
Horizontal and veri teal bars indicate the range of one standard deviation for each species. Samples used inthis figure are indicated in Table 5.

Observation and comparison. This species
is similar to M. hahajimana in genital morphology. However, the former differs fromthe latter in having more tightly meandering,fold-like pilasters on upper and middle penial
walls and in having longer epiphallus.
Distribution. This species is found on
leaves of trees in central mountain area of
Chichijima (Locs. 6, 7, 8).

Mandarina hayamii, n. sp.
Figures 11-12, 15-18

Material, Holotype: CM 18468-a selectedfrom sample Y 14 (P). Paratype: CM I 8468
[N=13, sample YI4(P)].
Diagnosis. Medium-sized species of Mandarina characterized by sharp peripheral
angle, closed or very small umbilicus andsharply pointed apex.
Description. Shell medium in size, thinand triangular In shape. Apex pointed

Satoshi Chiba244(mean PI/HI value is 0.185). Spire weakly
domed and relatively low. Suture shallow.
Last whorl inflated with a strong peripheral
angle. Umbilicus closed or very small.
Whorls 4.7-5.0 in number. Color pattern
0000.
Measurements (mm).
H AH AW IPA KE
Specimens WH D
Holotype(CMI8468-a) 4.9 27.2 17.9 13.5 16.0 0.47

5(C~~~Zts~b) 4.9 25.9 17.8 13.4 14.2 0.49

5

Observation and comparison. This species
resembles M. exoptata in the generalmorphology of shell. However, the former
differs from the latter in having apparently
larger shell and sharper apex, almost or perfectly closed umbilicus and lower position of
peripheral angle (mean of IPA: 0.472 (M.
hayamii), 0.420 (M. exoptata)).
Distribution. All the specimens were collected from the Pleistocene fissure deposits at
Loc. 14 in Chichijima.
Mandarina sp.
Figure 11-16

1903. Mandarina mandarina var. trifasciata Pi1sbry,
p. 137, fig. 7.
1978. Mandarina mandarina: Minato, p.49, pI. 3,
fig. 5. (non Sowerby, 1839).

Material. RM18469 (N=2, sample FI)
Description. Shell medi urn-sized for the
genus. Spire rather high and domed.
Suture deep. Last whorl with rounded
periphery. Aperture rounded in shape.
Base rounded and convex. Periostome thickened and reflected. Whorls 5.5 in number.
Color pattern 1n30.
Measurements (mm).
SpecimenWH

D

H

AH AW IPA

RM 18469-a 6.1 20.5 18.8 12.0 11.9 0.42

Observation and comparison. The present
species is regarded as M. mandarina trifasdata Pilsbry, 1903 described from Nakodojima on account of the color pattern (nnnO)

and general shell shape. This species is similar to M. chichijimana in shell form andcolor pattern. However, it is at present
difficult to determine whether this IS
conspecific with M. chichijimana or not,because genital morphology and juvenile
shell features have not yet been realized.
Distribution. Nakodojima (Mukojima
Islands) at present.

Discussion

Classification of Mandarina species.
All the extant Mandarina species have theirown characteristics in the external and internal penial features and juvenile shellmorphology. On this basis, I here consider
the probable phylogenetic relationship ofMandarina including fossil species.
Penial morphology in the extant species
can be classified into three types: A, Band C,
as summarized below.
Type A. Basal penis slender, upper andmiddle penis uniformly thicked. Middle
penial wall ornamented with columns oftightly, regularly, equilaterally folded pilasters (Figure 5). Verge large, longer thanwide. M. mandarina, M. chichijimana andM. hirasei possess the penis of this type.
Type B. Basal penis distinctly thick, middle penis narrow. Middle and upper basal
penial walls sculptured with columns of regularly, tightly, equilaterally folded pilasters.
The pilasters distinctly outgrowth (Figure 5).
Verge small, wider than long. The penis of
this type is observed in M. aureola, M. poUta
and M. ponderosa.
Type C. Basal penis slender, upper penis
slightly thick. Middle and upper penial
walls uniformly sculptured with separate columns of slightly meandering, fold-like pilasters. Verge large, longer than wide. M.
suenoae and M. hahajimana have the penisof this type.
In most species geographic variation ofjuvenile shell characters is much smaller thanthat of adult shell characters. In M. chichi-

886.

Morphologic diversity of Mandarina

245

3.5

3

,...,

'"E 2.5().......
«l...«lOJ

...
OJ

-

x

x

2
Habi tdt

::l

...
OJ

Tree

0.

c:x:

Species

'oj

o

o (~

1.5

SampleN• H. hiriJsei

H14(H), H5.6. H. hahajimana", H. suenoae

J20
58

16
11
6

• H. exoptata

ElO

6

OM. chichijimanc'l

Cb14
Ca3
Ca14(P)
M6

14
11
11

020, 023
A23, A27
P27

15
14

114(P)
Y14(P)
La14(H)

12

H.
H.
o H.
'" H.
\) H.
(OJ

~\

Groundchichijimanachichijimana
mandarina
politaaureolao H. ponderosa
io• N. hayami ix

UnknownM.

eN. luhu80a

O.5L-______L -______L -______L -_ _ _ _ _ _L __ _ _ _

o

2

3

4

~L_

____

5

~L_

6

____

~L_

7

8
7

7
15

_ _ _ _~

8

Shell weight (g)Figure 14. Scatter plots of shell weight vs. apertural area for 14 samples of 12 Mandarina species.
This figure shows that tree snails and ground snails can be clearly classified into two clusters by the two
characters.

jimana, for example, the range of variation of
the mean value of the character HID (seeTable 4) is from 0.674 to 0.865, while that of
the character H II DI (see Table 5) is from
1.23 to 1.28. Based on the statistical data
listed in Table 5, juvenile shell features ofextant and extinct Mandarina species aregrouped in the following three morpho types.
Morphotype I. Juvenile shells with a highspire (mean HI I D I = 1.19-1.28) and a longaperture (mean AHIIAWI=1.94-2.12) witha high position of periphery (mean PIIHI=
0.072-0.120). This form is shared by M.
mandarina, M. nola, M. chichijimana, M.
hirasei, M. luhuana, M. titan and M. io.
Morphotype 2. This type is characterized
by a moderately high spire (mean HIIDI=

1.11- 1.19) and rounded aperture (mean AH I
A W = 1.76-1.86) with a moderately high position of periphery (mean PIIHI=0.1020.150). M. aureola, M. polita and M.
ponderosa possess the juvenile shells of thistype.
Morphotype 3. Juvenile shell having a
low spire (mean HI I D I = 1.03-1.10) and awide aperture (mean AHIIA WI= 1.55-1.71)
with a low position of periphery (mean PII

HI=0.147-0.200). M. hahajimana, M.
exoptata, M. suenoae and M. hayamii sharethe juvenile shell morphology of this type.
At least in extant species, the classificationof Mandarina based on penial morphology
matches well with that based on juvenile shellmorphology. This fact strongly suggests that

Satoshi Chiba

246

V~V8b!
~
7

8

9

10

VCV~{)
11

12

13

14

~fJ)v\5J
15

16

17

18

Figure 15. Juvenile shell morphology of 14
species of Mandarina (cross section) 1: M. mandarina, M8; 2: M. nola, N 14(P); 3: M. chichijimana(A), Ca3; 4: M. chichijimana (A), CaI4(P); 5:
M. chichijimana (8), Cb14; 6: M. hirasei.
H14(H); 7: M. io, Il4(P); 8: M. luhuana (A),
La14(H); 9: M. luhuana (8), LbI4(P); 10: M.
titan, T 15(P); 11: M. aureola. A25; 12: M.
polita, P 23; 13: M. ponderosa(A), Pa 27; 14: M.
ponderosa (8), Pb 19; 15: M. hahajimana, 120;
16: M. exoptata, E20; 17: M. suenoae. S8; 18:
M. hayamii. Y14(P). Scale bar indicates 1 mm.

juvenile shell characters are useful for reconstructing phylogenetic relationships of Mandarina species. Based on juvenile shell features, extinct species could be classified aswell as living species.
I treat the species with Type A, Type Band
Type C penis as constituting Stock I, Stock II
and Stock III, respectively. I tentatively
include extinct species belonging to Morphotype I in Stock I, Morphotype 2 in Stock
II and Morphotype 3 in Stock III.
Among the species belonging to Stock III,M. exoptata and M. hahajimana are now
restricted in distribution to Hahajima Island,
while M. suenoae and M. hayamii are foundin Chichijima Island. The former two
species share more pointed apex and narrower
juvenile umbilicus than the latter two species.

Judging from the overall shell morphologies,
M. exoptata and M. hahajimana are respectively regarded as allopatric sister taxa of M.
suenoae and M. hayamii. It seems certainthat the former two and the latter two species
have evolved independently in Hahajima andChichijima, forming two substocks.
Species forming Stock I (M. mandarina,
M. nola, M. chichijimana, M. hirasei, M. io,
M. luhuana and M. titan) are all distributedin Chichijima Islands. Adult shell morphologies of M. luhuana and M. titan are distinct from those of other Mandarina species
in having markedly large and flat shells.
However, these two species are phylogenetically close to M. mandarina or M.
chichijimana, which have similar adult shells
to M. aureola or M. polita belonging to
Stock II. It suggests that remarkable radiation of adult shell morphology has occurredin Chichijima Islands. Extant species ofStock I occurring in Chichijima include bothtree species (M. hirasei) and ground species(M. mandarina and M. chichijimana).
This fact suggests that the adaptation of M.
hirasei to the trees occurred in Chichijima
Islands at different times from that of othertree species (M. suenoae, M. exoptata andM. hahajimana).
Species forming Stock II (M. aureola, M.
polita and M. ponderosa) are all groundsnails and indigenous to Hahajima Islands,
though their adult morphology is often
superficially similar to that of some species ofStock I of Chichijima Islands. This factindicates speciation occurred independently
in Chichijima and Hahajima Islands.

Adaptive significance of adult shellform. Classification of Mandarina species
based on adult shell characters is little correlated with that relying on penial anatomy.
However, adult shell form is useful to assume
the habitats of fossil species. The plots ofshell weight versus apertural area in adultshells (Figure 14) show that tree snails (M.
hirasei, M. hahajimana, M. exoptata and886.

Morphologic diversity of Mandarina

247

•

mm

020
023
,. 023(P)M. pollls

0o.... 20 .

cQ,

Cl

0

~

if>

Ql

:x: 18·
mm

"13

8
0

- M. chichfJimana

0···· M b 1 4

24 .

,···Mb14(P)

....

~

Cl

Ml0(H)

Ql

:x:

~ 0

co • •
o roo co

20·

18 .

o

'13 00

o

0

mm

mm

" x

•

M. aureola••......

A 18

o

A25

,

·A18(P)~DoS 0 000

Cl
Ql

o

:x: 20.

o '0

00

o

•• 0

ogooo·

0'_.

o

o
25

30

o

mm

Diameter

18.

21

.•
•

,,

,

,"

22·

0

20

30

25

Diameter

-;.-

o

.0 •

.• .

20

•

,?'

,,

•

•• • •

22 .

•

•
.~
••

oot

o0 00 •

0

•.

,

,

0

_.

••

~x

x

, ,

•

IS ••

•

o Q e.

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o
25

30

mm

DiameterFigure 16. Scatter plots of height vs. diameter in adult shell of the 3 Madarina species, showing thewide shell size variation among samples from different habitats.

M. suenoae) have a relatively lighter shelland a larger apertural area than groundsnails, which enables climbing life. Treesnails have usually a wide aperture (smaller
AH / A W) with a relatively shorter innerlip(smaller IW / A W or IH / AH). In Mandarina, tree snails show pale coloration. For
instance, M. hirasei, M. suenoae and M.
exoptata lack any dark coloration, and M.
hahajimana has no or narrow color bands.
These tree snails undoubtedly share (1) a lightshell, (2) a large and wide aperture with ashort innerlip, and (3) pale coloration. By
using these criteria, habitat of each fossil
species can be assumed. M. io and M.
hayamii were probably tree snails, whileother fossil species are regarded as groundsnails (Figure 14).
It is difficult to recognize the adaptive
significance of shell morphology in the treesnails. Large aperture and thin shell may be
advantageous for tree snails to adhere to

trunks or leaves. However, there is an alternative interpretation for the above morphologic characteristics. For instance, it isprobable that tree snails cannot obtainsufficient calci urn carbonate to construct a
thick shell. The peculiar shell features ofthese tree snails may have resulted both from
adaptational and environmental factors.
The mutually similar features of tree snails,
especially M. hirasei and M. hahajimana,
are interpreted as due to convergence.
Adult shell features in ground species of
Mandarina also seem to indicate their habitats. Scatter diagram of shell height versus
shell width in some samples of three selected
species (Figure 16) shows that samples frommountain or relatively wet habitats (Locs. 10,
18, 20) and Pleistocene fossil samples havelarger shell size than samples from coastal
localities (Locs. 14,23,25). In M. poUta and
M. aureola, mountain and Pleistocene samples share a relatively low shell. The same

Satoshi Chiba

248

t\
\1
~

~

Figure 17. The set of non-paedomorph, forma
A (left) and paedomorph, forma B (right) and theirjuvenile of M. ponderosa.

relationship can be seen in other ground
species of Mandarina. This suggests thatmountain environment prevailed over coastal
environment during the Pleistocene when sea
stood lower level. On the contrary, mountain environment had been replaced bycoastal condition as the sea-level ascended.
The reason of these relationships between thesize or flatness of shell and the environment ispoorly known. However, in the Bermudian
land snail Poecilozonites larger shell is
produced under wet climate (Gould 1969a).

~I
Species

10,000Also, Gould (1969b) suggested that in
another land snail Cerion the larger shell sizeof Pleistocene samples than living samples
was probably due to the rich vegetation of the
Pleistocene time. Gould's idea can beapplied to the case of Mandarina judging
from the similar historical change of adultshell size in many species. Emberton (1988)
mentioned that increase of flatness is anadaptive feature for crevice-dwelling life
habit in the Triodopsinae land snails. However, such morphologic feature cannot be well
documented in M. chichijimana and M.
polita. For instance, M. polita commonlyoccurs in limestone crevices (e.g. sample 023),
but the crevice specimens have rather higher
spire than the animals living under fallen
leaves. Vermeij (1980) suggested that inmany land snails high spire is produced under
severe environment (for instance, dry climate
or deficient foods) owing to the slow down ofgrowth rate. Higher spire of coastal andliving samples than mountain and the Pleistocene samples in M. aureola and M. polita
may be attributable to dry and less favorable
condition.
Deep coloration of adult shell is a common
feature in the Pleistocene and extant mountain Mandarina species. For instance, speci-

30.00020,000chlchilimana (A)I

M. chlchilimana (B)

I

M.

I

M.lo
M. h'ras.'M.

luhuana (B)M.

luhuana (A)

M.

titan

M.

nola

M. hay.mll

40,?00 yr.BP

I

~
I

CJ
c:=J
I
I

Figure 18. Chronologie ranges of fossil species, indicated by ESR and 14C datings.

886.

Morphologic diversity of Mandarina

mens in mountain samples of M. aureola
have a wider color band than those in coastal
samples (some specimens with color pattern(123)0 in coastal samples are assumed to be
hybrids with M. ponderosa). And in the
Pleistocene samples of M. aureola the color
band is markedly wide to merge with otherband, suggesting their mountainous habitat.
The Pleistocene form of M. luhuana hascolor pattern (123)0, but this color pattern israre in the Holocene form.

Evolutionary history of Mandarina.
Gould (1969a) documented that in Bermudian Poecilozonites that a paedomorph
subspecies branched from a non-paedomorph
subspecies in the glacial period. Paedomorph and non-paedomorph combination like
Bermudian land snails can be found in
Mandarina. In Mandarina, angular periphery, thinner shell and clear striation on theshell surface are all considered to be
produced by paedomorphosis. Based onthese criteria, forma B and forma C of M.
luhuana are regarded as paedomorphs offorma A and forma D of the same species.
The paedomorph forma B is an extinct form,
occurring only in the Pleistocene deposits.
The other paedomorph forma C occurs in
non-limestone area, and non-paedomorph
forma A are known from the Holocene
deposits of limestone area. The three formaeof M. ponderosa also show a paedomorphic
relationship (Figure 17). In the last glacial
period (ca, 13,300 yr B.P.) a paedomorph,forma C, was distributed in Okimura area,
Hahajima Island. It became extinct in the
Holocene period in this area. Anotherpaedomorph, forma B is restricted to themountain area, while forma A, a nonpaedomorph of forma B, never occur in themountain area. Such a paedomorph isthought to be adaptive to mountainous (cooland wet) condition and lime-poor environment. The reason of local extinction of
paedomorphs in limestone area can be explained as follows; in glacial period wet

249

climate produced thick humus soil and it wasfavorable to paedomorphs. In Holocene thepresent coastal area became dry, and limestone was exposed. In short frequent extinction event of paedomorphs may have resulted
from the above climatic change since the lastglacial period.
M. chichijimana has an interesting morphotype set; one morpho type possesses aclear umbilicus and narrow color bands, andanother a closed umbilicus and wide anddark color bands. The former is forma A,
and the latter is formae Band C. Living
animals of forma A are distributed in Anijima, but fossil forma A occurs in the southern part of Chichijima. Forma B, now living in the southern part of Chichijima,
appeared in 25,000 yr. B.P., when the sea
probably stood at the lowest level, and at thattime forma A was disappeared in that area.
Living forma A is distributed on plateau
where is moderately dry environment covered
with scrubby sclerophyllous evergreen forest,and never occurs surrounding the plateau.
On the other hand, forma B occurs from bothareas of plateau and valleys. Such a plateau
area is widely distributed in Anijima but
occupies small area in Chichijima, and this is
the reason why forma A is not distributed in
Chichijima now. However, it is assumed
that suitable condition for forma A prevailed
widely at that time also in Chichijima,
because such a wide plateau as that of Anijima is thought to have covered Chichijima
formerly (Asami 1970). The erosion of theplateau is thought to be progressed especiallyin the main glacial period because of theeffect of the lower sea level. The substitution of these two formae is thought to havebeen rapidly accomplished in view of theirfossil records and the result of ESR dating(Figure 18). The following two possibilities
can be presumed about the process of substitution.
1. Forma B evolved from forma A about
25,000 yr B.P. in the southern part of Chichijima.

Satoshi Chiba

250

2. Forma B migrated to the area whereforma A became extinct.
The possibility of the case 2 is rather unlikely~ because forma B of M. chichijimana
can live both on the dry plateau and in thewet valley. Judging from the later appearance of fossil record and the distribution offorma B, I regard that forma B evolved fromforma A about 25,000 yr. B.P. in the valley
area newly developed in southern Chichijima.
Owing to the low mobility, the distribution
area of the two formae have been unchanged
since that time.
Forma C of M. chichijimana is now distributed in Ototojima. Though there is no
fossil record of forma C, the mutual resemblance in shell form between forma Band
forma C indicates that the latter branchedfrom forma A in the similar manner with theappearance of the former. The above
phenotypic level evolution in M. chich ijimana had occurred in Chichijima andOtotojima independently.
The presence of morphologically dissimilar
populations within the same species or among
species of the same stock strongly suggeststhat the adult shell morphology is remarkably
flexible and strongly influenced by the local
environment.
Conclusion
The endemic land snail genus Mandarina
in the Bonin Islands seems to be an interestingorganism for considering the tempo and modeof evolution from the viewpoint of historicalbiology. Analyses of genitalia anatomy andshell morphology on many living and fossil
samples have lead me to the following conclusions.
1. Classification of Mandarina based on
the early shell characters matches well withthat based on genitalia. In every species
juvenile shell morphology is little influenced
by habitat conditions, and it can be used forphylogenetic reconstruction.
2. Mandarina species can be classified

into three stocks, Stock I, Stock II and StockIII. Stock I consists of seven species containing two tree species, Stock II three ground
species and Stock III four tree species.
Species belonging Stock III are distributed inboth Chichijima and Hahajima Islands andhave counterparts in both islands. However,Stock I and Stock II are restricted to Chichijima and Hahajima, respectively. Speciationin Stock I and Stock II, and in each counterpart in Stock III occurred distinctly in Chichijima and Hahajima Islands at several
times, often followed by surprisingly rapid
and remarkable morphological change andby radiation to tree and ground habitats.
Mutual resemblance of shell features among
M. hirasei, M. hahajimana and M. exoptata
belonging to different stocks is interpreted asconvergence owing to their leave- or trunkadhering life habit.
3. In many species adult shell features arestrongly influenced by habitat or environmental conditions. By analyzing these charactersquantitatively, we can presume the life habits
and habitat conditions of fossil species.

Acknowledgments. I thank Professor
Itaru Hayami and Associate Professor Kazushige Tanabe for their critical reading of thismanuscript and for numerous helpful suggestions. Drs. Katsumi Abe and Tatsuo Oji,
and other colleagues at the Paleobiological
Laboratory of University of Tokyo kindly
provided fruitful discussion for improvementof this paper. Mr. Kiyonori Tomiyama ofTokyo Metropolitan University, Mr. Rei Ueshima of University of Tsukuba and Mr.
Eisaku Ozeki of Hahajima tourism officer
supplied me with many specimens of Mandarina and offered me valuable suggestion.
Mr. Kazuhiro Tanaka of the Central ElectricPower Institute gave me an opportunity to use
an ESR equipment, to whom I express mysincere gratitude.

886.

Morphologic diversity of Mandarina

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251

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R.A. (eds.), Skeletal growth of aquatic organisms: Biological records of environmental
Change. Plenum Press, New York.

Mukojima ~W~, Ototojima *>~, Anijima £~, Chichijima Y:.~, Minamijima~, Hahajima a~, Hirasima f~, Imotojima M::~, Meijima fJf.~.

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252

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A whale skeleton at

1,200 m below sea level: ta-

phonomic implications for vertebrate carcass falls indeep waters ............ , ...................... ·Allison, P.A.
t~lli'ilm O)~~*clfi Ic;e:i!-t Q 7 T::/ -v ::l f)J<!t!.lt1tE 0) it:tk ......................................................... ;§j~~

JlJ p ~;lt i1!llill 0) ilIJi ~ ~ B fllfi ll'f Tp G it -t Q Thalassinoides t Callianassa IC"J C' -C .............. ·!pjiiUt9c
TliIle~**$Ifill'f*O)~E~~-E~~ffit~!tD¥!.J

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Hayamina l\I;O)-~fiIC"Jc'-C ...... ~i1!l JEt. EBf\;IEz
Tj'ffie~*O) Ptychomya (=tJ:ft) IC"Jc'-C.... ·............ · .......................... ·EB~IEZ· EB* j:~
Notes on Tenuipteria c[ argentea (Conrad. 1858)(Bivalvia) from the Upper Maastrichtian (Cretaceous)of Hokkaido ...................................... ·Noda. M.

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noumi, San-in district. Southwestern Honshu. Japan.................... ··· ............ ·Nomura, R. and Seto. K.

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IC"J C' -C) ....................................... Matsumoto. T.
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On Hauericeras dt; Grossouvre,

et Shimizu. a Cretaceous ammonite species).............................. to*:i!fl~ • ttl* "1'. l13till~)'t~OO#TliIl.OO$&K~~Q • •~MU.O)llR~ll'fIJr~"""""···"""""·"""""""""2'i:EB!l;jfi: • ttJlJ$:5/:#.~~ii"aO)~OCIfill'fK~~Qn~~~R~~Elfirt............................................................ 1ti:Ji!E13Jl1[*OO~:1J0)*~i!t~!t~fL~1r.E* t ~~JlJ~0)~1IlI;{~........ " ............................... ,............ ······!!!fttif-;!<:

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shima, Japan

New members approved at the Council Meeting on June 23, 1989
Masahiko Shiba
Kenichi Miyata
Chang-Suk ShinPeter Anthony Allison
Y oshiko Kawabata
Gen Ishizaki
Mitsuharu Nakajima
Takashi Sato
Hiromi Matsuoka
Takashi Hasegawa
Atsuo Igarashi
Masao Iwai
Hajime Taru
Yuji Takakuwa
Hisayoshi Kato
Manabu Takasu
Hiroshi Sugano
Seceding members(Ordinary members)
Y oshimasa Kurashige
Kyuya Shinbo
Chounosuke Okamura(Fellow)
Masahisa Amano
Deceased member(Honarary member)
Kiyoshi Asano

Hikaru Nishizawa
J unichi I wai

Yoshijiro Kato
Manabu Kobayashi

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Transactions and Proceedings of the PalaeontologicalSociety of Japan

September 30, 1989

New Series No. ISS

CONTENTS
TRANSACTIONS
880. Tatsuaki Kimura and Bong-Kyum Kim: New taxa in the Late Triassic
Daedong Flora, South Korea, Part 2 .................................. 141
881. Y oshinari Kawamura and Kazuaki !ida: An early Middle Pleistocene murid
882.
883.

884.

rodent molar from the Kobiwako Group, Japan ........................ 159
Y oshihiro Tanimura: Denticu/opsis praehyalina, sp. nov.: An early Middle
Miocene pennate diatom from Dogo, Oki Islands, southwest Japan ........ 169
Tatsuro Matsumoto and Akito Asai: Cenomanian (Cretaceous) inoceramids(Bivalvia) from Hokkaido and Sakhalin I. Birostrina nipponica (Nagao etMatsumoto) ............................................ ',' .... : ....... 178
Natsuhiko Kojima: Dinoflagellate cyst analysis of Holocene sediments from
Lake Hamana in central Japan ........................................ 197

Masayuki Ehiro and Fuminori Takizawa: Foordiceras and Domatoceras(nautiloid cephalopods) from the Upper Permian Toyoma Formation, southern Kitakami Massif, northeast Japan .................................. 212
886. Satoshi Chiba: Taxonomy and morphologic diversity of Mandarina (Pulmonata) in the Bonin Islands .......................................... 218
PROCEEDINGS .......................................................... 252
885.