ISSN 0031-0204

Transactions and Proceedingsof thePalaeontological Society of Japan
New Series

No.

174

Palaeontological Society of J a pan
June 30, 1994

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The fossil on the cover is Isocrinus (Chladocrinus) hanaii Oji, an Early Cretaceous(Aptian) crinoid, which was described from the Hiraiga Formation exposed at Haipe,
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Museum of the University of Tokyo coli. cat. no. ME6950, paratype specimen, length
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Trans. Proc. Palaeont. Soc. Japan, N .S., No. 174, pp. 411-425, 8 Figs., June 30, 1994

968.

MEDIARIA MAGNA YANAGISAWA, SP. NOV.,A NEW FOSSIL RAPHID DIATOM SPECIESUSEFUL FOR MIDDLE MIOCENE
DIATOM BIOSTRATIGRAPHY*YUKIO YANAGISAWA
Geology Department, Geological Survey of Japan,
1-1-3 Higashi, Tsukuba, Ibaraki 305

Abstract. A new fossil diatom species Mediaria magna Yanagisawa sp. nov. isdescribed from the lower Middle Miocene Oidawara Formation in Mizunami area, Gifu
Prefecture, Japan. Morphologic investigation by light and scanning electron microscopes
has revealed that Mediaria magna is distinct from Mediaria splendida f. splendida and M.
splendida f. tenera by its unique characteristics. M. magna is of great value in Neogene
diatom biostratigraphy because it is easily identifiable even when fragmented and also
because it is very short-lived, being restricted to the lower part of the early Middle Miocene
Denticulopsis lauta Zone (NPD 4A) of the Neogene North Pacific diatom zone (Akiba,1986). Scanning electron microscopy reveals the presence of a raphe in the genus Mediaria
for the first time. The genus has a raphe of simple slit without fibulae and therefore it
cannot be placed in the order Bacillariales Hendey. It is morphologically similar to some
genera in the family Catenulaceae Mereschkowsky in the order Thalassiophysales Mann.

Key words.

Diatom, fossil, Mediaria, Miocene, Neogene, biostratigraphy.

stratigraphic study, I have found another
Mediaria species which is distinct from thetwo previously described taxa. In this paper,
the new species Mediaria magna Yanagisawa
sp. nov. is described from the lower Middle
Miocene Oidawara Formation in Mizunami
area, central Japan on the basis of detailed
light and scanning electron microscopic
observation. In addition, I have made alight and scanning electron microscopy on M.
splendida f. splendida and M. splendida f.
tenera for comparison. Moreover, the systematic position of the genus Mediaria isbriefly discussed.

Introduction
The fossil pennate diatom genus Mediaria
was erected by Sheshukova-Poretzkaya (1962)
as a monotypic genus including only Mediaria splendida Sheshukova from the Neogene
deposits of north Sakhalin of Far East Russia. About a decade later, Schrader (1973)
described an additional member M. splendida
f. tenera from DSDP Hole 173 off California.
Since then, Mediaria splendida f. splendida
and its forma tenera have been reported froma number of areas in the world, and used asimportant markers in Neogene diatom biostratigraphy (e.g. Barron, 1985a).
In the course of Neogene diatom bio-

Materials and method
Samples used for this study are as follows:'Received September 21, [993; revised manuscript
accepted February [4, [994(I) Samples Mzn 05,06,09, II and 14 from4[ IYukio Yanagisawa412

the Oidawara Formation in Mizunami area,
Gifu Prefecture, central Japan (Figures 1,2).
The samples were collected by Fumio Yoshida of the Geological Survey of Japan. (2)Sample JDS-11833 from the lower part of theTaga Group, Kitaibaraki, Ibaraki Prefecture,
Joban Coal field, northeast Japan, offered by
Fumio Akiba of Japan Petroleum Explora-

135"• Mediaria magna
CJ M. splendida f. splendidao M. splendida f. tenera
44"

42"

Japan Sea

40"

38"

Pacific
Ocean

34"
100

Figure 1.

Map

showingthe

200 Ianlocationstion Co. Ltd. (3) Samples from Deep Sea
Drilling Project Site 438 (Holes 438A and4388) (Figure I).
Samples were processed following themethod described in Koizumi (1985). A
strewn slide for light microscopy (lM) was
prepared for each sample on an 18 X 18 mm
cover glass and the cover glass was mounted
in Pleurax on a glass slide. For scanningelectron microscopy (SEM), diatom valves
were picked from dried samples and mounted
on sample stages, using one hair of a tiny
paint brush under a long-focused objective
lens. SEM observation was performed witha JOEL T330A scanning electron microscopeat the Geological Survey of Japan.
SEM observation was made on specimens
obtained from the Oidawara Formation in
Mizunami area. Stratigraphic distributionof this genus was examined in the sequence ofDeep Sea Drilling Project Holes 438A and
4388. In this study, samples analyzed by
Akiba et al. (1982), Maruyama (1984) andAkiba (1986), together with those depositedin DSDP Reference Center in National Science Museum (Tokyo) were re-examined withspecial attention to the genus Mediaria.
The Neogene North Pacific diatom zonation of Akiba (1986) and the classification
system of Round et al. (1990) are utilized inthis paper.

ofMediaria magna Yanagisawa sp. nov., M. splendida
Sheshukova f. splendida and M. splendida f. tenera
Schrader in Japan. DSDP Hole 438 (this study) ;I : Shimokurosawa Formation, Ichinoseki area
(Maruyama, 1984); 2: Otsuka Formation, Matsushima area (Akiba et al., 1982); 3: Taga Group,
Tomioka, Futaba area (Yanagisawa et al., 1989);
4: the lower part of the Taga Group, Kitaibaraki,
Joban Coalfield (this study); 5: Genjigawa Formation, Hitachi-ota area (Maruyama, 1984); 6: Katta
Formation, Nakaminato area (Maruyama, 1984); 7:
Nakayama Formation, Sado Island (Hasegawa,1977); 8: Hojuji Diatomaceous Mudstone andAwagura Formation, Suzu area, Noto Peninsula(this study); 9: Higashibessho Formation, Yatsuo
area (this study); 10: Omine Mudstone, lozen area
(Ito, 1986); II : Oidawara Formation, Mizunami
area (Mori, 1974; Akiba, 1979; this study).

Observation and description
Genus Mediaria Sheshukova, 1962

Mediaria magna Yanagisawa sp. nov.
Figures 3-1-3, Figures 4-1-8.
Synonymy: Mediaria splendida SheshukovaPoretzkaya, Mori, 1974, pI. 100, fig. 5; Akiba,
1979, pI. 3, fig. 23; Akiba et al., 1982, pI. 2, fig.
34, non pI. 2, fig. 35; Ito, 1986, pI. 3, fig. 9 ;Mediaria splendida Sheshukova-Poretzkaya(robust form), Maruyama, 1984, pI. 12, fig. 17,
non pI. 12, fig. 16.

Description. - Valve robust, broadly lan-968.

New fossil diatom Mediaria magna Yanagisawa

413

Table 1. Characters in Mediaria taxa. Numbers in parentheses for M. splendida f. splendida
and M. splendida f. tenera indicate measurement in original descriptions of the two taxa. Other
numbers indicate measurement in this study.

Length
Cum)

Width
Cum)

Transapicalstriae in 10 Jim

Longitudinalrows in 10 Jim

M. splendida f. splendida60- 87(70-100)

13.5-17( 10-16)

13-14(13-14)

11-12(11-12)

M. splendida f. tenera

81-115(70- 100)

12-15( 6- 8)

14-15(15-16)

11-13(14-15)

M. magna

82-18822-37

9.5-108-10'Mediaria taxa': areolae spacing in each transapical striae.

ceolate with elongate acute apices, 82-188 J.lm
long, 22-37 J.lm wide (Figure 5, Table I).
Valve face strongly plicated with respect toapical axis; raphe-bearing side convex,
whereas rapheless side concave with the partnear the transapical axis being raised (Figure4-1). A small triangular area near each apex
is hyaline and the rest of the valve face iscovered with relatively coarse areolae. The

Figure 2. Map showing locations of samples in
Mizunami area, Gifu Prefecture, Japan. Mzn 06:
the type locality of Mediaria magna Yanagisawa sp.
nov. Topographic maps "Minokamo" (left) and"Ena" (right), I : 50,000 in scale, Geographical Survey Institute of Japan.

areolae are arranged to form transapicalstriae, 9.5- 10 in 10 J.lm, with areolae in eachstriae, 8-10 in lOJ.lm (Table I). The striae
are slightly curved, more radiating toward theapices. The areolae are also arranged inquincunxes on the midway of the valve, butnear the raphe-bearing margin, are arranged
in two or three longitudinal rows parallel tothe margin. Around the transapical axis, theareolae are in an irregular arrangement withseveral minute areolae (Figure 4-7) Areolae
circular or semicircular, somewhat elongatedtransapically, 0.5-0.65 J.lm in diameter.
Each areola is occuluded by bars parallel tothe apical axis, the bars being commonly 3-4
and rarely 5 (Figure 4-8). The areolae of themarginal row along the rapheless margin areconspicuously elongated transapically, 0.71.5 J.lm long, with 4-10 bars (Figure 4-6).
Valve mantle is present only along the raphebearing side, about 8-9 J.lm in height. The
valve mantle is covered with areolae arranged
in four longitudinal rows, which gradually
decrease in number toward the apices (Figures 4-1,4). A raphe, consisting of two simple slits without internal fibulae (Figure 4-3),
runs the length of the valve along the border
between the valve face and valve mantle. A
relatively large terminal pore of the slit, about
1 J.lm in diameter, opens near each apex (Figures 4-2,5) and continues internally to form atubelike structure curving to the valve interior(Figure 4-3). This tubelike structure is
probably a kind of helictoglassa (Mann,Yukio Yanagisawa

4141977), a structure present at the internal raphe
end near the pole in many raphe-bearing
diatoms (Round et al., 1990).
Holotype. - Figure 3-1 (GSJ F 14585, deposited in the Geological Survey of Japan).
Type sample.- Mzn 06, massive diatomaceous mudstone from the Oidawara Formation of the Mizunami Group, collected by
Fumio Yoshida of Geological Survey ofJapan from a small road-cut cliff near Shukunohora, Mizunami City, Gifu Prefecture(35'24'31.22"N, 137'16'17.80"E; Figure 2).
The diatom flora of this sample is assignable
to the lower part of the Middle Miocene
Denticulopsis lauta Zone (NPD 4A) of Akiba(1986).
Remarks. - This new species is mainly
characterized by its broader and more robust
valve as well as its relatively coarser areolation compared with Mediaria splendida f.
splendida and M. splendida f. tenera (Figure
5, Table I). The species also differs from thelatter two taxa in having elongated andpointed apices, a plicated valve face, rounded
areolae, quincunx arrangement of areolae on
the valve face and three to five bars in eachareola. In fossil samples, the species is commonly found as a small broken fragment, but
it is easily identified and distinguished fromM. splendida f. splendida and M. splendida f.
tenera because of its larger areolae and morerobust valve wall.
Mediaria magna has been figured previously by many researchers as M. splendida (Mori,
1974; Akiba, 1979; Akiba et al., 1982;
Maruyama, 1984; Ito, 1986). Among them,Maruyama (1984) was the first to note that
this new species is a distinct form different
from the more slender form of M. splendida.
~

He illustrated this new species as M. splendida (robust form).
Stratigraphic occurrence. - Mediaria
magna is a very short-lived species, with its
occurrence confined within the lower part ofthe early Middle Miocene Denticulopsis lauta
Zone (NPD 4A) of Akiba (1986) (Figure 6).
In DSDP Hole 438A, the first occurrence of
this species lies between the first occurrence ofDenticulopsis lauta (Bailey) Simonsen andthe last occurrence of D. praelauta Akiba et
Koizumi (Figure 7). The last occurrence ofM. magna approximates or is slightly below
the first occurrence of Cavitatus lanceolatus
Akiba et Hiramatsu. The same stratigraphic
occurrence of M. magna has been recognizedin the Otsuka Formation in Matsushima area,
the Higashibessho Formation in Yatsuo area,
and the Hojuji Diatomaceous Mudstone andthe Awagura Formation in Suzu area
(Yanagisawa, unpublished data). The firstand last appearance datums of M. magna canbe estimated at 15.65 and 15.4 Ma, respectivelyon the basis of the age calibration of Oda(1986) and the sediment accumulation curvein DSDP Hole 438A.
Mediaria magna will provide a most usefuland reliable guide to the recognition of thelower part of the D. lauta Zone (NPD 4A)
because of its limited stratigraphic range aswell as its easily identifiable characteristics.
This new species, coupled with Cavitatuslanceolatus (Akiba et al., 1993) and Denticulopsis lauta and its related species(Yanagisawa and Akiba, 1990), can serve toimprove the precision and resolution of the
Middle Miocene diatom biostratigraphy in
the North Pacific (See Figure 7).
Geographic distribution. - At the present,

Figure 3. Light photomicrographs of Mediaria. Scale bar equals 10,um. 1-3. Mediaria magna
Yanagisawa sp. nov., Oidawara Formation, Mizunami area; (I) Holotype, GSJ F14585, Sample Mzn 06,
change of focus; (2) Sample Mzn II ; (3) GSJ F14586, Sample Mzn 06. 4,5. Mediaria splendida Sheshukova f. splendida, Sample JDS 11833, the lower part of the Taga Group, Kitaibaraki, Joban Coalfield; (4)GSJ F14589a, change of focus; (5) GSJ F14589b. 6-8. Mediaria splendida f. tenera Schrader; (6) GSJ
F14589c, Sample JDS 11833, the lower part of the Taga Group, Kitaibaraki, Joban Coalfield; (7) GSJ
F14587, Sample Mzn 05, Oidawara Formation, Mizunami area; (8) GSJ F14588, Sample Mzn 05, Oidawara
Formation, Mizunami area.

968.

New fossil diatom Mediaria magna Yanagisawa________ 6

4 15

Yukio Yanagisa wa

416

I. -

• • /J

8

Figure 4. Scanning electron photomicrographs of Mediaria magna Ya nagisawa sp. nov. Sample
Mzn 06, Oidawara Formation, Mizunami area. Scale bars equal 10 JIm in Figure I and I JIm in Figures
2- 8. 1. Inner view of va lve face and val ve mantle. 2. Outer view of valve apex, showing a terminal poreof raphe (arrow head). 3. Inner view of valve apex, showing a tube-like structure of raphe (arrow). 4.
Inner oblique view of valve. 5. Outer view of valve apex. Note a termin a l pore of ra phe (arrow) . 6.
Inner valve surface. 7. Irregular arrangement of areolae in the middle of the valve face. 8. Areolae withbars on valve face.

968.

New fossil diatom Mediaria magna Yanagisawa

417

200,-----------------------------~

Age

North PacificStratigraphic
diatom zones
ranges of.-Akiba (1986)
Mediaria taxa
Q

C-

Ma

Z

8

0

~
~

100

D. katayamae 6A
D.dimorpha5D

Thalassiosira
yabei

5C

..J

r-10
o

l!

""

:-

Mediaria magnao M. splendida f. splendida• M. splendida f. tenera
O+----T----.----T----.----T--~
40
10
20 Width (I!m) 30

11

12

II)

Denticu/opsis
praedimorpha 58

C

OJ

13

f}

)j

~

]-

:a C. nicobarica 5A

f}
...:

~

D. hyalina

48

~

~

{I-O'o-.- ~] ..

i-li15

16
II)

c

17

18

.9

D.lauta

4A

D. praelauta

38

g

>.

"5
~

~

l

):

~---.L

Crucidenticula 3A
kanayaeII)~

M. magna has been found only in Middle
Miocene sediments in Japan; DSDP Hole
438A (this study), the upper part of the
Otsuka Formation in Matsushima area
(Akiba et al., 1982; this study), the Genjigawa Formation in Hitachi-ota area (Maruyama, 1984), the Oidawara Formation in
Mizunami area (Mori, 1974; Akiba, 1979,
this study), the Omine Mudstone in Iozen
area (Ito, 1986), the upper part of the Higashibessho Formation in Yatsuo area (thisstudy) and the Hojuji Diatomaceous Mudstone and the Awagura Formation in Suzu
area (this study) (Figure I). Since the genus
Mediaria is broadly distributed in the world,
M. magna will very likely be found outside
Japan in the future.
Etymology. - The species name is derived
from its large size.

~

~

'"0

14

~

+

II)

Figure 5. Scatter plot of valve width (W) versus valve length (L) in Mediaria taxa. Closed circles: Mediaria splendida f. tenera Schrader (L=11.6W-53.1, r=0.484); Open rhombuses: Mediaria
splendida Sheshukova f. splendida (L=5.8W-12.6,
r=0.887); Open circles: Mediaria magna Yanagisawa sp. nov. (L=6.9W-75.8, r=0.802). Specimensof M. splendida f. tenera and M. magna are from thesamples Mzn 05,06,09, II, 14 in the Oidawara Formation, Mizunami area, and those of M. splendida f.
splendida are from the sample lDS-11833 in thelower part of the Taga Group, Kitaibaraki, loban
Coalfield.

••••

Thalassiosira
Jraga

2

•••
•

19

Figure 6. Stratigraphic ranges of Mediaria taxa
in the western North Pacific.

Mediaria splendida Sheshukova, 1962
f. splendida
Figures 3-4, 5.
Sheshukova-Poretzkaya, 1962, p. 210-211, text-fig. 5,
plate-fig. 2; 1967, p.306, pI. 47, fig. 14; pI. 48,
fig. 8; Schrader, 1973, pI. 3, figs 14, 15; Koizumi, 1973, pI. 7, figs. 5,6; Barron, 1976, pI. I,
fig. 21 ; Baldauf and Barron, 1982, pI. 7, fig. IS ;Akiba et al., 1982, pI. 2, fig. 35, non pI. 2, fig. 34 ;Maruyama, 1984, pI. 12, fig. 16, non pI. 12, figs.
15, 17; Barron, 1985a, p. 786, fig. 12.1 ; Gersonde and Burckle, 1990, pI. 4, fig. 14.
Synonymy: Trachysphenia australis Peit sensu

Yukio Yanagisawa

418

'"

OJ

North PacificDiatom zones

" ""

~~

-

Age
Akiba
(1986)

Q

!:I.
;Z

Ma

14
Denticulopsis
hyalina

OJ" .S"""" ~"~ ~'"""" "" .Sls"'-' '-' '-']- :.§"
a
6
.§
~
'" '"
"" "" ""'" ~ "~ .Sls" :<;"".~ §c .Slc s" "l:: ]"" "'- .~ "'·s"" ·s"" ·s"" .Sl "'.Sl" !
~ ~ ~ .g" !'"
a
G'
G'
'"
'"c ~ .g"
.g
c
c
.~
.§ §l
"e«: "8«: «:" \..l... Q"" Q Q Q (3 Q"" Q Q

.Sl
"'-

~ "...
S}~.....:~
,,~

~]

~

""~

]~

.S!
...

~+

::;:"

E;-~

'"

.!:)

"

~

DiatomDatum
Levels1148

FAD D. hyalina

QJ

=
QJ

<:.J

0

15

~
QJ

:a'C
~

Denticulopsis---- -4A - -- ------lauta--- ------- - - -- - -- ---- -- --Denticulopsis
praelauta:::r:---- ------------

QJ

<:.J

------- ------- ---- -. --- --- .. LAD D.praelauza
FAD D. praelauza

I
I

- -

--

ell
[;l.l

10

- --

FAD D.laUla

QJ

0

..

38

··
=
- -.------- --Crucidenticula
·
~
3A
··
kanayae
....
:
;:
·
:
17

16

-'~J--- - ----------I- LAD D. okunoi-- ----------- -- - -- --------------- 4 FAD D.okunoi-- ----------- -- ---- --------------- 4 FAD C. lanceolazus-----~------- ----- -- - - -- - ---- - --- -- - -. --- r- LAAD C. kanayae~FAD

A. ingens

Figure 7. Stratigraphic .occurrence of Mediaria magna Yanagisawa sp. nov. This figure is made on
the basis of stratigraphic analysis of DSDP Holes 438A and 438B. Ages of zone boundaries after Oda(1986). Ages of other diatom datums were estimated by sediment accumulation curve in DSDP Holes
438A and 438B. F AD, LAD and LAAD indicate the first, last and last abundant appearance datums,
res pect ivel y.

Jouse, 1959, pI. 3, fig. I; 1963, pI. 10, fig. 13;
Rhizosolenia sp. b, Mertz, 1966, p.23, pI. 5, figs.
5-7.

Observation. - Valve lanceolate withacutely rounded apices. Valve face almost
flat, but slightly concave at raphe side. Specimens observed in this study measure 60-87
J.Lm long and 13.5-17 J.Lm wide (Figure 5,
Table 1). Valve face covered with fineareolae except for a small hyaline area neareach apex. Areolae arranged in transapicalrows forming striae, which are slightly curved
and more radiating toward the apices. The
areolae also form curved longitudinal rows

parallel to the raphe-bearing margin. The
trans apical striae and the longitudinal rows
are spaced, 13-14 in 1OJ.Lm and 11-12 in 10
J.Lm, respectively (Table 1).
Although this species was not examined byelectron microscopy in this study, its finevalve structures may be the same as those of
the forma lenera described below, because of
intimate morphologic similarities between the
two taxa.
Remarks. - The forma resembles theforma lenera, but differs from the latter by its
broader valve outline (Figure 5) and slightly
coarser areolation (Table 1). However, thetwo taxa are hardly distinguishable when they

968.

New fossil diatom Mediaria magna Yanagisawa

are fragmented. Mediaria splendida f. splendida differs from M. magna by its more
slender valve outline (Figure 5), finer areolation and non-q uincunx arrangement ofareolae.
Stratigraphic occurrence. - In DSDP
Holes 438A and 438B, the first occurrence of
this species may lie slightly above the base of
the Crucidenticula kanayae Zone (NPD 3A)
of Akiba (1986) (Figure 6). However, thespecies may range down to the upper part of
the Thalassiosira fraga Zone (NPD 2) in theLower Miocene sediments in Boso Peninsula,
Japan (Akiba, personal communication,1992). Its last consistent occurrence is in theThalassiosira yabei Zone (NPD 5C) and its
last occurrence lies in the Denticulopsis
dimorpha Zone (NPD 50).
Geographic distribution. - Reported occurrences of M. splendida f. splendida indicatethat it is a middle- to high-latitude species(Barron, 1985a). The species has been mainly recorded from the middle-to high-latitude
Northern Hemisphere; i.e. from Sakhalin(Jouse, 1959; Sheshukova-Poretzkaya, 1962,1967), Japan (Barron, 1980, Akiba et al.,
1982, Maruyama, 1984), California (Schrader,
1973, 1974a; Barron, 1975,1976,1981; Baldauf and Barron, 1982) and the NorwegianSea (Schrader and Fenner, 1976; Baldauf,
1987). It has also been reported from theSouthern Ocean (Schrader, 1976; Ciesielski
1983; Gersonde and Burckle, 1990) and Peru
(Mertz, 1966). However, this species has
never been documented from tropical regions(e.g. Schrader, 1974b; Barron, 1983, 1985b).

Madiaria splendida f. tenera Schrader, 1973
Figures 3-6-8, Figures 8-1-7.
Schrader, 1973, p. 706, pI. 3, fig. 13; Gersonde andSchrader, 1984, p. 101-102, pI. I, fig. 8.
Synonymy: Mediaria splendida SheshukovaPoretzkaya, Barron, 1976, pI. I, fig. 22; Schrader
and Fenner, 1976, pI. 8, fig. 18; Hasegawa, 1977,
p. 55, pI. 25, figs. 1-3; Abbott and Andrews,
1979, p.246, pI. 4, fig. 2; Abbott and Ernissee,
1983, p. 30 I, pI. 13, fig. 4; Powers, 1988, pI. 6, fig.

419

6; Fourtanier and Machare, 1988, pI. 3, fig. 32 ;Yanagisawa et al., 1989, pI. 5, fig. 42; Mediaria
splendiaa Sheshukova-Poretzkaya (slim form),
Maruyama, 1984, pI. 12, fig. 15.

Observation. - Valve delicate, narrowly
lanceolate with nearly parallel sides in the
middle, and with acutely rounded apices (Figures 3-7, 8). Valve face almost flat, butsomewhat concave at the raphe side (Figure8-1). Specimens observed in this study measure 81-115,um long and 12-15,um wide
(Table I, Figure 5). According to Schrader's(1973) description, the transapical striae andthe longitudinal rows are spaced, 15-16 in IO,urn and 14-15 in IO,um, respectively, but
those of my specimens are slightly coarser;
the transapical striae and longitudinal rows
are 14-15 in IO,um and 11-13 in IO ,urn,
respectively (Table I). Areolae except for
marginal areolae are nearly quadrangular inshape, transapically elongated, ca. 0.2 X 0.4,urn in size. Each areola is occluded with anarrow bar parallel to the apical axis (Figures
8-5, 6). The areolae of the marginal rows
along both margins are elongated transapically, occluded with 3-5 bars (Figures 8-5,
6). Valve mantle is present only at the rapheside (Figure 8-4), with two longitudinal rowsof areolae of the same size at those on thevalve face (Figures 8-1, 3, 7). A rapheoccupies almost the whole valve length along
the border between the valve face and valve
mantle. It is interrupted at the middle (Figures 8-6, 7), consisting of two simple raphe
slits without fibulae. A relatively large terminal pore (about O.4,um in diameter) opens
near each apex (Figure 8-3), and continues
internally to form a tubelike structure whichcurves to the valve center (Figures 8-2,4).
Remarks. - This taxon is distinguishedfrom M. splendida f. splendida by its more
slender valve (Figure 5) and slightly finer
areolation (Table I). However, the differences are not so clear that it might be rather
difficult to distinguish the two taxa whenvalves are fragmented to small pieces of punctated plates.

420

Yukio Yanagisawa

The valve structures of M. splendida f.
tenera are almost the same as those of M.
magna; the both taxa have in common such
structures as the lanceolate valve outline, thehyaline triangular area near each apex,
areolae occuluded with bars, the large terminal pores of raphe and associated internal
tubelike structures. However, M. splendida
f. tenera is different from the latter species inhaving a more slender valve outline (Figure5), smaller areolae (Table I) and quadrangular shape of areolae occuluded with a single
bar.
Stratigraphic occurrence. - Since M. splendida f. splendida and M. splendida f. tenera
are hardly distinguishable from each other inmoderately or poorly preserved fossil materials where specimens are fragmented, it wasdifficult to clarify the precise stratigraphic
range of M. splendida f. tenera in DSDP
Holes 438 A and 438B.
According to Schrader's (1973) occurrence
chart of DSDP Hole 173, M. splendida f.
tenera occurs in the interval from Cores 17-3
to 16-1. On the basis of re-examination ofHole 173 by Barron and Keller (1983), thisinterval can be placed from the middle part ofthe late Miocene Denticulopsis hustedtii Zone
to the upper part of the Thalassiosira antiqua
Zone of Barron (1981). As this forma has
also been reported in the Lower Pliocene
Trubi marls of Sicily (Schrader and Gersonde, 1978) and in Upper Miocene Messinian
sediments from southwest Spain, Algeria andSicily (Gersonde and Schrader, 1984), the lastappearance of this forma may lie in the Early
Pliocene. In Hole 438A, however, noMediaria specimens are found in the Upper
Miocene to Lower Pliocene interval. Thus

the stratigraphic range of M. splendida f.
tenera appears to be largely diachronous.
Geographic distribution. - This forma has
been recorded from various areas in the
middle to high latitudes; DSDP Hole 173 off
California (Schrader, 1973), the Monterey
Formation in Upper Newport Bay section,
California (Barron, 1976), the Shimokurosawa Formation in Ichinoseki area, Japan(Maruyama, 1984), the Taga Group in the
Futaba area, Japan (Yanagisawa et al.,1989), the Nakayama Formation in Sado
Island, Japan (Hasegawa, 1977), the Pisco
Formation in Peru (Fourtanier and Machare,1988), the Hawthorn Formation of South
Carolina and Georgia (Abbott and Andrews,1979), the Pungo River Formation of North
Carolina (Abbott and Ernissee, 1983), Messinian sediments in southwest Spain, Algeria
and Sicily (Gersonde and Schrader, 1984), theLower Pliocene Trubi marls of Sicily(Schrader and Gersonde, 1978), and DSDP
Hole 348 in the Norwegian Sea (Schrader andFenner, 1976).

Discussion
Despite the biostratigraphic utility of thegenus Mediaria, the taxonomic status of thegenus has long been obscure. SheshukovaPoretzkaya (1962, 1967) reported the presenceof a keel (canal raphe) on the valve shoulderof M. splendida and hence she placed thegenus Mediaria in the family Nitzschiaceae
Grunow. However, the presence of a keel
(canal raphe) cannot be ascertained from her
figures and no subsequent diatom study has
recognized or mentioned the keel in the
specIes. Probably for this reason, a precise~ Figure 8. Scanning electron photomicrographs of Mediaria splendida f. tenera Schrader. Sample
Mzn 06, Oidawara Formation, Mizunami area. Scale bars equal lO,um in Figure 1 and l,um in Figures
2-7. 1. Outer oblique view of valve. Note a raphe along the shoulder of the valve. 2. Inner view of valve
apex with detached mantle. Arrow head indicates a tube-like structure of raphe. 3. Outer view of valve
apex, showing a terminal pore of raphe (arrow head). 4. Inner view of valve apex. Note a tube-likestructure of raphe (arrow). 5. Inner view of valve interior. 6. Outer view of valve surface with interrupted
raphe slit. Arrow head indicates the interruption of raphe at the middle. 7. Outer view of valve face andvalve mantle. Arrow head indicates the interruption of raphe at the middle.

968.

New fossil diatom Mediaria magna Yanagisawa

421

Yukio Yanagisawa422

systematic position has not been given to thisgenus in recent diatom taxonomic syntheses(Simonsen, 1979; Round et al., 1990).
Scanning electron microscopy by this study
has ascertained the presence of raphe in thisgenus for the first time. As mentioned
above, Sheshukova-Poretzkaya (1962, 1967)
placed the genus Mediaria in the family
Nitzschiaceae Grunow (=the order Bacillariales Hendey in Round et al., 1990) because of
the presence of keel (canal raphe). This
study, however, has revealed that the raphe ofMediaria is not a canal raphe but a simple
fissure without fibulae. Since the presence offibulae in the raphe is the most characteristicfeature of the Bacillariales (Round et al.,1990), the genus Mediaria can not be included in Bacillariales.
Madiaria shows a slight resemblance to thegenera Catenula and Amphora in lacking
fibulae and having an eccentric raphe lying at
the junction of the valve face and mantle. If
this morphologic similarity is essential, thegenus Mediaria may be assigned to the family
Catenulaceae Mereschkowsky in the orderThalassiophysales Mann. ~owever, further
study is needed to confirm the taxonomic
position of the genus Mediaria.

Conclusion
A new species Mediaria magna is herein
described, which is very short-lived and usefulas an index fossil for the lower part of theearly Middle Miocene Denticulopsis lauta
Zone (NPD 4A) of Akiba (1986). Light andscanning electron microscopy revealed that
M. magna is distinct and clearly distinguishable from M. splendida f. splendida and M.
splendida f. tenera by its unique characteristics.
The presence of a raphe has been ascertained in this genus for the first time using
scanning electron microscopy. The raphe ofthis genus is a simple slit without fibulae andtherefore the genus cannot be assigned to theorder Bacillariales Hendey. It rather resem-

bles some genera in the family Catenulaceae
Mereschkowsky in the order Thalassiophysales Mann.

Acknowledgments
I would like to express special thanks to
Fumio Akiba (JAPEX Research Center ofJapan Petroleum Exploration Co. Ltd.), Itaru
Koizumi (Hokkaido University), John A.
Barron (U.S. Geological Survey) andElisabeth Fourtainer (California Academy of
Sciences) for their critical review of an earlydraft of this manuscript, and also for theirvaluable suggestions on taxonomy and biostratigraphy. I also thank Fumio Yoshida(Geological Survey of Japan) and Hiroshi
Noda (Tsukuba University) who kindly provided samples used in this study.

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Mizunami :fffiI~, Shukunohora &i1"J, Oidawara Formation ~f*~, Ichinoseki -~, Simokurosawa Formation r~tR~, Matsushima :f'l~, Otsuka Formation *~~, Tomioka '/§/lill,
Futaba m¥, Taga Group ~~~fF, Kitaibaraki ~t~~, Joban Coalifield m~ER:E8,
Hitachi-ota mlSi:t:E8, Genjigawa Formation iI]\.f.\;JII~, Sado ~i1t, Nakayama Formation
J:j:I0.J~, Suzu ~1+1, Hojuji Diatomaceous Mudstone ittE~ltll:it¥Je;'5, Awagura Formation~:ft~, Yatsuo /\~, Higashibessho Formation :~IUJUPJT~, [ozen I2:EE0.J, Omine Mudstonefij ¥Je;'5 .

'*

968.

New fossil diatom Mediaria magna Yanagisawa425~M~ilTi!t!t51Il~~':1fFfltt1t1:i!t)J0) 1 iIT;fI Mediaria magna Yanagisawa sp.
nov.: w~1tE!Ui$i0) I ~'fi Mediaria magna sp. nov. 1r, il!XJiil.liF<fffif~nHtilil~:5HIJT.o i:j:I$i:j:I~.~• • ~G~.Lko*k, *'fi~~~ m.~ffiO)i:j:I~.~ • • m~G~mL
t.:. Mediaria splendida Sheshukova f. splendida, ~ ~ -U~• • ip G ~ G nt.:. M. splendida f.
tenera Schrader K: -:Jl~c, :J\:;~. Jt~~~-TJIJj~~I;: ~ .ol\'l~!:: ~~O)J;tij!XHTl~, f- n{"nO) 7' ~ -IT0)!f?j~ 1r8)j G iJ' I;: L t.:. a Mediaria magna f;J:*~-C~3tI;t~1rj'ifi?, !f?jffO)~~i¥J!f?j~I;: ~ I) ft!!.0) 2 7' ~ -ITiJ' G f;J:a}jlBjH;:I25jjIJ~ n.o o ;:: O)'fif;J:, .Ff:~i¥J~mfllHl~IWi:j:I
Wli:j:I~t!!:?)J:MO) Denticulopsis lauta Zone (NPD 4A) O)T$I;:llJUE~ n, ~.~i¥JI;:~60
cffFflc+;Ii).oo I;t~, Mediaria JMI;:*liE~ (raphe) iJ!:ff:tET.o;:: !::iJ!Jt~~~-TJIJj~~IU:.0 l\'l~0)*S*, f;J: c: 60 cTitWJ ~ nt.:.o *JMO)*liE~fJ:Fa't1Z (fibula) 0) I;t l~1j!*Ill;tm@-C;li) I) ,;::0);:: !::iJ'G*JMf;J:, Fa't1Z1rj'if-:J;::!:: 1r!f?j~!::T.o Bacillariales EH;:-2i"60.o;::!:: f;J:-C~ I;tl~o *JMf;J:tJL::' Thalassiophysales § Catenulaceaef40)~-:JiJ'O)JMI;:1J:)cl~.oo;fpj]rR*x

Trans. Proc. Palaeont. Soc. Japan, N.S., No. 174, pp.426-448, 8 Figs., June 30, 1994

969. TAXONOMIC STUDIES OF THE NEOGONIOLITHONFOSLIEI COMPLEX (CORALLINACEAE, RHODOPHYTA)
IN THE RYUKYU ISLANDS*Y ASUFUMI IRYU
Institute of Geology and Paleontology, Faculty of Science,
Tohoku University, Aobayama, Sendai, 980
and

SHINY A MATSUDA
College of Education, University of the Ryukyus,
Nishihara, Okinawa, 903

Abstract. Taxonomic studies of the" Neogoniolithon fosliei complex" are conductedon the basis of the Recent materials collected from reefs on lshigaki-jima (Ishigaki Island),the Ryukyu Islands, southwestern Japan. Detailed morphological and anatomical examination reveals that nonarticulated coralline algae comprising the complex are classified into
three species: N. fosliei, N. tenuicrustaceum sp. nov., and Neogoniolithon sp. A. The
arrangement of bi-/tetrasporangia in the conceptac1e chamber (across the fioor or peripheryonly) or the presence or absence of the central columella is proved to be of potential
taxonomic significance for distinguishing Neogoniolithon from Spongites.
Key words.

Corallipe algae, Neogoniolithon, Spongites, Ryukyu Islands.

later assigned it to Neogoniolithon (Lemoine,
1965, 1966). In these taxonomic studies, including the proto log of the present species,
only a few figures were given to show anatomical features. Gordon et al. (1976) and
Adey et al. (1982) gave detailed
morphological-anatomical descriptions of N.
fosliei based on materials from Guam and
Hawaii, respectively, falling into disagreements about its outer appearances and internal structures. In the Ryukyu Islands arefound non articulated coralline algae which
can be identified as N. fosliei sensu Gordon etal. (1976) and N. fosliei sensu Adey et al.
(1982). Moreover, in his experimental study
on succession and growth rates of nonarticulated coralline algae, Matsuda (1989)
found that N. fosliei covered an artificial sub-Introduction

Neogoniolithon fosliei was first described byHeydrich (l897a) as Lithothamnion fosliei
based on the specimens from EI Tor, Red Sea,
and was soon transferred to Lithophyllum(Heydrich, l897b). Foslie assigned thisspecies to Archaeolithothamnium (Foslie,1898) and later to Goniolithon (Foslie, 1901).
Setchell and Mason (1943) emended the highly confused generic circumscription of
Goniolithon and differentiated Neogoniolithon
from it. Neogoniolithon fosliei was selected
as the type species of the genus Neogoniolithon. Lemoine (1911) considered that thisspecies was referable to Lithophyllum, but'Received April 25, 1994; accepted May 6, 1994
426

969.

Neogoniolithon fosliei complex

strate placed in an upper forereef environment off Ishigaki-jima. Neogoniolithon fosliei in his sense is apparently different from N.
fosliei sensu Gordon et al. (1976) and that of
Adey et al. (1982).
Consequently, there exists an "N. fosliei
complex" which comprises N. fosliei sensu
Gordon et al. (1976), N. fosliei sensu Adey etal. (1982), and N. fosliei sensu Matsuda(1989) in the Ryukyu Islands, and thus thequestion which arises is: Which of the three
is N. fosliei? The aim of this paper is toclarify such ambiguity in the taxonomy of the
N. fosliei complex.

25Sll). Pieces of the fixed materials weredecalcified with a 5% trichloroacetic acid- or
acetic acid-sea water mixture, dehydrated in a
graded series of ethanol or ethanol-normal
buthanol mixture, embedded in paraffin, andcut to lO,um in thickness. Sections were
stained in Delafield's haematoxylin and eosin.
Permanent slides of N. fosliei sensu Matsuda
on which the study of Matsuda (1989) was
based were also re-examined. Epithallial
cell dimensions were measured under an
optical microscope and the other cell measurements were made on scanning electron
micrographs. These measurements represent
the size of cell lumens, not including cell
walls. The specimens examined in this study(Table I) are housed in the Institute of Geology and Paleontology, Faculty of Science,
Tohoku University, Sendai (IGPS).

Materials and Methods
All the specimens were collected at
Ishigaki-jima, Ryukyu Islands (Figure I).
Some of them were dried and the others fixedand preserved in sea water with 8-10% formalin. Fractures of the dried material were
coated with gold and then observed with ascanning electron microscope (JEOL-JSM-

V

""1,

"6'~/

"

0

427

/~

/

•o~.

',,~( ~

..

.,.
~.

/J>()o' 'c!'o
~

;j,,,
.....

. a c::,.

~u,~,;::/~~::.,~,
,

/

~
0
.

;;:
, ... -- ""-2km

Figure 1.

YONEHARAe

,,

,,

A
,
\

.......... ,

,,

0

10km

')

Map showing localities where specimens were collected.

428

Yasufumi Iryu and Shinya Matsuda
Table 1. List of the specimens examined. All the specimens were collected by Y. Iryu
and S. Matsuda, but the samples of IGPS ColI. Cat. Nos. 99310 and 99311 were collected by
Y. Iryu and those of IGPS ColI. Cat. Nos. 102469 and 102470 by S. Matsuda.
IGPS ColI.
Depth
Loc.
Date
Species(m)Cat. No.
y/m/dN. fosliei sensu Gordon et at. (1976)
100957
8
St. A
1987/7/23
St. A=N. fosliei
10095815
1987/7/23
29
St. A
1009591987/7/23
10096329
St. A
1987/7/24
N. fosliei sensu Adey et at. (1982)
99310
17
St. A
1985/9/6= Neogoniolithon sp. A
99311
18
St. E
1985/9/12
99312
15
St. A
1985/9/11
100964
1
St. C
1987/7/29
100965
1
St. C
1987/7/22
100966
5
St. A
1987/7/22
100967
16
St. A
1987/7/23
100968
1
St. C
1987/7/29
1009691
St. C
1987/7/30
1009701
St. C
1987/7/30
100971
16
St. A
1987/7/23
100972
5
St. A
1987/7/22
1009738
St. A
1987/7/23
100974
5
St. A
1987/7/22
100975
16
St. A
1987/7/23
100976
5
St. A
1987/7/22
100977
8
St. A
1987/7/23
100978
1
St. C
1987/7/30
1009791
St. C
1987/7/30
1009801
St. C
1987/7/30
100981
12
St. B
1987/7/21
100982
5
St. A
1987/7/22
10098316
St. A
1987/7/23
10098416
St. A
1987/7/23
100985
5
St. A
1987/7/22
1009868
St. A
1987/7/23
100987
8
St. A
1987/7/23
100988?
St. A
1987/7/23
1009895
St. A
1987/7/22
1009905
St. A
1987/7/22
100991
16
St. A
1987/7/23
10099216
St. A
1987/7/23
100993
12
Sr.A
1987/7/23
10099416
St. A
1987/7/23
100995
16
St. A
1987/7/23
100996
5
St. A
1987/7/22
100997
5
St. A
1987/7/22
1009988
St. A
1987/7/23
N. fosliei sensu Matsuda (1989)
1009992
St. A
1987/7/25= N. tenuicrustaceum sp. nov.
1010002
St. A
1987/7/25
1024592
St. A
1987/7/24
1024602
St. A
1987/7/25
102461
2
St. A
1987/7/25
102462
2
St. A
1987/7/25
102463
2
St. A
1987/7/24
1024642
St. A
1987/7/24
1024652
St. A
1987/2/25
1024662
St. A
1987/7/24
1024672
St. A
1987/7/25
1024682
St. A
1987/7/25
1024693
St. F
1979/5/14
1024703
St. D
1977/10/3

969.

Neogoniolithon fosliei complex

Observations
1.

Nonarticulated coralline algae forming the
Neogoniolithon fosliei complexa.

External appearance

Plants of N. fosliei sensu Gordon et al.
(1976) are anchored to the substratum ventrally by cell adhesion (Figure 2-1). The degreeof adhesion varies from full to localized.
They consist of a crust, more or less conforming to the contour of the substratum, with arather flattened to irregularly lobed dorsal
thallus surface, never having protuberances orbranches. They are thick (up to 5 mm) andextensive (exceeding 20 em in diameter).
The dorsal thall us surface is dull and pale
gray to pale pink. The thallus margin ismore or less smooth. Large, convex to conical, protruding conceptacles (1,200-l,700,u m
in diameter) are scattered over the dorsal
thallus surface except for the peripheral partof the thalli. With the scanning electron
microscope (SEM) a number of polygonal
concavities are observed on the dorsal thallus
surface (Figure 2-5). These concavities,
termed epithallial concavItIes (Garbary,1978), are due to the collapse of epithallial
cells during specimen preparation as noted
for some other nonarticulated coralline
species (Garbary and Veltkamp, 1980; Masaki et al., 1984; Woelkerling et al., 1985;
Woelkerling and Irvine, 1986; May andWoelkerling, 1988). Epithallial concavities
are evident, and each concavity is lined byridges in some parts, whereas in the otherparts where they are not so distinct very shallow hollows are barely recognized. A pinhole, a trace of the primary pit-connection,
can be observed at the center of some concavItIes. Holes from which trichocyte hairs
protruded are scattered among the concavities, not forming distinct fields or clusters.
Plants of N. fosliei sensu Adey et al. (1982)
are firmly attached to the substratum ventrally
by cell adhesion and crustose, with a flattened
dorsal thallus surface (Figure 2-2). They are429

up to 3 mm in thickness and do not exceed IS
em in diameter. The dorsal thallus surface isglossy and minutely rugulose. Color is lightpink to pale orange on the vegetative surface,but attaining yellowish spots on conceptacle
domes and white to pale yellowish brown
patches or rings on scars caused by breaking
out of conceptacles. The thallus margin isserrated. Convex to conical, protruding conceptacles (800-1,500,um in diameter) aredispersed over the dorsal thallus surface.
The number of conceptacles is highly variablefrom specimen to specimen. With the SEM,
it is clear that dorsal thallus surface is characterized by numerous, rounded to polygonal
epithallial concavities and ridges between the
concavities (Figure 2-5). The epithallial
concavities of these plants are much deeper
and more distinct than those of N. fosliei
sensu Gordon et al. (1976). Holes fromwhich trichocyte hairs emerged are sporadically found among the concavities.
Plants of N. fosliei sensu Matsuda (1989)
are tightly anchored ventrally to the substratum by cell adhesion (Figure 2-3). They
form a crustose thallus less than 500,um thickand up to 10 em in diameter. The dorsal
thallus surface is not glossy but dull, regulose,
and pale yellow to orange yellow. The thallus margin is minutely serrated. Small conical conceptacles evenly scattered over thedorsal thallus surface are numerous, 600-760,urn in diameter. With the SEM, it is observed that the dorsal thallus surface is pavedwith numerous, polygonal to subrounded,
flat, domed or slightly depressed, dorsal wallsof epithallial cells, lacking epithallial concavities (Figure 2-6). Such a surface texture
indicates that, as shown below, the dorsal
walls of the epithallial cells here are muchthicker than in the previous cases, which is
why they evaded collapse during specimen
preparation. A trace of the primary pitconnection is found as a pinhole at the centerof some concavities. Holes from which trichocyte hairs emerged are dispersed on thedorsal thall us surface.

Yasufumi [ryu and Shinya Matsuda

430b.

AnatomyThalli are organized in a dorsi ventral
manner in all cases, viz. N. fosliei sensu
Gordon et al. (1976)., N. fosliei sensu Adeyet al. (1982), and N. fosliei sensu Matsuda(1989). In fractures or vertical sections, three
regions are easily discernible: epithallium,
perithallium, and hypothallium, from dorsum
to venter (Figures 3-1, 3-2 and 3-3.)b-l.

Epithallium

Epithallium of N. fosliei sensu Gordon etal. (1976) consists of a single layer ofrounded, subisodiametric to laterally elongated cells with thickening dorsal lateral cell
walls, which Adey et al. (1982) called covercells (Figure 3-4). Cells are 6-IO,um longand 7-15,u min diameter. In the field, it isfrequently found, as noted by Gordon et al.
(1976), that the epithallium of these plants issloughed off and observed as a semitransparent membrane.
Neogoniolithon fosliei sensu Adey et al.
(1982) has an epithalli urn composed of asingle layer of cells. Cells are generallyrounded and laterally elongated, 4-10,um
long and 7-17 ,u m in diameter, but they are
subisodiametric where the shedding of epithallium and subsequent new cell formation
occurs (Figure 3-5). Thickening of dorsal
lateral cell walls is not observed and the cell
walls are thinner than those of N. fosliei sensu
Gordon et al. (1976) and N. fosliei sensu
Matsuda (1989), resulting in the most distinct
epithallial concavities of the three plants.
Epithallium of N. fosliei sensu Matsuda(1989) is formed of a single layer of rounded
and laterally elongated cells (Figures 3-6 and
3-7). Cells are domed, with thick dorsal
lateral cell walls (up to lO,um in thickness)
which forms convexities on the thall us surface~

observed with the SEM. The dorsal lateralcell walls are as thick as or thicker than thecell lumina, being up to lO,um in thickness.
Cells are 3-8 ,urn long and 7-14 ,urn in diameter.
b-2.

Peri thallium

Perithallium of N. fosliei sensu Gordon etal. (1976) is multilayered and its constituent
filaments are straight (Figures 3-1,3-4 and 4I). Cells are rounded, subisodiametric tovertically elongated, 6-16,u m long and 5-13
,urn in diameter. The vertical cell walls ofolder (= ventral) portions are thick (up to 8,urn) due to heavy calcification, which makesthese cells more rounded than those newer(=dorsal) portions. Some cells containfloridean starch granules. Fusions between
cells of adjacent filaments are commonly seen.
Neogoniolithon fosliei sensu Adey et al.
(1982) has a multilayered perithallium
consisting of undulated filaments (Figures 32, 3-5 and 4-2). Cells are somewhat
rounded, sub-isodiametric to vertically elongated, 9-20,um long and 7-l5,um in diameter. Floridean starch granules are containedin some cells. Cell fusions are common.
Perithallium of N. fosliei sensu Matsuda(1989) is multilayered and consists of rather
straight filaments, cells of which are laterally
elongated, subisodiametric or vertically elongated, 8-l5,um long and 5-13 Jim in diameter(Figures 3-3, 3-6 and 4-3). Floridean starch
granules are rarely found. Cell fusions arecommonly seen.
b-3.

Trichocytes

The trichocytes of N. fosliei sensu Gordon
et al. (1976) are arranged in vertical columns
at the thallus surface or within the perithallium, not forming lateral fields or clusters(Figures 3-\ and 3-4). The abundance of

Figure 2. Habit (1,2, and 3) and scanning electron micrographs of thallus surfaces (4,5, and 6).
Note holes from which trichocyte hair cells emerged (arrow) and traces of primary pit connection, each ofwhich is observed as a pinhole at the center of epithallial concavity (arrow head). I: Neogoniolithon fosliei
sensu Gordon et al. (1976), IGPS ColI. Cat. No. 100958. 2: N. fosliei sensu Adey et al. (1982), IGPS
ColI. Cat. No. 99310. 3: N. fosliei sensll Matsuda (1989), IGPS ColI. Cat. No. 102459. 4: N. fosliei sensll
Gordon et al. (1976), IGPS 100957. 5: N. fosliei sensll Adey et al. (1982), IGPS CoIl. Cat. No. 100966.
6: N. fosliei sensu Matsuda (1989), IGPS ColI. Cat. No. 100999.

969.

Neogoniolithon losliei complex

431

432

Yasufumi Iryu and Shinya Matsuda

trichocytes in the plants is variable from
specimen to specimen, but they are found in
all the specimens examined in this study. Up
to 20 trichocytes are arranged in each column,
the cell size of which is 6-27 ,um length and
14-22,um in diameter. A terminal trichocyte in the column is two-celled, verticallyelongated, and larger in cell size than lower
subisodiametric to laterally elongated cells,
when observed at the thallus surface. It isevident in N. fosliei sensu Gordon et al.
(1976) that the trichocytes persist after epithallial and perithallial cells are produced fromthem and after sinking into the perithallium
they never degenerate or are filled with endogenously orginating filaments of peri thallial cells, unlike Neogoniolithon notarisii(Foslie) Setchell et Mason (Cabioch, 1971).
Neogoniolithon fosliei sensu Adey et al.
(1982) has trichocytes arranged in verticalcolumns at the thallus surface or within theperithallium (Figure 3-5). All the plants
examined have trichocytes, although theirabudance varies. Up to 10 trichocytes arearranged in a column. Each of the columns
at the thallus surface consists of a terminal
trichocyte which is two-celled and verticallyelongated, and lower subisodiametric to laterally elongated cells, where the cell size of theterminal trichocyte is much larger than that of
the lower cells. Cells are 4-34,um long and6-28,um in diameter. Thichocytes persist
after burial in the perithallial tissue.
All the plants of N. fosliei sensu Matsuda(1989) have trichocytes arranged in verticalcolumns, where up to 10 cells are observed(Figures 3-7 and 4-3). A terminal trichocyte
in the column at thallus surface is two-celled,
vertically elongated, and larger than those oflower subisodiametric to laterally elongatedcells. Cells are 7-29 ,um long and 12-29,um

diameter. Thichocyte hairs are multicelled,
up to 80,um long and ca. 5,um in diameter(Figure 3-7). Trichocytes persist after sinking into the perithallium.
b-4.

Hypothallium

Hypothallium of N. fosliei sensu Gordon
et al. (1976) is multilayered and up to 400,um in thickness (Figures 3-1 and 4-4). In
longitudinal section, the proximal portions offilaments are more or less parallel to thethallus surface and the distal portions are
curved upwards (towards the dorsal thallus
surface) and downwards (towards the ventral
thallus surface). The filaments form recumbent, convexly arching tiers of cells (coaxial).
Cell fusions are common. Cells are 4-35,um
long and 8-l5,um in diameter.
Neogoniolithon fosliei sensu Adey et al.
(1982) has a multilayered hypothallium lessthan 250 ,um thick (Figure 4-5). Its constituent filaments are, in longitudinal section,
initially more or less parallel to the thallus
surface and become curved upwards or merely
slanted downwards. The filaments do notform recumbent arching tires of cells (noncoaxial) in most part, but an occasional coaxial cell arrangement is observed where thesubstratum is more or less depressed (Figure4-6). Cell fusions are common. Cells are
l2-42,um long and 7-16,um in diameter.
Hypothallium (Figures 3-3 and 4-7) of N.
fosliei sensu Masuda (1989) is multilayered,noncoaxial, and much thinner (less than 120,um thick) than those of N. fosliei sensu
Gordon et al. (1976) and N. fosliei sensu
Adey et al. (1982). Cell fusions are common. Cells are 9-40,u m long and 5-16,u m
in diameter.
b-5.

Reproductive tissue

Tetrasporangial conceptacles of N. fosliei
sensu Gordon et al. (1976) are uniporate.

~
Figure 3. Vertical sections through thalli (1,2, and 3) and the uppermost parts of perithallia (4, 5, 6,
and 7). The letters "e", "i", "p" and "h" indicate epithallium, intercalary meristem, perithallium, andhypothallium, respectively. Note trichocytes in vertical columns (arrow) and trichochyte hair (7). 1 and
4: Neogoniolithon fosliei sensu Gordon et al. (1976), IGPS ColI. Cat. No. 100958. 2 and 5: N. fosliei
sensu Adey et al. (1982), IGPS ColI. Cat. No. 99311. 3, 6, and 7: N. fosliei sensu Matsuda (1989), IGPS
ColI. Cat. No. 102470.

969.

Neogoniolithon fosliei complex

433

---30

---100 pm

2:---S00pm

4-7:

pm

434

Yasufumi Iryu and Shinya Matsuda

Their roofs are raised conspicuously above
the surrounding thallus surface, showing a
conical outer appearance (Figure 5-1).
Anatomically, conceptac1e roofs consist offilaments which originate from an area surrounding the conceptac1e floor (= fertile area)
and terminate at pore canals. Cells forming
the roofs are disposed concentrically in thelower part of the roofs adjacent to the upper
conceptac1e walls, which show a coaxial cellarrangement in the hypothallium. Mature
conceptac1es have roofs which are 25-38 cells
thick. Pore canals (300-500,um long and70-200,um in diameter) are lined by wellstained cells which are orientated perpendicular to or at an acute angle with the canals andprojecting into them. Tetrasporangia standacross the whole conceptac1e chamber floor
where sterile filaments or paraphyses areabsent and a central columella is missing.
The conceptac1e chambers are laterally compressed ellipsoidal, 760-1,040,um in diameter, and 170-380 ,u m high. Conceptac1es
become completely buried in the perithallial
tissue with subsequent vegetative growth andsome of them are invaded by s~condary tissue.
Sexual conceptac1es have not been found.
Neogoniolithon fosliei sensu Adey et al.
(1982) has asexual conceptac1es, anatomical
features of which are the same as those of N.
fosliei sensu Gordon et al. (1976), except forhaving sterile filaments among the tetrasporangia (Figures 5-2 and 5-3). Mature conceptac1es have roofs 12-15 cells thick, pore
canals (150-200,um long and 60-80,um indiameter) lined by layers of well stained cells,
and laterally compressed ellipsoidal chambers(550-890,um and 140-170,um high) containing tetrasporangia across the chamber floor.
Conceptac1es become buried and some ofthem are invaded by secondary tissue.

Female conceptac1e roofs are produced bycircumconceptacular filaments which grow toform extremely laterally compressed conicalchambers. The roofs are /2-17 cells thick atpore canals which are 40-160,um long and up
to 100,um in diameter and lined by wellstained cells orientated more or less perpendicular to the canals (Figure 6-1). Chambers are 440-710 ,u min diameter and 100-190,urn high, and each of them contains several
tens of supporting cells across the chamberfloor. The supporting cell has one or two
carpogonial filaments, each of which consistsof a lower hypogynous cell and a terminal
carpogonium. Some carpogonia were seen
with trichogynes (Figure 6-2). Carposporangial conceptac1es are similar to tetras po rangial conceptac1es in such anatomical features
as roof structure and pore structure (Figure 63). Conceptac1e roofs are conspicuously
raised above the surrounding thallus surface
and consist of 11-15 layers of cells. Porecanals are 100-130,um long and up to 80,um
in diameter. Chambers are 490-780,um indiameter and 140-160,um high, and containcarposporophytes. Mature carposporophytes consist of a fusion cell, several-celledgonimoblast filaments, and terminal carposporangia (Figure 6-4). A fusion cell isthin, continuous, and irregularly shaped, covering most of the fertile area in the conceptacle chamber. Mode of fusion cell formation
cannot be determined. Gonimoblast
filaments arise from the entire dorsal surfaceof the fusion cell. Male conceptac1es havenot been found.
Asexual conceptac1es of N. fosliei sensu
Matsuda (1989) show the same anatomical
features as those of N. fosliei sensu Gordon etal. (1976) (Figures 5-4 and 5-5). The plants
examined in this study contain bisporangia,~
Figure 4. Scanning electron micrographs of epithallia (1,2, and 3) and hypothallia (4,5,6, and 7).
Note cell fusions (f), floridean starch gravels (s), and trichocytes (t) in vertical columns buried in perithallial
tissues. 1 and 4: Neogoniolithon fosliei sensu Gordon et al. (1976), IGPS Coil. Cat. No. 100959. 2: N.
fosliei sensu Adey et al. (1982), IGPS Coil. Cat. No. 100964. 3 and 7: N. fosliei sensu Matsuda (1989),
IGPS Coil. Cat. No. 100999. 5 and 6: N. fosliei sensu Adey et al. (1982), IGPS ColI. Cat. No. 100965.

969.

Neogoniolithol1 fosliei complex

435

436

Yasufumi Iryu and Shinya Matsuda

".

..

,{

"

'::''J",'t./;I '~~t , "~V~ ;t .~, (.~" ;:f.rIt~.! ':"",,~ : ,' ~''~';-Wm~t~i;;;\~;Mi,; ;(t:-;: ,-.~

1 : --250/Jm

2,3:

200/Jm

4,5: --100/Jm

Figure 5. Asexual conceptacles (1 - 5), 1: Mature tetrasporangial conceptacle of N. fosliei sensu
Gordon et aI, ( 1976), IGPS ColI. Cat. No, 100958, 2: Stage in tetrasporangi a l conceptacle developmentof N. fosliei sensll Adey et aI , (1982), IGPS Coll, Cat. No. 100998, 3: Mature tetrasporangi a l conceptacle of N. fosliei sensu Adey et al. (198 2), IGPS Coil. Cat. No , 100998, 4 and 5: Mature bisporangi a lconceptacle of N. fosliei sensu Matsuda (1989), IGPS ColI. Cat, No , 102470 (4) and IGPS Co il. Cat. No,
102469 (5),969.

Neogoniolithon jos/iei complex

437

..

~.
. ~ t\i7

1 , 3 : - - 100 lJ m

2,4:---

Figure 6. Female and carposporangi a l conceptac\es of N. fosliei sensu Adey et al. ( 1982). 1:
Female conceptacle. 2: Supporting cell s and ca rpogonial fil a ments. Each supporting cell (s) has a
carpogoni a l fil a ments, each of which is composed of a dorsal hypogynous cell (h) and a terminal
carpogonium (c). Some ca rpogonia have trichogynes (t). 3 : C arposporangi a l conceptac\e. 4: Carposporophyte. Note that a fu sion cell , a d o rsal gonimobl ast filament (g), and a terminal carposporangium (c). 1- 4: IGPS Coli. Cat. No. 100996.

but tetrasporangia have not been observed.
Mature conceptacles have roofs which are 1529 cel ls thick at pore canals (160- 220 J1m longand 50- 65 J1m in diameter). Conceptaclechambers are laterally compressed ellipsoidal ,450- 480J1m in diameter and 1l0- 150J1m
high, and contain bisporangia across theentire chamber floor. Conceptacles becomeburied and invaded by secondary tissue.
Sexual conceptacles have not been fo und .
All the three plants show almost the sameanatomical features of tetrasporangial conceptacles. This implies that their tetrasporangial conceptacle development proceeds in theYasufumi [ryu and Shinya Matsuda

438

same manner. This mode is in agreementwith that of Neogoniolithon fosliei reported by
Penrose (1992b).
c.

Ecological features

Neogoniolithon fosliei sensu Gordon et al.
(1976) is distributed in forereef environment
to a depth of 35 m, especially common at
depths from 5 to 30 m. It covers more or lesssmooth hard substrates, and is found as large
patches up to 20 cm in diameter. It is arather minor species in the Ryukyu Islands(lryu and Matsuda, 1987). Sloughing oft' theepithallium as observed in N fosliei sensu
Gordon et al. (1976) is known in some othernonarticulated corallines (Adey, 1965;
Suneson, 1982; Masaki et al., 1984). It is
explained that such strategies are to remove
germlings of other algal spores and microorganisms from the thallus surface.
Assessed was standing crop (coverage, relative density, and frequency) of N fosliei sensu
Adey et al. (1982) (as Spongites sp. A) growing on a well illuminated, flat substrate in aforereef environment to a depth of 30 m by
Iryu and Matsuda (1988). Nfosliei sensu
Adey et al. (1982) is less dominant thanPorolithon onkodes, Lithophyllum insipidum,
and Neogoniolithon conicum at I m depth.
This plant increases with depth to its peak at
15 m depth, where its standing crop is thehighest of all the coralline-algal species
examined. Below 15 m depth it decreases
with water depth, and is absent at depths
greater than 30 m. It has the greatest mean
coverage of the coralline-algal species in thedepth range studied (5.7%). The present
species is distributed also in the moat, where
it occurs approximately as commonly as in
the shallowest forereef environment.
Neogoniolithon fosliei sensu Matsuda(1989) is not a dominant plant, and has beenfound at very restiricted environments of thereef. It covers rather flat substrate originating from various kinds of corals located at thereef edge to forereef shallower than 5 m depth,
where the water is very turbulent. No mate-rial has been collected from any other parts of
the reef. Matsuda (1989) noted that N fosliei sensu Matsuda (1989) (as N fosliei) was
less dominant than P. onkodes, L. insipidum,
and N conicum (as Paragoniolithon
conicum), and covers less than 5% of the welllighted artifical substrates (polyvinyl chloride
plates) placed on the ridge of a spur. But thecoverage of N fosliei sensu Matsuda (1989) issignificantly higher on the plate set on a reefrock projecting into a narrow groove than theformer. He estimated the lateral growth rateof the present plant as approximately 3 mm/month in case of no grazing.
2.

Lectotype specimen of Neogoniolithon Josliei

Since the specimens studied in the originaldescription of N fosliei by Heydrich (1897a)
are missing (Koster, 1969), the isotype specimen (Heydrich, Red Sea, EI Tor, no. 50: see
Foslie, 1904, pI. 9, fig. I; 1929, pI. 46, fig. I)
deposited in the "Foslie Crustose Coralline
Herbarium" ofDet Kongelige Norske Videnskabers Selskab Museet, Trondheim, Norway(TRH) was chosen by Adey et al. (1982) as
the holotype specimen. However this isapparently the lectotype specimen (Woelkerling, 1985). Anatomical micrographs of thelectotype specimen were provided by Woelkerling (1985, 1987, 1988) and Penrose(1992b).
The plant of the lectotype specimen consists of a part of the irregular crustose thallus
which covers a coral branch. Anatomicallythe lectotype specimen has a dorsiventral
organization. Epithallium is composed of asingle layer of laterally compressed, rounded
cells. Peri thalli urn is multi layered. Trichocytes are present solitarily at the dorsal
thallus surface or in vertical columns at thesurface or within the perithallium. In thelatter case, up to 16 cells are arranged in eachcolumn. Hypothallium is multilayered andcoaxial. Cell fusions are recognized both in
the hypothallium and perithallium.

969.

Neogoniolithon fosliei complex

Taxonomic Implications
It is obvious that the differences In morphology and anatomical features of vegetativeand reproductive tissues described above arethought to be great enough for classifying thethree plants into three different species. The
comparative study of the three plants withnonarticulated coralline algal species hitherto
known leads to the following conclusions.
(I) Neogoniolithon fosliei sensu Gordon
et al. (1976) is conspecific with the typespecimen of N. fosliei housed in TRH.
(2) The temporary name "Neogoniolithon
sp. A" should be given to N. fosliei sensu
Adey et al. (1982) in spite of similarities to
N. myriocarpum (Foslie) Setchell and Mason
in external morphology and some anatomical
features.
(3) Neogoniolithon fosliei sensu Matsuda(1989) is not assisgnable to any coralline
species, and thus herewith described as N.
tenuicrustaceum sp. nov.

Neogoniolithon Josliei (Heydrich)
Set chell et Mason
Neogoniolithon fosliei, 1943, Setchell and Mason, p.
90; Lemoine, 1965, p. 7; Lemoine, 1966, p. 13 ;Womersley and Bailey, 1970, p. 311; Gordon etal., 1976, p.261, pI. 6, figs. 2-5, pI. 7, fig. I ;Zhang and Zhou, 1980, p. 352, pI. 2, figs. 1-4;
Zhang, 1983, p. 80, pI. 43, fig. 3; Cribb, 1983, p.
51; Cribb and Cribb, 1985, p. 62; Woelkerling,
1985, p.148, figs. 49-51; Woelkerling, 1987, p.
147, figs. 2, 5, 6; Woelkerling, 1988, p. 140, fig.
135; Penrose, 1992b, p. 339, figs. 1-29.
Basionym. - Lithothamnion fosliei Heydrich,
1897a, p. 58, text-fig. I, pI. 3. figs. 9-11.
Synonymy.Lithophyllum fosliei (Heydrich) Heydrich, 1897b, p.
410; Lemoine, 1911, p. 142, text-fig. 71.
Archaeolithothamnion fosliei (Heydrich) Foslie, 1898,
p.4.
Goniolithon fosliei (Heydrich) Foslie, 190 I, p. 8 ;Foslie, 1903, p. 470, pI. 25, fig. 3; Foslie, 1904, p.
46, text-fig. 19, pI. 9, figs. 1-5; Howe, 1918, p.
294; Foslie, 1929, p. 29, pI. 46, figs. 1-5; ?Johnson, 1961, p.932, pI. 275, fig. 7 (fossil material);
Johnson, 1964, p. 25, pI. 13, fig. 2 (as Goniolithon
cf. G. fosliei).

439

Lectotype. - Heydrich, Red Sea, EI Tor,no. 59, housed in TRH.
Japanese name. - Foslie-ishimo (Yoshida
et al., 1990).
Description. - Thallus crustose, anchoredto substratum full to localized, extensive,
sometimes exceeding 20 cm in diameter, thick(up to 5 mm in thickness); surface smooth tolobed; abundant large raised conical conceptacles scattered; color pale red or grayish
red. Epithallium single-layered; cells laterally elongated, 6-IO,um long and 7-15,um indiameter. Perithallium multilayered, cells 616,um long and 5-13,um in diameter;
fusions common. Trichocytes arranged inlong vertical columns, up to 20 cells in eachcolumn; 6-27,um long and 14-22,um indiameter. Hypothallium coaxial, 200-400,urn thick; fusions common; cells 17-49,um
long and 11-20,um in diameter. Secondary
hypothallium formation often seen.
Tetrasporangial conceptacles conical, 1,2501,700,um in outside diameter, 760-1,040,um
in inside diameter, and 170-380,um high.
Tetrasporangia across floor of conceptaclechamber.
Remarks. - Penrose (1992b) noted thatthe present species shows a wide range ofvariation in its morphology and habit: irregularly lobed crust epiphytic on seaweed;
epilithic plant with flattened thallus surface
or wart-like protuberances; and unattachedbranching mass (=rhodolith). In contrast,
all the previous authors stated that thisspecies has thick (up to a few millimeters),
flattened to lobed, crustose thalli, not possessing any protuberances or branches, and isepilithic or growing on corals. In the Ryukyu Islands, the wide variation noted by
Penrose (1992b) is not observed. It seems
that Penrose (1992b) underestimated the taxonomic significance of growth form and habitat of nonarticulated coralline algae.
Based on their study of the original typecollections of Melobesia brassica-fiorida Harvey and M. notarsii Dufour, Woelkerling etal. (1993) stated that these species and N.

440

Yasufumi [ryu and Shiny a Matsuda

1,2: --100 11m
Figure 7. Ground secti o n of the lectotype specimen o f Neogoniolilhon myriocarpum (Foslie) Setchelland Maso n housed in TRH (Levander, Red Sea, Massank a, 1894- 95 , Mus. Zoo!., Hel singfors, slide 557).
Note undulated perithalli al filaments (arrow head) and secondary hypotallium disposing coa xial (arrow).
The letters " h", "p" , and "sh" indicate hypothallium, perith a llium , and secondary hypothallium , respectively.

fosliei are conspecific and that the specificepithet brassica-florida (Harvey, 1849) has
nomenclatural priority over the others.
However, little can be known of the reproductive tissue from the lectotype specimens,
because the male conceptacle with remains ofspermatangia can be observed in the lectotypeof Melobesia brassica-florida and the empty
tetrasporangial (or carposporangial) conceptacle can be seen in that of M. l1otarsii.
Moreover, growth forms of the lectotype specimens of Melobesia brassica-florida (warty
appearance) and M. notarsii (crust-like towarty) are different from that of N. fosliei.
Th us, it cannot be considered that these three
species are conspecific.
Distribution. - Red Sea (Heydrich, 1897a ;Reinbold, 1903 ; Lemoine, 1911,1965, 1966;
Papenfuss, 1968), Indian Ocean (Foslie, 1903,
1904; 1929), Western Pacific (Foslie, 1904 ;Johnson , 1964; Gordon et aI., 1976; Tsuda
and Wray, 1977; Zhang and Zhou , 1980;
Zhang, 1983; Iryu and Matsuda, 1987; Y 0shida et al ., 1990 ; Kawana et al ., 1992) ,Mid-Pacific (Adey et al. , 1982), South Pacific(Setchell , 1926; Lemoine, 1965 ; Womersley
and Bailey, 1970), and Australia (Howe,
1918 ; Cribb, 1983 ; Cribb and Cribb, 1985 ;Penrose, 1992b).
Geologic range . - Pleistocene (Johnson ,1961 ; Jryu , 1992) to Recent.

Neogoniolithon sp. A

Description. - Thallus crustose, firmly
adherent to substratum, less than 10 cm indiameter, thick (up to 3 mm in thickness) ;surface glossy and minutely rugulose ; abundant raised conical conceptacles scatteredexcept for thallus margin ; color light pink topale orange on vegetative surface but attaining yellowish spot on conceptacles. Epithallium usually a single cell layer; cells
rounded , laterally elongated , 4-IO,um longand 7- 17,um in diameter. Perithallium
multilayered ; cells 9-20,um long and 7- 15,urn in diameter ; fusions common . Trichocytes in long vertical columns, up to 10

969.

Neogoniolithon fosliei complex

cell in each column, 4-34,um long and 16-28,urn in diameter. Hypothallium multilayered, noncoaxial, 200-400,um thick; fusions
common: cells 13-42,um long and 7-16,um
in diameter. Tetrasporangial conceptacles
conical, 800-1,500,u m in outside diameter,
550-890,um in inside diameter, and 140-170,urn high. Tetrasporangia across floor ofconceptacle chambers; sterile filaments present among tetrasporangia. Female conceptacles slightly raised above thallus surface, 44071O,um in inside diameter and 100-190,um
high; several tens of supporting cells acrosschamber floor. Carposporangial conceptacles conical, 490-780,um in inside diameterand 140-160,um high. Gonimoblast
filaments arising all over the dorsal surface of
fusion cell; fusion cell thin and continuous
covering most of chamber floor.
Remarks. - With respect to the outermorphology and internal structure observedin ground section, this species is very similar
to Neogoniolithon myriocarpum Foslie, whose
lectotype specimen (Foslie, 1904, pI. 9, fig. 6;
1929, pI. 40, fig. 6) chosen by Adey andLebednik (1967) was housed in TRH (Figures
7-1 and 7-2). At present, it cannot be determined whether the present species isconspecific with N. myriocarpum, becausesome important features, such as epithallium
and reproductive tissue, cannot be observedin ground section. In order to clarify thisproblem, the lectotype specimen and material
collected from the type locality (Red Sea)should be investigated for the important features mentioned above. This species isconspecific with Neogoniolithon sp. A of Iryu
and Matsuda (1987) and Spongites sp. A of
Iryu (l99Ia, 199Ib), Iryu and Matsuda (1988),
Kawana et al. (1992) and Iryu (1992).
This species has a fusion cell which is thin,continuous and irregularly shaped, covering
most of the ferti Ie area in the carposporangial
conceptacle chamber (Figures 6-3 and 6-4).
This contrasts with the occurrence of the
discontinuous fusion cell of N. fosliei shown
by Penrose (l992b).

441

Distribution. - Western Pacific (lryu andMatsuda, 1987, 1988), Mid-Pacific (Adey etal., 1982).
Geologic range. - Pleistocene (Iryu, 1992)
to Recent.

Neogoniolithon tenuicrustaceum Iryu
et Matsuda sp. nov.
Holotype. - I.G.P.S. Coil. Cat. No. 102459(Figure 2-3).
Type Locality. - Kabira, Ishigaki-jima,
Ryukyu Islands.
Etymology. - The specific epithet "tenuicrustaceum" refers to the thi n crustose thall usof the present species.
Japanese name. - Usukawa-ishimo (newname).
Description. - Crustae tenues, ad 500,um
crass., ad 10 cm diam., firme adhaerentes
ad substratum; superficies rugulosa; color
flavida ad sub-aurantiaca; multa conceptacula parva tholiformia super superficiem
sparsa. Epithallium ex unico strato cellularum tholiformium constans; increassationes
membranae dorsalis lateralis perspicuae;
cellulae 3 -8,um long. et 7-14,um diam.
Perithallium pluristratosum; fusion cellulae
saepe adest; cellulae 8-15 ,um long. et 513,um diam. Trichocystae in lin is verticalibus dispositae, vel in linea, velcumulatae 2-10 cellularum, 7-29,um long.
et 12-29,um diam. Hypothallium, pluristratosum tenue, minus quam 120,um crass.,
non coaxiale; fusion adest; cellulae 9-40
,um long. et 5-16,um diam. Conceptacula
tetrasporangialia uniporata, 600- 760 ,um
diam. exteriora, 450-480,um diam. interiora
atque 110-150,um alt. Tetrasporangia
trans totum pavimentum conceptaculi
disposita.
Crust thin, up to 500,um thick, up to 10 cm
in diameter, firmly adherent to substratum;
surface rugulose; color pale yellow to orange
yellow; abundant small raised conceptacles
scattered over surface. Epithallium a single
layer of domed cells; dorsal lateral wallYasufumi lryu and Shinya Matsuda

442

thickenings marked; cells 3-8,um long and7-14,um diameter. Peri thallium multilayered; cell fusion frequent; cells 8-15,um long.
and 5- J3,um diameter. Trichocytes arranged in vertical columns, 2-10 cells in eachcolumn, 7-29,um long and 12-29,um indiameter. Hypothallium multilayered, thin(less than 120,u m thick), non coaxial; fusion
present; cells 9-40,um long and 5-16,um indiameter. Tetrasporangial conceptacles
uniporate, 600-760,um in outside diameter,
450-480 ,u m in inside diameter, and 110-150,urn high. Tetrasporangia across entire conceptacle floor.
Distribution. - Ryukyu Islands (lryu,
1991 b; Kawana et at., 1992).
Geologic range: - No fossil material is
known.

Discussion
1.

Generic circumscription of Neogoniolithon

The genus Neogoniolithon was defined by
Setchell and Mason (1943) as coralline algae
which have all of the following features: (I)thall us nonarticulated; (2) hypothalli urn coaxial: (3) trichocytes arranged in verticalcolumns; (4) conceptacles (asexual, male,and female) uniporate; and (5) tetrasporangia (al ways ?) across the chamber floor of theconceptacle. Hamel and Lemoine (1953)
modified and extended the generic concept toinclude two types of species with a coaxial
and a noncoaxial hypothallium. Then, thisextended concept had been accepted by mostworkers (Adey, 1970; Cabioch, 1972; Gordon et al., 1976; Johansen, 1976, 1981;
Adey et at., 1982), with further modification,
disregarding feature (5) of Setchell and
Mason (J 943). Woelkerling (1985), however, explicitly limited Neogoniolithon toincl ude species with a coaxial hypothalli urn
as defined in the original proto log, and reassessed the status of the genus Spongites toencompass species with a noncoaxial hypothallium. By this time, the classification

scheme is completed in which those generawith multilayered perithalli urn throughout
the vegetative tissue in the subfamily Mastophoroideae could be divided by means ofdifferences in trichocyte occurrence andarrangements and in hypothallium organization into six genera: Hydrolithon Foslie(1909), Porolithon Foslie (1909), Pseudolithophyllum emend. Adey (1970), Spongites
Kiitzing (1841), Neogoniolithon Setchell and
Mason (1943), and Paragoniolithon Adey etal. (1982). On the other hand, Woelkerling(1985) noted the possibility that such characters are too variable to provide a reliablebasis for delineating those genera. Penrose
and Woelkerling (1988) confirmed Woelkerling's statement, and considered the genera
Porolithon, Hydrolithon, and Pseudolithophyllum emend. Adey (1970) to be heterotypicsynonyms of Spongites. Penrose (1991,
1992a, 1992b) proposed a new classification
scheme in which Neogoniolithon, Spongites,and Hydrolithon are distinguishable from one
another on differences in reproductive tissues,i.e., tetrasporangial conceptacle development
and anatomy, spermatangial arrangement,
and carposporophyte morphology.
Neogoniolithon was considered to be distinguished from the other species by possessing
all of the following features: (I) tetrasporangial conceptacle roof formed by filaments
surrounding the fertile area; (2) spermatangia simple and borne on both the floor androof of male conceptacle chambers; and (3)gonimoblast filaments arising from the entire
dorsal surface of fusion cells.
The above historical review attests theimportant fact that the occurrence oftetrasporangia across the entire conceptaclechamber floor (= feature (5) given by Setchelland Mason (1943)) has been completely neglected since the 1970's, although Hamel andLemoine (1953) and Masaki (1968) used it as
one of the characters to circumscribe
Neogoniolithon. Our study of the
Neogoniolithon-Spongites complex in the Ryukyus reveals that plants belonging to the969.

Neogoniolithon fosliei complex

1,2:--500I1m
3:
1,000 11m

443

4:--25 0 I1 m

Figure 8. Fossil N. jos/iei (I a nd 2), Neogonio/ithon sp. A (3), and Hydro/ithon onkodes (4). I:
IGPS Coil. Ca t. No. 99304. 2: IGPS Co il. Cat. No. 99305. 3: IGPS Co il. Cat. No. 99313. 4: IGPS
Coil. Cat. No. 99334.

complex either have bi-j tetrasporangia acrossthe whole conceptacle ch a mber floor withouta centra l col umella, spermatangia occurri ng
on both the floor and roof of the male conceptacle chambers, and gonimob last filaments
arising dorsally from the entire surface of afu sion cell, or have bi- j tetrasporangial
conceptacles formed peripherally in the conceptacle chamber floor with a central
columel la, spermatangia confined to the floorof male conceptacle and gonimob last

filaments ansmg only from the margin of afusion cell. Other combinations of thesethree features are not observed. Judging
from previous taxonomic works with a complete set of asexual , male and female conceptacles, the same is true of pl a nts of the
Neogoniolithon-Spongites comp lex. Masaki(1968) reported that Neogoniolithon accretum(Foslie et Howe) Setchell et Mason possesses
the former combination , while he showedthat the following 9 species, which shou ld beYasufumi Iryu and Shinya Matsuda

444

referred to Spongites in the current sense,
have the latter one: Lithophyllum absimile
Foslie et Howe; L. caribaeum Foslie; L.
decipience (Foslie) Foslie; L. samoense Foslie; L. shioense Foslie; L. yendoi Foslie;
Porolithon boergesenii (Foslie); P. colliculosum Masaki; and P. orbiculatum Masaki. Moreover, Chamberlain (1993) showedthat Spongites yendoi (Foslie) Chamberlain
and S. decipiens (Foslie) Chamberlain havethe latter combination of reproductive features. These observations imply the possibility that the position of bi-/tetrasporangia
within the conceptacle chamber or the presence or absence of a central columella may beof potential significance to delineate
Neogoniolithon and Spongites, as well as
gametangial and carposporophyte features.
The use of the position of bi-/tetrasporangia
within the conceptacle chamber leads
phycologists to much easier identification ofplants of the Neogoniolithon-Spongites complex than the use of the latter characters,
because sexual plants are much less abundant
than asexual ones and it is not easy to observe
the reproductive features of sexual plants.
2.

Paleontological implicationsa.

Generic delineation of Neogoniolithon, Spongites, and Hydrolithon in fossils

The introduction of the new classification
scheme for the Neogoniolithon-SpongitesHydrolithon complex requires revision of thegeneric delineation of the fossil corallines
assigned to the complex. Thus, we, paleo algologists, must deal with the problem ofwhether the three genera can be distinguishedfrom one another in fossils.
It is impossible to distinguish Neogoniolithon from Spongites because the criteria
used for delineating the two genera are notpreserved in fossils. Whereas Hydrolithon
must, theoretically, be differentiated from theother genera because it has tetrasporangial
conceptacles, the development and morphology of which are quite different from those of

the others: the tetrasporangial conceptaclepore canals of Hydrolithon are lined by a ringof vertically elongated cells arranged nearlyparallel to the canals and never projecting
into the canals, reflecting that the conceptacleroofs are formed by filaments among thetetrasporangia, while in Neogoniolithon andSpongites, the roof formation is due to thegrowth of filaments surrounding the tetrasporangia and the pore canals are lined by several
layers of cells perpendicular to or at an acuteangle with the canals and projected into
them. This difference is recognized in thecoralline algal skeletons, and thus it may beobservable in fossils if the skeletons are completely preserved. However, according toour observation on fossil corallines of the
Pleistocene Ryukyu Group, it is not always
determinable, except for some cases, whether
the fossil corallines have the former type of
asexual conceptacle pore canals or the latter,because the cells lining the pores are notpreserved in fossils due to post-mortem
destruction (Figure 8-4). Consequently, infossils, Hydrolithon cannot be strictly distinguished from Neogoniolithon and Spongites.
It is concluded that Neogoniolithon, Spongites, and Hydrolithon are not distinguishable
from one another in fossils based on current
taxonomic concepts which are applicable toliving coralline algae. How then should
paleoalgologists classify the algae coming
under this complex? Two ways appear to
be possible. One would be to lump the three
genera together as a single "genus". In thiscase, the "genus" reveals a much broader
spectrum of the subfamily Mastophoroideae
and becomes a mere unit without any
phylogenetic, paleobiogeographic, or
paleoecologic significance. The other would
be to adopt the older classification scheme
which Adey and Macintyre (1973) set up withsome modification, if needed. The "genera"in this case are of little phylogenetic value,
but are units of paleobiogeographic andpaleoecologic significance, because each"gen us" shows a characteristic geographic

969.

Neogoniolithon fosliei complex

distribution and has a peculiar ecologic nichein the present-day marine environment (Adey,
1970). These pieces of knowledge enable us
to utilize fossil nonarticulated coralline algae
as excellent paleoenvironmental indicators.
A comparison of the utility of these twoalternatives shows that the latter is muchbetter for paleoalgology, and thus is adopted
here.
b.

Fossil counterparts

Neogoniolithon fosliei (Figures 8-1 and 82) and Neogoniolithon sp. A (Figure 8-3)
abundantly occur in the Pleistocene Ryukyu
Group consisting of reef and its related sediments. They can be used as indicators of thewater depth at which the group accumulated,because of their abundant occurrence andtheir specific depth range on the present-day
reefs of the Ryukyu Islands (lryu and Matsuda, 1988). Iryu (1992) discriminated four
fossil nonarticulated coralline algal species
assemblages from the group, each of which
was thought to represent a peculiar depth
range. His Assemblage B is characterized by
the presence of N. fosliei or Neogoniolithon sp.
A and the absence of Porolithon onkodes.
The assemblage is considered to have existed
at depths from 20 to 35 m. Outcrops where
Assemblage B is recognized have many pileup thalli of N. fosliei and Neogoniolithon sp.
A, which, together with other nonarticulated
corallines and corals, form a more or lessconvex mound called the "sediment binding
structure" (Iryu, 1992, Fig. 9). Fossil N.
tenuicrustaceum is unknown.
It is expected that fossil N. fosliei and
Neogoniolithon sp. A occur in reef limestonesof the Indo-Pacific regions as well as the
Ryukyu Islands. Their known occurrence ishowever very limited (N. fosliei from the
Pleistocene (?) of Funafuti, Johnson, 1961).
This does not indicate their actual occurrence, because fossil corallines have not been
fully studied in such regions. Further
research is needed to know their geologic

445

range and paleogeographic distribution.

Conclusions(I) Neogoniolithon fosliei sensu Gordon
et al. (1976) is conspecific with the lectotype
specimen of N. fosliei.
(2) Neogoniolithon fosliei sensu Adey etal. (1982) is described as Neogoniolithon sp.
A, although it is very similar to N. myriocarpum in some outer and skeletal features.
(3) Neogoniolithon fosliei sensu Matsuda(1989) is not referable to any of the nonarticulated coralline algae hitherto known, andthus is described as a new species, N. tenuicrustaceum.
(4) The arrangement ofbi-jtetrasporangia
in bi-jtetrasporangial conceptacle chambers
may be used to di fferentiate Neogoniolithon
from Spongites.
(5) Neogoniolithon, Spongites, andHydrolithon cannot be strictly distinguishedfrom one another as fossils.

Acknowledgment
We are most grateful to Profs. Kei Mori
and Kunihiro Ishizaki of the Institute ofGeology and Paleontology, Tohoku University for critical reading of the manuscript.
Thanks are expressed to Dr. Sigmund Sivertzen of Det Kongelige Norske Videnskabers
Selskab museet, Trondheim, Norway for giving one of the authors (Y.I.) an opportunity
to examine the Foslie Crustose Coralline
Herbarium. Our appreciation is expressed to
Mr. Jun Nemoto and Masaaki Shishido of theInstitute of Geology and Paleontology, Tohoku University for making photographs andthin sections of fossils, respectively, and to
Ms. Kaori Ueshiro of Misaki Primary School,
Kume-jima, Okinawa Prefecture, for preparing slides of living coralline algae.

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446

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Yasufumi Iryu and Shinya Matsuda

448

Oceanologia et Limnologia Sinica, vol. II, p.

linaceae of the Xisha Islands, Guangdong Province, China. III. The genus Neogoniolithon.

351-357.

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Trans. Proc. Palaeont. Soc. Japan, N.S., No. 174, pp. 449-457,4 Figs., June 30, 1994

970. ORDOVICIAN (LLANVIRNIAN) STROMATOPOROIDS
FROM THE YOUNGWOL AREA, SOUTHERN KOREA*AKIHIRO KANO
Department of Earth & Planetary Systems Science, Faculty of Science,
Hiroshima University, Higashi-hiroshima, 724

DONG-JIN LEE
Department of Geology, Andong National University,
Andong 760-749, Korea

DUCK KEUN CHOI and CHAN-MIN YOO
Department of Geological Sciences, Seoul National University,
Seoul 151-742, Korea

Abstract. The Ordovician stromatoporoid Labechiella regularis (Yabe and Sugiyama)
has been recovered from the shallow ramp facies of the Yeongheung Formation (L1anvirnian) of the Ogcheon Fold Belt in southern Korea. The skeletal characteristics of thisspecies have been altered by diagenesis. It represents the first discovery of a stromatoporoid
from the southern part of the Korean peninsula. This Middle Ordovician stromatoporoid
occurrence extends the geographical range of the species, previously reported from other partsof Asia.
Key words.

L1anvirnian, Ordovician, stromatoporoids, Ogcheon Belt, southern Korea.

region, except that of Yabe and Sugiyama(I 930a, b), which included two northern
Korean localities. Stromatoporoids havenot previously been recognized from southern
Korea.
This study describes stromatoporoids fromthe Yeongheung Formation of southern
Korea, to which is assigned a Middle Ordovician (Llanvirnian) age.
During recent sampling, 45 specimens werecollected from the Yeongheung Formation in
Youngwol County, Kangwon Province ofsouthern Korea. All the well preserved specimens proved to represent the labechiid
stromatoporoid Labechiella regularis (Yabeand Sugiyama, 1930a). This species, as well

Introduction
Ordovician stromatoporoids of the North
China-Korea Platform, inclusive of North
China, Manchuria and the Korean peninsula,
are poorly documented. The first study ofstromatoporoids from the North ChinaKorea Platform was by Yabe and Sugiyama(I 930a, b), followed by Endo (1932), Ozaki(1938), Yang and Dong (1962), Dong (1982),
Dong and Wang (1984) and Lin and Webby(1988, 1989). However, these publications
have mostly focused on the North China'Received October 27, 1993; revised
accepted April 12, 1994

manuscript

449

450

Akihiro Kano, Dong-jin Lee, Duck Keun Choi and Chan-Min Yoo

as most other labechiid stromatoporoids ofthe same age reported previously from otherareas of the North China-Korea Platform, isolder than, or contemporaneous with thosefrom the Chazy Group of North America
that, prior to the 1980s, were mainly regarded
as the oldest stromatoporoids (Stock, 1983).

Geologic and stratigraphic settings
The Cambro-Ordovician sedimentary rocks
distributed both in the southern and northernparts of the Korean peninsula constitute theJoseon Supergroup. In southern Korea it isextensively exposed as widely scattered localities within the Ogcheon Fold Belt (Figurela), presumably a continental margin depression trending northeast to southwest, but
most sections are in the Taebaeksan Limestone Plateau of Kangwon Province, southern
Korea.
The Yeongheung Formation represents theuppermost part of the Joseon Supergroupoccurring in Youngwol County and its vicinity. The formation consists of dark grey
dolomitic limestone and grey to bluish grey
limestone intercalated in places with several
thin beds of shale and argillite, and wasprobably deposited in the axial zone of theextended Ogcheon Basin (Chang, 1985).

Y 00 (1991) recognized four repetitions of ashallowing-upward cycle, each composed of ashallow ramp facies migrating upward into
peritidal facies. Thickening upward of theperitidal facies in each grand cycle indicatesthat the Yeongheung Formation was deposited during the four regressive phases.
The detailed stratigraphic correlation andage determination of the formation have beenhampered by scattered exposures, lack of
distinctive marker horizons and lack of agediagnostic megafossils. Based on thetrilobite genus Basiliella and some poorly
preserved cephalopods, Kobayashi (1966)previously correlated the Yeongheung Formation with the Middle Ordovician Toufangian Series in Liaoning and Shandong Provinces of North China.
In recent attempts to provide a more refinedbiostratigraphy based on conodonts, Lee(1989) has dated the middle part of the
Yeongheung Formation as late Llanvirnian(Middle Ordovician) in age. He reported
some conodont species including Plectodina
onychodonta from the middle part of the
Yeongheung Formation, from which thestromatoporoids described herein were collected, and correlated this part of thesequence with the Upper Majiagou Formation of North China. Plectodina ony-

12S027'oo'-®-- National Road
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~Figure 1. Localities of stromatoporoids of the middle part of Yeongheung Formation (b), Youngwol County, southern Korea (a). Crosses point to stromatoporoid localities I and 2 dealt with herein.

970.

Ordovician stromatoporoids from Korea

METERS

100

KEY

a:

en

II

D

90
a.

~

g

80
a:

en

70

~
~

.

~g:~
~.

Lime Mudstone
Peloidal Packstone
Bioturbated Limestone
Fossiliferous
Wackestone I Packstone
Laminated Dolostone
Mud-flake Conglomerate
Oolitic Grainstone

60
a.

50

40

30

20

a:

en

10

o

L

H
SEA LEVEL

Figure 2. Measured section at Namgyo near Mungog-ri (Figure Ib), showing stratigraphic positionsof localities of Labechiella regularis with relationship of relative sea level fluctuations inferred from thevertical changes in sedimentary facies. Vertical lithologic changes represent a threefold repetition of ashallowing-upward cycle. Arrow I indicates lower stromatoporoid bed at locality I, Arrow 2 indicates
upper stromatoporoid bed at locality 2, respectively. SR: Shallow Ramp Facies; P: Peritidal Facies(modified from Yoo, 1991).

451

452

Akihiro Kano, Dong-jin Lee, Duck Keun Choi and Chan-Min Yoo

chodonta is a biostratigraphic indicator of
the late Ll a nvirni a n, e.g., the Upper Majiagou
Formation in North China (An , 1981), a unit
which also contains some of the earliest
stromatoporoids in the North China-Korea
Platform (Yabe and Sugiyama, 1930a, b ;Dong, 1982).
The fossil localities and occurrences
Megafossi Is are rare and in general very
poorly preserved in the Yeongheung Formation . The stromatoporoid specimens werecollected from a measured section in the
middle part of the formation near the villageof Mungog-ri , about 13 km NN E from Youngwol (Figure Ib). In this section two
stromatoporoid-bearing horizon s were recognized : each from a lithofacies of prominent
burrow-mottling, suggesting deposition during deeper subtidal intervals (Figure 2). The
fact that scattered cri noid ossicles and orth id
cephalopod fragments are occasionally foundin these horizons also suggests as open shelfwith of comparatively high energy environment (shallow ramp facies of Yoo , 1991).
Some stromatoporoid skeletons found inupper horizons were in growth position witha laminar to domed shape (Figure 3) , and inlarger skeletons well developed mamelons

were observed. Latilaminae are in manycases clearly observed in outcrops, showingthat earlier generations of skeletons expanded
outwards on the muddy bottom. According
to Kano 's (1990) definition of the ecomorphotypes of the laminar-domed
stromatoporoids, such a growth habit indicates that the species is ambitopic.
Some specimens, however, were not analyzed due to their poor preservation.
Although the external form of the skeletons ispreserved , dolomitization and silicification
often obscure the internal structures of theskeletons. However, a number of better
preserved specimens were avai lable to allow
the description , diagnosis and an estimate ofvariation in the species.

Systematic description

Taxonomic procedures.- The problem of
the present species is the diagenetic alteration(dolomitization a nd / or s ilicification).
Skeletal microstructures of most specimens
are poorly preserved and the original structure of so me important elements (e.g., wall
microstructure, thickness of original walls
and pill ars) is difficult to recognize. For thisreason certain measurements (thickness oflaminae a nd pillars) should be given limited

Figure 3. Extern a l growth modes of Labechiella regularis. (a) A la min ar specimen resting on a
muddy subst rate in growth positi o n (Locality 2). (b) A to ppled d o med specimen (Locality I). Scale incentimeters a nd inches.

970.

Ordovician stromatoporoids from Korea

emphasis in taxonomic subdivision. The
silicification seriously destroys the skeletal
structures, and some silicified specimens do
not even preserve their gross structure (Figure4f). The dolomitization is a less serious
problem. Therefore, the description isrestricted to specimens which are notsilicified.
Classification of the extinct group of the
Palaeozoic stromatoporoids at the higher taxonomic level has been in debate. Affinity to
the Phylum Porifera is the opinion of the
majority (e.g., Stearn, 1972,1975, 1982;
Webby, 1986) because some of thestromatoporoids exhibits an internal structure
which is similar to that of the recent calcareous demosponges. However, because no
spicules have been found to confirm theiraffinities within the sponges, other possible
affinities (Mori, 1982; Kazmierczak, 1976;
Kazmierczak and Kempe, 1990) cannot be
refuted.
In this study suprageneric assignments wereused following Webby (1979, 1993). Terminology of external forms refers to Kershaw
and Riding (1978).
Class Stromatoporoidea Nicholson and
Murie, 1878
Order Labechiida KUhn, 1927
Family Labechiidae Nicholson, 1879
Genus Labechiella Yabeand Sugiyama, 1930aType species: Labechiella serotina(Nicholson, 1886)

Labechiella regularis(Yabe and Sugiyama)
Figures 3 and 4a-e

Labechia regularis Yabe and Sugiyama, 1930a, p. 56,
pI. 18, figs. 5-6, pI. 21, fig. 8; Ozaki, 1938, p. 210,
pI. 26, figs. 2a-d; Yavorsky, 1955, p. 56, pI. 24,
figs. 4-5, Webby, 1969, p.649, pI. 120, fig. I, pI.
121, figs. 3-6, pI. 124, figs. 1-2.
Labechia regularis var. tenuis Yabe and Sugiyama,
1930a, p.57, pI. 21, figs. 9-10, Yabe andSugiyama, 1930b, p. 9, pI. 3, fig. I, pI. 4, figs. 1-2.

453

Labechia tuvensis Yavorsky, 1968, p. 48, pI. I, figs. 34.

Tuvaechia regularis (Yabe and Sugiyama).
Bogoyavlenskaya, 1971, p. 309, pI. 2, fig. I.
Labechiella regularis (Yabe and Sugiyama). Webby,
1979, p.92, figs.3a-b, Webby, 1991, p.200, fig.
39.

Material.-Eleven specimens from Locality
I and one from Locality 2 (Figures I and 2).
All specimens are in the collection of the
Department of Geology, Andong National
University, Andong, Korea.
Description.- The species exhibits a low
domed to laminar form and commonly shows
ragged margins with sediment layers within
the skeletons (Figure 4c). Skeletons are
small, mostly less than 10 cm in width and 5
cm in height, although the largest specimen
reaches 60 cm in width and 25 cm in height(Figure 3a). Mamelons are recognized on
the upper surfaces of some specimens and arespaced from 2 to 5 cm apart. Latilaminae
are commonly found from 8 to 15 mm inwidth.
Skeletons consist of thin laminae intersected by thick recrystallized pillars in verticalsection (Figure 4a). Laminae are parallel,
fiat, or slightly concave, and continuous
between pillars over a few centimeters. Spacing of laminae is regular and the distance
between two laminae mostly ranges from
0.20-0.60 mm (Figure 4e). Pillars seem to be
thick (0.2-0.4 mm), persistent, and often
extending through more than five laminae,
however the pillars are selectively altered bydiagenesis. The dolomitized pillars commonly consist of large blocky dolomite crystals with fringes of smaller crystals (Figure4e). The pillars may have been once dissolved and later filled by dolomite. In tangential section, the pillars are spaced from
0.7-0.12 mm apart (Figures 4b and d).
Remarks. -Gross skeletal structures, suchas spacing of laminae and pillars, indicatethat the present specimens resemble Labechiella regularis. Pillars of the present specimens display lighter center and darker mar-

454

Akihiro Kano, Dong-jin Lee, Duck Keun Choi and Chan-Min Yoo

Figure 4. Internal skeletal structures of the stromatoporoids collected from the Yeongheung Formation at Namgyo. (a)-(e) Labechiella regularis Yabe and Sugiyama. (a-b) Vertical a nd tangential
sections of a specimen from Locality I (NAM 25) . Laminae are parallel to each other and intersected by' hollow' pillars. The sca le bar is I cm lo ng. (c) Vertical section of a specimen from Locality I (NAM
40). Micritic sediment fills a space between the latilaminae. The scale bar is I cm lon g. (d) Tangential
section of a specimen from Locality I (N AM 44) . A concentric arrangement of laminae represents amamelon-like structure. The scale bar is I cm long. (e) Magnified view of vertica l sect ion ofa specimen
from Locality I (NAM 16) showing that pillars consist of blocky dolomite crystals fringed by finer-grained
crystals. The scale bar is I mm long. (I) A specimen seriously altered by diagenesis (N AM 8). The
upper part of the skeleton is replaced by fine-grained dolomite crystals and ex hibi ts a micritic microstructure. The lower part of the skeleton is silicified, thu s obliterating the gross structure. The scale bar
is I cm long.

970.

Ordovician stromatoporoids from Korea

gins which look like the 'hollow' pillars that
may characterize the genus Stromatocerium(Nestor, 1976). However, the 'hollow' structure of the present specimens is diagenetic.
Furthermore, Webby (1969,1979) described
Labechielfa regularis with the pillars exhibiting light colored centers, and he also considered them to be secondary structures.
Labechiella mingshankouensis (Ozaki)
from the Ordovician of the Northern China
also exhibits regular laminae, however they
are more widely spaced. L. variabilis (Yabeand Sugiyama) is also similar to L. regularis,
however it exhibits wider and less regularspacing of laminae.
L. regularis was first reported as a speciesof Labechia by Yabe and Sugiyama (1930a),although it has the parallel and regular horizontal skeletal elements of typical members ofLabechiella. Bogoyavlenskaya (197 I)
proposed a new genus Tuvaechia with L.
regularis as the type species. According to
Bogoyavlenskaya (197 I), Tuvaechia wasdifferentiated from the forms of Labechiellaserotina type by having an isolated distribution of pillars in tangential sections. At thetime of proposal of Tuvaechia, Bogoyavlenskaya (1971) had only investigated the platesof Yabe and Sugiyama (\ 930a) using additional drawings to repair poorly preserved
skeletal parts. Furthermore, there is anotherproblem in the proposal. Mori (197 I) had
already showed that both isolated and fused
distributions of pillars can be seen in single
specimens of some labechiid stromatoporoids(e.g., Labechia conferta) and that they cannot
have a taxonomic importance, such as
differentiating characteristics between Tuvaechia and Labechiella.
Occurrence.-L. regularis has been reported from the Middle to Late Ordovician ofChina (Yabe and Sugiyama, 1930a; Ozaki,
1938), northern Korea (Yabe and Sugiyama,
1930b), Siberia (Yavorsky, 1955. 1968 ;Bogoyavlenskaya, 197 I) and Australia(Webby, 1969,1991).
It is widely accepted that the stromatopor-

455

oids originated in the Llanvirnian (Webby,
1969,1980,1984.1987; Stock, 1983) with theglobally distributed stromatoporoid assemblage dominated by labechiids (Webby,
1993). Stromatoporoid faunas of the
Llanvirnian have a low diversity but a wide
distribution, suggesting their rapid dispersal.
They became more diverse in the Caradocian
and replaced the algal-sponge associations in
the reef environment (Webby, 1984; Copper,
1988).

Acknowledgments
We would like to express our appreciation
to Prof. B.D. Webby (Sydney Univ.) and Prof.
K. Mori (Tohoku Univ.) who discussed taxonomic problems and read the manuscript.
We also thank Prof. Y. Okimura (Hiroshima
Univ.) for his comments on aspects of thesedimentology. K. Jiju, H. Yuguchi, and A.
Yamada (Hiroshima Univ.) also helped in
the preparation of this work.

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Palaeont., vol. 8, p. 207-217.
Mori, K., 1970: Stromatoporoids from the Silurian
of Gotland, part 2. Stockholm Contr. Geol.,
vol. 22, p. 1-152.
- - , 1982: Coelenterate affinity of stromatoporoids.
Stockholm Contr. Geol., Hessland volume, p.
167-179.
Nestor, H.E., 1976: Rannepaleozoyskie stromatoporoidei basseyna reki Moiero (sever Sibirskoi
platformi). Inst. Geol. Akad. Nauk Eston.
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Nicholson, H.A., 1879: On the Structure andAffinities of the Tabulate Corals of the Palaeozoic Period. 342 pp. Blackwood & Sons, Edinburgh,- - , 1986: On some new or imperfectly known
species of stromatoporoids. Ann. Mag. Nat.
Hist. (5), vol. 17, p. 225-239.
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Ozaki, K., 1938: On some stromatoporoids from theOrdovician limestone of Shantung and south
Manchuria. Shanghai Science Institute, Jour.,vol. 2, p. 205-223.

Stearn, c., 1972: The relationship of thestromatoporoids to the sclerosponges. Lethaia,
vol. 5, p. 369-388.
- - , 1975: The stromatoporoid animal. Lethaia,
vol. 8, p. 89- 100.
- - , 1982: The unity of the Stromatoporoidea.
Proc. 3rd. North A mer. Paleont. Conv., vol. 2, p.
511-516.
Stock, C.W., 1983: Stromatoporoids: geologicalhistory. In, Broadhead, T.W. ed., Sponges andSpongiomorphs, p. 167-172, University of Tennessee, Department of Geological Sciences,
Studies in Geology, vol. 7. University of Tennessee.
Webby, B.D., 1969: Ordovician stromatoporoids
from New South Wales. Palaeontology, vol. 12,
p.637-662.
- - , 1979: The Ordovician stromatoporoids.
Proc. Linnean Soc. New South Wales, vol. 103,
p.83-121.
- - , 1980: Biogeography of Ordovician
stromatoporoids. Palaeogeogr. Palaeoclimat.
Palaeoecol., vol. 32, p. 1-19.
- - , 1984: Ordovician reefs and climate: a review.
In, Bruton, D.L. ed., Aspects of the Ordovician
System, p. 89-100. Palaeontol. Contribution
from the University of Oslo, No. 294.
- - , 1986: Early stromatoporoids. In, Hoffman,
A. and Nitecki, M.H. eds., Problematic Fossil
Taxa, p.148-166. Oxford Univ. Press, NewYork.
- - , 1987: Biogeographic significance of some Ordovician faunas in relation to East Australian
Tasmanide suspect terranes. In, Leitch, E.C.
and Scheibner, E. eds., Terrane Accretion and
Orogenic Belts, American Geophysical Union
Geodynamics Series, vol. 19, p. 103-117.
- - , 1991: Ordovician stromatoporoids from Tasmania. Alcheringa, vol. 15, p. 191-227.
- - , 1993: Evolution history of Palaeozoic Labechi ida (Stromatoporoidea). Mem. Assoc. Austral. Palaeontol., vol. 15, p. 57-67.
Yabe, H. and Sugiyama, T., 1930a: On some Ordovician stromatoporoids from South Manchuria, North China and Chosen (Corea), with noteson two new European forms. Sci. Rep., Tohoku
Univ., ser. 2, vol. 14, p.47-62.
- - and - - , 1930b: Notes on two stromatoporoids from Chosen (Corea). Japanese Jour.
Geology and Geography, vol. 8, p.9-1O.
Yang, J. and Dong, D., 1962: Stromatoporoidea ofChina. 40 p. Science Press, Beijing. (in Chinese)
Yavorsky, V.I., 1955: Stromatoporoidea Sovetskogo
Soyuza, Pt. I. Trudy Vses. Nauchno-Issled.
Geol. Insf., n.s., vol. 8, p. 1-173. (in Russian withEnglish abstract)- - , 1968: Ordovician Stromatoporoidea of Tuva.

970.

Ordovician stromatoporoids from Korea

Vses. Paleont. Obshch. Yezhegodn., vol. 18, p.
48-52. (in Russian)Yoo, C.-M., 1991 : Depositional environments of the457

Yeongheung Formation (Middle Ordovician).
Unpublished M. Sc. thesis, Seoul National
University, Seoul, 119 p.

Macha-ri ~~£, Mungog-ri :>(:8-£, Namkyo T¥H~, Youngwol ¥~.
~@!IYoungwolt.J'a?O)::t)v ~'I:::"A*C (LIanvirnian) "~L!±l: ~oo~t*$O) Youngwol

1'JJiH: 7t:ffi-g-.o Llanvirnian ($$;;t Iv r: c· A *) O)~#ij'I1:EEk;fi~;b' GI~HL!±l1I::E Labechiella regularis (Yabe and Sugiyama) ~~i!r l t.:. ll:i\'.fSHi r: 0 71 HI::~J3dI::1'Fm ~~It, 1tmO)fruHj:fl'liJ§O)i*t¥IH::'T l tJ ~tffl:li IJ' v'7'J!, laminae t pillars 0)!fJ1>&;b' GJ:~cO)
fitil'lJJE:7'J!Q]ijgl:tt>.o. :2f>:ll:i\'.M'i~OO7'J'GO):ijH)]0)~fL!±l1I::EO)~i!r-r·tt>.o t t tJ I:, i!t,w1¥J1:JiI.-r tJ~tJ'i!:lp~fL!R1I::EO) 1 -:Jl:tt>.o t~;z.o. $$;;t Iv r c"A*0)~fL!R1I::E~~0)1l71*'I1:'i1[\;v';b!, :2f>:fi ~-alb -r, 117 <O)fi;b!J.tv 'J:fu:E!ll.I¥J7t:ffi ~iF l-r:13 D, ~fL!R'iJi11::0)fJJ:l!ijl&lll§'l:~;iffi 1:1lt~ l-r v' '? t.: t ~;Z GtL.o.
J'ij'!Jlf~7.£: • Dong-lin Lee' Duck Keun Choi • Chan-Min YooTrans. Proc. Palaeont. Soc. Japan, N.S., No. 174, pp. 458-483, 16 Figs., June 30, 1994

971.

PLAGIACANTHIDAE (RADIOLARIA) FROM THE UPPER
MIOCENE OF EASTERN HOKKAIDO, JAPAN*
SATOSHI FUNAKAWA
Department of Geosciences, Faculty of Science, Osaka City University,
3-3-138, Sugimoto-cho, Sumiyoshi-ku, Osaka, 558

Abstract. Well-preserved radiolarians are abundant in diatomaceous siltstones of the
Taiki Formation (Upper Miocene) in the Toyokoro Hills region, and the Chokubetsu,
Atsunai and Shiranuka Formations (Middle Miocene to Lower Pliocene) in the Atsunai
Coast region, eastern Hokkaido, Japan. Fifteen samples are studied from five routes;
Oikamanai River, Yudou River, Noyaushi River, Ishii-zawa River and Atsunai Coast routes.
Plagiacanthidae species are a principle component of these assemblages.
Seven genera of Lophophaeninae (including two new genera and six new species), twoof Clathromitrinae and one of Sethoperinae are described. Three groups of Plagiacanthidae
having characteristic internal skeletal structures are recognized.
• Group I : The first segment is distinguished from the second segment by only AL.
• Group 2: The first segment is distinguished from the second segment by AL and VL(instead of AL and LL when V is lacking).
• Group 3: The first segment is distinguished from the second segment by DL and VL, or
AL-AL, AL and VL, or DL and LL.
All genera of groups I and 2 are included in Lophophaeninae, while two genera ofgroup 3 are in Clathromitrinae, one is in Sethoperinae and one is in Lophophaeninae.
Key words.
Hokkaido.

Radiolaria, Plagiacanthidae, internal skeletal structure, Upper Miocene,

the possibility that the internal skeletal structure was formed during late ontogeny andrecommended a classification of Nassellaria
based only on the external skeletal structure.
Swanberg and Bj~rklund (1987) studied living nassellarians to clear up the question of
the skeletal growth and revealed that arches
connecting two internal spicUles are formed
during a "precephalic stage". Recently, Nishimura (1990) studied the growth line structure of the nassellarian skeleton, and insisted
that the internal skeletal structure of nassellarians was formed during early ontogeny andwas an effective element in higher taxonomic
classification such as the family level. The
studies of Swanberg and Bj~rklund (1987)
and Nishimura (1990) suggest that it is suitable to classify Nassellaria at the suprageneric

Introduction
The suprageneric classification of Nassellaria has been approached in two ways, namely based on the internal skeletal structure andthe other based on the external skeletel structure. Riedel (1967, 1971) classified mainly
Cenozoic Nassellaria based on the wholeskeletal structure including the internal
skeletal structure. Petrushevskaya (1971 a,
197 I b, 1975, 1981) introduced a classification
scheme based on the internal skeletal structure. Takemura (1986) also classified Jurassic N assellaria based on the internal skeletal
structure. Empson-Morin (1981) suggested'Received October 6, 1993; revised
accepted A pri I 12, 1994

manuscript

458

971.

Radiolaria from the Upper Miocene of Hokkaido

level based on the internal skeletal structure
rather than the external one. Although suprageneric classifications based on the internal skeletal structure were introduced bysome authors, the specific and generic constancy of each internal skeletal element is
indistinct. Petrushevskaya (1971 a, 1971 b)
used AL for the suprageneric level and did
not use V and AD for any taxonomic levels.
Nishimura (l990) used V for specific level
and AL and AD for the suprageneric level.
It is necessary to ascertain the taxonomic
levels (specific, generic or suprageneric) at
which each internal skeletal element is constantly present.
Plagiacanthidae are an important group in
the radiolarian assemblages of the present
study. The family Plagiacanthidae wasdefined by Hertwig (1879), and emended by

Oikamanai River

Petrushevskaya ( 1971 a). Petrushevskaya(197Ib) divided it into two families and four
subfamilies. Nishimura (1990) broke up thisgroup into five families.
The present study clears up the correlation
between internal and external skeletal structures, and confirms which internal skeletal
elements are constant at the specific, genericor suprageneric level. In addition, this study
introduces one monogeneric and two
polygeneric groups of Plagiacanthidae basedon the internal skeletal structure that is constant at the generic level.

Materials and method of study
The study area is in eastern Hokkaido atabout Lat. 42°50'N to 43°00'N, Long.
143°50'E to 144°00'E (Figure I). The routes

0
~±=~

/

Figure 1.

459

Index map showing localities of study routes.

Satoshi Funakawa

460

4. Ishii-zawa River
Route
Is-1

1. Oikamanai River Route" , Oik-6
I....----

I,~

Oik "

-

, , ' Tk

400 [m],I

5. Atsunai Coast Route,,A ~ ~ 5-20"

1260791092601~""!-20-30°

Yd-53

Tk

I

0 JR LineSn

At'

400[m]

2. Yudou River RouteToyokoro Hills region
Tk : Taiki Formation
Oik : Oikamanai Formation
Atsunai Coast region
Ch
Chokubetsu FormationAt
Atsunai Formation
Sn
Shiranuka Formation
Figure 2.

Map showing localities of study samples.

Atsunai Coast Region

Toyokoro Hills Region
Diatom zones(Ma) (Kolzuml, 1985)

ci
IL

.
.."

5

Thalassiosira
oestrupii

6

Neodenticula
kamtschatica

Vudou River

Noyaushl River

Atsunal Coast

Ishii River-- -------- -- -- -- --- ----- -------- ------ ------ -----r;;;l-----------------~AIC-4
90102405

r:l

GVd-53.59

90102414<:

7

Rouxiacali/ornica

0

Tk

~

.
......

Oikamanal River

Thalassionema
schraderi~

8

Denticulopsis
katayamae:::l9Denticulopsis
dimorpha---- -- -------- ---- --- -- -- - -- --- - - --- -- -- ---r=r~~C:I-4 - - - - - - - - - - - - - -91092601------- -- --------- - - --- - -- - - - -- - - ---- - ------- - -- ---- - - - -- - - - - - - - -91092607- - --- --- -- -------- - - -----Oik-6.7~
Tk
NY-81.89
rP_'t:I-'---- --- - -- ---- - - - ---- - -- -- -- - -- - - -----------------------------------------------------------------NY-65. 69

T~~ -~-I~-1

Thalassiosira
yabei

Figure 3. Ages of study samples. Diatom zones are from Koizumi (1985) and their ages are fromOda (1986). Abbreviations of formation names are the same as those in Figure 2.

971.

Radiolaria from the Upper Miocene of Hokkaido

examined are mainly the Upper Miocene
strata, including the Taiki Formation(Yamaguchi and Satoh, 1989; Yamagishi etal., 1990) distributed in Toyokoro Hills
region, and the Chokubetsu, Atsunai and
Shiranuka Formations (Tada and lijima,1986) distributed in the Atsunai Coast region(Figure 2). Well-preserved radiolarian fossils are abundant in diatomaceous siltstones
from these formations. The present study isbased on 15 samples from 5 routes; Oikamanai River, Yudou River, Noyaushi
River, Ishii-zawa River and Atsunai Coastroutes. Each sample, sampling route, formation name and correlation with diatom zones(from Koizumi, 1985) are shown in Figure 3.
In the Noyaushi River route, although horizons of Ny-65 and -69 are situated higher
than Ny-81 and -89 which indicate theDenticulopsis katayamae Zone, they indicate
the Denticulopsis dimorpha Zone. This
points out that Ny-65 and -69 are allochthonous blocks derived from lower horizons,
possibly by slumping of sea floor deposits.
The radiolarian assemblages are composedof species that belong to the Actinommidae,

90102405 -Legend[ilij•

Plagiacanthidae

DgActinommidae

Spongodiscidae, Theoperidae andPlagiacanthidae (Fig. 4). Plagiacanthidae
species are one of the main groups of theseradiolarian assemblages.
To extract radiolarian specimens, crushedrock samples are immersed in a solution ofhydrofluoric acid. To restrain the dissolution of radiolarian skeletons by hydrofluoric
acid, crushed rock samples are left in a mixed
solution of hydrofluoric acid, hydrochloric
acid and hydrogen peroxide for no longer
than six to eight hours. This mixed solution
consists of:
HF (0.5,,-,1.0%)+HCI (lO,,-,15%)+H 2 0 2 (15"-' 20%), in a ratio of I : I : 1.
After extraction of specimens, they aresieved through a 75 J1 mesh screen, the residue
on the screen is cleaned by boiling in thesolution of hydrogen peroxide (5 to 8 %) for
about 10 to 30 minutes and then adding alittle hydrochloric acid and boiling until thereaction is ended (about 5 to 10 minutes).
Finally, the residue is sieved through a 75 J1
mesh screen again, washed by distilled water,and dried. Radiolarian specImens are
picked from the dried residue, mounted on an
SEM stub, coated with gold and observed
under the SEM.
Stratigraphic ranges (applying the diatom
zones from Koizumi, 1985) of described
species are defined by the observations for thesmear slides studied by Funakawa (1993).

Spongodiscldae

D90102414 -Other Nassellaria

461

Other Spumellaria

Terminology of internal and external
skeletal structures
91092601--

[200

[o[m]

91092607 Oik-6Oik-7 -o50

100[%]

Oikamanai River Route

Figure 4. Relative abundance of radiolarians
at the family level in the Oikamanai River route.
This chart shows that Plagiacanthidae are one of themain groups in the yielded radiolarian assemblages.

The terminology of the internal skeletal
structure follows Dumitrica (1991). Theinternal skeletal elements of Nassellarians are
divided into internal spicules and connecting
arches. In this study, the confirmed internal
spicules of Plagiacanthidae are median-bar(MB), apical spine (A), dorsal spine (D),ventral spine (V), right and left lateral spines(L) and right and left secondary lateral spines(I) (Figure 5). The basic scheme of connecting arch follows Petrushevskaya (1968), "skel-

Satoshi Funakawa

462

AL

VL----+."lIil>JoV

axial projection

To observe Plagiacanthidae externally, thefollowing structures are recognized: anapical rib on the first segment extended fromA, an apical horn extended from the apicalrib or directly from A, a ventral hornextended directly from V, dorsal and lateralribs on the second segment extended from D
and L, and three feet extended from dorsal
and lateral ribs or dircetly from D and L.

first segment

Taxonomic descriptions
ventral hornapical horn...d:~d1~""'- second
segment"""1--- footFigure 5. Terminology of the internal andexternal skeletal structures of Plagiacanthidae (thesefigures are for Pseudodictyophimus gracilipes). Secondary lateral spines (1) are not designated in thisfigure.

eton connecting two basic spicules". Additionally, the present siudy proposes adefinition that the loci of these arches are notdisturbed by pore arrangement. Because
they are formed during a "precephalic stage"(Swanberg and Bj¢rklund, 1987), later
skeletal growth is controlled by their position. In Plagiacanthidae, two AL (connecting A and L), two VL (connecting V and L),
two DL (connecting D and L), AD (connecting A and D, LL (connecting both L), ALAL (connecting both AL at the dorsal side),
two AI (connecting A and I), two LI (connecting L and I at the right and left sides), two Dl(connecting D and l) and VL-VL (connecting
right and left VL at the ventral side) are
confirmed in the present study. Where theseconnecting arches are in the shell, distinct orindistinct furrows are formed along them.
By the combination of furrows along VL, LL,
DL, AL-AL, LI and Dl, the first segment IS
distinguished from the second segment.

Suborder N assellaria Ehrenberg, 1875
Superfamily Plagiacanthoidea Hertwig, 1879,
emend. Petrushevskaya, 1971 a
Family Plagiacanthidae Hertwig, 1879,
emend. Petrushevskaya, 1971 a
Subfamily Lophophaeninae Haeckel, 1881,
emend. Petrushevskaya, 1971 b
Genus Amphiplecta Haeckel, 1881, emend.
Petrushevskaya, 1971 b

Type species: Amphiplecta acrostoma
Haeckel, 1887.
Remarks.- The skeleton is composed oftwo segments. Internal skeletal structure iscomposed of MB, A, D, L, V, AL and VL.
The junction of A and AL is on the shell.
The first segment is cylindrical and distinguished from the second segment by AL and
VL or the furrows along them. The apicalrib is well-developed. A skeleton-like AD ispresent and located outside the shell. The
second segment is widely expanded but poorly developed, with indistinct dorsal and lateral ribs.
Amphiplecta acrostoma Haeckel
Figure 6, 1a-I b

Amphiplecta acrostoma Haeckel, 1887, p. 1223-1224,
pI. 97, fig. 10.

Amphiplecta

acrostoma Haeckel; Petrushevskaya,
1971 b, p. 103, pI. 54, figs. 2-7.

Remarks.- The first segment is cylindricaland its apex is not closed. The shell of the971.

Radiolaria from the Upper Miocene of Hokkaido

463

Occurrences - 90102414, 91092607, Oik-6,
Yd-59 and Atc-14.
dance .

Few to very rare in abun-

Stratigraphic range - The lo wer limit is in
the Denticulopsis dimorpha Zone, the upper
limit is not confirmed.
Genu s Ceratocyrtis BUtschli , 1882, emend.
Petrushevskaya, 1971 b

Figure 6.

la, Ib: A mphip/ecla

acrosloma

Haeckel , Atc-14. la: left la teral) view; 2a:oblique basa l (left lateral view. Arrow of la points
to the a pical rib . Scale bars: l a=50,urn ; Ib = 20
,urn.

first segment is a rough meshwork formed bythin pore bars without fine spines. The
apical horn extends at the apex of the first
segment but is poorly developed. Pores are
irregularly shaped and randomly arranged .
Axial projection is distinct. Th e second segment is very poorly developed below AL and
VL as divergent spines extending from D and
L. A ske leton-like AD tends to be broken
because it is not within the shell.
Dimensions. - Measurements are based onnine specimens. Diameter at the apex of thefirst segment is 54- 90 (average is 67) ,um, themaximum of the first segment is 58-119 (92),urn, total height of the shell (a lm ost equal tothat of the first segment) is 70- 143 (112) ,u m.

Type species: Cornutella cucutlaris Ehrenberg, 1873 (designated by Petrushevskaya,
1971 b).
Remarks. - The skeleton is composed oftwo segments. Internal skeleta l structure iscomposed of MB, A, D, L, V, AL and VL.
Some specimens lack V , and LL is present
instead of VL. The junction of A and AL ison the shell. The first segment is distinguished from the second segment by the furrows a long AL and VL (or LL) . The first
segment is hemispherical with a short apicalrib . The second segment is bell-shaped with out di stal feet. Dorsal and lateral ribs areabsent.
In this genus , the apical horn and ventral
horn are poorly developed . It is distinguished from Pseudodictyophimus andCory thomelissa by the absence of the dorsal
and lateral ribs and distal feet, and from
Lophophaena by its small first segment.
Ceratocyrtis histricosus (J¢rgensen)
Figure 7, I a-I b

He/olho/us hislricosus J¢rgensen , 1905, p . 137, pI. 16,
fi gs. 86- 88.

Ceralocyrlis histricosus (J¢rgensen): Bj¢rklund , 1976,
pI. 8, figs. 19 - 24, pI. II , figs. 4, 5.

Remarks. -S urface of the shell is smooth
without spines. The first segment is hemispherical and with a poorly developed apicalhorn . Pores in the first segment are circu lar
and randomly arranged . Axial projection is
as long as a spine. The distal end of thesecond segment is open with teeth around it.
Pores in the second segment are circular to sub-

Satoshi Funakawa

464

circular and larger than in the first segment.
This species is similar to Ceratocyrtis histricosus in Sugiyama (1993) although having
the smooth-surfaced second segment.
Dimensions.-Measurements are based on
20 specimens. The maximum diameter of thefirst segment is 24-36 (29) ,urn, of the second
segment 69-148 (l01) ,urn, total height of theshell (not including apical horn) is 64-138(86) ,urn.

Occurrences.-All samples. Few to rare
in abundance.
Stratigraphic range.-All zones. The
upper and lower limits are not confirmed.

unrelated to the internal spicules.
Etymology.- The specific name means"many horns" in Latin
Occurrences.-90102405, 90102414, Yd-53
and 59. Common in abundance.
Stratigraphic range-the species isrestricted to the Neodenticula kamtschatica
Zone and dies out in the middle to upper partof the zone. In the Yudou River route, its
disappearance process is characteristic. In
the middle part of the same zone, the relative
abundance of this species is 3% to 15% justabove a horizon where it occurs abundantly,
it disappears abruptly. Refer to Funakawa(1993), Fig. 6.

Ceratocyrtis multicornus Funakawa, sp. nov.

Ceratocyrtis sp.

Figure 7, 2a-2b

Figure 7, 3a-3b

Arachnocorys sp. B group; Funakawa, 1993, pI. 2,
figs. 1a-3b.

Description.-Surface of the shell is spiny.
Some specimens identified as this species havepoorly developed V and VL. When V ispoorly developed, it is only recognized as an
upwardly directed projection at the intersection of MB and L. The apical horn andventral horn are poorly developed. The
apical rib is indistinct because of the complicated meshwork structure of the shell. Poresin the first segment are circular and irregularly arranged. Axial projection is present but
small. The distal end of the second segment
is fully open with teeth around it. In somespecimens, the lower part of the second segment is distinguished from the upper part bypore shape and arrangement. In the lower
part, pores are quadrangular but in the upper
part they are circular to subcircular.
Dimensions.-Measurements are based on
10 specimens. The maximum diameter of thefirst segment is 23-30 (27) ,urn, of the second
segment 53-85 (72) ,urn, total height of theshell (not including apical horn and distalteeth) is 64-86 (74) ,urn.
Remarks.- This species is distinguishedfrom Ceratocyrtis histricosus by fine and complicated skeleton of the second segment and asmaller shell than that of C. histricosus. It is

Holotype.-OCU CR-0002 (90102405)
Description.-Surface of the shell is somewhat spiny. The first segment is hemispherical with one to five stout horns that do notextend from A but are simple projections of
the shell. The apical horn· and ventral hornare poorly developed. Pores in the first segment are circular to subcircular and randomly
arranged. Axial projection is present. The
furrows subdividing the first and second segments are distinct. The second segment isconical to bell-shaped. The distal end of thesecond segment is fully open with teeth
around it. Pores in the second segment are
subcircular and irregularly arranged, larger
than those in the first segment. Pore bars arethin and narrow.
Dimensions.-Measurements are based on
14 specimens. The maximum diameter of thefirst segment is 29-36 (32) ,urn, of the second
segment 69-104 (81) ,urn, total height of theshell (not including apical horn and distalteeth) is 53-94 (73) ,urn.
Remarks.- This species is distinguishedfrom other species of Ceratocyrtis by having
one to five or more horns on the shell that are971.

Radiolaria from the Upper Miocene of Hokkaido

465

Figure 7. la, lb : Ceratocyrtis histricosus (J¢rgensen), Ny-89. I a: ventra l to left latera l view ; I b :basal view. 2a, 2b: Ceratocyrtis multicornus Funakawa, sp. nov. , OCU CR-0002, 90102405, holotype.
2a : left latera l view ; 2b: basal view. Arrow I of 2a points to the ap ica l rib , 2 to the furrow a long AL
a nd 3 to the furrow a lo ng VL. 3a, 3b : Ceratocyrtis sp. , 91092601. 3a: ventral view; 3b: basal view.
Scale bars: 2b a nd 3b=20,um ; others=50,um.
.

distinguished from C. multicornus sp. nov. by
its fine and complicated skeleton and theabsence of some horns on the first segment.
Occurrences. - 90102414 and 91092601.
Common to very rare in a bundance.
Stratigraphic range. - This species occurs
commonly in the Thalassionema schraderi
Zone, rarely in Neodenticula kamtschatica
Zone. The upper and lower limits are notconfirmed .
Genus Lophophaena Ehrenberg, 1847 ,
emend. Petrushevskaya, 1971 b

Typespecies: Lophophaena galeaorci
Ehrenberg, 1854 = Lophophaena apiculata
Ehrenberg, 1873.

Remarks.- The skeleton is composed oftwo segments. Internal skeletal structure
consists of MB, A, V, D, L, AL and VL.
The junction of A and AL is on the shell.
The first segment is distinguished from theseco nd segment by the furrows along AL and
VL. The first segment is a lmost spherical toellipsoidal with a short apical rib. The second segment is bell-shaped to subcylindrical.
Development of feet, dorsal and lateral ribs isvariable.
Lophophaena simplex Funakawa, sp. nov.
Figure 8, I a-2c

Holotype.-OCU CR-0003 (Ny-89)
Description .-The first segment is subspher-466

Satoshi Funakawa

ical to ellipsoidal. One to four (occasionallymore) robust horns that are unrelated to theapical rib are on the shell. These horns areshorter than the half-height of the first segment. The apical horn and ventral horn are
unbladed and poorly developed. Pores in
the first segment are circular to subcircularand randomly arranged. Axial projection ispresent and in some specimens it is welldeveloped like a spine. The second segment
is bell-shaped with indistinct dorsal and lateral ribs, without feet extended from them.
In most specimens, there are many external
unrelated to internal spicules on the lower
part of the second segment. Pores in thesecond segment are circular to subcircularand randomly arranged but in the lower partare arranged weakly along longitudinal ribs.
The distal end of the second segment is openwith teeth, but in some specimens, tends to beclosed by a porous plate. Surface of thesecond ~egment is without spines.
Dimensions.-Measurements are based on
12 specimens. The maximum diameter of thefirst segment is 47-69 (54) ,um, of the second
segment 78-102 (91) ,um, total height of theshell (not including apical 'horn) is 98-133(lll),um.
Remarks.- This species is distinguishedfrom other species of Lophophaena by its
stout horns, and from Ceratocyrtis multicornus sp. nov. by its larger subspherical toellipsoidal first segment.
Etymology.- The specific name means"simple" in Latin.
Occurrences.-Oik-6, 7, Ny-65, 69, 81, 89
and Is-I. Few to very rare in abundance.
Stratigraphic range.- The upper limit is in

the Denticulopsis katayamae Zone.
lower limit is not confirmed.

The

Lophophaena triangula Funakawa, sp. nov.
Figure 8, 3a-4b(?) Lophophaena sp.; Petrushevskaya, 1971 b, pI. 57,

fig. 7.

Holotype.-OCU CR-0004 (Ny-8l)
Description.-Surface of the shell, especially that of the first segment, has numerous
fine spines. The first segment is spherical tosubspherical. AL and VL form a distinct
internal ring. Bacause the junction of AL
and VL is situated on a similar horizon to thejunction of A and AL, the furrows and internal ring lie nearly in the same horizon. The
apical horn and ventral horn are unbladed
and poorly developed. Pores in the first
segment are circular to subcircular and randomly arranged, almost equal in size. Axial
projection is present. The second segment isbell-shaped with three distinct dorsal andlateral ribs that are indistinct externally.
Pores in the second segment are circular to
subcircular and randomly arranged, vary insize, with almost all of them being larger thanthose of the first segment. Generally, thedistal end of the second segment is fully open,
but in some specimens it tends to be closed bya porous plate. The development of theporous plate is variable. Feet extending
from distal end of the second segment are
unbladed and longer than the height of thesecond segment. Some specimens have feetthat do not extend from the internal spiCUles(Figures 8-4a, 4b)~
Figure 8. la-2c: Lophophaena simplex Funakawa, sp. nov. la, lb: OCU CR-0003, NY-89,
holotype. la: left lateral view; Ib: basal view. Arrow I of la points to the furrow along VL, 2 to thefurrow along AL and 3 to the ventral horn. 2a, 2b: NY -89. 2a: right lateral view; 2b : enlargement of
oblique basal (right lateral) view; 2c: enlargement of dorsal view. Arrow of 2a points to the ventral hornand 2c to the apical horn. 3a-4b: Lophophaena triangula Funakawa, sp. nov. 3a, 3b: OCU CR-0004,
NY -81, holotype. 3a: left lateral view; 3b: basal view. Arrow I of 3a points to the furrow along VL,
2 to the furrow along AL, 3 to the ventral horn and 4 to the apical horn. 4a, 4b: NY -81. 4a: dorsal view;
4b: enlargement of basal view. Arrow I of 4a points to the apical rib, 2 to the AL, 3 to a foot unrelated
to the internal spicule and 4b to the ventral horn. Scale bars: la,2a,3a,4a=50,um; others=20,um.

971.

Radiolaria from the Upper Miocene of Hokkaido

467

468

Satoshi Funakawa

Dimensions.-Measurements are based onnine specimens. The maximum diameter ofthe first segment is 41-58 (49) ,um, of thesecond segment 72-92 (82) ,um, total height ofthe shell (not including apical horn and distal.
foot) is 74-96 (83) ,um.
Remarks.- This species is distinguishedfrom Pseudodictyophimus gracilipes (Bailey)by the unbladed feet and large, almost spherical first segment, and from Lophophaena
simplex sp. nov. by its three feet and distinct
dorsal and lateral ribs. This species is similar to Lophophaena sp. of Petrushevskaya(1971 b), but pores are larger and fewer than
Petrushevskaya's ( 1971 b) species.
Etymology.- The specific name means "triangle" in Latin.
Occurrences.-Ny-65, 69, 81, 89 and Is-l
Few to rare in abundance.
Stratigraphic range.- The upper limit is in
the Denticulopsis katayamae Zone. The
lower limit is not confirmed.
Genus Marimoum Funakawa, gen. nov.

Diagnosis.- The skeleton is composed oftwo segments. Internal skeletal structure iscomposed of MB, A, D, L, V, DL, VL and
AL. In some specimens, right or left (orboth) 1, AI, Dl, Ll and one VL-VL arepresent. The first segment is bell-shaped tohemispherical and distinguished from thesecond segment by DL and VL and the furrows along them in most specimens. When
1, AI, DI and VL-VL exist, the boundary
dividing the two segments consists of VL, Ll
and Dl. At the dorsal side of the first segment, the shell tends to be double-layered.
The inner layer includes the apical rib, andthe outer one is a cobweb-like meshwork.

Type species.-Marimoum robustum Funakawa, sp. nov. (by monotypy).
Remarks- This genus is distinguishedfrom Amphiplecta by having DL and welldeveloped outer layer on the dorsal side of
the shell. It has a skeleton externally similar
to that of Cryptogyrus Sugiyama, 1993, but isdistinguished from the latter by its distinct
DL.
Etymology.- The generic name is derived
from the Japanese word for spherical algal
growths unique to Lake Akan, eastern Hokkaido, Japan (neuter gender).
Marimoum robustum Funakawa, sp. nov.
Figure 9, la-4d

Holotype.-OCU CR-0006 (Yd-59)
Description.-Many specimens do not have
1 but one (right or left) or two 1 exist in somespecimens. When 1 are present, also present
are Ll and Dl instead of DL. The combination of these arches and the angles between
MB and 1 are variable. The arch composition of the boundary dividing the two segments is DL and VL in most specimens, Ll
and VL, or Dl, Ll and VL or Dl, Ll, VL and
VL-VL in a few specimens (Figure 10). The
furrows along these arches are indistinct
because of the spiny surface of the shell.
Indistinct apical horn extends from the apicalrib. Surface of the inner layer is spiny, pores
there are circular and very small. The outerlayer is a cobweb-like meshwork on the dorsal side of the shell. Axial projection. The
second segment is less than 1/3 of the heightof the first segment and lacks distinct feet.
Similar to the first segment, the surface of thesecond segment is spiny and cobwebby.
Internal skeletal elements are characteristi-~
Figure 9. la-4d: Marimoum robustum Funakawa, gen. et sp. nov. la, Ib: OCU CR-0006,
9 \09260 I, holotype. la: ventral to left lateral view; I b: basal view. 2a,2b: Atc-4. 2a: dorsal to rightlateral view; 2b: basal view. Arrow of 2a points to the apical rib. 3a, 3b: Y d-59. 3a: right lateralview; 3b: basal view. 4a-4d: Atc-4. 4a: dorsal to right lateral view; 4b: basal view; 4c: enlargementof basal view; Ad: enlargement of dorsal view. Arrow I of 4a points to I, 2 to AI, 3 to DI, I of 4b to
VL-VL, 2 to VL, white arrow of 4c to AI, black arrow to VL-VL and black arrow of 4d to the apical horn.
Scale bars: la,2a,3a,4a and 4b=50pm, others = 20 pm.

971.

Radiolaria from the Upper Miocene of Hokkaido

469

Satoshi Funakawa

470

cally robust.
Dimensions.-Measurements are based on
12 specimens. The maximum diameter of thefirst segment is 39-50 (45) pm, of the second
segment 60-81 (69) pm. Total height of theshell is 71-88 (82) pm.
Remarks.- The internal skeletal structuresof this species have much variation (Figure10). One or two 1 are regarded as intraspecific variation because their development
and direction are unstable when they exist.
In the same way, the elements, AI, DI and
VL-VL are subject to intraspecific variation,
because most specimens lack them and the
combination of them varies when they doexist. This species is distinguished from
Cryptogyrus trachylobus Sugiyama, 1993, by
its doublelayered shell on the dorsal side of
the shell and its smaller pores in the inner
layer of the first segment. It resembles
Botryopera (?) leptostraca Sugiyama, 1993,
externally but is distinguished by the internal
skeletal structure. This species has shorter
skeleton between the junction of Land AL
and the junction of AL and VL (equal to"L-R" in Sugiyama, 1993) than is the case in
B. (?) leptostraca.
Etymology.- The specific name means"stout" in Latin.
Occurrences.-90102405, 90102414, Yd-53,
59, Atc-4 and 14. Common to few in abundance.
Stratigraphic range.- This species occurs
commonly in the Neodenticula kamtschatica
Zone. The lower limit is in the Thalassionema schraderi Zone. In the Atsunai
Coast route, this species occurs in the Thalassionema oestrupii Zone and its upper limit is
not confirmed.
Genus Peridium Haeckel, 1881

Type species: Peridium spinipes Haeckel,
1887.
Remarks.- The skeleton is composed oftwo segments. Internal skeletal structure
consists of MB, A, D, L, V, AL and VL.

When V is not present LL is present insteadof VL. The first segment is large and inverted drop-shaped with a long distinct apical rib
and its apex is closed. The shell has circular
to subcirular pores. The junction of A and
AL is on the shell. The second segment ispoorly developed.
This genus is distinguished from Amphiplecta by the inverted-dropshape of the first
segment. Perometissa Haeckel, emend.
Petrushevskaya, 1971 b, and ArachnocoralHum Haeckel, emend. Petrushevskaya,
1971 b, have a similarly shaped first segment
but are distinguished from Amphiplecta by
their well-developed second segment. This
genus also resembles Cryptogyrus but is distinguished by its shorter skeleton between thejunction of Land AL and the junction of AL
and VL (or LL), that is equal to "L-R" in
Sugiyama (1993), than in the latter genus.

Peridium sp. aff. P. spinipes Haeckel
Figure II, la-Ie
air. Peridium spinipes Haeekel, 1887, p. 1154, pI. 53,
fig. 9.

Description.- The first segment is large,
inverted-drop-shaped. Pores in first segment
are circular to subcircular. Surface of thefirst segment is somewhat spiny. The apex of
the first segment is closed. Axial projection
is distinct. The second segment is poorly
developed and truncated conical-shaped.
Pores in the second segment are larger thanthose in the first segment.
Dimensions.-Measurements are based on
only two specimens. The maximum diameter of the first segment is 76-80 pm, totalheight of the shell (almost equal to that of thefirst segment) is 96-100 pm.
Remarks.- This species has a skeleton similar to that of P. spinipes but differs from thelatter species by broader pore bars and the
spiny surface of the shell. Skeletal structuresof this species resemble the inner layer ofMarimoum robustum gen. et sp. nov., but it is971.

Radiolaria from the Upper Miocene of Hokkaido

I

IT

471

ill

N

~~OL

Vt ......•.~A
A{i-.).;

Apical view

\L)
ff

AL

17

~
L

AL

Left lateral
view

AL

f

> AI
.

'.

OL

OL

17

LI

VL-VL

01

LI

Figure 10. The simplified figures of the internal skeletal structures of Marimoum robustum. Thesefigures show the high variability of the internal skeletal structure. Figures in column I are for the
specimen of Fig. 9-2; II are for Fig. 9-1, that is the holotype; III are for Fig. 9-3; IV are for Fig. 9-4.
In these figures, gray indicates connecting arches and black internal spicules.

distinguished from the latter species by its fineskeleton and the absence of DL, and from
Cryptogyrus trachylobus by its thinner porebars and its shorter skeletons between thejunction of Land AL and the junction of AL
and VL.
Occurrences.-Only Atc-4. Very rare inabundance.
Stratigraphic range.-Neodenticula kamtschatica Zone.

Peridium sp.
Figure I I, 2a-2b

Description.-V and VL are absent and LL
is present instead of VL, AL and LL form thefurrows between two segments. The first
segment is cylindrical and its gradual diameter gradient is weak and increases upwardly.
Its apex tends to be closed. In the first segment, pores are few, circular to subcircularand randomly arranged. Pore bars are verybroad. The apical rib is long and distinct.
The apical horn is poorly developed andrecognized only as a small projection at theapex of the shell. Axial projection is distinct. The second segment is very poorly
developed and recognized only as downwardly directed short spines diverging from D andL.
Dimensions.-Measurements are based on
five specimens. The maximum diameter ofthe first segment is 64-72 (68) ,urn, total heightof the shell (almost equal to that of the first
segment) is 80-100 (94) ,urn.
Remarks. -The internal skeletal structureof this species is characterized by the absenceof V and presence of LL instead of VL. It is
unclear whether these characters are particular to this species or a matter of intraspecificvanatlOn. This species is distinguished from
Peridium sp. aff. P. spinipes by broader porebars and fewer pores in the first segment thanin the latter species. This species is distinguished from Amphiplecta acrostoma by large
and few pores.
Occurrences. - Atc-4 and Is-I. Very rare
in abundance.
Stratigraphic range.-The upper and lower
limits are not confirmed.

Satoshi Funakawa

472

Figure 11. la-Ie: Peridium sp. afT. P. spinipes Haeckel , Atc-4. I a: left lateral view; I b: basal
view ; Ic: enlargement oblique basal (left lateral) view. Arrows of la and Ic point to the apical rib. 2a,2b: Peridium sp., 91092607 . 2a: dorsal to right lateral view ; 2b: oblique basal (right lateral) view.
Arrow of2a points to the apical rib. Scale bars : Ib, Ic = 20/Lm; others= 50/Lm .

Genus Pseudodictyophimus
Petrushevskaya, 1971 b

Typespecies.-Dictyophimus

gracilipes

Bailey, 1856.

Remarks. - The skeleton is composed oftwo segments. Internal skeletal structure
consists of MB, A, D, L, V, AL and VL.
The junction of A and AL is on the shell.
The first segment is hemispherical with shortapical rib. The second segment is bellshaped with three distinct dorsal and lateralribs .

Pseudodictyophimus graci/ipes (Bailey)
Figure 12, la-Ib

Dictyophimus gracilipes Bailey, 1856, p. 4, pI. I, fig. 8.
Pseudodictyophimus graciiipes (Bailey); Petrushevskaya, 1971b, pI. 48, figs I, 3- 6, pI. 49, figs. 6- 7.

Pseudodictyophimus sp. ; Nishimura, 1990, p.96, pI.
18, fig s. Sa-b (not pI. 16, figs . 9-IOb) .

Remarks. - Surface of the shell is smooth
without spines. The apical horn is fine andunbladed. The ventral horn extends
obliquely upward and is almost as long as the971.

Radiolaria from the Upper Miocene of Hokkaido

apical horn. Pores in the first segment arecircular to subcircular and randomly arranged. Axial projection is distinct. The second segment is bell-shaped and its horizontal
section is weakly trigonal because of distinct
dorsal and lateral ribs. Pores in the second
segment are circular to subcircular and randomly arranged, larger than those of the first
segment. Distal end of the second segment isfully open. Three-bladed distal feet extend
outside from near the end of the second segment, and their length is equal to or greaterthan the diameter of the second segment.
Pseudodictyophimus sp. in Nishimura(1990) has skeletal structures almost the sameas in this species except for the presence of
AD. Nishimura's (1990) species may be included in this species because the present
study confirms that the development of theskeleton-like AD in this species is a matter of
intraspecific variation.
Dimensions.-Measurements are based on
25 specimens. The maximum diameter of thefirst segment is 21-35 (30) j.lm, of the second
segment 50-88 (72) j.lm, total height of theshell (not including apical horn and distalfeet) is 42-76 (62) j.lm.
Occurrences.-All samples. Common torare in abundance.
Stratigraphic range.-All zones. The
upper and lower limits are not confirmed.

Pseudodictyophimus tanythorax
Funakawa, sp. nov.
Figure 12, 2a-3b

Holotype.-OCU CR-0005 (Oik-7)
Description.-Surface of the shell is smooth,
without spines. The first segment is hemispherical. The apical horn is unbladed or
three-bladed. The ventral horn is shorter
than the apical horn. Pores in the first segment are circular to subcircular and randomly
arranged. Axial projection is distinct.
Development of the second segment is variable but in most specimens it is welldeveloped. Pores in the second segment are473

circular to subcircular and randomly arranged, vary in size, being generally larger thanthose of the first segment. The distal end of
the second segment is fully open and surrounded by teeth. Three-bladed feet extend
outside at the lower part of the second segment.
Dimensions.-Measurements are based on
24 specimens. The maximum diameter of thefirst segment is 28-40 (33) j.lm, the second
segment is 63-85 (70) j.l m, total height of theshell (not include apical horn and distalteeth) is 58-100 (79) j.l m.
Remarks.- This species has a highly variable skeleton due to the development of thesecond segment and feet. This species isdistinguished from P. gracilipes by its longand stout apical horn and straightly prolonged feet. It is distinguished from Lophophaena triangula sp. nov. by its long andstout apical horn and a smaller first segment
than in the latter species.
Etymology.- The specific name means"long thorax" in Greek.
Occurrences.-All samples. Common tovery rare in abundance.
Stratigraphic range.-All zones. The
upper and lower limits are not confirmed.
Genus Tripodocyrtis Funakawa, gen. nov.

Type species- Tripodocyrtis elegans Funakawa, sp. nov. (by monotypy).
Diagnosis.- The skeleton is composed oftwo segments. Internal skeletal structure
consists of MB, A, D, Land AL. The junction of A and AL is on the shell. Connecting arches in this genus comprise only AL,
without VL or LL. The first segment isdistinguished from the second segment at theapical to lateral side by the furrows along AL, .
but at the ventral side the boundary between
the two segments is not recognizable because
VL and LL are absent. The first segment ishemispherical with a short apical rib. The
second segment is widely expanded bellshaped with three distinct dorsal and lateral

Satoshi Funakawa

474

Figure 12. la, lb: Pseudodictyophimus graci/ipes (Bailey), Ny-81. I a: right lateral view ; I b :oblique basal (right latera l) view. Arro w I of la points to the furrow a long AL, 2 to the furrow along
VL. 2a-3b: Pseudodictyophimus tany thorax Funakawa, sp. nov. 2a, 2b: OCU CR-OOOS , Ny-69 ,holotype. 2a: left lateral view; 2b: basal view . Arrow I of 2a points to the furrow along AL, 2 to thefurrow along VL and 3 to the apical rib. 3a, 3b: Is-I . 3a: right lateral view ; 3b: basal view. Scalebars: Ib = 20,um; others = 50JLm.

ribs extending to distal feet.
Remarks.- This genus is distinguishedfrom Pseudodictyophimus, Ceratocyrtis andLophophaena by the absence of V, VL and
LL.
Etymology. - The generIC name means" three feet basket" in Greek (masculine gender).

Tripodocyrtis elegans Funakawa, sp. nov.
Figure 13 , 1a-2b

Dictyophimus sp. cf. D. p/atycepha/us Haeckel ; Ni-

shimura, 1990, p. 17, fig. 7.

H%type. - OCU CR-OOOI (Ny-89)
Description. - The shell is somewhat spiny.
The apical horn is unbladed, very weak andshorter than the cephalic height. Pores in
the first segment are circular to subcircularand randomly arranged. Axial projection is
distinct. The horizontal section of the second segment is somewhat triangular becauseof three distinct dorsal and lateral ribs .
Pores in the second segment are circular to
subcircular and randomly arranged, generally

971.

Radiolaria from the Upper Miocene of Hokkaido

they are larger than those of the first segment.
Three feet extend downward at the distal endof the second segment. Feet are long, unbladed and almost equal to the diameter ofthe second segment. The distal end of thesecond segment is fully open .
Dimensions. - Measurements are based on
18 specimens. The maximum diameter of thefirst segment is 30- 47 (36) ,um , of the second
segment 60- 102 (77) ,um, total height of theshell (not including apical horn and feet) is

36- 65 (53) ,um.
Remarks. - This species is distinguishedfrom Pseudodictyophimus gracilipes by theabsence of the furrows at the ventral side.
This species is distinguished from

Pseudodictyophimus gracilipes tetracanthus

475(Popofsky) in Petrushevskaya ( 1971 b) by the
unbladed feet. It differs from Dictyophimus
platycephalus Haeckel by its weak apicalhorn and incomplete furrows between the firstand second segments. Dictyophimus sp. cf.
D. platycephalus Haeckel in Nishimura(1990) has been described as having AD. In
this study, although some specimens placed
into this species have an indistinct skeletonlike AD, most specimens lack it. Therefore
the ske leton-I i ke AD is not stable at the
specific level and its existence is regarded as amatter of intraspecific variation within thisspecies.
Etymology. - The specific name means " elegance" in Latin .

Occurrences. - 90 I 024Q5,

90 I 02414,

Figure 13. la-2b: Tripodocyrtis elegans Funakawa, gen. et sp. nov. la, lb: OCU CR-OOOI ,Ny-89, holotype. la: ventral view ; lb: basal view. 2a, 2b: Oik-6. 2a: dorsal view; 2b: basal
view. Arrow I of2a point to the furrows along AL, 2 to the apical rib . Scale bars: la and 2a = 50.urn ;Ib, 2b = 20 .u rn .

Satoshi Funakawa

476

91092601 , 91092607, Oik-6, 7, Ny-81 , 89,
A tc-4, 14 an dIs-I. Few to very rare In
abundance.
Stratigraphic range.-All zones. The
upper and lower limits are not confirmed.

distal feet.

Corythomelissa horrida Petrushevskaya
Figure 14, la-Ib

Corythomelissa horrida Petrushevskaya, 1975, p. 589590, pi , II, figs. 14- 15, pI. 21, fig. 9.

Subfamily Clathromitrinae Petrushevskaya,
1971bGenus Corythomelissa Campbell, 1951Type

species: Lithomelissa

cory thium

Ehrenberg, 1873.
Remarks.- The skeleton is composed oftwo segments. Internal skeletal structure
consists of MB, A, D, V, L, AL, VL and
AL-AL. The junction of A and AL is inside
the shell , so the furrows along AL are incomplete. AL-AL is at the dorsal side of theshell and forms a weak furrow. The first
segment is distinguished from the second
segment by the furrows along AL-AL, AL
and VL. The first segment is hemisphericalto cup-shaped without the apical rib . The
apical horn extends from A directly at or near
the apex of the first segment. The second
segment is bell-shaped with distinct dorsal
and lateral ribs that extend downward as

Remarks. - The skeleton is composed oftwo segments. The shell is very robust andits surface is spiny. The furrows subdividing
the first and second segments are indistinct
because of the many spines on the shell. The
first segment is hemispherical or cup-shaped.
The apical horn is robust and three-bladed.
The ventral horn is three-bladed , shorter andnarrower than the apical horn. Pores in thefirst segment are subcircular and randomly
arranged. Axial projection is distinct. Feetare three-bladed and their length is generally
less than the diameter of the second segment.
In most specimens, the distal end of the second segment is fully open but, in some specimens, it tends to be closed by a porous plate.
The development of the porous plate is variable. Pores in the second segment are circular to subcircular and randomly arranged .
This species is identified as C. horrida
although it is somewhat larger than Petru-

Figure 14. la, lb: Corythomelissa horrida Petrushevskaya, Oik-7.
view. Scale bars: = 50 ,urn.

la: dorsal view; Ib: basal

971.

Radiolaria from the Upper Miocene of Hokkaido

shevskaya's (1975) specimens.
Dimensions.-Measurements are based on
I I specimens. The maximum diameter of thefirst segment is 56-68 (63) j.lm, of the second
segment 106-144 (120) j.lm. Total height ofthe shell (not including apical horn and distalfeet) is 74-126 (96) j.lm.
Occurrences.-91092607, Oik-6, 7, Ny-8l,
89, Atc-4, 14 and Is-I. Very rare in abundance.
Stratigraphic range.-All zones. The
upper and lower limits are not confirmed.
Genus Euscenarium Haeckel, 1887,
sensu. Petrushevskaya, 1981

Type species: Euscenium tricolpium
Haeckel, 1887.
Remarks.- The skeleton is composed oftwo segments. Internal skeletal structure
consists of MB, A, V, D, L, DL, VL, AL and
AD. The first segment is hemispherical tobell-shaped, large and well-developed with anapical horn. The apical horn extends directly from A near the apex of the first segment.
The first segment is distinguished from thesecond segment by DL and VL and furrows
along them. The second segment is poorly
developed with distinct dorsal and lateral ribsthat extend downward as distal feet.
Euscenarium sp. aff. E. tricolpium (Haeckel)
Figure IS, la-Ib
aff. Euscenium tricolpium Haeckel, 1887, p. 1147, pI.
53, fig. 12.
aff. Archiscenium tricolpium (Haeckel); Petrushevskaya, 1971 b, p. 75, pI. 36, fig. 2. = Euscenarium
tricolpium (Haeckel); Petrushevskaya, 1981, fig.
28.
(?) Cladoscenium tricolpium (Haeckel); Jprgensen,
1905, p. 134, pI. 15, figs. 71 - 73.

Description.-In the first segment, the shellis constricted by three longitudinal furrows
along AL and AD where they are in the shell.
The first segment is bell-shaped and its surface
is smooth without spines, pores are absent in

477

most specimens. When pores are present,
they are circular and very small. Threebladed apical horn is very stout. The ventral
horn extends horizontally, shorter and narrower than the apical horn. In some specimens, A has a pair of distinct trigonal or
spiny lateral projections on its middle part.
D has a pair of trigonal lateral projections.
Axial projection is distinct. The second segment is composed of a porous wall with teeth
around its distal end. Dorsal and lateral ribs
are distinct. Three feet, which extend fromdorsal and lateral ribs, are three- or fourbladed and well-developed. They almost
equal in length the height of the first segment.
Dimensions.-Measurements are based onnine specimens. The maximum diameter ofthe first segment is 50-78 (64) j.lm, of thesecond segment 56-88 (77) j.lm. Total heightof the shell (not including apical horn anddistal feet) is 57-82 (71) j.lm.
Remarks.- This species resembles Euscenium tricolpium Haeckel, 1887, and Euscenarium tricolpium (Haeckel) in Petrushevskaya (197Ib) but differs from them by thedorsal side of the first segment. In Euscenium tricolpium and Euscenarium
tricolpium, the dorsal side of the first segment
is composed of little, narrow bars interconnected but in this species that part is composed of a robust wall with a few small pores.
Occurrences.-90 I 02405, 90 I 02414,
91092601, Yd-53, 59, Atc-4 and 14. Rare tovery rare in abundance.
Stratigraphic range.-In the Atsunai Coastroute, this species occurs in the Thalassiosira
oestrupii Zone and the upper limit is notconfirmed. The lower limit is in the Thalassionema schraderi Zone.

Euscenarium (?) sp.
Figure 15, 2a-2b

Description.- The first segment is hemispherical, and its shell is robust. Pores in thefirst segment are circular to subcircular, randomly arranged and variable in size. The

478

Satoshi Funakawa

apical horn is three-bladed and smaller inlength than the height of the first segment. V
extends horizontally to a ventral horn that is
unbladed and generally poorly developed,
and which is shorter than the apical horn. D
has a pair of lateral projections and A has apair of trigonal or spiny lateral projections
and a dorsal projection. AD is recognizeddistinctly only near the junction from A.
Axial projection is distinct. The second segment is poorly developed, truncated conicalto subcylindrical with dorsal and lateral ribs.
Pores in the second segment are circular to
subcircular, randomly arranged and equal insize to those in the first segment. Three longfeet are three-bladed and generally theirlength is larger than the diameter of the second segment. The height of the second segment is less than that of the first segment, andits diameter is 1.5 times that of the first segment.
Dimensions.-Measurements are based on
only two specimens. The maximum diameter of the first segment is 75-77 pm, of thesecond segment 54-62 pm. Total height ofthe shell (not including apical horn and distalfeet) is 107-135 pm.
Remarks.- This species is distinguishedfrom Pseudodictyophimus gracilipes andTripodocyrtis elegans by the furrows along
DL and VL and an internal ring formed by
DL and VL. It is distinguished from Euscenarium sp. aff. E. tricolpium by its porous
first segment. The generic assignment of thisspecies is questionable because three furrows
along AL and AD on the first segment areabsent (see the description of Euscenarium in
Haeckel, 1887, p. 1146). In this study, thisspecies is included in Euscenarium because of
the similarity of the internal skeletal structure
between this species and Euscenarium sp. aff.
E. tricolpium. Further study is needed toconfirm the generic assignment of this species.
Occurrences.-Only Ny-81. Very rare inabundance.
Stratigraphic range.-Denticulopsis katayamae Zone.

Subfamily Sethoperinae Haeckel,
emend. Petrushevskaya, 1971 a
Genus Clathrocorys Haeckel, 1881

Type species: Clathrocorys Haeckel, 1887.
Clathrocorys (?) sp.
Figure 15, 3a-3b
Clathocorys sp.; Nakaseko and Nishimura, 1982, pI.
49, fig. 4.

Description.- The skeleton is composed oftwo segments. Internal skeletal structure
consists of MB, A, D, L, V, AL, AD, DL and
LL. V extends obliquely upward and protrudes outside as the ventral horn at the lower
part of the first segment. VL is absent. The
first segment is large, hemispherical and distinguished from the second segment by distinct furrows along DL and LL, and by awell-developed internal ring formed by thesearches. The shell of the first segment isrobust with fine spines. Three-bladed apicalhorn is stout and extends directly from A at
the apex of the first segment. The ventral
horn is very poorly developed and recognized
only as a fine spine. Parts of AD and AL arealmost in the shell. Three ribs located on
the outside of the first segment along AL and
AD connect the apical horn and the three feet.
In the first segment, pores are very small or
absent. The second segment is composed ofa latticed wall, pyramidal and triangular inhorizontal section with three distinct dorsal
and lateral ribs. Pores in the second segment
are subcircular to irregular in shape and randomly arranged.
Dimensions.-Measurements are based onseven specimens. The maximum diameter ofthe first segment is 57-72 (63) pm, of thesecond segment 80-240 (143) pm. The maximum height of the first segment is 41-52 (47)pm, total height of the shell 60-224 (122) pm.
Remarks.- The generic assignment is questionable because the species differs in external

971.

Radiolaria from the Upper Miocene of Hokkaido

479

Figure 15. la, Ib: Euscenarillm sp. afT. E. trico/pium (Haeckel) , 9109260 I. I a: left lateral view ;I b: basal view. Arrow I of I a points to the furro w a long DL, 2 to the furrow along AL, 3 to the ventral
horn, I of I b to the projection s of D and 2 to the projection of A. 2a, 2b: Euscenarillm (?) sp., Ny-81.
2a: dorsal view; 2b: enlargement of basal view. Arrow of 2a points to the projection of A. 3a, 3b :C/athrocorys (?) sp., 90102414. 3a: ventral to right lateral view ; 3b: enlargement of basal view.
Arrows of 3a point to ribs along AL. Scale bars: l a,2a and 3a = 50,um; others=20 ,um.

form from the type species, C. murrayi, theinternal skeletal struture of which is unknown. In this paper, the generic name,Clathrocorys, is used for this species following Haeckel (\887). The second segment of
this species tends to be broken, so the diameter and height of the second segment are very
unreliable. This species is distinguishedfrom Euscenarium (?) sp. by the three distinct
external ribs on the first segment.
Occurrences. - 90 I 02405, 90 I 02414, Y d-53

and AtcA.

Rare to very rare in abundance.

Stratigraphic range. - In the Atsunai Coastroute, this species occurs in the Thalassiosira
oestrupii Zone and the upper limit is notconfirmed .

The

lower

limit

IS

In

the

Neodenticula kamtschatica Zone
Discussion
The constant internal skeletal elements at
the generic level are MB, A, L, D, AL, VL,480

Satoshi Funakawa(LL), DL and AL-AL. Detailed observationof the internal skeletal structures of
Plagiacanthidae makes the following clear.
Development of V is variable in some species.
Clathocorys (?) sp. has LL constantly but VL
are absent. When V is lacking, LL is constant in Lophophaeninae except for
Tripodocyrtis. Development of AD is alsovariable in some genera. Only two species,
Euscenarium sp. aff. E. tricolpium andClathrocorys (?) sp. have AD consistently,
other species have poorly developed AD recognized only as an indistinct skeletal element.
In some specimens included in Marimoum
robustum, I, AL, Ll, DI and VL-VL arepresent but they fall within the intraspecificvariation of this species as mentioned in theremarks on this species. V, AD, I, AI, Ll, DI
and VL-VL are therefore apparently not ofvalue for the suprageneric classification of
Plagiacanthidae.
The correlation between the internal andexternal skeletal structures is clarified. Connecting arches that are constant at the genericlevel control completely the boundary
between the first and second segments. This
indicates that the boundary between the twosegments is the most important criterion forsuprageneric taxonomy within the Plagiacanthidae.
In this study, the following three groups arerecognized in Plagiacanthidae (Figure 16),
characterized by the composition of connecting arches that form the boundary between
the two segments. The generic compositionof each group is also shown in Figure 16.
• Group 1 : Internal spicules are composedof MB, A, D and L. Connecting arches arecomposed only of AL. The boundary
between the two segments is restricted to theapical to lateral side of the shell, the furrows
are formed along AL. MB is situated inside
the second segment. This group ismonogeneric.
• Group 2: Internal spicules are composedof MB, A, D, L, and V. Connecting arches
are composed of AL and VL. The boundary

between the two segments completely encircles the shell, the furrows are formed along
VL or LL on the ventral side and along AL
on the apical to lateral side. MB is situatedinside the second segment. This group ispolygeneric.
• Group 3: Internal spicules are composedof MB, A, D, L, and V. Connecting arches
are composed of AL, LV (LL) and DL. The
boundary between the two segments completely encircles the shell. The furrows areformed along VL or LL at the ventral side
and along DL or AL and AL-AL at thedorsal side. MB is situated near the boundary of the first and second segments. This
group is polygeneric.
The correlation between these groups andsubfamilies of Petrushevskaya (1971 b) is thatall genera of groups 1 and 2 are included in
Lophophaeninae, while two genera of group
3 are in Clathromitrinae, one is in Sethoperinae and the other in Lophophaeninae (Figure 16).
These three groups in the present study are
effective to establish a phylogeneticclassification at the suprageneric (family andsubfamily) level. In this study, the following
two phylogenetic problems are pointed out.
Corythomelissa horrida has some skeletalsimilarties with Euscenarium and Clathrocorys, such as the absence of the apical rib
and the presence of the arches on the dorsalside of the shell. In the present study,
although differences exist in the internal
skeletal structure, in that' C. horrida has
AL-AL and the latter two have DL, thisspecies is included in group 3 based on theskeletal similarities am'ong these three taxa.
To explicate the group to which this species
belongs, study of the internal skeletal structures of its ancestral forms is needed.
Another problem concerns the taxonomic
complex formed by groups 2 and 3. The
inner layer of the first segment of Marimoum
gen. nov., which has DL, is similar to the first
segment of Peridium, which does not have
DL. Although they are included in different

GROUP 1
Arches subdividing two
segments

GROUP 2

GROUP 3,

only AL,DL and VL !AL, AL-AL and VL: DL and VL

AL and VL or AL and LL~

rtJDL and LL

flAL_~LrtJ

AL~t-9 ~b:~ ~~ ~ \"
~
IE]

I""",

z
Apical viewyLeft lateral view

L

~
y

II

LL

LL

r

~V~L

'"

~~L~~

~~

~ U"l'
cY j: rfI .Jj\L-'~a\~{!+~ ~
I
I
Tripodocyrtis~~~

Amphiplecta

Peridium

Ceratocyrtis
Lophophaena
Pseuedodictyophimus

Subfamilies ofPetrushevskaya(1971b)~~~tfiQ~V\~~y \\e W!J ~L

VLAL

Composition of internal
MB, A, D, V, L; AL and VL (LL instead of VL
skeletal elements
MB, A, D, L; AL when V lacks)

Generic
composition'0.

Lophophaeninae

~L ~

ffI\

VL

~
LL

MB, A, D, V, L; AL and VL.. _.... -.... __ .... __ .... ,. .... _.. -........ _............
_...... -, --_ ...................... ----,. .. _...... --- .................... -.. ..
DL

;

AL-AL

: DL and AD?

: DL, LL and AD

Marimoum : Corythomelissa lEuscenarium ; Clathrocorys
,
,,
,
,
,
,,
,

Clathromitrinae

::tl

!:l

!:l..

is'

is''
....
is'
~

~

So

'"

~

~

~
is'

~
~

'"

~

~

;0;;0;-!:l§::Sethoperinae

Figure 16. Three groups of the Plagiacanthidae based on the composition of connecting arches that form the boundary between thefirst and second segments. Figures of Marimoum are for the holotype specimen of Marimoum robustum. In these figures, black indicatesconnecting arches, light gray internal spicules, and dark gray the shell wall. Composition of the internal skeletal elements, genericcompositions and correlation between these groups and the subfamilies of Petrushevskaya (1971 b) are shown.

00"""

Satoshi Funakawa

482

groups in this study, it is possible that they
are somewhat phylogenetically correlated
based on the skeletal similarity mentioned
above. On the other hand, two genera ofgroup 2, Ceratocyrtis and Pseudodictyoph im us, have different skeletal charactersfrom Peridium, for example, their small
hemispherical first gegment and welldeveloped second segment. These skeletal
differences indicate that the former two genera may differ in phylogeny from the latter
one, although their internal skeletal stucturesare similar. These taxonomic complexes
indicate that group 2 is polyphyletic, with
one of its memebers phylogenetically correlated with a member of group 3.
The skeletal structures of Plagiacanthidae
treated in this study are limited during thelate Miocene age. In order to elucidate theabove phylogenetic problems, it is necessary
to study them phylogenetically for a longer
time interval, for example, Paleogene to
Recent.
Acknowledgements

The author is grat.eful to Prof.
Toyosaburo Sakai of Utsunomiya University
for his discussions and many suggestions, toProf. Itaru Koizumi of Hokkaido University for his diatom identifications, to Prof.
Akira Yao of Osaka City University for his
many suggestions, to Dr. Atsushi Takemuraof Hyogo University of Teacher Education
for his advice, and to Dr. Chris Hollis of
Utsunomiya University for assistance withEnglish expression.
References
Bailey, J.W., 1856: Notice of microscopic forms
found in the sounding of the Sea of Kamtschatkawith a plate. A mer. Jour. Sci, Arts, ser. 2, vol.
22, no. 64, p. 1-6.
Bjprklund, K.R., 1976: Radiolaria from the Norwegian Sea, Leg 38 of the Deep Sea Drilling
Project. In, Talwani, M., Udintsev, G., et al.,
In it. Repts. DSDP, vol. 38, U.S. Govt. Printing

Office, Washington, D.e., p. 1101-1168, pis. 1-24.
Biitschli, 0., 1882: Beitrage zur Kenntnis derRadiolarien skelette, insbesonder der Cyrtida.
Zeitschr. Wiss. Zool., vol. 36, p. 485-540, pis. 3133.
Campbell, A.S., 1951: New genera and subgenera ofRadiolaria. Jour. Paleont., vol. 25, no. 47, p.
527-530.
Dumitrica, P., 1991: Middle Triassic Tripedurnulidae, n. fam. (Radiolaria) from the Eastern
Carpathians (Romania) and Vicentinian Alps
(Italy). Rev. Micropaleont., vol. 34, no. 4, p.
261-278, pis. 1-3.
Ehrenberg, e.G., 1838: Uber die Bildung derKreidefelsen und des Kreidemergels durch
unsichtbare Organismen. Kgl. Akad. Wiss.
Berlin, Abhandl., 1838, p. 59-147.
- - , 1847: Uber die mikroskopischen kieselschaligen Polycystinen als machtige Gebirgsmassevon Barbados und iiber das Verhaltniss der aus
mehr als 300 neuen Arten bestehenden ganz
eigenthiimlichen Formengruppe jener Felsmasse
zu den jetzt lebenden Thieren und zur Kreidebildung. Eine neue Anregung zur Erforschung desErdlebens. KgL Akad. Wiss. Berlin. Ber., Jahre
1847, p.40-60.
- - , 1875: Fortsetzung der mikrogeologischenStudien als Gesammlt-Uebersicht der mikroscopischen Palaontologie gleichartig analysirter
Gebirgsarten der Erde, mit specieller Rucksicht
auf den Polycystinen-Mergel von Barbados.
KgL Akad. Wiss. Berlin, AbhandL, Jahre 1875, p.
1-225.
Empson-Morin, K., 1981: Campanian Radiolaria
from DSDP Site 313, Mid-Pacific Mountains.
Micropaleontology, vol. 27, no. 3, p.249-292.
Funakawa, S., 1993: Late Miocene radiolarian fossils from eastern Hokkado, Japan. News ofOsaka Micropaleont., Spec. Vol., no. 9., p.293311, pis. 1-2. (in Japanese with English abstract)
Haeckel, E., 1881: Entwurf eines RadiolarienSystems auf Grund von Studien Challenger
Radiolarien. Jenaische Zeitschr. Naturwiss.,
vol. 15, p.418-472. .
- - , 1887: Report on the Radiolaria collected by H.
M.S. Challenger during the years 1873-1876.
Rept. Voyage Challenger, Zool., vol. 18, p. iclxxxviii, 1-1803, pis. 1-140, I map.
Hertwig, R., 1879: Der Organismus der Radiolarien.
p. I-IV, 1-149, pis. 1-10.
Koizumi, I., 1985: Diatom biochronology for thelate Cenozoic northwest Japan. Jour. GeoL Soc.
Japan, vol. 91, no. 3, p. 195-211.
Jprgensen, E., 1905: The protist plankton and thediatoms in bottom samples. Bergens Mus. Skr.,
1905, p.49-151, 195-225, pis. 1-18.
Nakaseko, K. and Nishimura, A., 1982: Radiolaria

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Radiolaria from the Upper Miocene of Hokkaido

from the bottom sediments of the Bellingshausen
Basin in the Antarctic Sea. Rept. Tech. ResearchCenter, Japan National Oil Corporation, no. 16,
p. 91-244, pIs. 1-66.
Nishimura, H., 1990: Taxonomic study on Cenozoic
Nassellaria (Radiolaria). Sci. Rept. Inst. Geosci., Univ. Tsukuba, sec. B, vol. II, p. 69-172.
Oda, M., 1986: Some aspects and problems concerned with microfossil biochronology for the
Neogene in Central and Northeast Honshu,
Japan. In, Nakagawa, H., Kotaka, T. and Takayanagi, Y. eds., Essays in Geol. (Kitamura
Commem. Vol.), p.297-312.
Petrushevskaya, M.G., 1968: Gomologii v skeletakh
radiolyarii Nassellaria. I. Osnovnye dugi v
semeistve Cyrtoidea. ZooL Zhurnal. vol. 47, no.
9, p. 1296-1310.
- - , 1971 a: On the natural system of PolycystineRadiolaria (Class Sarcodina). In, Farinacci, A.
ed., Proc. II Planktonic Conference, p. 981-992.
Tecnoscienza, Rome.
- - , 1971b: Radiolarii Nassellaria v planktone
Mirovogo Okeana. Issled. Fauny Morey,
Leningrad, Nauka, vol. 9, p.5-294.
- - , 1975: Cenozoic radiolarians of the Antarctic,
Leg 29, DSDP. In, Kennet, J.P., Houltz, R.E.,
et al., Init. Repts. DSDP, vol. 29, U.S. Govt.
Printing Office, Washington, D.C., p. 541-675,
pIs. 1-44.
- - , 1981: Radiolyarii otryada Nassellaria Mirovogo Okeana. Opredeliteli po Faune SSSR.
Izv. Zool. Inst. Akad. Nauk. SSSR, no. 128, p.
1-406.

483

Riedel, W.R., 1967: Class Actinopoda. In, Harland, W.B., et al. eds., The Fossil Record,
Geological Society of London, p. 291-298.
- - , 1971: Systematic classification of PolycystineRadiolaria. In, Funnel, B.M., and Riedl M.R.

eds., The Micropaleontology of the Ocean,
Cambridge University Press, p.649-661.
Sugiyama, K., 1993: Skeletal structures of Lower
and Middle Miocene lophophaenids (Radiolaria)
from central Japan. Trans. Proc. Palaeont. Soc.
Japan, N.S., no. 167, p.44-72.
Swanberg, N.R. and Bj¢rklund, K.R., 1987: The
precephalic development of the skeleton of Amphimelissa setosa (Actionopoda: Nassellarida).
Marine Micropaleont., vol. II, p.333-341, pI. I.
Tada, R. Iijima, A., 1986: Stratigraphy and geologyof the Neogene Atsunai Group of the Atsunai
and Urahoro areas in southeastern Hokkaido,
Northern Japan. Jour. Geol. Soc. Japan, vol.
92, no. I, p. 31-44 (in Japanese with English

abstract).
Takemura, A., 1986: Classification of Jurassic nassellarians (Radiolaria). Palaeontographica, Abt.
A, vol. 195, p. 29-74. pIs. 1-12.
Yamagishi, H., Oka, T. and Okamura, T., 1990:

Geomorphology and geology of southern Tokachi area. With Geological Sheet Map at scale
I : 50,000. Geol. Surv. Hokkaido, p. 1-71. (inJapanese with English abstract).
Yamaguchi, S. and Satoh, H., 1989: Geology of the
Nukanai district. With Geological Sheet Map
at scale I: 50,000.

Geol. Surv. Japan, p. 1-78

(in Japanese with English abstract).

Hokkaido ~U/ljj]!, Taiki ::kW, Toyokoro :i:g;[, Chokubetsu @:55U, Astunai ~p;j, Shiranuka
B*l, Oikamanai §::'~EE, Yudou ooi\iiJ, Noyaushi / -V '7 V, Ishii-zawa E#iR.
~t)fijm]lum, J:.$~tIT~iJ' ~ imtfft ~ Plagiacanthidae H: ~tffljj]!*$I;: :5t:ffi'T .0 1:.$
CPfi*1tO)~lIffV}v r :'6iJ' t;, f:t, *1'¥O) ~tzTt:t:lb1&$.1t;EiJ~:g,.j£:T.o 0 Plagiacanthidae f4
f:t:lb1&$.1t;EtfJtO)±~1lIJRlGfi~lll·~ t), 2 fi~ 6 fifi~~tJ 10 ~ 16 fiH1I\l55U lA.:o 1~ t;,nt.:@li*O)p;j$1f~O)~$t:tl!l~iJ' t;" fip;jl'~1t;T.o p;j$1f~~ff, fiv-"'.}v:JO J: rJ~
V-"'.}vl'3CJE C: t:t.o p;j$1f~~ff H1I\l55U l t.:o ~ V-"'.}vl'3CJE C: t:t.o p;j$1f~~fff:t, ~J: t) jl§ij*O):5t~HT-? 1:.-C·;;}Fm-h:1i3tJJl'~.o o ~ 0) -?"/?, @li*O) first segment C: second
segment ~ IR55UT.o connecting arch 0)1lIJRlGf:t, Plagiacanthidae f40)~rt~ ~millUT.o:ll5i tJ!I!
~ t:t~*l' ~ .0 0 ;;$:jjjfJl;l' f:t, ~ 0) connecting arch 0)1lIJRlG 1;:£-:1(" -C Plagiacanthidae f4~ 3 :5t~tfl;:~55U l t.:o ~ t.:, ~ n t;, O):5t~tfl;::JO It.o **1t~B"Jt:tr",'Jj!jt~ ~1J)3 t;, iJ' I;: l t.:ofit" Im-Trans. Proc. Palaeont. Soc. Japan, N.S., No. 174, pp.484-494, 4 Figs., June 30, 1994

972. DISCOVERY OF MIDDLE PENNSYLVANIANFUSULINACEANS AND CONODONTS FROMTHE COPACABANA GROUP IN THE LAKE
TITICACA REGION, BOLIVIA *SUMIO SAKAGAMI
Department of Earth Sciences, Faculty of Science
Chiba University, Chiba, 263
and

YOSHIHIRO MIZUNO
Division of Environmental Science, Graduate School of Scienceand Technology, Chiba University, Chiba, 263

Abstract. Fusulinaceans and conodonts indicating the Atokan (early Middle Pennsylvanian) of North America are now discovered for the first time from the lower part of the
Copacabana Group which was previously considered Virgilian (latest Pennsylvanian) to
Leonardian (early Middle Permian) in age. The fusulinaceans, Profusulinella sp. indet. andProfusulinella munda Thompson, and conodonts, Diplognathodus orphanus (Merrill),
Idiognathodus delicatus Gunnell and Neognathodus medadultimus Merrill are describedand illustrated. These faunules may be included in the Midcontinent-Andean Province.
Key words. Profusulinella, Conodonts, Lake Titicaca region, Copacabana Group,
Middle Pennsylvanian.

schwagerina Zone in the Copacabana Group.
At the same time, they also noted that the"Triticites Zone" of the Copacabana Groupin the Cuyavi and Yampupata routes wasabnormally thicker than in the Yaurichambi,
Ancoraimes, and Matilde routes. During
our laboratory work, we discovered somefusulinaceans and conodonts indicating an
Atokan (Pennsylvanian) age for the"Triticites Zone" In the Cuyavi and
Yampupata routes.
Map of the study area around Lake
Titicaca is shown in Figure 1.

Introduction
Since 1980, Sakagami and his collaborators
have been working on a biostratigraphic
study of the Upper Paleozoic CopacabanaGroup in Central Andes. Three succeeding
fusulinacean zones, the Triticites Zone,
Pseudoschwagerina Zone and Eoparafusulina Zone, have been established in the
Copacabana Group around Lake Titicaca(Sakagami, ed., 1984, 1986). Furthermore,
after reviewing, revising and correlating thestratigraphic sections, Sakagami et al. (1991)
placed the boundary between the Carboniferous and Permian at the base of the Pseudo-

Acknowledgements'Received December 2, 1993; revised manuscript
accepted April 12, 1994

We would like to express our gratitude to
484

972.

Fusulinaceans and conodonts from Bolivia

485

Cu46b- Pro/lL>uL!1lP.Lla Ilunda Thompson

Ht

Cu46a { Pro/usuliJ1£Lla sp. indel.
Idzol/7ll1tlwdus del icalus Gunne II(::;:::r::;:::~- Cu43 -PER U

Idiol/7ll1tlwdus deLicatlL' Gunne II

I

Di/>lol/7ll1tlwdus OT/>htmus (Merr i I J)

F;::r::;::::}-- Cu39

Neol/7ll1tlwdus medadul timus lIerr i II

Idiol/7ll1tlwdus del icatus Gunne II

Figure 1.
Yampupata.

Location map showing Cuyavi and
I:::r:':::r:::f-- Cu32 - Di/>lol/7ll1tlwdus OT/>htmus OIerr i I J)

p::;:r::r-- Cu29 - idiol/7ll1thodus del icatus GunDe II

Professor Juichi Yanagida of Kyushu University, Mr. Tetsuya Kawabe of Chiba University, Kiyoshi Okamoto, former member of
JICA, and Mr. Raul Garcia D. of the Servicio
Geologico de Bolivia for their kind cooperation in the field and discussions.

iLegendGeological setting and age determination
In the Cuyavi route, the CopacabanaGroup overlies the Carboniferous Gondwana
Series with a slight angular-unconformity.
The Copacabana Group along this routeconsists mainly of limestone, marl, dolomite
and· mudstone-shale associated with sandstone and cherty rock. The thickness ismeasured as more than 380 m although theupper limit is not confirmed. The Carboniferous Atokan faunules described here arefound from the lower part of the group (Cu04
to Cu46b), which was previously considered
to be Virgilian (lower part of the Triticites
Zone) (see Figure 2).
The fusulinacean faunules are known fromthe Cu46a and Cu46b horizons. Profusulinella sp. indet. from the lower horizon(Cu46a) is similar to some species describedfrom midcontinental North America asmentioned in the description. Profusulinella
sp. indet. is also found in a float collectedaround the YplO horizon in the Yampupata~

LiEstone

III-.stone, Shale

Sandstone

40

Cull

{ Di/>lol/7ll1tlwdus OT/>htmus (llerr i I J)
Idiol/7ll1tlwdus del icatus GunDe II

30

I=i=""i"'t--- Cu04 -Idiol/7ll1thodus del icatus Gunne II

20

10

Figure 2. Columnar Section of the lower partof the Copacabana Group at Cuyavi route (Revised
from Sakagami, ed., 1986).

486

Sumio Sakagami and Yoshihiro Mizuno

route. Profusulinella munda from the upperhorizon (Cu46b) was originally reported
from the Middle Pennsylvanian of Texas(U .S.A.) by Thompson (1948). Accordingly,
these fusulinacean faunules may be includedin the Midcontinent-Andean Province.
The conodonts are known from the Cu04,
Cull, Cu29, Cu32, Cu39, Cu43, and Cu46a
horizons in the Cuyavi route. Idiognathodus delicatus Gunnell is found from theCu04, Cull, Cu29, Cu39, Cu43, and Cu46a
horizons, Diplognathodus orphan us (Merrill)from the Cu II, Cu32, and Cu39 horizons, andNeognathodus medadultimus Merrill fromthe Cu39 horizon (see Figure 2).
Idiognathodus delicatus has been reported
from the late Morrowan to early Virgilian
Series of the U.S.A. (Gunnell, 1931; Ellison,
1941 ; Webster, 1969; von Bitter, 1972;
Baesemann, 1973; Manger and Sutherland,1984), the Lower Pennsylvanian of Colombia(Stibane, 1967), and the Middle Carboniferous of Japan (Koike, 1967; Igo, 1974) andEurope (Boogaard and Bless, 1985).
Diplognathodus orphan us was reported
from the early to late Atokan Series in the
U.S.A. (Merrill, 1973; 'Grayson, 1984;
Grubbs, 1984; Manger and Sutherland,1984), and from the Middle Carboniferous ofJapan (Igo, 1974) and Europe (Boogaard andBless, 1985).
Neognathodus medadultimus was reported
from the early Atokan to middle Desmoinesian Series in the U.S.A. (Murray andChronic, 1965; Merrill, 1972; Grubbs, 1984;
Manger and Sutherland, 1984) and from theLower Pennsylvanian of Colombia (Stibane,1967).
Manger and Sutherland (1984) reported
Morrowan-Atokan conodont faunas from the
Marble Falls Limestone in the eastern Llano
region of Texas (U.S.A.). They stated that
Idiognathodus delicatus, Diplognathodus orphanus and Neognathodus medadultimus

were found in association from a horizon
slightly below the Profusulinella horizon of
middle Atokan age.
In view of the above facts and data, it isundoubtedly certain that the middle Atokanof the Pennsylvanian System is present in thelower part of the Copacabana Group distributed in the Lake Titicaca region, although
the boundary between the Profusulinellabearing Zone (Atokan) and the upper
Triticites-bearing Zone (Virgilian) is still
obscure.
Repository: All specimens treated in thepresent study will be registered in the Collections of the Department of Earth Sciences,
Faculty of Science, Chiba University, Japan.
Descriptions of fusulinaceans
and conodonts
1.

Fusulinaceans

Genus Profusulinella Rauzer-Chernousova& Belyaev, 1936
Profusulinella sp. indet.
Figures 3-1-7

Shell minute, rather loosely coiled andellipsoidal with straight axis of coiling.
Mature shell attains 5 volutions, the length
and width are 1.1 to 1.5 mm and 0.6 to 0.9mm, respectively, giving form ratios 1.6 to 2.0.
Proloculus spherical, its average diameter is
0.085 mm. Average radi us vectors of the firstto fifth volutions of 7 specimens 0.079,
0.132, 0.201,0.311 and 0.421 mm, respectively.
Average ratios of the half-length to radius
vector of the first to fifth vol utions in 5 specimens 1.1, 1.3, 1.5, 1.7, and 1.7, respectively.
Spirotheca is composed of a tectum andupper and lower tectoria, gradually thickened
from inner to outer volutions except for thelast volution. Average thickness of spirotheca of the first to fifth volutions of 6 specimens 0.011, 0.013, 0.018, 0.020 and 0.019,
respectively. In most parts of the shell, septa~
Figure 3. 1-7. Profusulinella sp. indet., x 20 except for 5b (x 30) which is the enlarged photographof Sa. 8-26. Profusulinella munda Thompson, X 20 except for 22b (x 100) which is the enlarged part of
22a. The specimen numbers are indicated in Tables I and 2.

972.

Fusulinaceans and conodonts from Bolivia

:"

.~. ;

•
.

,. ,.'
.~

~

-

.

.~~

. '

...",· 6

487

488

Sumio Sakagami and Yoshihiro Mizuno

are more or less the same thickness as spirotheca. They are almost plane in the median
portion but become fluted only in axial
regions. Average septal counts of the first to
fourth volutions of 2 specimens 10, 13, 16 and19, respectively. Chomata about half as highas the chambers, asymmetrical, tunnel sides
are steep but polewards slopes are low.
A verage tunnel angles of second to fourth
volutions of 5 specimens 21,33,36 and 43
degrees, respectively.
Remarks: -The present form resembles
Profusulinella marblensis Thompson (1947),
which was originally described from theupper part of the Marble Falls Limestone on
the east side of the Llano Uplift of Texas(U.S.A.) in essential characters except for theshell form; the form ratio in the latter is
1.3 instead of 1.6 to 2.0 in the former. The
present form is also not unlike Profusulinella
copiosa Thompson (1948), which was originally described from the lower Middle Pennsylvanian rocks in Powwow Canyon of
Texas, in essential characters but the latter hasa more rounded shell form and larger
pro loculus. The present form is most similar
to Profusulinella fittsi (Thompson), describedfrom the lower part of the Atoka Formationof Oklahoma by Thompson (1935), in sizeand general shape except for the somewhat
smaller proloculus and much wider chomata
of the latter species.
Occurrence: -Rare in Cu46a horizon of
the Copacabana Group in the Cuyavi route,and also in a float collected from Yp 10 horizon in the Yampupata route.
Specimen nos: -DESC-94001a, 94001b,
94001c, 94002a from Cuyavi; DESC-94003a,
94003b, 94004a from Yampupata.

Profusulinella munda Thompson 1948
Figures 3-8-26

Profusulinella munda Thompson, 1948, p. 82, 83, pI.
27, fig. 4; pI. 30, figs. 1-7.

Shell small and inflated fusiform withstraight axis of coiling. Mature shell attains
6 volutions, the length and width are 1.8 to
2.4 mm and 1.0 to 1.5 mm, respectively, giving
form ratios 1.6 to 2.0. First to second volutions ellipsoidal to discoidal, but the outer
volutions become inflated fusiform.
Proloculus spherical and minute, its outside
diameter is 0.09 to 0.13 mm, averaging 0.11mm, that is rather large for the shell size.
Shell rather loosely coiled. Average radius
vectors of the first to sixth volutions of 19
specimens 0.098, 0.166, 0.258, 0.388, 0.481 and
0.712 mm, respectively. Average ratios of thehalf-length to radius vector of the first to sixth
volutions in 14 specimens are l.l, 1.3, 1.3, 1.6,
1.7 and 1.8, respectively.
Spirotheca composed of a tectum andupper and lower tectoria, gradually thickened
from inner to outer volutions except for thelast volution. Average thickness of spirotheca of the first to sixth volutions of 19 specimens are 0.014, O.oI8, 0.023, 0.032, 0.031 and
0.027 mm, respectively. Septa in most partsof the shell have the same thickness as the
spiro theca. They are almost plane in the
median portion but become fluted only inaxial regions. A verage septal counts of thefirst to fifth volutions of 4 specimens 8, 16, 19,
22 and 28, respectively. Chomata about
one-third to half as high as the chambers,
tunnel sides steep but polewards slopes arelow. Average tunnel angles of second tosixth volutions of 13 specimens 21,23,28,35
and 38 degrees, respectively.
Remarks: -The present form quite agrees
with Profusulinella munda Thompson, which
was originally described from the upper partof the Green Canyon Group (lower Middle
Pennsylvanian) in Texas (U.S.A.) by Thompson (1948), in essential characters. The present form can be easily distinguished from
Profusulinella manuensis Roberts (in Newell
et al., 1953), which was described from theAlto Rio Manu of Peru, by its shell size andother characteristics. The present form canalso be distinguished from the abovedescribed Profusulinella sp. indet. by larger

972.

Fusulinaceans and conodonts from Bolivia

489

Figure 4. 1,2. Diplognathodus orphanus (Merrill), la, lb : lateral and upper views, respectively,
Reg. no . DESC-94016, 2a, 2b: lateral and upper views, respectively, Reg. no. DESC-94020. 3- 5.
Idiognathodus delicatus Gunnell , upper views, Reg. nos. DESC-94023, 94026, 94022, respectively. 6,7.
Neognathodus medadultimus Merrill , upper views, Reg. nos. DESC-94029, 94030, respectively. All
figures are in X 60.

shell size.

Occurrence: -Abundant from Cu46b
horizon in the Copacabana Group , Cuyaviroute.
Specimen nos: -DESC-94005a, 94005b,
94006a, 94006b, 94006c, 94006d, 94007a,
94007b, 94008a, 94009a, 94009b, 940 lOa,
940 lOb, 940 II a, 940 II b, 94012a, 94013a,
94014a, 94015a.
2.

Conodonts

Genus Diplognathodus Kozur & Merrill ,1975

Diplognathodus orphan us(Merrill, 1973)
Figures 4- 1, 2

Spathognathodus orphan us Merrill , 1973, p. 309, pI.
3, figs. 45 - 56; Jgo , 1974, p. 235, pI. 2, figs. 10- 13.

Diplognathodus coloradoensis (Murray & Chronic);
Landing and Wardlaw, (part), 1981 , pI. I, figs. I,
6, 7, 9, 10, [ not figs. 4, 5, 8 = Diplognathodus

coloradoensis (Murray & Chronic) ] ; Savage andBarkeley, 1985, p. 1473, figs. 12 (9 - 16).
Diplognathodus orphanus (Merrill) ; Grayson, 1984,
p. 48, pI. I, fig. 6, pI. 2, figs. 24, 25; Grubbs, 1984,
p. 69, pI. I, figs. 3, 4 ; Manger and Sutherland,
1984, pI. I, fig. 4; Boogaad and Bless, 1985, p.
145, fig. 6 ( 1- 4) .

Platform narrow and smooth . Blade-likecarina passes through the center of the platform , 5 or 6 nodes present on it. Free blade
thi n, possesses 6 denticles. Anterior denticle
is shorter than the others. Two low nodes
present between free blade and carina. Free
blade almost twice as high as carina in lateralview.

Remarks : -Diplognathodusorphanus

resembles Diplognathodus coloradoensis(Murray & Chronic), but can be easily distinguished by the character of the carina; it isdenticulate in the former but relatively nondenticulate with a smooth ridge in the latter.

.j>.

Table 1.

'"oMeasurements of Profusulinella sp. indet. (in mm)
Half LengthReg. no.

FigureLenght

Width

F.R.

D.P.
2

I

3

4

5
0.768

I

D ESC-9400 I a

3-1

1.4

0.8

1.8

?

?

0.128

0.218

0.550

2

D ESC-9400 I b

3-2

1.2

0.6

2.0

0.08

0.077

0.192

0.320

0.576

3

DESC-94001c

3-3

4

DESC-94002a

3-4

1.I

0.7

1.6

0.07

0.064

0.179

0.269

0.397

0.525

5

DESC-94003a

3-5a, b

1.5

0.9

I.7

0.09

0.102

0.205

0.384

0.666

0.900

6

DESC-94003b

3-6

7

DESC-94004a

3-7

0.6

?

'0.7
1.4

V)

0.09

0.7

2.0

;;::

0.09

Radius Vector

0.090

0.167

0.282

Ratio of HljRv

I

2

3

4

5

I

2

3

4

5

I

0.064

0.115

0.179

0.269

0.431

?

1.I

1.2

2.0

1.8

2

0.090

0.154

0.230

0.333

0.9

1.3

1.4

I.7

0.077

0.141

0.218

0.385

0.064

0.102

0.179

0.256

0.385

1.0

1.8

1.5

1.6

1.4

5

0.090

0.154

0.243

0.371

0.525

1.1

1.3

1.6

1.8

I.7

6

0.090

0.141

0.192

0.307

0.481

7

0.077

0.115

0.167

0.256

0.333

1.2

1.5

I.7

I.7

2.1

5

2

0.022

25

30

32

19

41

46

I

?

0.013

0.016

0.016

0.010

0.013

0.016

0.016

3

4

5

3

?

?

?

0.026

4

0.016

0.013

0.016

0.016

0.016

21

30

41

?

30

35

40

24

45

5

0.010

0.016

0.022

0.022

0.019

6

0.013

0.013

0.019

0.022

0.019

7

0.010

0.010

F.R.: Form ratio.

0.016

~
;0;~!::)

-.

;::

0.019

D.P.: Diamater of proloculus.

?

?

~

~

s:.
~"

~

Septal Count (degrees)

Tunnel Angle (degrees)

4

2

o·

~

Thickness of Spirotheca
3

;::

;::

3

2

0.704

'!::)

4

I

0.431

I

2

3

4

?

12

15

17

10

14

17

21

N"

5

?

;;::
;::

c

972.

Fusulinaceans and conodonts from Bolivia

491

On the basis of paleontological study of theupper Marble Falls Limestone of Texas(U.S.A.), Manger and Sutherland (1984) reported that the first appearance of Diplognathodus orphanus was earlier than that of Diplognathodus coloradoensis.
Occurrence: -One specimen from Cu 11,
three specimens from Cu32, and two specimens from Cu39 horizons, in the CopacabanaGroup, Cuyavi route.
Specimen nos: -DESC-94016 from
Cull; DESC-94017, 94018, 94019 from
Cu32; DESC-94020, 94021 from Cu39.

every respect.
Occurrence: -Two specimens from Cu04
and one specimen from Cu 11, Cu29, Cu39,
Cu43 and Cu46a in the Copacabana Group,
Cuyavi route.
Specimen nos: -DESC-94022, 94023 from
Cu04; DESC-94024, 94025, 94026, 94027 and
94028 from Cull, Cu29, Cu39, Cu43 andCu46a, respectively,

Genus Idiognathodus Gunnell, 1931
Idiognathodus delicatus Gunnell, 1931

Figures 4-6, 7

Figures 4-3-5

Idiognathodus delicatus Gunnell, 1931, p. 250, pI. 29,
figs. 23-25; Ellison, 1941, p. 134, 135, pI. 22, figs.
31-36; Ellison and Graves, 1941, pI. 3, figs. 20,
23; Koike, 1967, p. 304, 305, pI. 2, figs. 18-23;
Webster, 1969, p. 35-37, pI. 6, figs. 6-12; Thompson, 1970, p. 1046, pI. 139, figs. 24, 29; Merrill
and King, 1971, pI. 76, figs. 13-22; von Bitter,
1972, p.58, pI. 3, fig. 4; Baesemann, 1973, p.
699-700, pI. I, figs. 18, 19,23,24; Igo, 1974, p.
234, pI. I, figs. 1-9; Landing and Wardlaw,
1981, p. 1260, pI. 2, figs. 1-5; Grayson, 1984, p.
49, pI. I, figs. 1,2,12, pI. 3, figs. 2, 3, 5, 6, 21, 23,
25, pI. 4, figs. 1,6-8,17,24; Grubbs, 1984, p. 69,
pI. I, figs. 5-7; Manger and Sutherland, 1984, pI.
I, figs. 16, 17,; Boogaad and Bless, 1985, p. 146,
figs. 7(1-9), 9(8); Savage and Barkeley, 1985, p.
1464-1466, figs. 8.1-8.4; Wang, Lane, and Manger, 1987, p. 128-129, pI. 4, figs. 4-8.

Platform in upper view long, lanceolate,tapers posteriorly and ornamented by 6 to 10
parallel transverse ridges.
Accessory lobes containing 3 or more nodelike ridges which are parallel with carina arepresent on both sides of anterior portion of
platform. In larger specimens, accessory
lobes on both sides of carina are developed
into many smaller nodes.
Remarks: -Boogaad and Bless (1985)
documented the ontogenetic development of
Idiognathodus delicatus. The present specimens agree with their growth stage forms in

Genus Neognathodus Dunn, 1970
Neognathodus medadultimus
Merrill, 1972

Gnathodus roundyi Gunnell; Murray & Chronic(part), 1965, p.598, pI. I, figs. 1,2 only.
Streptognathodus colombiensis Stibane, 1967, (part),
p. 335-336, pI. 36, figs. 3-5 only.
Neognathodus medadultimus Merrill, 1972, p.824825, pI. I, figs. 2-7; pI. 2, fig. 19; Grubbs, 1984,
p. 71, pI. 3, fig. 3,4, 10- I3; Manger and Sutherland, 1984, pI. I, figs. 13, 14.

Platform in upper view long, roughly lanceo late, and pointed posteriorly. A long andstraight blade develops from carina at theanterior portion of the platform. Carina
gradually bends toward the posterior andfuses on the outer parapet at two-thirds lengthof the platform. Inner parapet, ornamented
with 9 or more node-like transverse ridges,
well developed and parallel with carina.
Remarks: -The degree of fusion of thecarina with the outer parapet is variable in
the present species. The present species
resembles Neognathodus medexultimus described originally by Merrill (1972) from thePottsville and Allegheny Groups (Atokan to
Desmoinesian) in eastern Ohio (U.S.A), but
can be distinguished from the latter by position of the fusion of outer parapet and carina.
The fusion in the present form occurs moreposteriorly. The present specimen is alsosimilar to Gnathodus kanumai (= Gnathodus cf. roundyi Koike, 1967, pI. 1, figs. 27,28), which was described by Igo (1974) fromthe Fusulinella biconica Zone of the Akiyoshi

Table 2.

Measurements of Profusulinella munda Thompson. (in mm)

Length

Width

~

IV

Half Length
FigureReg. no.
I
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

3- 8
3- 9
3-10
3-11
3-12
3-13
3-14
3-15
3-16
3-17
3-18
3-19
3-20
3-21
3-22a, b
3-23
3-24
3-25
3-26

DESC-94005a
DESC-94005b
DESC-94006a
DESC-94006b
DESC-94006c
DESC-94006d
DESC-94007a
DESC-94007b
DESC-94008a
DESC-94009a
DESC-94009b
DESC-940lOa
DESC-940IOb
DESC-94011a
D ESC-940 \1 b
DESC-94012a
DESC-94013a
DESC-94014a
D ESC-940 15a

2.4
2.2
2.1
1.9
2.0
2.1
1.9
2.2
2.4
2.9
2.1
1.8
2.3
2.2

1.5
1.3
1.4
1.3
1.2
1.0
1.1
1.3
1.2
1.1
1.3
1.2
1.0
1.5
1.1
1.0
1.3
1.4
1.2

F.R.
1.6
1.6
1.6
1.6
1.8
1.8
1.7
1.7
2.0
1.9
1.9
1.8
1.8
1.8

D.P.
0.09
0.13
0.12
?
0.12
0.10
0.10
0.13
0.09
0.12
0.13
0.09
0.10
0.10
0.13
0.10
0.12
0.13
0.08

I

2

3

4

5

6

0.154

0.269

0.410

0.653

0.896

1.203

0.128
0.102
0.128

0.243
0.192
0.269

0.410
0.320
0.448

0.602
0.512
0.742

1.088
0.845
0.998

1.280
1.090

0.102

0.205

0.320

0.525

0.794

1.075

0.077
0.128
0.128
0.090

0.141
0.256
0.307
0.192

0.267
0.448
0.538
0.384

0.512
0.704
0.896
0.550

0.768
0.960
1.115
0.845

1.088

0.064
0.128
0.090
0.090

0.192
0.230
0.192
0.166

0.384
0.320
0.422
0.333

0.666
0.512
0.678
0.576

1.088
0.832
0.934
0.845

1.600
1.024

::s

1.216

~
~
;;:

0.090

0.179

0.320

0.576

0.883

1.152

~

~

1.216

2

3

4

5

6

1

2

3

4

5

6

0.090
0.102
0.102
0.090
0.102
0.102
0.090
0.128
0.090
0.115

0.192
0.154
0.179
0.154
0.179
0.167
0.141
0.218
0.141
0.192

0.295
0.256
0.282
0.240
0.269
0.256
0.230
0.320
0.205
0.282

0.431
0.384
0.448
0.358
0.410
0.384
0.320
0.461
0.320
0.431

0.527
0.525
0.627
0.512
0.563
0.563
0.431
0.589
0.486
0.602

0.806
0.704

1.7

1.4

1.3

1.5

1.7

1.5

1.3
1.1
1.3

1.4
1.2
1.5

1.5
1.3
1.6

1.3
1.4
1.8

1.7
1.6
1.7

1.1

1.5

1.4

1.6

1.8

1.8

0.9
1.1

1.0
1.3

1.3
1.6

1.6
1.6

1.5
1.6

1.6

0.614
?
0.666

~

-.
~

\::)

$:l..

a·
~
t:::;.

1

0.717

c·
;>:;-

Ratio of HI/R v

Radius Vector

1
2
3
4
5
6
7
8
9
10

~

I::

::s
c

II

0.115

0.205

0.307

0.448

0.640

12

0.077

0.128

0.192

0.320

0.448

13

0.102

0.167

0.294

0.461

0.538

14

0.077

0.154

0.256

0.397

0.550

15

0.115

0.166

0.243

0.358

0.499

16

0.077

0.141

0.230

0.346

0.499

17

0.102

0.166

0.243

0.358

0.525

0.704

18

0.102

0.166

0.282

0.397

0.576

0.806

19

0.090

0.141

0.218

0.346

0.499

0.678

1.1

1.5

1.8

2.0

1.7

0.640

1.2

1.5

2.0

1.7

1.9

1.9

0.781

0.8

1.2

1.5

1.7

2.0

2.0

1.1

1.4

1.3

1.4

1.7

Thickness of Spirotheca

1.2

1.4

1.8

2.0

1.9

0.9

1.0

1.4

1.6

1.6

1.7

1.0

1.3

1.5

1.7

1.7

1.7

Tunnel Angle (degrees)

Septal Count (degrees)

'0

~

~

I

2

3

4

5

6

2

3

4

5

6

I

0.024

0.024

0.026

0.029

0.032

0.032

?

?

?

?

?

2

0.013

0.019

0.026

0.032

0.029

0.029

3

0.019

0.019

0.022

0.035

0.026

19

19

22

37

42

20

20

28

23

28

""
I:l

20

20

28

31

32

I:l...

4

?

0.019

0.022

0.029

0.032

5

0.016

0.022

0.029

0.042

0.042

6

0.013

0.016

0.016

0.026

0.029

7

0.013

0.016

0.016

0.029

0.032

0.029

8

?

0.019

0.022

0.032

0.032

0.019

9

0.016

0.016

0.022

0.032

0.035

0.028

10

0.010

0.016

0.035

0.051

11

0.013

0.022

0.026

0.029

12

0.016

0.016

0.022

0.042

0.029

13

0.013

0.016

0.022

0.032

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494

Sumio Sakagami and Yoshihiro Mizuno

Limestone in Japan, but can be distinguishedfrom the latter by having a bent carina insteadof a straight one as in Gnathodus kanumai,
and by the less developed outer parapet.
Occurrence: -Three specimens from
Cu39 horizon in the Copacabana Group, in
the Cuyavi route.
Specimen nos: -DESC-94029, 94030,
94031.
References cited
Baesemann, J.F., 1973: Missourian (Upper Pennsylvanian) conodonts of northeastern Kansas.
Jour. Paleont., vol. 47, no. 4, p. 689-710, pis. 1-3.
Boogaard, M. van den and Bless, M.J.M., 1985:
Some conodont faunas from the Aegiranum
Marine Band. Proc. K. Nederlandse A cad.
Wetenschap, Ser. B., vol. 88, no. 2, p. 133-154.
Ellison, S., 1941: Revision of the Pennsylvanianconodonts. Jour. Paleont., vol. 15, no. 2, p.
197-143, pis. 20-23.
- - and Graves, R.W. Jr., 1941: Lower Pennsylvanian (Dimple Limestone) conodonts of theMarathon Region, Texas. Missouri Univ.
School Mines and Metallurgy, Tech. Ser., vol.
14, p. 1-13, pis. 1-3.
Grayson, R.C. Jr., 1984: Morrowan and Atokan(Pennsylvanian) conodonts from the Northeastern margin of the Arbuckle Mountains Southern
Oklahoma. In, Sutherland, P.K. and Manger,
W.L. ed., Atokan Series (Pennsylvanian) and its
Boundaries-A Symposium. Oklahoma Geol.
Surv. Bull. vol. 136, p. 41-63, pis. 1-4.
Grubbs, R.K., 1984: Conodont platform elementsfrom the Wapanucka and Atoka Formations(Morrowan-Atokan) of the Mill Creek Syncline
Central Arbuckle Mountains, Oklahoma. Ibid.,
vol. 136, p. 65-79, pis. 1-3.
Gunnel, F.H., 1931: Conodonts from the Fort Scott
Limestone of the Missouri. Jour. Paleont., vol.
5, no. 3, p. 244-252, pI. 29.
Igo, Hh., 1974: Some Upper Carboniferous
conodonts from the Akiyoshi Limestone, Southwest Japan. Bull. Tokyo Gakugei Univ. Ser.
IV, vol. 26, p.30-238. pis. 1,2.
Koike, T., 1967: A Carboniferous succession of theconodont faunas from the Atetsu Limestone inSouthwest Japan (Studies of the Asiaticconodonts, Part VI). Tokyo Kyoiku Daigaku
Sci. Rep., Sec. C. Geol. Min. and Geogr., vol. 9,
no. 93, p. 279-318, pis. 1-4.
Kozur, H., 1975: Beitrage zur Conodontenfauna desPerm. Geol. Palaont. Mitt. Innsbruck, vol. 5, p.

1-44, pis. 1-4. (in German with English abstract)
Landing, E. and Wardlaw, B.R., 1981: Atokan
conodonts from the Pennsylvanian outlier of theMichigan Basin. Jour. Paleont., vol. 55, no. 6, p.
1251-1269, pis. 1,2.
Manger, W.L. and Sutherland, P.K., 1984: Preliminary conodont biostratigraphy of the MorrowanAtokan boundary (Pennsylvanian), Eastern
LIano Uplift, Central Texas. In, Sutherland,
P.K. and Manger, W.L. ed., Atokan Series (Pennsylvanian) and its Boundaries -A Symposium.
Oklahoma Geol. Surv. Bull., vol. 136, p. 115-119,
pI. I.
Merrill, G.K., 1972: Taxonomy, Phylogeny, andBiostratigraphy of Neognathodus in Appalachian Pennsylvanian rocks. Jour. Paleont., vol.
46, no. 6, p. 817-829, pis. I, 2.
- - , 1973: Pennsylvanian nonplatform conodont
genera, I: Spathognathodus. Ibid., vol. 47, no. 2,
p. 289-314, pis. 1-3.
- - . and King, C.W., 1971: Platform conodontsfrom the lowest Pennsylvanian rocks of theNorthwestern Illinois. Ibid., vol. 45, p. 645-664,
pis. 75, 76.
Murray, F.N. and Chronic, J., 1965: Pennsylvanianconodonts and other fossils from insoluble residues of the Minturn Formation (Desmoinesian),Colorado. Ibid., vol. 39, no. 4, p. 594-610, pis.
71-73.
Newell, N.D., Chronic, J. and Roberts, T.G., 1953:
Upper Paleozoic of Peru. Geol. Soc. A mer.,
Mem., no. 58, 276 p., 43 pis.
Sakagami, S., ed., 1984: Biostratigraphic study of
Paleozoic and Mesozoic Groups in Central
Andes - A n Interim report -. 82 p. (incl. 25pis.), Dept. Earth Sci., Chiba Univ.
- - , 1986: Ditto. - An Interim report (2)-.
i-vii +83 p., Ibid.
- - , Yanagida, J., Kawabe, T., Mizuno, Y.,
Okamoto, K., Garcia, R., Rangel, C. and Aldana,M., 1991: Paleontological analysis on Late
Paleozoic Era in Central Andes - Report onfield work in 1990. Jour. Geogr. (Tokyo), vol.
100, no. 3, p. 433-443. (in Japanese with English
abstract)
Savage, N.M. and Barkeley, S.1., 1985: Early to
Middle Pennsylvanian conodonts from theKlawak Formation and the Ladrones Limestone,
Southeastern Alaska. Jour. Paleont., vol. 59,
no. 6, p. 1451-1475.
Stibane, F.R., 1967: Conodonten des Karbons aus
den nordlichen Anden Slidamerikas. N. Jb.
Geol. Palaont., Abh., vol. 128, p.329-340, pis.
35-37.(in German with English abstract)
Thompson, M.L., 1935: Fusulinids from the lower
Pennsylvanian Atoka and Boggy Formations ofOklahoma. Jour. Paleont., vol. 9, no. 4, p.291-

972.

Fusulinaceans and conodonts from Bolivia

306, pI. 26.
- - , 1947: Stratigraphy and fusulinids of PreDesmoinesian Pennsylvanian rocks, Llano Uplift, Texas. Ibid., vol. 21, no. 2, p.47-164, pis.
31-33.
- - , 1948: Studies of American fusulinids. Univ.
Kansas Paleont. Contr., no.4 (Protozoa, art. I),
p. 1-184, pis. 1-38.
Thompson, T.L., 1970: Lower Pennsylvanianconodonts from McDonald County, Missouri.
Jour. Paleont., vol. 44, no. 6, p. 1041-1048, pI.
139.
von Bitter, P.H., 1972: Environmental control of
conodont distribution in the Shawnee Group(U pper Pennsylvanian) of Eastern Kansas.
Univ. Kansas Paleont. Contr., no. 59, p. 1-105,
pis. 1-16.
Wang, Z.H., Lane, H.R. and Manger, W.L., 1987:
Carboniferous and early Permian conodont zonation of north and northwest China. Cour.
Forschungsinst. Senckenberg, no. 98, p. 119-158,
pis. 1-8.
Webster, G.D., 1969: Chester through Derry
conodonts and stratigraphy of northern Clark
and southern Lincoln Counties, Nevada. Univ.
California PubL GeoL Sci., vol. 79, p. 1-121, pis.
1-8.

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t ::J / t: / r O)~~: ::. n L" Virgilian (<< ~ V }v r')' 7'::' 7 *clft~WD tl'i? Leonardian* *n(<<}v.b.*cI:j:lMiN~)
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496

ANNOUNCEMENTNew Journal Format
As one of the prime activities commemorating the 60th anniversary of the foundation of
the Palaeontological Society of Japan, theCouncil of the Society has voted to change
the format of the society's non-Japanese language publication, the Transactions andProceedings of the Palaeontological Societyof Japan, to a page size of 215 X 280 mm,
beginning with the April 1995 issue. Coincident with this size change, the journal will
have a new look, be given a new title and newcover design, and it will adopt a volume andnumber system with annual volume consisting of quarterly issues. The new journal title
is being carefully considered, so that it willreflect the Society's desire to make it a truly
international journal dedicated to the dissemination of fundamental knowledge on all
aspects of palaeontological research.

The new cover design should make thisjournal more eye-catching amongst rows ofscientific journals on the library book shelves,
thereby attracting the attention of prospective
readers. The new format should enable thepublication of more papers each year andallow for more variety in presentation of thecontents.
The most important change caused by the
new journal format concerns the illustrations.
Figures will be published at a page size of
172 X 230 mm, double column width of 170
mm, or single column width of 85 mm. Asof this date, all figures in submitted manuscripts must conform to the new journal format. Although the change may inconvenience some authors who are in the process of
preparing manuscripts for this jounal, theEditor will make every effort to make thistransition as smooth as possible.
The Editors

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Transactions and Proceedings of the PalaeontologicalSociety of Japan

June 30, 1994

New Series No. 174

CONTENTS
TRANSACTIONS
968. Yukio Yanagisawa: Mediaria magna Yanagisawa, sp. nov., a new fossil
raphid diatom species useful for Middle Miocene diatom biostratigraphy .. 411
969. Yasufumi Iryu and Shinya Matsuda: Taxonomic studies of the Neogoniolithon josliei complex (Corallinaceae, Rhodophyta) in the Ryukyu Islands. . .. 426
970. Akihiro Kano, Dong-jin Lee, Duck Keun Choi, and Chan-Min Yoo:
Ordovician (Llanvirnian) stromatoporoids from the Youngwol area, southern
Korea .............................................................. 449
971. Satoshi Funakawa: Plagiacanthidae (Radiolaria) from the Upper Miocene ofeadern Hokkaido, Japan ............................................ 458
972. Sumio Sakagami and Y oshihiro Mizuno: Discovery of Middle
Pennsylvanian fusulinaceans and conodonts from the Copacabana Group in
the Lake Titicaca region, Bolivia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 484
ANNOUNCEMENT ....................................................... .496