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Trans. Proc. Palaeont. Soc. Japan, N.S., No. 177, pp. 1-20, 16 Figs., April 30, 1995

1982 I Cenozoic diatom genus Rossiella Desikachary etMaheshwari: An emended description
YUKIO YANAGISAWA
Geology Department, Geological Survey of Japan, 1-1-3 Higashi, Tsukuba, Ibaraki, 305 Japan

Received 25 August 1994; Accepted 10 February 1995
Abstract. An emended definition of the fossil diatom genus Rossiella Desikachary et Maheshwari ispresented along with a detailed description of its five member species, including two new ones. The
stratigraphic range and geographic distribution of each species based on analysis of some deep-sea
cores and literature survey are provided. The genus is closely related to the genera Bogorovia Jouse
and Koizumia Yanagisawa, but is clearly distinguished from them by the absence of transapicalcostae. On the basis of certain characteristic features, the genus Rossiella can be placed in thefamily Cymatosiraceae Hasle, von Stosch et Syvertsen. Two new species are described, Rossiellafennerae Yanagisawa sp. nov. and R. fourtanierae Yanagisawa sp. nov.
Key words: Taxonomy, diatom, fossil, Rossiella, biostratigraphy
Introduction
Rossiella is a fossil marine diatom genus created by
Desikachary and Maheshwari (1958) based on a species
that was originally described as Stoschia? paleacea
Grunow in Van Heurck (1883). Although the genus wasmonotypic when erected, it has received many species
during the past two decades and become a relatively
large diatom group including some useful marker species
for Paleogene and Neogene diatom marine biostratigraphies (e.g. Fenner, 1985; Barron, 1985b). Recently, thetaxonomy of the genus was clarified by Gersonde andSchrader (1984), Desikachary et al. (1984) and Fourtanier(1987), but the phylogeny and evolutionary lineage of thisgenus remain poorly known.
In this study, a detailed morphologic and biostratigraphic examination of the genus Rossiella and its related
genus Bogorovia Jouse was performed, and as a result
the presence of three distinct groups of species that meritseparate generic recognition was revealed. The three
genera are Rossiella emend., Bogorovia emend. andKoizumia gen. nov. In a previovs paper (Yanagisawa,1994), the new genus Koizumia was established anddescribed with its three species, one of which was formerly included in the genus Rossiella.
In this paper, an emended definition of the genus
Rossiella is presented with a detailed description of its
five members, Rossiella symmetrica Fenner emend.
Yanagisawa, R. fennerae Yanagisawa sp. nov., R. fourtanierae Yanagisawa sp. nov., R. paleacea (Grunow) Desikachary et Maheshwari and R. elongata (Barron) Desikachary. Furthermore, the stratigraphic range and geo-

graphic distribution of each species based on analysis ofdeep-sea cores and literature survey are provided. The
emended description of the genus Bogorovia is given
separately (Yanagisawa, 1995).
Material and methods
For the biostratigraphic study, samples from the Upper
Oligocene to Upper Miocene sections of DSDP Holes 71,
77B and 70A, and from the Lower Miocene throughQuaternary section of DSDP Hole 438A were analyzed(Table 1).
Holes 71, 77B and 70A were drilled in the easternequatorial Pacific, and the composite section of thesethree cores offers an almost continuous and complete
Upper Oligocene to Upper Miocene sequence for diatom
biostratigraphy in the low-latitude area (Barron, 1981b,
1983, 1985a). Slides of some selected samples studied
by Barron (1983, 1985a) and the slides deposited in the
DSDP Reference Center in the National Science Museum(Tokyo) were examined in this study.
Hole 438A is located in the northwestern Pacific, offnortheast Honshu, Japan. It contains an almost complete reference section for Lower Miocene throughQuaternary North Pacific diatom biostratigraphy (Barron,
1980; Akiba et al., 1982; Maruyama, 1984; Akiba, 1986).
In this study, slides analyzed by Akiba et al. (1982),
Maruyama (1984) and Akiba (1986), together with those
deposited in the DSDP Reference Center in the National
Science Museum (Tokyo) were re-examined with special
attention to the genus Rossiella. For taxonomic study
and SEM observations, several selected samples wereYukio Yanagisawa

2

Table 1. Cores and samples used in this study.
No. Cores & samEles
I DSDP Hole 70A

Fonnation

References and remarks

Eastern equatorial Pacific 6°20.08' N. 140"21.72' W

DSDP core

TraceYet al. (1971)

2 DSDP Hole 71

Eastern equatorial Pacific 4"28.28' N. 140°18.91' W

DSDP core

Traceyet al. (1971). Barron (1983)

3 DSDP Hole 77B

Eastern equatorial Pacific 0°28.90' N. 133°13.70' W

DSDP core

Hays et al.(1972). Barron(1981b. 1983)

40°37.79' N. 143°14.15' E

DSDP core

Scienti fie Party (1980). Barron( 1980)
Nishimura (1986)

4

Location

Area

DSDP Hole 438A Nonhwest Pacific

5 P 225

Central equatorial Pacific

3°13.32' N. 169°41.65' W

Piston core

M32

Ajigaura, Ibaraki. Japan

36°22.82' N. 140°37.42' E

Isozaki F.

Maruyama (1984)

7 Nmy 13A

Sumon. Niigata, Japan

37°22.11' N. 139°02.04' E

NishimyoF.

Yanagisawa et al.(1986)

6

also used (Table 1).
Preparation method for light microscopic (LM) study
varied. Slides of some selected samples from DSDP
Holes 71 and 77B were prepared by J.A. Barron, following
the method described in Barron (1976). The other samples were prepared following the method of Koizumi andTanimura (1985) or Maruyama (1984). Methods of LM
and SEM observations were described in Yanagisawa(1994)
Results
Morphology
Morphologic terminology was given in Yanagisawa(1994). General diatom morphologic terms follow Anonymous (1975), Ross et al. (1979), Simonsen (1979) andRound et al. (1990).
The valve outline of this genus is linear-Ianceolate, butmore linear or broadly lanceolate or elongated forms arealso observed (Figure 1). Rossiella symmetrica, R. fen-nerae and R. fourtanierae are isopolar in valve outline, but
the remaining two species, R. paleacea and R. elongata

have heteropolar valves with one apex broadly rounded
and the other acutely rounded (Figure 1). The apex ismore or less rostrate with an apical pore field consistingof fine puncta (Figure 12-5). Transapical costae (ribs) areabsent, and this is the most distinctive feature thatcharacterizes this genus. All members of this genus
have marginal ridges on both margins. As shown in
Figure 1, Rossiella symmetrica and R. fennerae possess
fused-type marginal ridges with three longitudinal rows ofpores (type 3), whereas the remaining three species arecharacterized by separate-type marginal ridges with asingle row of pores (type 1). Rossiella symmetrica and R.
fennerae with fused-type marginal ridges (type 3) may
form a long chain colony by the fusion of their marginal
ridges. On the contrary, the remaining three species
with the separate-type marginal ridge (type 1) may besolitary. Rossiella fennerae sometimes has valves withthe separate-type marginal ridge (Figures 8-7, 8-8).

o

o
o

o
o
o

o
o

000
000
000
000
000
000

o

o
o
o

o
o
o
o
o
o
o
o
o
o

000

000
000
000
000
000
000
000

o

R. symmetrica

ggg

o
o

000
000
000
000
000
000
000
000
000
000
000
000
000

o
o

o

.. g
o
o
o
o
o

000

R.fennerae

R. Jourtanierae

R.pa/eacea(primi ti ve)

R.pa/eacea(advanced)

o
o
o
o
o
o

o
o
o

o
o
o
o

o
o

Figure 1. Schematic drawings of Rossiel/a species. Left figure in each species is a valve outline in valve
view, showing the location of the rimoportula. Right figure is a girdle view of a valve or set of sibling valves,
showing the type of marginal ridge.

982.

Diatom genus Rossiella

Such valves may be separation valves as observed in
Aulacoseira granulata and Skeletonema costatum (Roundet al., 1990, p.26). The separation valve is a special
valve that differs from the other ordinary vegetative valvesin that it lacks a linking structure for colony chain formation, and may serve to separate an inconveniently long
chain into shorter chains.
A rimoportula (Iabiate process) is present generally in"one per cell pattern"; a frustule consists of a process
valve and a non-process valve, and thus this genus isheterovalvate. The genus Rossiella has three patterns of
the location of the rimoportula; subcentral, apical and

Sl

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-9

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0

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16

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20
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T. convexa

~

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'"=

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N. miocenica

e. yabei

lOB
lOA

18

Burckle, 1972
Barron, 1985aFenner, 1985

A. moronensis

98

C. coscinodiscus

7

C. gigas v. diorama

6

C. lewisianus

~

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0..

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16

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...i

Figure 2. Stratigraphic distribution of Rossiellaspecies in DSDP Holes 77B, 71 and 70A. Narrow horizontal
lines show samples examined. Each dot indicates thepresence of each species. Original data are presented inAppendix table.

T. schraderi
D. kalayamae
D. dimorpha

5C

Thalassiosira yabei

5B

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praedJmorpha

"'"
&.

5A
4B

1:"

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...

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D. hya/ina

4A
3B
3A

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2

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I

Thalassiosira spinosa

D.laulaD.oraelaUla..: ~""

I

0.:

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0.:
Bogorovia
veniamini

not zonedj...lRocellavigilans

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6A

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a

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5Br.;;:-

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8

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5A

N. koizumii

..:

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A.ocu/atus

9

Neodenlicuia
kilInlscMrica

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North Pacificdiatom zones

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15 ~

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L:ow-latitude r dIatom zones NTD
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Age
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central positions (Figure 4 in Yanagisawa, 1994). Rossiella symmetrica and R. fennerae which make a colony
chain by fusion of marginal ridges (type 3) have a subcentral rimoportula (Figure 1). The apical and central
positions of rimoportula are observed only in such species
as R. fourtanierae and R. paleacea , both of which havethe separated-type marginal ridges (type 1).
The valve face is more or less convex, perforated withareolae. Each areolae is occluded with a mesh-like
cribrum (Figure 15-3), but the cribrum is often completely
dissolved (Figure 15-2). The areolae of this genus arecoarse (ca. 1.2-1.5,um in diameter), polygonal in shapeand compactly packed (Figure 4).
The cingulum is composed of a few bands with rows
with small puncta (Figure 7-6), but its detailed composi-

.:!

r-~

m

'"~

Diatom zones

8:ll" ~"'" Sl!3 11.~ is. ~ ~
0::

I

~

::"
.!l

3

30

r-:0

§
~

Rocellavjgilansbr;-

Figure 3. Stratigraphic distribution of Rossiellaspecies. Low-latitude diatom zones after Barron (1985b)
and Fenner (1985), and North Pacific diatom zones after
Akiba (1986). Correlation to the time scale of Berggren
et al. (1985) is adjusted through Barron et al. (1985) and Oda(1986).

Yukio Yanagisawa

4

tion is not known at present.
Stratigraphic distribution

The stratigraphic occurrences of Rossiella species arepresented in Figure 2 and Appendix table for DSDP Holes
77B, 71 and 70A, using the biostratigraphic zonations ofBarron (1985b) and Fenner (1985). The result of analysis
of DSDP Hole 438A has already been presented in Figure
6 of Yanagisawa (1994).
The stratigraphic ranges of Rossiella species areshown in Figure 3, which is mainly based on Figure 2, as
well as on some other important biostratigraphic studies
such as Schrader (1973, 1974a, 1974b, 1976), Barron(1981a, 1981b, 1983, 1985a, 1985b, 1992), Fenner (1984a,
1984b, 1985), Fourtanier (1987, 1991), Gersonde and Burckle (1990), Baldauf and Barron (1991) and Harwood andMaruyama (1992). Correlation to the time scale of Berggren et af. (1985) is adjusted through Barron et af. (1985)
and Oda (1986).
Geographic distribution

The geographic distribution of each Rossiella species
was surveyed from literature. The results are shown in
Figures 6, 8, 11, 14 and 16. All species of the genus are
distributed mainly in the low-latitude oceanic regions in
the Pacific, Atlantic and Indian Oceans with rare occurrence in the middle latitudes, indicating that they are
essentially oceanic warm-water species.
Systematic descriptions

In this paper, the classification system of Round et af.
(1990) is adopted for the description of the genus Rossieffa because the system appears to be the most natural
system at present.
Class Coscinodiscophyceae Round et Crawford, 1990
Subclass Cymatosirophycidae Round et Crawford, 1990
Order Cymatosirales Round et Crawford, 1990
Family Cymatosiraceae Hasle,
von Stosch et Syvertsen, 1983
Subfamily Cymatosiroideae Hasle,
von Stosch et Syvertsen, 1983
Genus Rossiella Desikachary et Maheshwari,
1958 emend. Yanagisawa
Synonymy: Stoschia?, Grunow in van Heurck, 1883, pI. 128,
fig.6 (Stoschia? pa/eacea); Cussia, Schrader, 1974a,
p. 541 (Cussia pa/eacea).

Generic type.-Rossiella pafeacea (Grunow) Desikachary et Maheshwari 1958
Originaf description.-Valve elongately elliptical, withtapering rounded ends; valve surface slightly convex or
almost flat; central area and rosette absent; areolae
polygonal; no distinct marginal arrangement (Desikachary and Maheshwari, 1958).
Emended description.-Cell heterovalvate, rectangularor lanceolate in girdle view. Solitary, or forming separable or inseparable chain colonies. Some species withseparating valve or end valve separates chain colonies.
Cingula with several bands with or without fine puncta.
Valve slightly convex, linear or linear-Ianceolate or broadly lanceolate. Apices with small apical pore field, sometimes slightly rostrate. Marginal ridge always present,
separated or completely fused with sibling valve.
Rimoportula one per cell; a frustule consists of a process
valve and a non-process valve. Rimoportula located at
subcentral position near the margin, or at central or apical
positions. Areolae coarse to medium, compactly
packed. Transapical costae absent.
Comparison.- The genus Rossiella emended here ismorphologically very similar to genera Bogorovia andKoizumia, but is clearly distinguished from the latter two
genera in lacking transapical costae and having relatively
large areolae that are compactly packed.
Rossiella closely resembles genera in Cymatosiraceae
such as Cymatosira Grunow and Campyfosira Grunow in
Van Heurck in that they commonly possess a generally
dipolar outline, chain colonies connected by marginal
ridge or linking spines, rimoportula in the pattern of one
per cell, and an ocellus or apical pore field at each apex,
and therefore the genus Rossiella should be placed in thefamily Cymatosiraceae as defined by Hasle et af. (1983).
Stratigraphic occurrence.-Latest Early Oligocene toLate Miocene. The first species R. symmetrica appears
at the base of the b Subzone of Rocella vigi/ans Zone ofFenner (1984a, 1985) dated about 32 Ma (Figure 3). The
last species R. pafeacea disappears near the top of theLate Miocene Nitzschia porteri Zone (NTD 11).
Habitat.-Because of their dominant occurrence inoceanic sediments, all species of the genus are probably
holoplanktonic, and solitary or making a long chain formed by fused marginal ridges.
Geographic distribution.-AII members of the genus are
distributed mainly in the low-latitude area of the Pacific,
Atlantic and Indian Oceans, indicating that they arewarm-water species. They are also found rarely andsporadically in middle-to-high-Iatitude areas.
Discussion.- The diatom genus Rossiella has a very
complicated taxonomic history. The genus was createdby Desikachary and Maheshwari (1958) to receive a
species that was originally described as Stoschia?
pafeacea Grunow in Van Heurck (1883). The species
was later transferred to the genus Coscinodiscus by
Rattray (1889) and had been referred to as C. pafeaceus(De Toni, 1894; Kolbe, 1954) until 1958 when the genus
Rossiella was erected. Unfortunately, however, thisgeneric erection was not generally known until the 1980's,
and therefore R. pafeacea continued to be referred to as
Coscinodiscus pafeaceus (Kanaya, 1971; Burckle, 1972;
Schrader, 1973), while some species which were latertransferred into Rossiella were described under different
generic names such as Rhaphoneis, Coscinodiscus or
Cymatosira (e.g. Hajos, 1968; Koizumi, 1972; Schrader,
1973; Lohman, 1974). Furthermore, the independent
generic erection of the genus Bogorovia (Jouse, 1973) and982.
Table 2.

Diatom genus Rossiella5

Key to species based on light microscopy.

lao Valve isopolar.............................................................................................................. 2
lb. Valve heteropolar........................................................................................................ 4
2a. Valve linear ............................................................................................ R. symmetrica
2b. Valve lanceolate .......................................................................................................... 3
3a. Valve linear lanceolate ................................................................................. R.fennerae
3b. Valve broadly lanceolate ........................................................................ R.fourtanierae
4a. Valve not elongated......... .... ............. ..... ... ........ ....... .............. ........ .......... ... R. paleacea
4b. Valve elongated .......................................................................................... R. elongata

Cussia (Schrader, 1974a) produced further considerable
confusion in the taxonomy.
Schrader (1974a) created a new genus Cussia based on
Stoschia? pa/eacea without knowing of the genericerection of Rossiella, and described two new species(Cussia lancettula and C. moholensis) and proposed four
new combinations (Cussia paleacea, C. praepa/eacea, C.
mediopunctata and C. tatsunokuchiensis). Anothergenus Bogorovia was established by Jouse (1973) with B.
veniamini as the generic type. Although the latter genus
was originally monotypic, it later received five species,
Bogorovia pa/eacea, B. praepa/eacea, B. mediopunctata,B. tatsunokuchiensis and B. moholensis (Jouse 1976).
During the late 1970's, these species were referred to
Cussia or Bogorovia, until the generic erection of Rossiella was re-discovered by Gersonde (1980). In 1984, Gersonde and Schrader (1984) and Desikachary et al. (1984)
clarified the confused taxonomy of this diatom group, andmost of the species formerly included in Cussia or Bogorovia were transferred to Rossiella, exclusive of Bogorovia
veniamini which was left in the genus Bogorovia because
it has distinct transverse (transapical) rows of areolae with
distinct transverse costae (Desikachary et al., 1984).
This taxonomic treatment has been accepted by all
subsequent diatom studies (Barron, 1985a, 1985b; Akiba,
1986; Fourtanier, 1987; Gersonde and Burckle, 1990;
Baldauf and Barron, 1991; Harwood and Maruyama,1992). However, it is incosistent that R. mediopunctata,
R. tatsunokuchiensis and R. moholensis were removed to
the genus Rossiella despite the possession of distinct
transapical rows of areolae and transapical costae, bothof which are characteristic of the genus Bogorovia.
Detailed phylogenetic analysis shows that Rossiellaspecies lacking transapical costae constitute a morphologically well-cohesive group bounded by distinct
morphological gaps from Bogorovia and Koizumia.
Furthermore, this group has its own characteristic evolutionary trend and ecology.
Key to species of the genus Rossiella based on lightmicroscopy is presented in Table 2.

Rossiella symmetrica Fenner, 1984
emend. Yanagisawa

Figures 4-1-6Fenner, 1984b, p.333-334, pI. 1, fig. 2, non pI. 1, figs. 3, 4;
1984a, p. 1264; 1985, p. 737, figs. 5.5-5.7; Fourtanier,
1991, pI. 4, fig. 5.
Synonymy: Coscinodiscus praepa/eaceus Schrader, Burckle,
1978, figs. in p. 261, 262; Bogorovia aff. B. veniamini
Jouse, Abbott, 1980, p. 61, pI. 6, fig. 2.
Emended description.-Valve isopolar, linear in outline
with rounded apices, 13-51 ,um long, 5-8,um wide. Valve
face slightly convex, covered with irregularly disposedcoarse round areolae, 6-8 areolae in 10,um. Apices
slightly raised with apical pore field. Marginal ridge,
fused-type with three longitudinal rows of subroundedpores (type 3),7-8 pores in 10 ,um. A subcentral rimoportula, one per cell, located near edge of valve face.
Comparisons.-Rossiella symmetrica resembles R. fennerae, but differs from the latter by the linear valve outline
and narrower valve size (less than 8 ,um) (Figure 5). The
species is also similar to "Rossiella" gombosii* Desikachary in Desikachary et al. (1984) in valve appearance,
but is distinct by the absence of transapical costae andlarger and more densely packed areolae on the valve
face.
The species also shows a slight resemblance toPraecymatosira monomembranacea (Schrader) Strelnikova(Jouse ed., 1979, p.64, figs. 169-176; Gombos, 1983, p.
570, pI. 4, figs. 12, 13) , which was originally described as
Pseudorutilaria monomembranacea Schrader (Schrader
and Fenner, 1976, p. 994, pI. 22, figs. 1-6) or as Cymatosira
sp. B (Dzinordze et al., 1978, pI. 10, figs. 14-17), in having
a linear valve outline and medium areolae on the valve
face. Praecymatosira monomenbranacea was first reported from Middle Eocene deposits in the Norwegian Sea• The species will be transfered to the genus Bogorovia in
Yanagisawa (1995)

6

Yukio Yanagisawa

10

21

23

Figure 4. Light photomicrographs of Rossiella species. Scale bar equals 10 j.l m. Arrow heads indicate the locationof the rimoportula. 1- 6. Rossiella symmetrica Fenner. (1 - 5) DSDP Hole 71, 47 - 5, 59- 60 cm ; (6) DSDP Hole 71 , 45- 2, 61 - 62
cm . 7 -10. Rossiella fennerae Yanagisawa sp. nov. (9) holotype; (7) DSDP Hole 71, 36- 2, 125- 129 cm; (8) DSDP Hole 71,
39- 1, 87- 89 cm ; (9) DSDP Hole 71 , 37 - 5, 87- 89 cm ; (10) DSDP Hole 71 , 37 - 5, 87- 89 cm . 11-14. Rossiella fourtanierae
Yanagisawa sp. nov. (11) holotype, DSDP Hole 71 , 36- 6, 79- 80 em ; (12-14) DSDP Hole 71, 36- 2, 125-129 cm. 15- 17.
Rossiella pa/eacea (Grunow) Desikachary et Maheshwari (primitive form). (15) DSDP Hole 71,22- 2,88- 90 cm ; (16) DSDP Hole
71 , 21 - 6, 91 - 93 cm ; (17) DSDP Hole 71 , 23- 4, 77- 79 cm . 18- 20. Rossiella pa/eacea (Grunow) Desikachary et Maheshwari(advanced form). DSDP Hole 77B, 20- 6, 30- 31 cm. 21- 23. Rossiella e/ongata (Barron) Desikachary. (21) P 225, VII 20 ; (22)DSDP Hole 77B, 19- 2, 38- 40 cm; (23) DSDP Hole 77B, 22- 6, 35- 37 cm.

982.

Diatom genus Rossiella

100
0

o

0

.....

80

o

•• I

o

I

. : •Io.
... I • .

E 60

0

~

....

0

5

.3"" 40

o

o 9

~6~

0

q

0

0

8 0

~ 6 g~ 8

20

0

6 0

,0

6

oR. symmetrica
l

0

o

4

6

8

10

I

oR·fennerae

12

14

16

Width(lffil)

Figure 5. Scatter plot of valve width versus length of
Rossiella symmetrica Fenner and R. fennerae Yanagisawa
sp. nov. Samples from nos. 1, 2 in Table 1.

(Schrader and Fenner, 1976; Dzinoridze et al., 1978;
Jouse ed., 1979) and later found in Eocene sediments in
the South Atlantic (Gombos, 1983), and it is of great
importance to Eocene diatom biostratigraphy because of
its unique features as well as its usual abundance (Strelnikova,1990). Praecymatosira monomembranacea differs
fundamentally from R. symmetrica in linking structure; P.

7monomembranacea forms a colony chain by a longitudinalrow of processes along the apical axis, which is neverobserved in Rossiella species.
Stratigraphic range.~32.0-25.5 Ma. The first occurrence of this species defines the base of the b Subzoneof the Rocella vigilans Zone of Fenner (1984a, 1985) andits last occurrence falls in the Bogorovia veniamini Zoneof Fenner (1984a, 1985) (Figure 3).
Geographic distribution.~ This species has been reported mainly from warm-water regions (Figure 6). It isfound in the equatorial Pacific (Barron, 1983; this study),
the northwest Atlantic (Fenner, 1984a, 1984b, 1985), theAtlantic coast of the U.S.A. (Abbott, 1980), the equatorial
Indian Ocean (Fourtanier, 1991 ; Fenner and Mikkelsen,1990) and the Southern Ocean (Fenner, 1984b; Harwood
and Maruyama, 1992). It has not been reported from the
middle-to-high-Iatitude North Pacific.
Discussion.~Since the original description of R.
symmetrica by Fenner (1984b) includes the features of R.
fennerae sp. nov., the species description is emended
here. As Fenner's (1984b) description indicates, she hadalready noted morphologic change from R. symmetrica
emend. to R. fennerae sp. nov., but she regarded thechange as intraspecific variation. However, the two
species are distinct enough to be separated at the specific level.

Figure 6. Geographic distribution of Rossiella symmetrica Fenner. Closed circles: localities reportedwith figures. Open circles: localities reported without figures. 1. DSDP Hole 70A, equatorial Pacific (thisstudy). 2. DSDP Hole 71, equatorial Pacific (this study). 3. DSDP Hole 369A, northwest Atlantic, off northwest Africa (Fenner, 1984b, 1985). 4. Atlantic Slope Project core 22, off Atlantic coast of U.S.A. (Abbott, 1980).
5. DSDP Hole 758, equatorial Indian Ocean (Fourtanier, 1991). 6. DSDP Hole 714, equatorial Indian Ocean(Fenner and Mikkelsen, 1990). 7. DSDP Hole 747A, Indian sector of the Southern Ocean (Harwood andMaruyama, 1992). 8. DSDP Hole 278, Pacific sector of the Southern Ocean (Fenner, 1984b). 9. DSDP Hole
366A, equatorial Atlantic off Africa (Fenner, 1984a, 1984b).

Yukio Yanagisawa

8

Rossiella fennerae Yanagisawa sp. nov.
Figures 4- 7- 10; 7-1- 8.
Synonymy : Bogorovia veniamini Jouse, Gombos, 1976, pI. 12,
fig.1 (non pI. 1, figs. 6, 7 ; pI. 12, figs. 2, 4); Rossiellasymmetrica Fenner, 1984b, pI. 1, figs. 3, 4, non pI. 1, fig. 2;
Rossiella pa/eacea (Grunow) Desikachary et Maheshwari,
Barron, 1983, p. 512, pI. V, fig . 4 (non pI. V, figs. 5- 6).
Oescription. - Valve isopolar, linear-Ianceolate in out-line, 38- 92 j.lm long, 9- 15 j.lm wide. Apex with apicalpore field , variable in shape from broadly rounded tostrongly rostrate. Valve face slightly convex, covered
with irregularly disposed round areolae, 5- 8 areolae in 10
j.lm.
Marginal ridge, fused-type with three longitudinalrows of subrounded pores (type 3), 7- 8 pores in 10 j.lm.
Separation valve has separeted-type marginal ridge with
one row of pores (type 1). A subcentral rimoportula, one
per cell, located near edge of valve face, sometimes
surrounded by small satellite pores. Internal lip-shaped

Figure 7. Scanning electron photomicrographs of Rossiella fennerae Yanagisawa sp. nov. Sample DSDP
Hole 71, 36- 2, 125-129 cm. Scale bars equal 5 jim . 1. A set of fused sibling valves. 2. The opposite sideof the specimen in Fig. 7-1. Arrow indicates the outer opening of a rimoportula. 3. Enlargement of Fig. 7- 2.
4. A set of fused sibling valves. 5. Frustule composed of two separation valves. 6. Enlargement of Fig. 75. 7,8. Inner views of a separation valve. Arrow indicates a rimoportula.

982.

Diatom genus Rossiella

9

Figure 8. Geographic distribution of Rossiella fennerae Yanagisawa sp. nov. Closed circles: localities
reported with figures. Open circles: localities reported without figures. 1. DSDP Hole 71, equatorial Pacific(Barron, 1983; this study). 2. DSDP Hole 366A, equatorial Atlantic off Africa (Fenner, 1984b). 3. DSDP Hole
328B, southern Atlantic (Gombos, 1976). 4. DSDP Hole 744A, Indian sector of the Southern Ocean (Baldauf
and Barron, 1991). 5. DSDP Hole 748B, Indian sector of the Southern Ocean (Harwood and Maruyama, 1992).

opening of rimoportula diagonally oriented to the longitudinal axis. External opening of rimoportula is a simple
pore on marginal ridge. On non-process valve, a small
hyaline area present near edge of valve where a rimoportula might be located if it were present. Cingulum bands
perforated with fine puncta.
Holotype.-Plate 1, Figure 9 (GSJF 12783 deposited in
the Geological Survey of Japan).
Type locality and sample.-DSDP Hole 71, Core 37,
Section 5, Interval 87-89 cm, 4'28.28'N, 140'18.91W, eastern equatorial Pacific (Early Miocene in age, the A
Subzone of the Rossiella paleacea Zone, NTD 1A).
Comparisons.- The species differs from R. symmetrica
by more lanceolate valve outline, broader breadth (morethan 8.5 J-l m) (Figure 5) and more compactly packed
areolae. It shows close affinity with R. paleacea, but isdistinguished by isopolar shape of valve outline, the fusedtype marginal ridge with three longitudinal rows (type 3)
and the subcentral rimoportula (Figure 1). The species
differs from R. fourtanierae by more slender valve outline
and the location of the rimoportula. Rossiella elongata isdistinguished from R. fennerae by its elongated heteropolar valve outline and the type of marginal ridge.
Stratigraphic range.-25.5-20.6 Ma. In the tropical
Pacific, the first occurrence is in the upper part of the
Bogorovia veniamini Zone and the last slightly below the
top of the B subzone of the R. paleacea Zone (NTD 1B)(Figure 3).
Geographic distribution.- This speCies has been reported from low-latitude areas and the Southern Ocean(Figure 8); the equatorial Atlantic (Fenner, 1984b), theequatorial Pacific (Barron, 1983; this study) and theSouthern Ocean (Gombos, 1976; Baldauf and Barron,
1991; Harwood and Maruyama, 1992).
Oiscussion.- The valve apex of this species shows
very wide variation in shape, from broadly rounded (Figures 4-7, 4-10) to strongly rostrate (Figure 4-8, 4-9), andtherefore this species may be further subdivided.
Etymology.- The species name is dedicated to Dr.
Juliane Fenner, who first figured this species and described its direct ancestor R. symmetrica (Fenner, 1984b).

Rossiella fourtanierae Yanagisawa sp. nov.
Figures 4-11-14; 9-1-6.
Synonymy: Coscinodiscus paleaceus (Grunow) Rattray,
Jouse, 1973, pI. 4, fig. 4, non pI. 5, fig. 15; Bogorovia
paleaceus (Rattray) Jouse, 1976, p. 1233-1234, fig. 5, nonfig. 6; Bogorovia pa/eaceus (Grunow) Jouse, Jouse ed.,1977, pI. 54, fig. 11, non pI. 30, fig. 30; Rossiella paleacea(Grunow) Desikachary et Maheshwari (robust form), Barron, 1983, p. 512, pI. V, fig. 6 (not pI. V, figs. 4-5); Rossiellamagna (Lohman) Fourtanier, 1991, p.200, pI. 4, fig. 1 (nonCymatosira magna Lohman, 1974, p. 351, pI. 5, fig. 16).
Oescription.-Valve isopolar, broadly lanceolate inoutline with acutely rounded apices, 42-104 J-lm long,
13.5-34.5 J-lm wide. Valve face slightly convex, covered
with irregularly disposed round areolae, 6-7 in 10 J-lm.
Marginal ridge, separated-type with a single longitudinalrow of pores (6-7 in 10 J-lm). A small pore field present at
each apex. A rimoportula, one per cell, located near
center of valve face, with its internal lip-shaped opening
and external simple pore surrounded by a few small

Yukio Yanagisawa

10

Figure 9. Scanning electron photomicrographs of Rossiella fourtanierae Yanagisawa sp. nov. Sample
DSDP Hole 71, 36- 2, 125-129 cm. Broad and narrow scale bars equal 5 Jim and 1 ,um, respectively. 1,2. Innerviews of a non-process valve. Note hyaline area where a rimoportula might be located if present. 3,4. Outerviews of a process valve. Arrow indicates the outer opening of a rimoportula. 5. Enlargement of Fig. 9- 4,
showing the outer opening of a rimoportula (arrow head). 6. Inner view of a process valve. Arrow indicatesa rimoportula.

satellite pores. Non-process valve has a hyaline area on
valve face where a rimoportula might be located if it were
present.
Holotype. - Plate 1, Figure 11 (GSJF 14592 deposited in
the Geological Survey of Japan).
Type locality and sample. - DSDP Hole 71, Core 36,
Section 6, Interval 79- 80 cm, 4°28.28' N, 140 18.91 ' W,
eastern equatorial Pacific (Early Miocene in age, the A
Subzone of the Rossiella paleacea Zone, NTD 1A).
Comparisons. - Rossiella fourtanierae is characterized
by its broadly lanceolate valve outline. It is distinguishedfrom R. symmetrica and R. fennerae by the more broad
valve outline (Figure 10), a separated-type marginal ridge(type 1) and the central rimoportula (Figure 1). This
species differs from R. paleacea by its isopolar valve
outline and broader breadth (Figure 10).
Stratigraphic range .-22.4-19.8 Ma. The occurrence
0of this species is confined within the A and B Subzonesof the R. paleacea Zone (NTD 1A) in DSDP Hole 71 (Figure2), but Fourtanier (1991) reported that the last occurrenceof this species lies near the top of the R. paleacea Zone
in DSDP Hole 758A in the equatorial Indian Ocean.
Barron (1983) also figured this species from the uppermost
part of the R. paleacea Zone in DSDP Hole 495 of theeastern equatorial Pacific. The last occurrence of R.
fourtanierae therefore may lie near the top of the R.
paleacea Zone (Figure 4).
Geographic distribution. - The species is probably a
low-latitude species (Figure 11). It has been recorded
from the equatorial Pacific (Jouse, 1973,1976; Jouse ed.,1977 ; Barron, 1983 ; this study) and the equatorial Indian
Ocean (Fourtanier, 1991).
Discussion. - Fourtanier (1991) first noticed this species
as distinct from R. paleacea , but she regarded it as982.

Diatom genus Rossiella120,-------------------.

•

100• • ••

80

11

species is a distinct taxon (Fourtanier, 1991) and firstexamined the genus Rossiella using a scanning electron
microscope (SEM) in detail (Fourtanier, 1987).

Rossiella paleacea (Grunow) Desikachary etMaheshwari, 1958

o

•

•

Figures 4-15-20; 12-1-6.

••

40• R.fourtanierae

2000

o R. paleacea• R. elongata
O+-----,--~-~-~-_r-~-~

o

10

20
Width (Jlm)30

40

Figure 10. Scatter plot of valve width versus length of
Rossiella fourtanierae Yanagisawa sp. nov., R. paleacea(Grunow) Desikachary et Maheshwari and R. elongata (Barron) Desikachary. Samples from nos. 2, 3, 5-7 in Table 1.

Cymatosira magna Lohman and proposed the combination
Rossiella magna (Lohman) Fourtanier. Cymatosira magna
Lohman, however, is not R. fourtanierae, but can be safely
included in the variation of R. pa/eacea because theholotype valve of C. magna has an obviously heteropolar
outline.
Etym%gy.- The name of this species is dedicated to
Dr. Elisabeth Fourtanier, who first recognized that thisDesikachary and Maheshwari, 1958, p. 128, fig. 1 ; Barron,
1983, p. 512, pI. V, fig. 5 (not figs. 4, 6); Gersonde andSchrader, 1984, p. 104; Desikachary et al., 1984, p.337338, pI. 1, figs. 2-5,8-11; Fenner, 1984a, p. 1264; Barron,
1985a, pI. 8, fig.2; Barron, 1985b, p.790, figs. 9.6-9.7 ;Fourtanier, 1991, pI. 4, fig. 4; Radionova, 1991, p.82, pI.
23, figs. 1-3.
Basionym: Stoschia? paleacea Grunow in Van Heurck, 1883,
pI. 128, fig. 6.
Synonymy: Coscinodiscus paleaceus (Grunow) Rattray, 1889,
p. 597; De Toni, 1894, p. 1301-1302; Kolbe, 1954, p.34,
pI. 3, figs. 32a-b; Kanaya, 1971, p.555, pI. 40.5, fig. 10;
Burckle, 1972, pI. 1, figs. 7-8; Schrader, 1973, p. 703, pI. 3,
figs. 10-12; Jouse, 1973, pI. 5, fig. 15, non pI. 4, fig.4;
Cymatosira magna Lohman, 1974, p.351, pI. 5, fig. 16;
Cussia paleacea (Grunow) Schrader, 1974a, p.543, fig. 1 :11-14; Schrader, 1974b, p. 914; Gombos, 1975, p.316,
pI. 4, figs. 8-10; Barron, 1980, p. 672; Abbott and Ernissee, 1983, p. 299, pI. 12, fig. 2; Bogorovia pa/eaceus(Rattray) Jouse, 1976, p.1233-1234, fig. 6, non fig. 5;
Bogorovia praepaleaceus (Schrader) Jouse, Jouse ed.,1977, pI. 48, figs. 15-16; Bogorovia paleaceus (Grunow)
Jouse, Jouse ed., 1977, pI. 30, fig. 30, non pI. 54, fig. 11 ;Rossiella paleacea var. pa/eacea (Grunow) Schrader, Barron, 1981b, pI. II, fig. 1 ; Bogorovia paleacea var. paleacea(Grunow) Jouse, Barron, 1981a, pI. 4, fig. 13.

Figure 11. Geographic distribution of Rossiella fourtanierae Yanagisawa sp. nov. Closed circles: localities reported with figures. 1. DSDP Hole 71, equatorial Pacific (Barron, 1983; this study). 2. R/V "Vityaz"
Core 5996, equatorial Pacific (Jouse, 1973, 1976, 1977). 3. DSDP Hole 495, eastern equatorial Pacific, offcentral America (Barron, 1983). 4. DSDP Hole 758A, equatorial Indian Ocean (Fourtanier, 1991).

12

Yukio Yanagisawa

Original description .-Elongately and irregularly elliptical, frequently with shallow lateral undulations, major axis
.0425 to almost flat ; central space and rosette absent.
Markings polygonal, 6 to 7 in .01 mm. Subequal, withoutorder or in obscure rows; around the border a distinct
band of areolae (as Coscinodiscus paleaceus (Grunow)
Rattray, 1889, p.597).
Additional description. - Valve linear-Ianceolate, heteropolar with one apex broadly rounded and the otherelongated and acutely rounded, 18-89 j.lm long, 7- 19 j.lm
wide. Valve apices somtimes slightly rostrate. Valve
face slightly convex, covered with irregularly disposedround areolae, 6- 8 areolae in 10 j.lm . Areolae might beoccluded by cribra in the same manner as in R. elongata,though the cribra have been dissolved in all specimens
observed. Marginal ridge, separate type with a single
longitudinal row of large subrounded pores (type 1), 6- 8
pores in 10 j.lm . A small pore field present at each apex.
A rimoportula present basically in a "one per cell" pattern
but some valves with two processes.
The position of the rimoportula on the valve facechanged through time (Figure 13). The rimoportula islocated very near the short apex in the primitive forms
from NTD 18 to NTD 7 (Figures 4-15-17). The advanced
forms from NTD 8- 9 have their processes nearly at thecentral part of valve (Figures 4-18, 4- 19, 12- 3). Moreover, some valves from NTD 8- 9 have an additionalrimoportula at the apical position (Figure 4- 20, 12-1, 12- 2).
Comparisons. - The species closely resembles R. fennerae, but differs by the heteropolar valve outline, aseparate-type marginal ridge and location of the rimoportula. It differs from R. fourtanierae by its heteropolar andmore slender valve outline (Figure 10). This species isdistinguished from R. e/ongata by a shorter (not elongated)valve (Figure 10) and the location of the rimoportula (Figure 1). Rossiella paleacea has been sometimes confusedwith Koizumia adaroi (Andrews, 1980; Hajos, 1986), butdiffers from K. adaroi by the absence of transapicalcostae. In some previous studies, Cymatosira lorenziana
Grunow has been misidentified as R. paleacea (Abbott
and Andrews , 1979; Powers, 1988), but the two species
are clearly distinguished by the type of colony formation

Figure 12. Scanning electron photomicrographs of Rossiella pa/eacea (Grunow) Desikachary et Maheshwari. Sample P 225, VII 20, equatorial Pacific. Scale bars equal 5 j.lm . 1,2. Inner views of a process
valve. Note two rimoportulae (arrow heads). 3. Outer view of a process valve. Arrow indicates a rimoportula. 4, 6. Inner views of a non-process valve. Note hyaline structureless area where a rimoportula might belocated if present. 5. Valve apex with an apical pore field.

982.

NTD IB-4

NTD 5

1.0 -r--"""'K'----,

Diatom genus Rossiella

13

NTD 8

NTD 6-7

NTD 9

0.5

0
1.0

0

0

1.0

1.0

0

1.0

0

1.0

0

(0.50, 0.14)(0.50, 0.13)(0.49,0.18)(0.45, 0.35)(0.43, 0.20)(0.49,0.35)(O.39,0.l9)

n=12

n=22

n=8

n=8

n=6

Figure 13. Change in the location of rimoportula of Rossiella paleacea (Grunow) Desikachary et Maheshwari. NTD numbers indicate diatom zone numbers of the Neogene low-latitude diatom zones of Barron(1985b). Closed circles indicate the average location of rimoportula. Open circles show an additionalrimoportula recognized in some specimens from NTD 8 and 9. Numbers in parentheses indicate the coordinates of mean location of rimoportulae. n = numbers of specimens measured.

and the areolae pattern on the valve face.
Cymatosira andersoni Hanna, a diatom species described from the Middle Miocene sediments in SharktoothHill, California (Hanna, 1932, p.187-188, pI. 10, fig. 6),
seems to be slightly similar to R. paleacea, but differs bya central hyaline area and central areolae arranged nearlyin longitudinal rows. Further study is needed to make acorrect taxonomic placement of this species.
Stratigraphic range.-20.9-6.8 Ma. In this study ofDSDP Hole 71 (equatorial Pacific), the first occurrence of
this speCies is recognized in the middle part of the B
Subzone of the R. paleacea Zone (NTD 1B) (Figure 2). On
the contrary, Barron (1983, 1985b) reported it at the baseof R. paleacea Zone, utilizing it to define the base of thiszone. This difference may be due to species identification; R. paleacea of Barron (1983, 1985b) includes R.
fennerae and R. fourtanierae as well as R. paleacea s. str.
The base of the R. paleacea Zone defined by Barron(1983) in Hole 71 seems to be coincident with the firstabundant occurrence of R. fennerae and so the base ofthis zone should be redefined (See appendix). The last
occurrence of R. paleacea approximates the top of the
Nitzschia porteri Zone (NTD 11) in the low-latitude area
(Barron, 1985a, 1985b) (Figure 3), estimated at 6.8 Ma(Barron, 1992).
The stratigraphic range of R. paleacea is shortened in
the middle-to-high-Iatitude North Pacific (Yanagisawa,
1994, fig. 6) or in the Southern Ocean (Baldauf and Barron,1990).

Geographic distribution.-Rossiella paleacea was firstdescribed from Nancoori and Naparima Islands of India(Grunow in van Heurck, 1883; Rattray, 1989), numerous
reports of this species have subsequently been mademainly from low-latitude areas and the middle latitudes of
the Northern Hemisphere (Figure 14).

Rossiella elongata (Barron) Desikachary in
Desikachary et al., 1984

Figures 4-21-23; 15-1-8
Desikachary in Desikachary et al., 1984, p.338.
Basionym: Bogorovia paleacea var. elongata Barron, 1981a,
p.528, pl.4, figs. 11-12.
Synonymy: Coscinodiscus paleaceus? var. 2, Jouse, 1973,
pI. 5, fig. 16; Coscinodiscus paleaceus (Grunow) Rattray,
Hasegawa, 1977, p.83, pI. 17, figs.5a, 5b; Rossiellapaleacea var. elongata (Barron) Schrader, Barron, 1981b,
p.141, pI. II, fig. 2; Rossiella paleacea var. elongata (Barron) Barron, 1985a, pI. 8, fig. 3; Radionova, 1991, p.82.
Additional description.-Valve elongated lanceolate,heteropolar with one apex broadly rounded and the otherelongated and acutely rounded, 41-104,um long, 7-13,um
wide. Some valves have asymmetric sides with one side
more convex and the other side more straight (Figures 151,15-5). Valve face slightly convex, covered with densely packed round areolae, 6-7 in 10 ,um. Areolae occluded by the mesh-like cribra (Figure 15-3). Marginal ridge,

14

Yukio Yanagisawa

Figure 14. Geographic distribution of Rossiella paleacea (Grunow) Desikachary et Maheshwari. Closed
circles: localities reported wth figures. Open circles: localities reported without figures. 1. DSDP Hole 71,
equatorial Pacific (this study). 2. DSDP Hole 77B, equatorial Pacific (this study; Barron 1981b, 1983, 1985a,
1985b; Fourtanier, 1987). 3. DSDP Hole 66.1, equatorial Pacific (Gombos, 1975; Radionova, 1991). 4. U.S.
"Monsoon" Expedition MSN-132P, equatorial Pacific (Jouse, 1973, 1976). 5. Swedish Deep-Sea Expedition,
Core 60, equatorial Pacific (Kolbe, 1954). 6. Swedish Deep-Sea Expedition, Core 76, equatorial Pacific (Kolbe,1954). 7. Geological Survey of Japan piston core P 225, equatorial Pacific (this study). 8. DSDP Hole 575,
equatorial Pacific (Radionova, 1991). 9. DSDP Hole 472, northeast Pacific off Baja California (Barron, 1981a,
1985b). 10. Experimental Mohole Drilling Guadalupe Site, northeast Pacific off Baja California (Kanaya, 1971 ;Schrader, 1974a). 11. DSDP Hole 173, northeast Pacific off California (Schrader, 1973). 12. DSDP Hole 438A,
northwest Pacific off Japan (Barron, 1980; this study). 13. Nishimyo Formation, Sumon area, Niigata, Japan(this study). 14. Nancoori Island in Nicobar Islands, India (Grunow in Van Heurck, 1883; Desikachary et al.,1984). 15. Colebrook Island in Andaman Islands, India (Desikachary and Maheshwari, 1958; Desikacharyet al., 1984). 16. DSDP Hole 758, equatorial Indian Ocean (Fourtanier, 1991). 17. Trinidad Island (Lohman,1974). 18. Pungo River Formation, North Carolina, U.S.A. (Abbott and Ernissee, 1983). 19. DSDP Hole 369A,
northwest Atlantic off northwest Africa (Schrader, 1977). 20. La Miranda, Muro, Mallorca Island, Spain(Monjanel, 1987). 21. Lorca, Spain (Gersonde, 1980).
Note: Desikachary et al. (1984) figured R. paleacea from Kamortha Island and Naparima, but the exact
location of these sites are unknown at present.

separated-type with a single longitudinal row of pores(type 1),6-7 pores in 10 .urn. A small pore field present at
each apex. A subcentral rimoportula, one per cell, located near the valve margin, with its lip-shaped internal
opening oriented diagonally to the apical axis (Figure 152). In a non-process valve, a small hyaline area present
where a rimoportula might be present (Figure 15-6).
Comparisons.- The elongated valve outline characterizes R. elongata. This species differs from R. paleacea
by its elongated slender valve outline (Figure 10) and asubcentral rimoportula (Figure 1). It is distinguished fromR. symmetrica, R. fennerae and R. fourtanierae mainly by
its heteropolar elongated valve outline and the separatedtype marginal ridge.
Stratigraphic range.-13.5-7.5 Ma. In low-latitude
areas, the first occurrence of this species falls within the
Coscinodiscus lewisianus Zone (NTD 6) and its last
occurrence lies near the top of the B Subzone of the
Coscinodiscus yabei (Thalassiosira yabei) Zone (NTD 10B)

(Figures 2, 3). Although this species first occurs in the C.
lewisianus Zone (NTD 6), its first continuous occurrence
is in the lowermost part of the Actinocyclus moronensis
Zone (NTD 9) in DSDP Hole 77B (Figure 2), coincident
with the estimated age of its first occurrence at 10.6 Ma
by Barron (1992).
Geographic distribution.- This species occurs mainlyin the equatorial Pacific (Jouse, 1973; Barron, 1981a,
1981b, 1985a; Radionova, 1991 ; this study) (Figure 16). It
is also found relatively rarely at middle latitude areas(Barron, 1981a; Hasegawa, 1977; this study).
Discussion.- This speCies was described originally as
a variety of R. paleacea (Barron, 1981 a), but was later
raised to the specific rank by Desikachary et al., (1984).
This taxonomic change is supported by the substantial
difference in location of the rimoportula between R.
paleacea and R. elongata (Figure 1).

982 .

Diatom genus Rossiella

Figure 15. Scanning electron photomicrographs of Rossielia e/ongata (Barron) Oesikachary. Sample M
32, Isozaki Formation, Ajigaura area, Japan. Broad and narrow scale bars equal 10 jim and 1 jim, respectively.
1. Outer view of a non-process valve. 2. Inner view of a process valve. Arrow indicates a rimoportula. 3.
Outer view of a process valve. Arrow indicates the outer opening of a rimoportula. 4. Cross-sectional viewof a broken valve. 5. Inner view of a process valve. Arrow indicates a rimoportula. 6. Inner view of anon-process valve. 7,8. Valve apex with an apical pore field .

15

Yukio Yanagisawa

16

=

"

Cj. ', .
Del
Figure 16. Geographic distribution of Rossiella elongata (Barron) Desikachary. Closed circles: localities
reported with figures. 1. DSDP Hole 77B, equatorial Pacific (Barron, 1981a, 1981b; this study). 2. DSDP Hole
574, equatorial Pacific (Barron, 1985a). 3. U.S. "Monsoon" Expedition MSN 146P, equatorial Pacific (Jouse,1973). 4. DSDP Hole 472, northeast Pacific (Barron, 1981a). 5. M 32, Isozaki Formation, Ajigaura, Ibaraki,
Japan (this study). 6. Nakayama Formation, Sado Island, Niigata, Japan (Hasegawa, 1977).

Acknowledgments

References

Special thanks are given to Fumio Akiba (JAPEX
Research Center of Japan Petroleum Exploration Co.
Ud.), Itaru Koizumi (Hokkaido University), John A. Barron(U.S. Geological Survey) and Elisabeth Fourtanier (California Academy of Sciences) for their critical review of theearly draft of this manuscript and their helpful comments.
John A. Barron, Fumio Akiba, Yoshihiro Tanimura, Yokichi Takayanagi, Toshiaki Maruyama and Hiroaki Kobayashi kindly offered me the chance to examine DSDP
materials. Akira Nishimura, Fumio Yoshida and Eiichi
Honza provided some samples used in this study. Kimio
Okumura, Koichi Nakamura and Tamotsu Nagumo helped
me in literature search.

Abbott, W.H., 1980: Diatoms and stratigraphically significant silicoflagellates from the Atlantic Margin Coring
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Abbott, W.H., and Andrews, G.W., 1979: Middle Miocene
marine diatoms from the Hawthorn Formation within
the Ridgeland Trough, South Carolina and Georgia.
Micropaleontology, vol. 25, p. 225-271.
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Akiba, F., 1986: Middle Miocene to Quaternary diatom
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Trench, and modified Lower Miocene throughQuaternary diatom zones for middle-to-high latitudesof the North Pacific. In, Kagami, H., Karig, D.E.,
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Andrews, G.W., 1980: Neogene diatoms from Petersburg,
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Appendix
Redefinition of a diatom zone
The base of the Rossiella pa/eacea Zone (NTD 1) was
defined by the first occurrence of R. pa/eacea (Barron,
1983, 1985b). The present study, however, refined thespecies concept of R. pa/eacea and therefore the base of
the zone is not coincident with the first appearance of R.
pa/eacea s. str. Instead, the first abundant occurrence of
R. fennerae appears to approximate the base of this zone
defined by Barron (1983), and therefore this datum plane
is proposed to replace the first occurrence of R. pa/eacea
as the base of the R. pa/eacea Zone.

982.

Diatom genus Rossiel/aBaldauf, J.G. and Barron, J.A., 1991 : Diatom biostratigraphy: Kerguelen Plateau and Prydz Bay regions of theSouthern Ocean. In, Barron, J.A., larsen, B., et al.,Proceedings of the Ocean Drilling Program, Scientific
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Diatom genus Rossiella

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19

Yukio Yanagisawa

20

Appendix table. Occurrence of Rossiella species in DSDP Holes 70A, 71 and 77B. Diatom
zones after Barron (1985b) and Fenner (1985). Preservation: G=good, M=moderate, P=poor.
Abundance: A=abundant, C=common, F=few, R=rare. Abundance of each species, A=Abundant (>8%), C=common (5-7%), F=few (2-4%), R=rare «1%).
~

~

!!

Diatom zones

.!!

NTD
N. miocenica

0'"

C. yabe;Actinocyciw!!

Diatom zones~

29 ·302 ·3NTD

Craspedodisclls

G A

1~

M ~
e .il
"- <

2

71

28 ·4 . 70 ·72

M R

71

28 ·6 . 70 ·72

P R

e0

8

."~

~

.s
.~

t

~

~

~

~

§

&. o.!<,

0U

14 ·6 • 148 ·149 G A

71

29 ·2 . 70 ·72

P R

15 ·6

77 ·78

G A

R

F

71

29 ·4 • 70 ·72

P RFlOA 77B

17 ·1

18 ·20

M A

R R

71

29 ·6 . 70 ·72

M e

R

77B

17 ·6

23 ·25P R

30 ·2 . 70 ·72

M e

R

\8 ·2

23 ·25

P R

R
R R

71

77B

71

30 ·4 . 69 ·71

M F

R

77B

18 ·6

38 ·40

G A

R R

71

30 ·6 . 45 ·46

P R

F

77B

19 ·2

38 ·40G A

R

71

30 ·6 . 70 ·72

M e

R

77B

19 ·6

38 ·4038 ·40R R
R

31 ·2 . 70 ·72

20 ·2

M e
P e

71

77B

71

31 ·4 . 70 ·72

M e
M F

R

77B

20 ·2

59 ·60G A

F

71

31 ·6. 70 ·72

P R

R

77B

20 ·4

30 ·31P R

R

71

32 ·2 • 125 • 129 M e

R

F

77B

20 ·6

38 ·40G A

F

71

32 ·6 • 125 • 129 M e

Re

77B 21 ·2

38 ·40P A

R

71

33 ·2 • 87 ·89

M R

77B 21 ·6

35 ·37P F

F

71

33 ·5 • 75 ·80

M F

77B

22 ·2

35 ·3734 ·2 • 87 ·89

M F

22 ·6

35 ·37

M A
G A

71

77B

R R

71

34 ·4 .125 • 129 M e

77B

23 ·2

35 ·37P R

R

71

34 ·6 . 132 • 136 M F

77B

23 ·6

35 ·37P R

R

71

35·2.\32·136 M e

R

77B

24 ·2

35 ·37P R

R

71

35 ·6 . 125 • 129 M Ae

5B 77B

24 ·6

20 ·22987diorama6

FelegalJS

R

R

Ie

IB

Rossiella
pa/eacea

~

~

~.

F

lOB 77B

R.~'71" 28 ·2'" . 70 ·72 G A ~ 'R" '" '" '"

.!!

~

g
=

~

.~

liB 77B

C. gigas

C. I~;sianus~ ~ ::;.a, o.!<,

~

.
.
.g
~

~

~

G A

\3 ·1 · 100 ·101 G A
\3 ·3

~

"-

12A 77B

coscinodiscus

var.

~ <~

~

'"

12 ·1

moronensis

Craspedodiscus

U8

12B 77B
77B
N.porlui

e0

. 'j

t
ei .
.'"
1 ~ '". '" '" '" '"
.g

.~

R

F

R

R
R
F

R

e

R

P e

R

71

36 ·2 • 125 • 129 M R

R

F

71

19 ·2 .108·110 P R

F71

36 ·6 • 79 ·80

R

R

71

19 ·4

90 ·92P e

F

71

36 ·6 • 125 • 129 M e

71

19 ·6

86 ·88P Re71

37 ·2 . 87 ·89

R

e

71

20 ·2

88 ·90

P R

F

71

M e
37 ·4 . 100 • 102 M e

R

F

71

20 ·6 • 108 ·110 P Ae71

37 ·5 . 87 ·89

R

e

71

21 ·4

60 ·6271

38 ·2 . 125 . 129 P e

e

21 ·6

90 ·9338 ·4 • 80 ·81

P R

e

22 ·2

88 ·90

R
e

71

71

M A
P A
G A

F

71

71

39 ·1 . 87 ·89

M F

F

71

22 ·4

29 ·31P A

e

71

39 ·2 . 87 ·89

M R

71

22 ·6 • 116 ·118 P FF71

40 ·2 • 87 ·89

P R

71

23 ·2 • 117 ·119 P e

R71

40 ·6 • 87 ·89

P R

71

23 ·4

77 ·79P R

R

71

41 ·1 • 87 ·89

P R

R

71

24 ·2

78 ·80G e

R

71

42 ·1 • 91 ·92

P R

R

Denliculopsis

71

24 ·4

45 ·46

P A

R

BogorDvia

71

42 ·2 • 87 ·89

nicobarica

71

24 ·6

45 ·47

P A

F

veniamini

71

42 ·4 • 87 ·89

P R
M e

R

71

R

71

42 ·6 . 87 ·89

M F

71

25 ·1 • 128 ·130 P R
25 ·3
96 ·98 P A

F71

45 ·2 . 61 ·62

M R

R

71

25 ·5

92 ·94P R

F

71

47·2.106·107 P R

e

71

26 ·2

70 ·72P R

R

Rocella71

26 ·4

70 ·72G A

F

viaiJans

71

26.6

70 ·72P R

R

71

27 ·1 • 100 ·102 P R

Ceslodiscus

pepulum

5A

4B

4A

Triceral;um
pileus3

IA

Rocellagelida

b

a

G A

M e

R

R
R

71

47 ·5 . 59 ·60

P A

A

70A

8 ·4 • 83 ·84

P R

A

70A

12 ·3 • 90 ·91

G A

Trans. Proc. Palaeont. Soc. Japan, N.S., No. 177, pp. 21-42, 18 Figs., April 30, 1995

Cenozoic diatom genus Bogorovia Jouse .
An emended description
YUKIO YANAGISAWA
Geology Department, Geological Survey of Japan, 1-1-3 Higashi, Tsukuba, Ibaraki 305 Japan

Received 25 August 1994; Accepted 10 February 1995
Abstract. An emended definition of the fossil diatom genus Bogorovia Jouse is presented along witha detailed description of eight species. The stratigraphic range and geographic distribution of eachspecies are provided based on analysis of deep-sea cores and literature survey. The genus isclosely related to the genus Ressiella Desikachary et Maheshwari, but is distinguished from the latter
mainly by the presence of transapical costae. It also shows a close resemblance to Koizumia
Yanagisawa, but differs mainly by the structure of the marginal ridge. On the basis of certain
characteristic features, the genus Bogorovia can be placed in the family Cymatosiraceae Hasle, vonStosch et Syvertsen. Four new species are described and two new combinations are established;
Bogorovia barronii Yanagisawa sp. nov., B. curvata Yanagisawa sp. nov., B. puncticulata Yanagisawa
sp. nov., B. rostrata Yanagisawa sp. nov., B. gombosii (Desikachary) Yanagisawa comb. nov. and B.
lancettula (Schrader) Yanagisawa comb. nov.
Key words: Taxonomy, diatom, Bogorovia, fossil, biostratigraphy
Introduction
Bogorovia is a diatom genus erected by Jouse (1973) fora Late Oligocene marine diatom, B. veniamini Jouse,
which is of great importance in Late Oligocene to Early
Miocene diatom marine biostratigraphy (e.g. Fenner,
1985; Barron, 1985b). A detailed morphologic and biostratigraphic examination of the genus Bogorovia and its
related genus Rossiella Desikachary et Maheshwari hasrevealed the need for taxonomic revision of this diatom
group, showing that there are three distinct subgroups
that merit separate generic recognition; Bogorovia
emended, Ressiella emended and Koizumia gen. nov.
The latter two genera are dealt with elsewhere (Yanagis-

awa, 1994, 1995).
In this paper, an emended definition of the genus
Bogorovia is presented along with detailed descriptions of
its eight members. Furthemore, the stratigraphic range
and geographic distribution of each species are established on the basis of analysis of deep-sea cores andliterature survey.
Material and methods
For biostratigraphic study, samples from the Upper
Oligocene to Upper Miocene sections of DSDP Holes 71,
77B and 70A in the eastern equatorial Pacific were used
(Table 1). Slides of some selected samples studied by

Table 1. Cores and samples used in this study.
No. Cores & samples

Area

Location

Formation

References and remarks

Eastern equatorial Pacific

6°20.08' N. 140°21.72' W

DSDP core Tracey et al. (1971)

2 DSDP Hole 71

Eastern equatorial Pacific

4°28.28' N. 140°18.91' W

DSDP core Tracey et al. (1971), Barron (1983)

3 DSDP Hole 77B

Eastern equatorial Pacific0°28.90' N, 133°13.70' W

DSDP core Hays et al. (1972), Barron(l981 b, 1983)

4 DSDP Hole 438A Northwest Pacific

40°37.79' N, 143°14.15' E

DSDP core Scientific Party (1980), Barron(l980b)

5 P 225

Central equatorial Paci fic

3°13.32' N, 169°41.65' W

Piston core Nishimura (1986)

6 P3

Indian Ocean off Java

11°59.04' S, 113°31.37' E

Piston core

Yanagisawa (1987), Honza et al. (1987)

7 M32

Ajigaura, Ibaraki, Japan

36°22.82' N, 140°37.42' E

Isozaki F.

Maruyama (1984)

8 A-I

Tomioka, Fukushima, Japan 37°20.26' N, 140°59.31' E

Drill core

Yanagisawa et al. (1989)

DSDP Hole 70A

Yukio Yanagisawa

22

Barron (1983, 1985a) and the slides deposited in the DSDP
Reference Center in the National Science Museum(Tokyo) were examined in this study. Samples from theLower Miocene through Quaternary section of DSDP Hole
438A in the northwestern Pacific were also analyzed.
Slides analyzed by Akiba et at. (1982), Maruyama (1984)
and Akiba (1986), together with those deposited in the
DSDP Reference Center in the National Science Museum(Tokyo) were re-examined with special attention to thegenus Bogorovia. For taxonomic study and SEM observations, several selected samples were used to supplement the DSDP samples (Table 1).
Preparation methods for light and scanning electron
microscopy (SEM) were described in Yanagisawa (1994).
Results and discussion
As a result of taxonomic study, eight species arerecognized, including four new species and two new
combinations as follows: Bogorovia barronii Yanagisawa
sp. nov., B. curvata Yanagisawa sp. nov., B. gombosii(Desikachary) Yanagisawa comb. nov., B. tancettuta(Schrader) Yanagisawa comb. nov., B. praepateacea(Schrader) Jouse, B. puncticutata Yanagisawa sp. nov., B.

rostrata Yanagisawa sp. nov., B. veniamini Jouse ex
Yanagisawa

Morphology
Morphologic terminology for the genus was introducedin Yanagisawa (1994), and general terminology fordescription of frustule follows Anonymous (1975), Ross etat. (1979), Simonsen (1979) and Round et at. (1990).
The valve outline of this genus is linear-Ianceolate andisopolar (Figure 1). The apical axis is generally straight
except for B. curvata which has a curved apical axis.
The apex is rostrate with an apical pore field consisting offine puncta. All species have transapical costae (ribs)
which extend from both valve margins. The costae are
generally continuous, but some of them are interrupted at
the middle. For description, the spacing of transapicalcostae is classified into two categories; narrowly spaced
type (9-14 costae in 10 .um) and broadly spaced type (68.5 costae in 10.um).
All members of this genus have marginal ridges of the
fused-type wherein the marginal ridges of sibling valves
are completely fused so that a set of fused sibling valves
seems as if it were a frustule (Figure 1). The marginal
ridge is either of type 3 or type 2 (See Yanagisawa, 1994).

Rimoportula

AreolaeMarginal ridge

Transapical costa

Pair of--{sibling valves~~~~~§§~~~

Frustule

Outer openingof rimoportula-{~:§~~~~;
Separating valve

Figure 1. Structure of a chain of frustule of Bogorovia puncticulata Yanagisawa sp. nov.

983.

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f---

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200- 70A I--'-"m

r-u-

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f---

a

Figure 2. Stratigraphic distribution of Rossiella and Bogorovia species in DSDP Holes 77B, 71 and 70A.
Narrow horizontal lines show samples examined. Each dot indicates the presence of each species. Original
data are presented in Appendix table and appendix table in Yanagisawa (1995).

Q
,~

0

~

Yukio Yanagisawa

24

The type 3 is a fused-type marginal ridge with threelongitudinal rows of pores. The type 2 marginal ridges
have two longitudinal rows of pores. Bogorovia species
may form a long chain colony by the fusion of their
marginal ridges (Figure 1). In some species, valves withthe separate-type marginal ridge are observed. Thesemay be separation valves that may have a role to separate an otherwise interminably long chain into shorter
chains.

Age

Low·latitude
diatom zones e--"-

Bogorovia

NTD

Ma

'<'"3

NPD

NJLm~

17

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l:l

a: N. reinholdii I~

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!SA

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cci

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5

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Q)

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Craspedodiscus

.~
:::;

var. diorama

Q)

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coscinodiscus
C. gigas
C. lewisianus~

9moronensis~ Cestodiscus
peplum

l-

"I

cci

SB

2

>.

~

paleacea-

Rocella gelido

D./aUla3B D. prae/auJa
3A,-",!na1 ae

2Thalassiosira
[raga

I

Thalassiosira

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cci

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spinosa-------

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cci

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D. dimorphaThalassiosira
yabei

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l:l

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6A D. kaJtJ)'<ltnae~

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N. koizumii

1'N.~":::'l.aiica
NeodenticulaHftg N.por/eTi

3

98

kamtschalicaI~
I3A

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R. curvirostris
A. oculatus

7B~

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Q)
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10

14

a:

North Pacificdiatom zones

Bogorovia
veniamini

cci

1

B
co

b

(5
~

Geographic distribution
The geographic distribution of each species was surveyed from literature. The results are shown in Figures
7,10,11,15,17 and 18. All species of the genus are
distributed mainly at low latitudes in the Pacific, Atlantic
and Indian Oceans with rare occurrences at middle latitudes, indicating that they are essentially oceanic warmwater species
Systematics

cci

30 I -

Rocella.~ vigi/ans

Stratigraphic distribution
The stratigraphic occurrences of Bogorovia species arepresented in Figure 2 and Appendix table for DSDP Holes
77B, 71 and 70A. The stratigraphic ranges of eachspecies are shown in Figure 3, which is mainly based on
Figure 2 as well as on some other important biostratigraphic studies such as Baldauf (1985), Baldauf and Barron(1991), Barron (1981a, 1981b, 1983, 1985a, 1985b, 1992),
Fenner (1984a, 1984b, 1985), Fourtanier (1987,1991), Gersonde and Burckle (1990), Harwood and Maruyama (1992),
Sancetta (1982) and Schrader (1973, 1974a, 1974b, 1976).
Correlation to the time scale of Berggren et al. (1985) isadjusted through Barron et al. (1985) and Oda (1986).

nol zoned

00

...J

A rimoportula (Iabiate process) is present generally in"one per cell pattern"; a funstule consists of a process
valve and a non-process valve, and thus this genus isheterovalvate. In the non-process valve, a small structureless area is present where a rimoportula might belocated if it were present. The non-process valve of
Bogorovia puncticulata has a small knob which may be a
reduced rimoportula (Figures 13-1, 13-2), suggesting thatthe rimoportula of the non-process valve may be secondarily reduced. All species have a subcentral rimoportula without exception.
The valve face is convex. In some species, the valve
face is perforated with areolae, but others lack areolae, inwhich case the valve face is hyaline. The areolae of thisgenus are classified into four types for description:
medium (ca. 0.8,um in diameter), fine (ca. 0.4-0.5,um indiameter), very fine areolae (less than 0.1 ,urn in diameter)
and the absence of areolae (hyaline). The areolae arecircular in shape and distributed sparsely and randomlyon the valve face.
The cingulum is composed of a few bands with a rowof small puncta, but its detailed composition is not knownat present.

Ia

Figure 3. Stratigraphic distribution of Bogorovia
species. Low-latitude diatom zones after Barron (1985b)
and Fenner (1985), and North Pacific diatom zones after
Akiba (1986). Correlation to the time scale of Berggren
et al. (1985) is adjusted through Barron et al. (1985) and Oda(1986).

In this paper, the classification system of Round et al.
(1990) is adopted for the description of the genus Bogorovia because the system appears to be the most natural
system at present.

983.

Diatom genus Bogorovia

Class Coscinodiscophyceae Round et Crawford, 1990
Subclass Cymatosirophycidae Round et Crawford, 1990
Order Cymatosirales Round et Crawford, 1990
Family Cymatosiraceae Hasle,
von Stosch et Syvertsen, 1983
Subfamily Cymatosiroideae Hasle,
von Stosch et Syvertsen, 1983

Genus Bogorovia, Jouse, 1973 emend. Yanagisawa
Generic type.-Bogorovia veniamini Jouse ex Yanagisawa
Original description.-Valves lanceolate or linearlanceolate with slightly rostrate ends. No axial area
present. Valve surface with closely packed areolae, intransverse rows near the margin of the valve, elsewhere
randomly arranged. No intercalary bands or pseudosepta present (Jouse, 1973).
Emended description.-Cell heterovalvate, rectangularor lanceolate in girdle view, forming inseparable chain
colonies. Separation valve or end valve separates chain
colonies. Cingula with several bands with or without finepuncta. Valve slightly convex, linear-Ianceolate.
Apices with small apical pore field, mostly rostrate.
Marginal ridge always present, completely fused withsibling valve. Rimoportula one per cell; a frustule consisting of a process valve and a non-process valve.
Rimoportula located at subcentral position near themargin. Transapical costae developed.
Comparison.- The genus resembles the genus Rossie//a Desikachary et Maheshwari, but clearly differs from theTable 2.

25

latter genus mainly by having transapical costae, relatively small areolae or missing areolae. The genus Bogorovia is similar to the genus Koizumia, but the two genera
are distinguished by the type of marginal ridge; Bogorovia has marginal ridges of type 3 or type 2, whereas
Koizumia is characterized by a type 4 marginal ridge(Yanagisawa, 1994). Bogorovia is also discriminatedfrom Koizumia in having randomly distributed areolae on
the valve face, in contrast to the regularly arranged
areolae of Koizumia forming transpical and longitudinalrows.
Bogorovia closely resembles genera in the Cymatosiraceae such as Cymatosira Grunow and Campy/osira
Grunow in Van Heurck in that they commonly possess agenerally dipolar outline, chain colonies connected bymarginal ridge or linking spines, rimoportula in the patternof one per cell, and an ocellus or apical pore field at each
apex; the genus Bogorovia therefore can be included in
the family Cymatosiraceae Hasle, von Stosch et Syvertsen. Jouse (1973) has already suggested that the genus
Bogorovia has some relationship to Campy/osira andCymatosira.
Stratigraphic occurrence.-Late Oligocene to Middle
Pleistocene. The first species of this genus is B. gombosii which appeared in the uppermost part of the b
Subzone of the Rocella vigilans Zone of Fenner (1984a,
1985). The last species R. curvata is found in the
Pseudoeunotia dolio/us Zone (NTD 17).
Habitat.-Because of its dominant occurrence in oceanic sediments, most species of the genus are probably
holoplanktonic, making a long chain formed by fused

Key to species based on light microscopy.

lao Areolae present. .................................................................................................... 2
lb. Areolae absent. .................................................................................................... 6
2a. Areolae medium or fine ....................................................................................... 3
2b. Areolae very fine ................................................................................................. 5
3a. Areolae medium and transapical costae partially developed ............. B. gombosii
3b. Areolae fine and transapical costae well developed ........................................... 44a. Transapical costae broadly spaced and valve relatively large........... B. veniamini
4b. Transapical costae narrowly spaced and valve relatively smalL ....... .B. barronii
5a. Valve with slightly rostrate apices ................................................ B. puncticulata
5b. Valve with strongly rostrate apices ...................................................... B. rostrata
6a. Transapical costae narrowly spaced ..................................................................... 7
6b. Transapical costae broadly spaced ............................................... B. praepaleacea
7a. Valve not curved ............................................................................... B.lancettula
7b. Valve curved ........................................................................................ B. curvata

Yukio Yanagisawa

26

10

39

22

23

24

25

26

27

28

29

31

32

33

34 35

36

37

983.

Diatom genus Bogorovia

27

Figure 5. Scanning electron photomicrographs of Bogorovia gombosii (Desikachary) Yanagisawa comb.
nov. and B. barronii Yanagisawa sp. nov. Scale bars equal 5 .u m. 1,2. Bogorovia gombosii (Desikachary)
Yanagisawa comb. nov. DSDP Hole 71 , 36- 2, 125- 129 cm. (1) Inner view of valve. (2) Oblique view of a setof sibling valves. 3 - 5. Bogorovia barronii Yanagisawa sp. nov. Sample P 225 VII 20, equatorial Pacific. (3,4)
Outer view of a separation valve. (5) Enlarged view of a valve apex with an apical pore field .

marginal ridges.
Geographic dis tribution . -A II species are distributed
mainly in the low- latitude areas of the Pacific, Atlantic
and Indian Oceans, and rarely and sporadically occur also
in the middle- to high - latitude areas .
Key to species based on light microscopy is presented
in Table 2.

Bogorovia gombosii (Desikachary)
Yanagisawa comb. nov.
Figures 4-1,4- 2,5-1,5- 2
Basionym. Rossiella gombosii Desikachary in Desikacharyet al. , 1984, p. 338.
Synonymy. Bogorovia veniamini Jouse, Schrader, 1976, p.
630, pI. 5, figs. 22- 23; Gombos, 1976, p. 593, pI. 1, figs. 6,

7, pI. 12, figs. 2, 4 (non pI. 12, fig. 1) ; Genus et species
indet., Schrader, 1976, pI. 5, fig. 16 ; Rossiella sp., Gombos
and Ciesielski, 1983, p. 604, pI. 24, figs. 1- 2; Rossiella aff.
R. symmetrica Fenner, Fourtanier, 1991, pI. 4, fig . 2.
Additional description. - Valve lanceolate with slightly
rostrate rounded apices, 30 - 64 .u m long, 7 - 10.5,um wide
(Figure 6). Valve face slightly convex, covered withrounded medium areolae distributed randomly andsparsely, 6 - 7 in 10,um. On both valve sides, numerous
transapical costae present, 7 - 8.5 in 10,um , incomplete,
not reaching valve center (Figure 5 - 1). Marginal ridge,
fused - type with three longitudinal rows of rounded pores(type 3), 7 - 8.5 pores in 10,um (Figure 5 - 2). A small porefield present at each apex. A subcentral rimoportula,
one per cell, located near edge of valve face.

Figure 4. Light photomicrographs of Bogorovia species. Scale bar equals 10.um. 1, 2. Bogorovia gombosii(Desikachary) Yanagisawa comb. nov. DSDP Hole 71 , 37 - 5, 87- 89 cm . 3. Bogorovia veniamini Jouse ex Yanagisawa (an intermediate form to Bogorovia barronii). DSDP Hole 71 , 34- 4, 125- 129 cm . 4 -10. Bogorovia veniamini
Jouse ex Yanagisawa. (4, 6) DSDP Hole 71 , 37- 2, 87- 89 cm. (5) DSDP Hole 71 , 33- 2, 87- 89 cm. (7) DSDP Hole
71 , 36- 2, 125- 129 cm. (8) DSDP Hole 71 , 42- 2, 87 -89 cm. (9) DSDP Hole 71 , 31 - 2, 70- 72 cm. (10) DSDP Hole 71 ,39- 1, 87- 89 cm . 11-14. Bogorovia barronii Yanagisawa sp. nov. (14) holotype. (11 , 13, 14) DSDP Hole 71 , 26- 4,
70- 72 cm. (12) DSDP Hole 71,29- 4, 70- 72 cm. 15,16. Bogorovia puncticulata Yanagisawa sp. nov. (primitiveform). (15) holotype, P 225, VII 20, equatorial Pacific. (16) DSDP Hole 71 , 29- 4, 70- 72 cm. 17- 20. Bogorovia
puncticulata Yanagisawa sp. nov. (advanced form). (17) P 225, VII 20. (18) DSDP Hole 77B, 23- 2, 35- 37 cm . (19)DSDP Hole 77B, 15- 6, 77- 78 cm. (20) M 32, Isozaki Formation , Ajigaura area, Japan. 21. Bogorovia rostrata
Yanaisawa sp. nov. Holotype, DSDP Hole 77B, 23- 2, 35- 37 cm. 22 - 28. Bogorovia lancettula (Schrader) Yanagisawa comb. nov. (22) DSDP Hole 77B, 19- 6, 38- 40 cm. (23) DSDP Hole 77B, 17-1, 18- 20 cm . (24) DSDP Hole
77B, 20- 2, 38- 40 cm. (25) DSDP Hole 778, 20- 6, 38- 40 cm . (26) DSDP Hole 77B, 17- 6, 23- 25 cm. (27, 28)
DSDP Hole 778, 19- 6, 38- 40 cm. 29- 31. Bogorovia praepaleacea (Schrader) Jouse. DSDP Hole 778, 12- 1, 29- 30
cm. 32,33. Bogorovia puncticulata Yanagisawa sp. nov. (girdle views). (32) M 32, Isozaki Formation. Ajigauraarea, Japan. (33) DSDP Hole 71 , 29- 4, 70- 72 cm. 34, 35. Bogorovia lancettula (Schrader) Yanagisawa comb. nov.
(girdle views). (34) DSDP Hole 778, 20- 6, 38- 40 cm . (35) DSDP Hole 77B, 19- 6, 38- 40 cm . 36,37. Bogorovia
praepaleacea (Schrader) Jouse (girdle views). DSDP Hole 778, 17- 6, 23- 25 cm . 38- 40. Rossiella curvata
Yanag isawa sp. nov. P 3CC, Sunda Forearc off Java Island. (39) holotype.

Yukio Yanagisawa

28
60

A
50
40

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6 10

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10

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Length (11m)

50

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7

8
9
10
Width (11m)

Figure 6. Size variation in Bogorovia gombosii (Desikachary) Yanagisawa comb. nov. A. Scatter plot ofvalve width versus length. B. Scatter plot of valve length versus the number of transapical costae in 10 ,urn.
C. Scatter plot of valve width versus the number of transapical costae in 10 ,urn. Samples from no. 2 in Table
1.

Figure 7. Geographic distribution of Bogorovia gombosii (Desikachary) Yanagisawa comb. nov. Closed
circles: localities reported with figures. Open circle: locality reported without figures. 1. DSDP Hole 71,
equatorial Pacific (this study). 2. DSDP Hole 575A, equatorial Pacific (Fourtanier, 1987). 3. DSDP Hole 758,
equatorial Indian Ocean (Fourtanier, 1991). 4. DSDP Hole 278, Pacific sector of the Southern Ocean (Schrader,1976). 5. DSDP Hole 3288, South Atlantic (Gombos, 1976). 6. DSDP Hole 513A, South Atlantic (Gombos andCiesielski, 1983). 7. DSDP Hole 5188, South Atlantic (Gombos, 1983).

11

983.

Diatom genus Bogorovia

Comparisons .-Bogorovia gombosii bears a close
resemblance to Rossiella symmetrica , but differs from thelatter species by the presence of transpical costae andmore sparsely distributed smaller areolae on valve face.
It is also similar to Bogorovia veniamini, but distinguishedby its larger and more sparse areolae and the less developed transapical costae.
The species was first recognized by Gombos andCiesielski (1983) as Rossiella sp., but Fenner (1984a,
1984b) regarded it as synonymous with R. symmetrica.
Desikachary et at. (1984) erected the species based on
Gombos and Ciesielski 's (1983) specimen, but no one else
has referred to it to date. Fourtanier (1991) reported it as
Rossiella aft. R. symmetrica.
Stratigraphie range .-At low- latitudes, the first occurrence of this species is in the upper part of the Rocella29

vigitans Zone. It last occurs near the top of the A
Subzone of the R. pateacea Zone (NTD 1A) (Figures 2, 3).
Geographic distribution. - The species occurs in theequatorial Pacific (Fourtanier, 1987, this study), the equatorial Indian Ocean (Fourtanier, 1991) and the Southern
Ocean (Schrader, 1976; Gombos, 1976, 1983; Gombos
and Ciesielski, 1983) (Figure 7).

Bogorovia veniamini Jouse ex Yanagisawa
Figures 4- 3- 10, 8-1- 9.
Jouse, 1973, p. 351, pI. 4, figs. 1- 3 ; Jouse, 1976, p. 1233, figs.
1- 3 ; Jouse ed., 1977, pI. 54, figs. 1- 5 ; Barron, 1983, p.
512, pI. V, fig. 3; Barron, 1985a, pI. 8, fig. 12; Fenner,
1985, p. 727; Barron , 1985b, p.780, fig. 9.5 ; Kim andBarron, 1986, p. 177, pI. 5, figs. 11-12 ; Fourtanier, 1991, pI.

Figure 8. Scanning electron photomicrographs of Bogorovia veniamini Jouse ex Yanagisawa. DSDP
Hole 71 , 36- 2, 125-129 cm . Broad and narrow scale bars equal 5 Jim and 1 Jim , respectively. 1,2. Two setsof fused sibling valves. Arrows indicate the outer openings of rimoportulae. 3,4. Inner views of a valve,
showing a rimoportula (arrow heads). 5, 6. Outer views of a separation valve with separated- type marginal
ridge. 7. Inner view of a non- process valve (the opposite side of the specimen shown in Figs. 8- 3, 8- 4). 8,
9. Enlarged views of an apex with an apical pore field.

Yukio Yanagisawa

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4

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Length (Jlm)

Width (Jlm)

80

100

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Width (Jlm)

Figure 9. Size variation in Bogorovia veniamini Jouse ex Yanagisawa and B. barronii Yanagisawa sp. nov.
A. Scatter plot of valve width versus length. B. Scatter plot of valve length versus the number of transapicalcostae in 10 ,urn. C. Scatter plot of valve width versus the number of transapical costae in 10 ,urn. Samples
from nos. 2, 3, 5 in Table 1.

4, fig. 3; Radionova, 1991, p.98, pI. 23, fig. 7.
Additional description.-Valve linear-Ianceolate withslightly rostrate rounded apices, 18-82,um long, 6.5-12,urn wide (Figure 9). Valve face convex, densely punctuated by fine areolae distributed randomly, 8-10 areolaein 10 ,urn. Transapical costae, 5.5-8 in 10,um, extend
from both sides to form a zigzag-longitudinal line in valve
center. Marginal ridge, fused-type with three longitudinal rows of large round pores (type 3),5-6 pores in 10)lm(Figure 8-2). A small pore field is present at each apex
(Figure 8-8). A subcentral rimoportula, one per cell,
located near valve edge with an internal lip-shaped
opening (Figures 8-3, 8-4). Non-process valve with asmall hyaline area which a rimoportula might occupy if
present (Figure 8-7). Cingulum consisting of two or threebands (Figures 8-1, 8-2). Separation valves with a separated-type marginal ridge (type 1) are sometimes observed (Figures 8-5, 8-6; Fourtanier, 1987, pI. 14, fig. 5).
Holotype.-Plate 4, fig.1 in Jouse (1973) designated inthis paper (deposited in the collections of the Micropaleontological Laboratory of the Institute of Oceanology,
Academy of Science of Russia).
Type locality and sample.-R/V "Vityaz" Station 5996/
8, 630 cm depth in a core, 10 58'N, 153°23'W, central
equatorial Pacific (Early Miocene in age).
Comparisons.-Bogorovia veniamini resembles B. gombosii but differs by the smaller and denser areolation andthe well-developed transapical costae. It is discriminated from B. barronii by the broader and larger valve andwider spacing of transapical costae (Figure 9).
Stratigraphic range.- The first occurrence of this
speCies defines the base of the Bogorovia veniamini Zone0

(Fenner, 1984b) (Figure 3). Its last occurrence defines the
top of the R. paleacea Zone (NTD 1) (Barron, 1983). This
species is one of the most abundant constituents of thelate Oligocene to earliest Miocene marine diatom assemblage.
Geographic distribution.- The species is found abundantly at lOW-latitudes in the Atlantic, Pacific, and Indian
oceans (e.g. Jouse, 1973,1976; Barron, 1983; Fenner,
1985; Fourtanier, 1991; Radionova, 1991) and also in theSouthern Ocean (e.g. Baldauf and Barron, 1991 ; Harwood
and Maruyama, 1992) (Figure 10). It also occurs in Baja
California (Kim and Barron, 1986), the North Atlantic andnorthern Italy (Monjanel, 1987), but not in the high-latitude
North Pacific (Akiba et al., 1993).
Discussion.-As pointed out by Sancetta (1985), no
specimen was designated as holotype of this species by
Jouse (1973), and as no further action has been taken inthis regard, the species has remained invalid according to
Article 37 of the International Code of Botanical Nomenclature. It is hereby validated by the above designationof a holotype.
When Desikachary et al. (1984) clarified the taxonomyof the genus Rossiella, they did not transfer Bogorovia
veniamini Jouse to Rossiella bacause the species is sodifferent from the members of Rossiella in having transverse rows of areolae with distinct transverse (transapical)
costae. However, this taxonomic treatment of Desikachary et al. (1984) is apparently incosistent with theiradmission of Rossiella praepaleacea (Schrader) Gersondeet Schrader and the establishment of Rossiella gombossi
Desikachary, because the two species have the distinct
transapical costae which is one of the important featuresof the genus Bogorovia. Gersonde and Schrader (1984)

983.

Diatom genus Bogorovia

31

.-

07

08

09

Figure 10. Geographic distribution of Bogorovia veniamini Jouse ex Yanagisawa. Closed circles: localities reported with figures. Open circles: localities reported without figures. 1. DSDP Hole 71, equatorial
Pacific (this study; Barron, 1983, 1985b). 2. DSDP Hole 575A, equatorial Pacific (Barron, 1985a; Fourtanier,
1987; Radionova, 1991). 3. R/V "Vityaz" 5996, equatorial Pacific (Jouse, 1973, 1976; Jouse et al., 1977). 4.
San Gregorio Formation, La Ventana, Baja California, Mexico (Kim and Barron, 1986). 5. DSDP Hole 758,
equatorial Indian Ocean (Fourtanier, 1991). 6. DSDP Hole 714, equatorial Indian Ocean (Fenner and Mikkelsen,1990). 7. DSDP Hole 747A, Indian sector of the Southern Ocean (Harwood and Maruyama, 1992). 8. DSDP
Hole 748B, Indian sector of the Southern Ocean (Harwood and Maruyama, 1992). 9. DSDP Hole 744A, Indian
sector of the Southern Ocean (Baldauf and Barron, 1991). 10. DSDP Hole 278, Pacific sector of the Southern
Ocean (Fenner, 1984a). 11. DSDP Hole 357, South Atlantic (Fenner, 1984a). 12. DSDP Hole 366A, equatorial
Atlantic off Africa (Fenner, 1984a, 1984b). 13. DSDP Hole 369A, northeast Atlantic (Schrader, 1977; Fenner,
1984a, 1984b). 14. DSDP Hole 116, Rockall Plateau, North Atlantic (Monjanel, 1987). 15. Tripoli di Contignaco,
north Italy (Monjanel, 1987).

and Barron (1985b) also did not transfer Bogorovia
veniamini to the genus Rossiella without giving any reasons.

Bogorovia barronii Yanagisawa sp. nov.
Figures 4-11-14,5-3-5.
Synonym. Bogorovia sp., Akiba, 1980, p. 11, pI. 4, fig. 48.

Oescription.-Valve linear-Ianceolate with slightly rOStrate rounded apices, 20-43 j.lm long, 4.5-6.5 j.lm wide
(Figure 9). Valve face convex, covered with fine areolae,
10-12 in 10 j.lm. Transapical costae, 10-11.5 in 10 j.lm.
Marginal ridge, fused-type with three longitudinal rows ofpores (type 3), 10 pores in 10 j.lm. A small pore field ispresent at each apex (Figure 5-5). A subcentral rimoportula, one per cell, located near the valve edge. A separation valve with separated-type mariginal ridge (type 1) isobserved (Figures 5-3, 5-4).
Holotype.-Figure 4-14 (GSJF12755 deposited in the
Geological Survey of Japan).
Type locality and sample.-DSDP Hole 71, Core 26,

Section 4, Interval 70-72 cm, 4'28.28'N,140'18.91'W,
eastern equatorial Pacific (Early Miocene in age, theTriceratium pileus Zone, NTD 3).
Comparisons.-This species is very similar to Bogorovia veniamini, but it differs by its mOre narrowly spacedtransapical costae and narrower valve (Figure 9). It also
resembles B. puncticulata but is distinguished from thelatter species by its larger areolae.
Stratigraphic range.-At low-latitudes, the species
OCCurS from the middle part of the B subzone of the R.
paleacea Zone (NTD 1B) to the uppermost part of the T.
pileus Zone (NTD 3) (Figure 3). Reworked specimens are
sometimes found in the middle Miocene intervals in DSDP
Holes 71 and 77B (Figure 2).
Geographic distribution.- This new species has beenfound in DSDP Holes 71 and 77B, COre P 225 recovered inequatorial Pacific (this study), the Early Miocene HotaGroup in the Boso Peninsula, Japan (Akiba, 1980) and
DSDP Hole 545 in the North Atlantic off Africa (Monjanel,1987) (Figure 11).
Etymology.- The species name is dedicated to Dr.
John Arthur Barron, who has worked extensively on

32

Yukio Yanagisawa

Figure 11. Geographic distribution of Bogorovia barronii Yanagisawa sp. nov. Closed circles : localities
reported with figures. 1. DSDP Hole 71 , equatorial Pacific (this study). 2. DSDP Hole 77B, equatorial Pacific(this study). 3. Geological Survey of Japan piston core P 225, equatorial Pacific (this study). 4. Hota Group,
Boso Peninsula, Japan (Akiba, 1980). 5. DSDP Hole 545, northeast Atlantic off Africa (Monjanel, 1987).
marine diatom biostratigraphy and supplied the author thetype material of this species.

Bogorovia puncticulata Yanagisawa sp. nov.
Figures 4-15- 20, 4- 33,4- 34,12- 1- 5,13-1- 11 .
Synonymy. Bogorovia veniamini Jouss, Fourtanier and Machars, 1988, pI. 2, fig. 17; Rossiella sp. 1, Fourtanier, 1991,
pI. 4, fig. 6 ; Rossiella cf. lancettula (Schrader) Gersondeand Schrader, Yanagisawa, 1993, pI. 2, fig. 3.
Oescription. - Valve linear- Ianceolate with slightly rostrate rounded apices, 13- 51 jim long, 4 - 7 jim wide (Figure14). At each apex, an apical pore field is present (Figure12- 5). Valve face convex, punctated by very fineareolae, densely in the primitive form (10- 12 in 10 jim) andsparsely in the advanced form (8- 10 in 10 jim) . Transapical ribs, 8.5 - 14 in 10 jim. Marginal ridge, fused - typeFigure 12. Scanning electron photomicrographs of Bogorovia puncticulata Yanagisawa sp. nov. (primitiveform). Sample P 225, VII 20, equatorial Pacific. Broad and narrow scale bars equal 5,um and 1 ,um, respectively. 1. Inner view of a set of sibling valves. 2,3. Inner views of a separation valve. Arrow indicates arimoportula. 4. Enlargement of Fig. 12- 1, showing the outer opening of a rimoportula (arrow). 5. Enlarged
view of a valve apex with an apical pore field.

983.

Diatom genus Bogorovia

33

Figure 13. Scanning electron photomicrographs of Bogorovia puncticulata Yanagisawa sp. nov. (advancedform). Sample M 32, Isozaki Formation, Ajigaura area, Japan. Broad and narrow scale bars equal 5 Jim and
1 Jim , respectively. 1,3. Inner views of a non - process valve. Arrows indicate a small knob which may be a"reduced " rimoportula. 2, 4. Inner views of a process valve (the opposite side of the specimen shown in Figs.
13-1, 13- 2). Arrows indicate a rimoportula. 5. Girdle view of a set of sibling valves with fused - type marginal
ridge (type 3). 6,7. Outer views of a separation valve with separated - type marginal ridge (type 1). 8. Enlarged view of an apex with an apical pore field. 9. Oblique view of a set of sibling valves. Arrow indicates theouter opening of a rimoportula. 10,11. Views of valve interior and marginal ridge. Each arrow indicates arimoportula.

with three longitudinal rows of pores (type 3), 8- 10 poresin 10 Jim (Figure 13-1). Separation valve exceptionallyhas separated - type marginal ridge with one row of pores(type 1) (Figures 12- 2,13- 6). A subcentral rimoportula,
one per cell, located near valve edge with its internal lipshaped opening oriented diagonal to apical axis, and witha small external pore at the marginal ridge (Figures 13- 4,
13-11). Non-process valve with a small knob at theposition which a rimoportula might occupy if present(Figure 13- 2).
Holotype. - Figure 4- 15 (GSJF14593 deposited in the
Geological Survey of Japan).
Type locality and sample. - Piston core sample P225,
VII 20 cm (570 cm from the core top); 3°13.32' N,
169°41.65'W, 5,427 m in water depth, central Pacific.
The core was recovered by GH81 - 4 Cruise of the Geologi-

cal Survey of Japan (Nishimura, 1986). Core P225,768
cm in thickness, is composed of the upper Pleistocene
unit and the lowermost Miocene unit, which are bounded
by a hiatus 268 cm from the top. The type sample istaken from the lower unit of dark brown siliceous ooze.
The radiolarian fauna indicates Early Miocene age, ranging from 20.7 to 23.2 Ma (Nishimura, 1986). The diatom
assemblage from the sample is correlative with theTriceratium pileus Zone (NTD 3) of Barron (1985b).
Comparisons .-This species differs from Bogorovia
lancettula and B. praepaleacea by the presence of areolaeon the valve face. It is distinguished from B. barronii byfiner areolation. The species is similar to B. rostrata, butdiffers by its more slender valve outline and not sostrongly rostrate apices (Figure 14).
Stratigraphic range. - This species occurs from theYukio Yanagisawa

34

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20

30

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Length (~m)

50

60

3

4

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10

Width(~m)

Figure 14. Size variation in Bogorovia puncticulata Yanagisawa sp. nov. and B. rostrata Yanagisawa sp.
nov. A. Scatter plot of valve width versus length. B. Scatter plot of valve length versus the number oftransapical costae in 10 ,um. C. Scatter plot of valve width versus the number of transapical costae in 10 ,um.
Samples from nos. 2-5, 7,8 in Table 1.
upper part of the C Subzone of the R. paleacea Zone (NTD
1C) to the top of the 8 Subzone of the Coscinodiscus
yabei Zone (NPD 108) in the equatorial Pacific (Figures 2,3). It was found from the upper part of the Denticulopsis
praedimorpha Zone (NPD 58) to the lower part of theThalassiosira yabei Zone (NPD 5C) in DSDP Hole 438A
(Yanagisawa, 1994, fig. 6), but this range is much shorter
than that in the low-latitude.
Geographic distribution.- This new species is foundcommonly in the equatorial Pacific (this study) (Figure 15).
The species also has been figured from the equatorial
Indian Ocean (Fourtanier, 1991) and the Cabellas Formation in Peru (Fourtanier, 1987, Fourtanier and MacharE3,
1988). It occurs in DSDP Hole 438A and several
Japanese on-land sections (this study; Yanagisawa,1993).
Discussion.- The species shows a typical phyleticchange with gradual reduction of areolae through time.
The older primitive form has densely perforated puncta(Figures 4-15, 12-1-5), whereas the younger advanced
form is characterized by sparsely distributed areolae on
the valve face (Figures 4-16-20, 13-1-11). The youngest form carries only a few puncta (Figure 4-19), showing
very close resemblance to B. lancettula.
Etymology.- The species name is derived from its
minutely punctated valve face.

Bogorovia rostrata Yanagisawa sp. nov.
Figure 4-21.

Description.-Valve broadly lanceolate with strongly
rostrate rounded apices, 29-43,um long, 8.5-9.5,um wide
(Figure 14). Valve face convex, sparsely punctated byvery fine areolae, 8-10 in 10 ,um. Transpical ribs, 9.5-10
in 10,um. Marginal ridge, fused-type with three longitu-

dinal rows of pores (type 3), 10 pores in 10,um. A subcentral rimoportula, one per cell, located near valve edge.
Holotype.-Figure 4-21 (GSJF12808 deposited in the
Geological Survey of Japan).
Type locality and sample.-DSDP Hole 778, Core 23,
Section 2, Interval 35-37 em, 0'28.90'N, 133'13.70'W,
eastern equatorial Pacific (Middle Miocene in age, theCoscinodiscus lewisianus Zone, NTD 6).
Comparisons.-Bogorovia rostrata is very similar to theadvanced form of B. puncticulata in having sparsely
distributed small puncta on the valve face, but distinctly
differs from the latter by its very broad form with strongly
rostrate apices (Figure 14).
Stratigraphic range.- The species has its first occurrence in the lower part of the Coscinodiscus lewisianus
Zone (NTD 6) and its last occurrence in the lowermost
Actinocyclus moronensis Zone (NTD 9) (Figures 2, 3).
Geographic distribution.-At present, this species isfound only in DSDP Hole 778 (Figure 15).
Etymology.- The species is named from its strongly
rostrate apices.

Bogorovia lancettula (Schrader)
Yanagisawa comb. nov.
Figures 4-22-28,4-34,4-35.
Basionym. Cussia lancettula Schrader, 1974a, p.532, fig. 1 :5,9-10Synonymy. Cussia lancettula Schrader, Schrader, 1974b, p.
914, pI. 19, fig. 16 (non pI. 19, figs. 14-15); Schrader andFenner, 1976, p. 975; Kulm et al., 1981, pI. 1, fig. 11 ;Cussia sp. cf. C. lancettula Schrader, Barron, 1980a, pI. 6,
fig. 18; Rossiella lancettula (Schrader) Gersonde andSchrader, 1984, p.106.

Additional description.-Valve linear-Ianceolate with

983.

Diatom genus Bogorovia

35

Figure 15. Geographic distribution of Bogorovia puncticulata Yanagisawa sp. nov. and B. rostrata Yanagisawa sp. nov. Closed circles: R. punticulata localities reported with figures. Open circles: R. punticulata
localities reported without figures. Open triangle: R. rostrata localities reported with figures. 1. DSDP Hole71, equatorial Pacific (this study). 2. DSDP Hole 778, equatorial Pacific (this study). 3. Geological Survey ofJapan piston core P 225, equatorial Pacific (this study). 4. Caballas Formation, Pisco, Peru (Fourtanier andMachan!!, 1988; Fourtanier, 1987). 5. M 32, Isozaki Formation, Ajigaura, Ibaraki, Japan (this study). 6.
Minamiimogawa Formation (Teradomari F.), Imogawa, Niigata, Japan (Yanagisawa, 1993). 7. DSDP Hole 438A,
northwest Pacific off Japan (this study). 8. DSDP Hole 758, equatorial Indian Ocean (Fourtanier, 1991).

14

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Figure 16. Size variation in Bogorovia lancettula (Schrader) Yanagisawa comb. nov. and B. praepaleacea(Schrader) Jouse. A. Scatter plot of valve width versus length. B. Scatter plot of valve length versus thenumber of transapical costae in 10 ,um. C. Scatter plot of valve width versus the number of transapical costae
in 10 ,um. Samples from no. 2, 3 in Table 1.

8

36

Yukio Yanagisawa

Figure 17. Geographic distribution of Bogorovia lancettula (Schrader) Yanagisawa comb. nov. Closed
circles: localities reported with figures. Open circle: locality reported without figures. 1. DSDP Hole 77B,
equatorial Pacific (this study; Fourtanier, 1987). 2. Experimental Mohole Drilling Guadalupe Site, northeast
Pacific off Baja California (Schrader, 1974a). 3. DSDP Hole 420, eastern equatorial Pacific (Barron, 1980a). 4.
Dredge sample 46-16 from sea floor off Peru (Kulm et al., 1981). 5. DSDP Hole 238, equatorial Indian Ocean(Schrader, 1974b). 6. DSDP Hole 213, equatorial Indian Ocean (Schrader, 1974b). 7. Puente Gentil, Guadalquivir Basin, Spain (Monjanel, 1987). 8. DSDP Hole 362, South Atlantic off Angola (Schrader, 1978).
slightly rostrate and acutely rounded apices, 17-45,um
long, 3.5-5,um wide (Figure 16). Valve face convex,
hyaline without areolae. Transapical costae, 10-13 in 10,um. Marginal ridge, fused-type with two rows of pores(type 2), 9-10 pores in 10,um. A subcentral rimoportula,
one per cell, located near valve edge. A separation
valve with separated-type marginal ridge (type 1) has
been observed (Fourtanier, 1987, pI. 15, figs. 6, 7).
Comparisons.- The species differs from B. puncticulata
by the absence of areolae on valve face and the two rowsof marginal ridge (type 2). It is distinguished from B.
praepaleacea by the narrower interval of transapicalcostae and smaller valve size (Figure 16). This speCies
differs from B. curvata by its transapically symmetric valve
outline.
Stratigraphic range.- The first occurrence of thespecies lies in the middle part of the Coscinodiscus gigas
var. diorama Zone (NTD 7) (Figure 3). Its last occurrence,
though not preCisely known at present, may be near the
top of the Nitzschia jouseae Zone (NTD 14) according to
Schrader (1974b).
Geographic distribution.- The speCies is distributed
mainly at low latitudes (Figure 17). It was first reported
from the Experimental Mohole core off Baja California,
Mexico (Schrader, 1974a), but it is rather rare at middle tohigh latitudes in the Indian and Pacific Oceans, andcommon in the equatorial Pacific (Barron, 1980a; Kulm etal., 1981; Fourtanier, 1987; this study), the equatorial

Indian Ocean (Schrader, 1974b) and the South Atlantic off
Namibia (Schrader, 1978). Monjanel (1987) found thisspecies in the Miocene deposits in Spain.

Bogorovia praepa/eacea (Schrader) Jouse 1976
Figures 4-29-31,4-36,4-37.
Bogorovia praepaleacea (Schrader) Jouse, 1976, p. 1233; Bar-ron, 1981a, pI. 4, fig. 14, p.104.
Basionym. Coscinodiscus praepaleaceus Schrader, 1973, p.
703, pI. 3, figs. 1-9.
Synonymy. Cussia praepaleacea (Schrader) Schrader, 1974a,
p. 543, fig. 1: 8; Schrader, 1974b, p. 914; Koizumi,1975,
p. 876, pI. 4, figs. 36-37; Cussia lancettula Schrader,
Gombos, 1975, p.316, pI. 3, figs. 9-12; Rossiella praepa/eacea (Schrader) Gersonde, Barron, 1985a, pI. 8, fig. 1 ;Rossiella preapaleacea (Schrader) Gersonde andSchrader, 1984, p. 104-105; Yanagisawa et al., 1989, pI. 5,
fig. 34; Radionova, 1991, p.82.

Additional description.-Valve linear-Ianceolate withslightly rostrate and acutely rounded apices, 37-64,um
long, 5-7,um wide (Figure 16). Valve face convex,
hyaline without areolae. Transapical costae, 7-8.5 in 10,um. Marginal ridge, fused-type with two rows of pores(type 2), about 6 pores in 10,um. A subcentral rimoportula, one per cell, located near valve margin. Fourtanier(1987, pI. 15, figs. 1, 2) figured a separation valve withseparated-type marginal ridge (type 1).

983.

Diatom genus Bogorovia

37

Comparisons.-Bogorovia praepa/eacea shares somecommon features with B. /ancettu/a and B. curvata; e.g.
the hyaline valve face and type 2 marginal ridge, but it
differs from the latter two species by more widely spaced
interval of transapical costae (Figure 16). It is different
from B. puncticu/ata and B. barronii by the absence ofvalve face areolae. This species has been sometimes
confused with "Rossiella" mediopunctata (= Koizumia
adaroi (Azpeitia) Yanagisawa) (Barron, 1975; Abbott andAndrews, 1979; Gersonde and Schrader, 1984; Powers,
1988) or with K. akibae (Akiba et a/., 1982; Akiba, 1986),
but it is clearly distinguished from the latter two species
in lacking areolae on the valve face. In spite of its
specific name, B. praepa/eacea is not the ancestor of

Schrader (1973, table 1). Detailed examination of theholotype specimen is required to solve these problems.
If the holotype of B. praepa/eacea is proved to be K.
adaroi, then a new species name needs to be proposed
for the taxon.
The species name means that the species is antecedent to Rossiella pa/eacea, probably because Schrader(1973) regarded the species as the ancestor of R.
pa/eacea. However, B. praepa/eacea is not the precursorof R. pa/eacea nor closely related to R. pa/eacea.

Rossiella pa/eacea.
Stratigraphic range.- This species first occurs from the
middle part of the Actinocyc/us moronensis Zone (NTD 9)

Synonymy. Cussia lancettula Schrader, Schrader, 1974b, pI.
19, figs.14-15 (non pI. 19, fig. 16); Gen. indet., species
indet., Schrader, 1974b, pI. 19, fig. 17; Rossiella cf. lancettula (Schrader) Gersonde et Schrader, Yanagisawa,
1987, pI. 5, figs. 3-5.

in DSDP Hole 77B (Figure 3). In this study, however, thelast occurrence of this species could not be determined in
DSDP Hole 77B because of the lack of samples.
According to Sancetta (1982) and Baldauf (1985), thelast occurrence of B. praepa/eacea lies in the middle partof the A Subzone of the Tha/assiosira convexa Zone (NTD
13A) in DSDP Holes 503, 572 and 573 in the easternequatorial Pacific, and was estimated at about 5.9 Ma(Baldauf, 1985) or 6.0 Ma (Barron, 1985a, 1992) (Figure 3).
In this study, the estimated age of Barron (1992) is adopted.
In DSDP Hole 173, northeast Pacific off California,
Schrader (1973) recognized B. praepa/eacea last occurs
between the core 20-2 (55-56 cm) and core 20-3 (55-56cm), a horizon which Barron and Kellar (1983) assigned to
the lower part of the c Subzone of the Denticu/opsis
hustedtii-D. /auta Zone which is equivalent to the
Denticu/opsis dimorpha Zone (NPD 50) of Akiba (1986).
The horizon is about 8.9 Ma in age and so B. praepa/eacea disappeared earlier in the northeast Pacific thanin the equatorial Pacific.
Geographic distribution.- The species was first described from the mid-latitude North Pacific (Schrader,1973) and successively reported from this region(Schrader, 1974a; Koizumi, 1975; Barron, 1981a;
Yanagisawa et a/., 1989) (Figure 18). However, it appears
to be more common in the equatorial Pacific (Gombos,
1975; Sancetta, 1982; Baldauf, 1985; Fourtanier, 1987 ;this study), and may be a warm-water species.
Discussion.-As pointed out by Fourtanier (1987, p. 107108), there is some suspicion that the holotype specimenof B. praepa/eacea chosen by Schrader (1973) may be avalve of Koizumia adaroi. Despite the original description by Schrader (1973) that B. praepa/eacea has a hyaline
valve face (absence of areolae), the holotype specimen
seems to have circular areolae between the transapicalcostae on the valve face. However, I cannot assert thepresence of areolae with confidence because of therather poor photograph of the specimen. Another problem is that the holotype of B. praepa/eacea is from asample which is far above the main range of the species
in DSDP Hole 173 and interpreted as reworked by

Bogorovia curvata Yanagisawa sp. nov.

Figures 4-38-40.

Description.-Valve delicately silicified, linear-Ianceolate, apically curved with less convex ventral side andmore convex dorsal side, 16-30 j.lm long, 4.5-5 j.lm wide.
Apices slightly rostrate and acutely rounded. Valve facehyaline without areolae. Transapical ribs, 12-13 in 10
j.lm.
A subcentral rimoportula located near the valve
edge.
Holotype.-Figure 4-39 (GSJF14591 deposited in the
Geological Survey of Japan).
Type /ocality and samp/e.-Piston core sample P3CC,
Indian Ocean off Java Island, 1r59.04', 113°31.37', 4442 m
in water depth (Yanagisawa, 1987; Honza et a/., 1987).
Middle Pleistocene in age. The sample is assigned to
the Pseudoeunotia dolio/us Zone (NTD 17) of Barron's(1985b) low-latitude diatom zonation (Yanagisawa, 1987).
According to Nishida (1987), the sample can be placed in
the nannofossil CN14b Zone of Okada and Bukry (1980).
Buccinosphaera invaginata Haeckel (Radiolaria) in thissample suggests a late Middle Pleistocene age younger
than 0.2 Ma. In summary, integrating all available age
information gives the age of about 0.2 Ma for the sample.
Comparisons.- This new species is typified by its
curved valve outline, which is similar to the genus
Campy/osia. This character distinguished this species
from all other Bogorovia species. The species mostresembles B. /ancettu/a in having a hyaline valve face andalmost the same valve size.
Stratigraphic range.- The stratigraphic range of thisspecies is not well known at present. The oldest known
recorded occurrence of this species is in the lower part of
the Nitzschia jouseae Zone (NTD 14) (Schrader, 1976)(Figure 3). The youngest occurrence of this species isreported in the type sample which is dated about 0.2 Ma.
Geographic distribution.- This species has been reported only from the equatorial Indian ocean at present(Schrader, 1974b; Yanagisawa, 1987) (Figure 18).
Etym%gy.- The species name is derived from its
curved valve outline.

Yukio Yanagisawa

38

Bogorovia curvata A
B. praepaleacea

3£>11

Figure 18. Geographic distribution of Bogorovia praepaleacea (Schrader) Jouse and Bogorovia curvata
Yanagisawa sp. nov. Circle: Bogorovia praepaleacea; Triangle: Bogorovia curvata; Closed circles and triangles: localities reported with figures. Open circles: localities reported without figures. 1. DSDP Hole 77B,
equatorial Pacific (this study; Fourtanier, 1987). 2. DSDP Hole 66.1, equatorial Pacific (Gombos, 1975). 3.
DSDP Hole 573, equatorial Pacific (Baldauf, 1985). 4. DSDP Hole 572D, equatorial Pacific (Barron, 1985a;
Baldauf, 1985). 5. DSDP Hole 503, eastern equatorial Pacific (Sancetta, 1982; Baldauf, 1985). 6. Experimental Mohole Drilling Guadalupe Site, northeast Pacific off Baja California (Schrader, 1974a). 7. DSDP Hole 469,
northeast Pacific (Barron, 1981a). 8. DSDP Hole 173, northeast Pacific (Schrader, 1973). 9. DSDP Hole 303,
northwest Pacific (Koizumi, 1975). 10. Core A-1, Taga Group, Futaba area, Fukushima, Japan (Yanagisawa
et al., 1989). 11. DSDP Hole 238, equatorial Indian Ocean (Schrader, 1974b). 12. Piston core P 3, equatorial
Indian Ocean off Java, Indonesia (Yanagisawa, 1987; this study).

Note on some species related (?) to Bogorovia"Bogorovia" sparsipunctata Hendey
Hendey, 1981, p.99-100, pI. 4, fig. 22.

Remarks.- The species is characterized by its fusiform
valve outline and sparsely punctated valve surface. If it
is included in the genera Bogorovia or Rossiella, thespecies might be placed in Rossiella because the species
lacks transapical costae. However, B. sparsipunctata
has no affinity to any species in Rossiella. Until its
structure is elucidated by electron microscope examination, the correct taxonomic position of this species can
not be determined nor transferred to the genus Rossiella.
Therefore the species is referred to under its original
generic name.

and Andrews, 1979, p.241, pI. 3, fig. 14; Cymatosira sp.,
Abbott, 1980, pI. 1, fig. 13; Bogorovia (?) cypriata Gardette,
Desikachary et al., 1984, p.338, pI. 1, fig. 6; Cussia (?)
lancettula Schrader, Desikachary et al., 1984, p.338, pI. 1,
fig. 12Remarks.- The species found in fossil material havebeen sometimes reported as species of Bogorovia or
Cussia. Bogorovia cypriata Gardette is a fossil species
described from the Upper Miocene deposits of Cyprus(Gardette, 1978). However, its valve outline, size anddistribution of areolae and valve architecture are just thesame as those of Cymatosira lorenziana Grunow (Hasle etal., 1983), and therefore B. cypriata is a synonym of C.
lorenziana.

Cymatosira sp. A
Cymatosira lorenziana Grunow
Hasle et al., 1983, p. 19-22, fig. 1-25.
Synonymy. Cussia species 1, Schrader, 1974a, p. 543, figs. 118,19; Bogorovia cypriata Gardette, 1978, p. 762-763, p. 1,
figs. 1-12; Cussia pa/eacea (Grunow) Schrader, Abbott

Cussia sp. 1, Schrader, 1974b, p. 914, pI. 18, fig. 12; Cymatosiraaff. lorenziana Grunow, Akiba, 1980, p. 11, pI. 4, fig. 47.

Remarks.-Cussia sp. 1 of Schrader (1974a) closely
resembles C. lorenziana and therefore can be included in
the genus Cymatosira. However, Cymatosira sp. A is

983.

Diatom genus Bogorovia

distinct from the latter species in having a transapicalhyaline zone along the transapical axis. This species isfound commonly from the Early to Middle Miocene sediments of Japan (e.g. Akiba, 1980). It will be described asa distinct species elsewhere.

Acknowledgments
I would like to thank Fumio Akiba (JAPEX ResearchCenter of Japan Petoleum Exploration Co. Ltd.) and Itaru
Koizumi (Hokkaido University) for helpful advice andthorough review of the manuscript. Special thanks are
given to John A. Barron (U.S. Geological Survey) andElisabeth Fourtanier (California Academy of Sciences) for
their kind review of the early draft of this manuscript andtheir useful suggestion on diatom taxonomy. John A.
Barron, Fumio Akiba, Yoshihiro Tanimura, Yokichi Takayanagi, Toshiaki Maruyama and Hiroaki Kobayashi
kindly offered me the chance to examine DSDP materials.
I thank Akira Nishimura, Fumio Yoshida and Eiichi Honzafor providing some samples used in this study. Kimio
Okumura, Koichi Nakamura and Tamotsu Nagumo assisted in literature search.

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vol. 18, p.637-797. U.S. Govt. Printing Office, Washington, D.C.
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graphy of the tropical Indian Ocean. In, Fisher, A.L.,
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Govt. Printing Office, Washington, D.C.
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Schrader, H.J. and Fenner, J., 1976: Norwegian Sea
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M., Udintsev, G. et al., Initial Reports of the Deep Sea
Drilling Project, vol. 38, p. 921-1099. U.S. Govt. Printing Office, Washington, D.C.
Scientific Party, 1980: Initial Reports of the Deep Sea
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Simonsen, A., 1979: The diatom system: Ideas on
phylogeny Bacillaria, vol. 2, p.9-71.
Tracey, J.I.Jr. et al., 1971: Initial Reports of the Deep Sea
Drilling Project, vol. 8, 1037 p. U.S. Govt. Printing
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Yanagisawa, Y., 1987: Age assignments of dredge andpiston core samples based on diatom biostratigraphy.
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Thailand.
Yanagisawa, Y., 1993: Middle Miocene diatom assemblages from carbonate concretions in the Nanatani
Formation and a formation equivalent to the Teradomari Formation in the Neogene Niigata sedimentary basin of Japan. Diatom (The Japanese Journalof Diatomology), vol. 8, p. 51-62. (in Japanese withEnglish abstract)
Yanagisawa, Y., 1994: Koizumia Yanagisawa gen. nov., a
new marine fossil araphid diatom genus. Transactions and Proceedings of the Palaeontological Society of Japan, New Series, no. 176, p.591-617.
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abstract)41

Yukio Yanagisawa

42

Appendix table. Occurrence of Bogorovia species in DSDP Holes 70A, 71 and 77B. Diatom zones after
Barron (1985b) and Fenner (1985). Abundance of each species: A=abundant (>8%), C=common (5-7%), F=
few (2-4%), R=rare «1%).

Diatom zones

12B 77B 12·1. 29 ·30
12A 77B 13 ·1 . 100 ·101
77B 13 ·3, 2·3
N. pOrleri
liB 77B 14 ·6 , 148 ·149
lOB 77B 15·6, 77 ·78
C. yabeilOA 77B 17 ·1, 18·20
77B 17 ·6, 23 ·25
77B 18 ·2, 23 ·25
A. moronensis
9 77B 18 ·6, 38· 40
77B 19 ·2, 38·40
77B 19 ·6, 38·40
77B 20 ·2, 38·40
C.
8 77B 20 ·2, 59·60
coscinodiscus
77B 20 ·4, 30·31
77B 20 ·6, 38·40
C. gigas
77B 21 ·2. 38·40
var.
7 77B 21 ·6, 35·37
djoramo
77B 22 ·2, 35 ·37
77B 22 -6, 35 ·37
C. lewisianus
6 77B 23 ·2, 35·37
77B 23 ·6, 35 ·37
77B 24 ·2, 35 ·37
5B 77B 24 .(j, 20 ·22
7119·2,108·110
71 19·4, 90·92
71 19·6, 86·88
C.pepuJum
71 20·2, 88·90
SA 71 20·6, 108 ·110
71 21 ·4, 60 ·62
71 21 ·6, 90 ·93
71 22.2, 88·90
71 22·4, 29·31
71 22·6,116·1187123·2,117·1197123·4,77.79
4B 71 24·2, 78·80
D. nicobarica
71 24·4, 45·46
71 24·6. 45 ·47
71 25·1. 128 . 130
4A 71 25·3, % ·98
71 25·5, 92·94
71 26·2, 70·72
T.pileus
3 7126.4,70·72
7126.6,70·72
71 27·1 , 100 ·102

Diatom zones

R R

R R

N. miocenica

R

R
R R
R
R

R

R

F R
R R
R R

R

R R

R

R

R R
R

R R
R R R
R
F
R
R

R
R

R R

R

R R

C. elegans

R R
R R R
R R R
R R R
R
R
R

R R
R R

R. paleacta

R

R R
R

R

R
R
R

R. gelidaR

R. veniamin;

R
R
R
R

R
R

R R R

R

R

R

R. vigilans

71 28·2
70 ·7271 28·4
70 ·722 71 28·6
70 ·7271 29·2
70 ·7271 29·4, 70·72
71 29·6, 70.72'
71 30·2
70 ·7271 30·4
69 ·7171 30·6
45 ·46
Ie 71 30·6 70 ·72
7131·2
70·72
7131·4,70·72
7131·6,70·72
71 32·2 125 ·129
71 32·6 125 ·129
1B 71 33·2
87 ·8971 33·5
75·80
71 34·2
87 ·8971 34·4, 125 . 129
71 34·6 , 132 ·136 R
71 35·2 132 ·136
71 35·6 1.25 ·129 R
71 36·2 125 ·129 R
71 36·6
79·80 R
1A 71 36·6 125·129 R
71 37·2
87 ·89 R
7137·4,100·102 R
71 37·5, 87·89 R
71 38·2 , 125 • 129 R
71 38.4. 80·81
71 39·1
87 ·89 R
71 39·2
87·89 R
71 40·2
87 ·89 R
71 40·6
87 ·8971 41 ·1
87·89 R
71 42·19l ·9271 42·2
87 ·89 R
71 42·4, 87·89 R
71 42·6
87 ·89 R
71 45·2
61 ·62 R
71 47·2 , 106 . 107
b 71 47·5
59 ·6070A 8·4
83·84• 70A 12 ·3. 90·91

F
R

R
R
R

R

C C
R R
R R R
R

R
F
R
R R

R

R

FeR

R R

R R R

R R

C

C

e

e

F R

e

C

F

A R

A
R

R R
F
C
A
F

F
F

e
F

e

e

A
A
A
A
A
A
A

e

R

A
A

F

e
C
A

R
R
F
R
R
R
R
R
R

F
R
F
R
R
R
R
R
R
R

e

A
R
C
C
A

Trans. Proc. Palaeont. Soc. Japan, N.S., No. 177, pp.43-58, 11 Figs., April 30, 1995

Middle and Late Permian radiolarians from the
Semanggol Formation, Northwest Peninsular Malaysia
KATSUO SASHIDA 1, SHUKO ADACHP, HISAYOSHIIG0 1, TOSHIO KOIKE 2 , and IBRAHIM B. AMNAN3
l/nstitute of Geoscience, University of Tsukuba, Ibaraki, 305 Japan
2Geologicallnstitute, Faculty of Education, Yokohama National University, Yokohama, 240 Japan
3Geological Survey of Malaysia, Ipoh, Malaysia

Received 9 September 1994; Revised manuscript accepted 30 January 1995
Abstract. The Semanggol Formation exposed in the northwestern part of Peninsular Malaysia is
subdivided into the lower Chert, middle Rhythmite, and upper Conglomerate Members. Previous to
the present study, this formation was regarded as Triassic because of the occurrence of Daone/la andHa/obia in the middle Rhythmite Member. We newly recovered late Middle Permian radiolarians,
including Fo/licucu/lus monacanthus, from an allochthonous siliceous limestone block contained in
the upper part of the lower Chert Member exposed at Bukit Barak, 25 km northeast of Alor Setaro
Furthermore, moderately well preserved Late Permian radiolarians belonging to the Neoalbai/le/laoptima and N. ornithoformis Assemblages were discovered in chert beds of the same member
exposed at Bukit Nyan, 20 km east of Alor Setaro These Permian radiolarian faunas are very similar
to those reported from Japan, the Philippines, and southern China. We interpret the significance of
this occurrence in the paleobiogeography of Peninsular Malaysia during Late Paleozoic to Early
Mesozoic times. Eight species and five unidentified species belonging to 10 genera of Radiolaria aresystematically described in this paper.
Key words: Neoalbai/le/la, Peninsular Malaysia, Permian, Radiolaria, Semanggol Formation, Triassic.

Introduction
Peninsular Malaysia is geologically subdivided into two
continental blocks, the western Sibumasu and eastern
East Malaya blocks. As shown in Figure 1, these two
blocks are in contact with the Bentong-Raub Suture,
which is continued from the Uttradit-Nan Suture ofThailand and extends into Sumatra as the Lalang Line
(Metcalfe, 1988; Hutchison, 1989). Concerning the timing of the collision or amalgamation of these continental
blocks, there are diverse opinions such as CarboniferousPermian (Helmke, 1985); Triassic (Sengor et al., 1988;
Metcalfe, 1988; Mitchell, 1989); and JurassicCretaceous (Audley-Charles, 1988).
Sash ida, Igo, Hisada et al. (1993) pointed out that
establishment of detailed geochronology in siliceous andassociated fine-grained clastic rocks based on microfossils provides one of the keys to solve the abovementioned problem. We, however, did not have any
sufficient micropaleontological data in Peninsular
Malaysia for this purpose except for conodont age
assignment determined in chert beds exposed at Tawar,
Kedah (Koike, 1973). In November and December of
1991, we made a field survey in northwest Peninsular

Malaysia to clarify the geologic age of the Semanggol (orSemanggul) Formation. We were fortunate to discover
Late Permian radiolarians from the lower Chert Member
and late Middle Permian radiolarians from an allochthonous block probably contained in the upper part of thelower Chert Member. The lower and middle members
were assigned to Early to Middle Triassic by previous
workers (e.g., Tamura et al., 1975; Teoh, 1992). This
discovery was preliminarily reported by Sash ida, Igo,
Adachi et al. (1993) and is the first report of Permian
radiolarians in Peninsular Malaysia. These faunas arevery similar to those reported from Japan, the Philippines,
and southern China, and the occurrence in Malaysia is ofinteresting geologic significance as discussed below.
The first author (K.S.) systematically describes the
species of radiolarians belonging to the characteristic
genera including Albaillella, Neoalbaillella, and FollicuculIus herein.
Acknowledgments
This project was planned as a cooperative research
project by the Institute of GeOSCience, University ofTsukuba and the Geological Survey of Malaysia. Our

Katsuo Sashida et al.

44

I

I

and have been known as the Chuping and Kodiang
Limestones. These limestones mostly constitute isolated spectacular tower karst hills in the Quaternary plain.
They conformably overlie the Kubang Pasu Formation (e.
g., Foo, 1983). Conodonts in the Chuping and Kodiang
Limestones were repeatedly studied by Koike (1973, 1982)
and Metcalfe (1981, 1990a, 1992), and these authors
clarified the detailed geologic age of these limestones.
The name "Semanggol (or Semanggul) Formation" hasbeen informally used by several writers for the large tractsof flysch-type sedimentary rocks of the Middle to Late
Triassic distributed in Kedah and Perlis (Khoo, 1983; Foo,
1990; Teoh,1992). This formation occurs in a wide areaeast of the Chuping and Kodiang Limestones with analmost NS orientation (Figure 2). The stratigraphic relationship, however, between the Semanggol and both
overlying and underlying formations is unclear. Burton(1973) subdivided this formation into three members, thelower Chert Member, the middle Rhythmite Member, andI" , __ AI
- \
\

\

ST

\

\

MALAYA \o,

THAILANDo

20km

L,_ - - ' - _ - - - ' ,Figure 1. Index map showing the study area and thetectonostratigraphic terranes which constitute the continental mainland of Southeast Asia. The base map is slightly
modified from Metcalfe (1988, 1991).
field survey was funded by a grant under the Monbusho(Government of Japan) International Scientific Research
Program (No. 02140210 to H. Igo) and also supported by
the Geological Survey of Malaysia. We thank Messrs.
Yin Ee Heng (former Director-General), Khoo Hang Peng,and Shu Yeoh Khoon of Geological Survey of Malaysia,
who gave permission and facilities for our field survey.
Geologic setting
Jones (1978) first established a geologic framework forthe extensive area of northwest Peninsular Malaysia(Perlis and Kedah States), including the Langkawi Islands.
He divided Paleozoic and Mesozoic sedimentary rocks
into four lithostratigraphic units: the Machinchang Formation (Late Cambrian), Setul Formation (Ordovician to
Devonian), Kubang Pasu and Singa Formations (Late
Devonian to Early Permian), and Chuping Formation (Middle Permian to Triassic).
Recently, Teoh (1992) has mapped the Sungai Tiang
area of central Kedah and divided the Paleozoic andMesozoic rocks into the following three lithostratigraphic
units; the Mahang Formation (Early Silurian), Kubang
Pasu (Carboniferous), and Semanggol Formations (Middle
to Late Triassic). In Kedah and Perlis, Permian andTriassic limestones occur outside of this mapped area

Figure 2. Map showing the distribution of the Chuping
Limestone (1), Kodiang Limestone (2) and Semanggol Formation (3) and locations of two radiolarian localities, Bukit
Nyan and Bukit Barak. The base map is after Metcalfe(1990a).

984.

Permian Radiolaria from Peninsular Malaysia

the upper Conglomerate Member, but this subdivision is
now thought to be oversimplified by Malaysian geologists(e.g., Ahmad et al., 1987). The detailed stratigraphy andexact thickness of the Semanggol cannot be ascertained
due to the tightly folded structure and the absence ofmarker beds. Foo (1990) and Teoh (1992), however,estimated that the thickness of this formation is no lessthan 760 to 800 m. Under this circumstance, we
compiled an idealized geologic columnar section with thegeochronological scale of the Semanggol Formation asshown in Figure 3.
The lower Chert Member consists mainly of chert,
forms echelon ridges trending almost NS, and crops out
well in the western part of the area mapped as the
Semanggol. Good outcrops of this member can betraced along the roadcut from Pokok Sena to Kuala
Nerang and in operating and abandoned quarries east of
Pokok Sena in central Kedah. The cherts are commonly?

i. ' . 0"". .. .. '. . .0 . . .

. . ' ··0··.·. . . . 0.

I-.

Q)

.t:J

S
Q)

:::;E
~

·s

..<::
......

>.

..<::
~

u

.iii
(/J
~

'i:
E-<

I-.

Q)

.t:J

S
Q)

:::;E
......
I-.
I'::

Q)

..<::

·s u
~

I-.

Q)

0..

Ul
[012
......
~3----!!!J4~5

Figure 3. Generalized columnar section of the Semanggol Formation (not to scale). 1. conglomerate, 2. limestonelenticle, 3. alternation of sandstone and shale, 4. siliceous
shale, 5. chert.

45

black to gray, thinly bedded, tightly folded, and grade
upward into siliceous shales or mudstones.
Calcareous chert or cherty limestone beds and limestone lenses are intercalated in siliceous shale that
represents the upper part of the Chert Member, and oneof the field occurrences of these intercalations at an
active earth quarry of Bukit Barak was described in detailby Ahmed et al. (1987). They considered that theselimestones are pelagic in origin, and confirmed the occurrence of Triassic conodonts in the lensoid-shaped limestone bodies. Furthermore, in their interpretation thesebodies were not slumped-in but were contemporaneousin-situ deposits. Subsequently, Metcalfe (1990a) reported the occurrence of Carnian conodonts, such as
Neogondolella polygnathiformis (Budrov and Stefanov) inthese limestone lenses.
The middle Rhythmite Member conformably overlies
the lower member, and consists of rhythmically alternating beds of sandstone and shale. Each bed is commonlyless than 10 cm thick. Sandstone beds are interpreted
as turbidites, and commonly exhibit numerous syngenetic
structures and sedimentary features that are typical of"flysch-type" deposits. Shale beds of this member yield
well known Triassic pelecypod fossils such as Posidonia
kedahensis Kobayashi, Halobia talauana Wanner, Halobia
parallela Kobayashi, Halobia comata Bittner and others,
indicating an interval of Ladinian to Norian (Kobayashi,1963).
The upper Conglomerate Member conformably overlies
the middle member and is prevalent in eastern Kedah.
This member is predominantly irregularly interbedded
sandstone and shale with intercalations of numerous
conglomerate lenses or bands. Clasts of conglomerate
are commonly well-rounded pebble- to cobble-size chert,
metamorphosed crystalline quartz, and argillaceous
rocks. Some chert clasts contain radiolarian fossils.
The stratigraphic relationship among these three members is not entirely one of superposition, rather they seemto be partly intertonguing each other (Figure 3). The
depositional environment of the Semanggol Formation
was analyzed by Burton (1973), Metcalfe (1990a, etc.),
Teoh (1992), and others. According to them, the Kodiang
Limestone and some parts of the Chuping Limestone areheterofacies of the Semanggol Formation, and were
deposited in the shelf which was continued to the foreland toward the west. The lower Chert and middle
Rhythmite Members of the Semanggol were deposited in
the deeper part to the east. The latter member is apparently of turbidite origin. The characteristic sedimentary
facies in the upper Conglomerate Member suggests atransition to a shallower water environment.
Permian radiolarians in the Semanggol Formation
Localities
Bukit Barak: Middle Permian radiolarians wererecovered from a siliceous limestone block embedded insiliceous shale of the upper part of the lower Chert
Member exposed at a quarry of Bukit Barak (Figures 2, 4).

46

Katsuo Sash ida et a/.

A geologic sketch of this quarry was given by Ahmad eta/. (1987). They showed a 27-m-thick columnar section
and pointed out the occurrence of conodonts in lensoidshaped limestone bodies embedded in the siliceous shale
situated at the top of the column. These authors
stressed that the lensoid limestone bodies were notslumped-in but were contemporaneous in-situ deposits.
Subsequently, Metcalfe (1990a) studied these conodonts
and identified Metapolygnathus (= Neogondolella)polygnathiformis (Budurov and Stefanov), which is an
excellent indicator of the lower Carnian (lower Upper
Triassic).
During our field survey in 1991, we tried to restudy thesection shown by Ahmad et a/. (1987), but quarry operation was much progressed, and the outcrop measured bythem was already quarried out. We, however, could
observe a similar sequence and confirmed the intercalation of lensoid limestone bodies in siliceous shales.
Several samples of siliceous shales and limestones werecollected from various stratigraphic levels (Figure 4).
These samples were treated with HF (hydrofluoric acid) at
our laboratory with the same technique mentioned by
Sashida (1988). As a result, we encountered poorly
preserved but apparent Permian radiolarian specimens inresidue obtained from the lensoid siliceous limestone(sample BT -1). The only identified species among discreted specimens is Fol/icucullus monacanthus Ishiga andImoto. Under the microscope, this limestone is almost

completely silicified, and primary microfacies has been
obliterated by microcrystalline silica. Calcite crystals
are rare, but euhedral crystals of dolomite are commonly
scattered. Minute dark brown iron minerals are concentrated in some parts. Minute spheres and spines ofradiolarians are also commonly visible.
We could not recover any Triassic conodonts from thelimestones as reported by Metcalfe (1990a), but we madeseveral thin sections and discovered some other fossils.
Furthermore, there we recognized two types of limestones
containing Triassic fossils. Under the microscope, one
type is a micritic limestone including abundant peloids
and algal clasts, subordinate foraminifers, bryozoans, andfragments of Echinodermata. Preliminarily identified foraminifers are Aulotortus spp., Arenovidalina indosinica
Liem, Endothyra ? sp., G/omospira sp., and Dentalina sp.
The two first mentioned forms are known to occur in the
Middle to Upper Triassic. The other type is also micritic
limestone including abundant thin-shelled pelecypods
and radiolarian tests. These pelecypod-bearing
radiolarian limestones are common in the Middle to Upper
Triassic pelagic calcareous facies elsewhere in the world.
These paleontological facts indicate that the siliceous
shales intercalate both Permian and Triassic lenticular
limestones of which depositional environments are different. Our principal new finding, mentioned above, isdemonstration that the lensoid limestones intercalated inalmost the same level are of three different types, Middle
Permian radiolarian-bearing siliceous limestone, Triassic
foraminiferal-algal shallow water limestone, and pelagic
pelecypod-bearing limestone. Therefore, we concluded
that these limestone bodies are allochthonous blocks
instead of contemporaneous in-situ deposits as advocated by the previous authors.
Bukit Nyan: We made a geological survey at an
abandoned manganese quarry of Bukit Nyan (also spelled
Nyah or Nayan) located about 8 km south of Pokok Sena
(Figure 2). Bedded cherts about 100 m thick that apparently belong to the lower Chert Member of the Semanggol
are exposed at the quarry. Cherts are mostly thin-bedded and show a wide range of color, but are commonlybrown, maroon, and pale gray. They strike N10° -30 o E
and dip almost vertical (Figure 5). Under the microscopethese cherts contain aboundant minute spherules (0.2 mm
in average diameter) filled with spherulitic calcedony or
microcrystalline quartz. We collected more than 10
samples at this quarry of which four samples (CHU-41, 42,
43, and 44) yield moderately well preserved Late Permian
radiolarians. They are the species of the genera Neoa/baillella, Albaillella, Entactinosphaera, Nazarovella, Triplanospongos, and others.
Radiolarian fauna and age

Figure 4. Sketch map showing the Bukit Barak quarry
and collected point of Permian radiolarian-bearing siliceous
limestone.

As mentioned above, we newly recovered radiolarians
from a siliceous limestone block at the quarry of Bukit
Barak. These radiolarians are poorly preserved, andFollicucullus monacanthus Ishiga and Imoto, which is anapparent indicator of the upper part of the Middle Permian, is the only identified species. Other radiolarians

984.

Permian Radiolaria from Peninsular Malaysia

I dip (vertical) and strike
X sample location·o20m---''--...J'

L . . '- - ' ' - -. . . . . . . .

Figure 5. Sketch map showing the Bukit Nyan quarry
and radiolarian localities (after Sash ida, Igo, Adachi et al.,1993).

are spumellarians, but are not identified as to species. F.
monaeanthus was first described from bedded cherts in
the Yagi area of the Tamba district west of Kyoto, Japan(Ishiga and Imoto, 1980). This species is now accepted
as an index of the late Middle Permian Follieueullus
monaeanthus Zone (e.g., Ishiga et al., 1982c).
Samples collected from Bukit Nyan contain 13 species

47

of Late Permian radiolarians (Table 1). These radiolarians can be grouped into two assemblages. One assemblage occurs in two samples (CHU-41, 42 in Figure 5) andis characterized by the presence of Albaillella triangularis
Ishiga, Kito and Imoto, but lacks Neoalbaillella cfr. ornithoformis Takemura and Nakaseko. The other one isconfirmed in chert samples (CHU-43, 44 in Figure 5) andcharacterized by the assemblage of N. cfr. ornithoformisand spumellarians including Entaetinosphaera
pseudoeimelia Sashida and Tonishi, Nazarovella gracilis
De Wever and Caridroit, N. inflata Sashida and Tonishi,
and Triplanospongos musashiensis Sashida and Tonishi.
Albaillella triangularis, A. levis, and A. exeelsa were firstdescribed by Ishiga et al. (1982b) from the Yono area of
the Tamba district, west of Kyoto and the Nabejiri-yamaarea of Shiga Prefecture, Japan. Neoalbaillella ornithoformis was also introduced from the Tamba district (Takemura and Nakaseko, 1981). Associated spumellarians
with N. cfr. ornithoformis in CHU-43 and CHU-44, such as
Nazarovella gracilis and Triplanospongos musashiensis
were described from the Late Permian chert exposed in
Itsukaichi, Tokyo (e.g., Sashida and Tonishi, 1985).
Ishiga et al. (1982a) and Ishiga (1986) establishedassemblage-zones based on the stratigraphic occurrenceof the species of Neoalbaillella in the Upper Permian chert
facies of Southwest Japan. They set up two zones, theolder Neoalbaillella optima Assemblage-zone andyounger Neoalbaillella ornithoformis Assemblage-zone in
the Upper Permian. The former zone is characterized by
the joint occurrence of Albaillella triangularis and Neoalbaillella optima. The latter one is defined by the occurrence of Neoalbaillella ornithoformis. Albaillella exeelsa
and A. levis have a short range and first appear near theboundary between the two Neoalbaillella zones. Concerning the detailed geologic age of these zones, Ishiga(1986) and others placed it in the Dzhulfian and Dorashamian (Late Permian) based on the co-occurrence of
conodonts.
Two newly recovered radiolarian assemblages fromchert beds exposed at Bukit Nyan are correlated with the
Neoalbaillella optima Assemblage-zone and Neoalbaillella ornithoformis Assemblage-zone established in Japan;
their geologic ages are considered to be Late Permian(Dzhulfian to Dorashamian).
Appraisal of the occurrence of Permian radiolarians in
the Semanggol Formation
In this paper, we apprise the above-mentioned newly
obtained micropaleontological data and further discuss
paleogeography related to the geologic evolution of
Peninsular Malaysia and its neighboring regions in Permian to Triassic times.
Our present discovery shows that the geologic age of
the Semanggol Formation is not confined within the
Triassic as concluded by previous studies but extends
down into at least the Middle Permian. The presence oflensoid limestones of two different ages (late Middle
Permian and early Late Triassic) in almost the same
stratigraphic level of siliceous shale suggests that theKatsuo Sashida et al.

48

Table 1. List of Permian radiolarians from Bukit Nyan. Locality numbers are shown in Figure 5.
CHU~I~---4-1---------------------------44
42

Neoalbaillella cfr. ornithoformis Takemura and Nakaseko........ -Albaillella excelsa Ishiga, Kito and Imoto ........................ x
Albaillella levis Ishiga, Kito and Imoto .......................... xxx

Entactinosphaera pseudocimelia Sashida and Tonishi ............ Entactinosphaera sp. . ......................................... -

43

x
x
x
x
x

Octatormentum ? sp. . ......................................... -xNazarovella gracilis De Wever and Caridroit ...................... Nazarovella inflata Sashida and Tonishi ........................ Praedeflandrella sp. . ......................................... x

x
x
x
x
x
x
x
x

Pseudotormentus sp. . ......................................... x
Ishigaum ? sp. . ............................................... Triplanospongos musashiensis Sashida and Tonishi .............. -

x

x
x

x
x

x, taxon present; -, taxon not found.

limestones are allochthonous and the sedimentary environments of the Semanggol as analyzed by previous
authors should be revised.
In Permian time, two different and contrasting lithofacies, the western shallower limestone facies (Chuping
and Kodiang Limestones) and eastern deeper-sea
siliceous sedimentary rock facies (lower part of the
Semanggol Formation) were already present in northwest
Peninsular Malaysia as shown in Figure 6. The deposi-tion of these formations was continued in Triassic time,
but the depositional site of the Semanggol became shallower as indicated by its sedimentary features. Furthermore, the accretion of the Sibumasu block to the East
Malaya block became active in the Late Triassic andprovided a different sedimentary setting than that of thePermian as shown in Figure 7. The following lines briefly
summarize interpretation of these two diagrammatic figures.

Middle to Late Permian
Palaeotethys
Chuping Limestone, Kodiang
Limestone

Semanggol Formation

west

east
SIBUMASU

Figure 6. Schematic reconstruction of the sedimentary setting of the Chuping and Kodiang Limestones
and Semanggol Formation.

984.

Permian Radiolaria from Peninsular Malaysia

49

Late Triassic

Chuplng· Kodlang Limestones
accretionary wedges

acidic volcanism

Semantan Basin

SIBUMASU
west

Figure 7. Schematic cross section across the convergent region of Peninsular Malaysia in Late Triassic.
This diagram shows the collision of the Sibumasu block to the East Malaya block and development ofassociated sedimentary basins, wedges, and volcanism.

Carbonate facies is prevalent in the west and represented by almost continuous deposition of the Chuping and Kodiang Limestones. Previously, these limestones were thought to be two distinct lithogenetic unitsof the Permian and Triassic, respectively. Subsequentstudies, however, concluded that the geologic age ofthese limestone units is Middle (7) Permian to Late
Triassic (e.g., Metcalfe, 1981,1984, 1990a, 1992; Fontaine
et al., 1988). Similar limestones are also exposed in
Peninsular Thailand and have been called the Permian
Ratburi Limestone. Recently, Triassic fossils have been
discovered from the Ratburi Limestone in PeninsularThailand (e.g., Igo et al., 1988; Sashida and Igo, 1992),
and the Chaiburi Formation was introduced for the Triassic limestone (Ampornmaha, 1993 MS; Adachi et al.,1993). These carbonate facies are also known in north
Sumatra and form an elongate Permian and Triassic
limestone complex in Sibumasu (Metcalfe, 1989, 1990a).
The boundary between the Permian and Triassic in thislimestone complex is roughly settled at Gunong Keriang
and Bukit Hantu in Kedah by conodont studies (Metcalfe,
1981, 1984). The boundary is also presumed in the limestone complex of the Phatthalung area of southern
Thailand (Ampornmaha, 1993MS). The boundary
between the Permian and Triassic in these limestone
sections is said to be conformable, but the exact boundary has never been reported because carbonate rocks
near the boundary are completely dolomitized and do not
successively yield any reliable uppermost Permian (Dora-sham ian) and lowermost Triassic (Griesbachian) fossils.
The limestone that yields Smithian, Spathian, and Anisianconodonts and radiolarians in northwest Peninsular
Malaysia and southern Peninsular Thailand are mostly
thin-bedded micritic limestone with intercalations of thinchert layers and nodules (e.g., Metcalfe, 1984; Sashida
and Igo, 1992). These limestones are considered to havebeen deposited in oft-shore, deeper, and low-energy
environments. The upper part of the carbonate complex
was represented mainly by thickly bedded algalforaminiferal limestone with interbeds of coral-spongebuildups in places. It was deposited in a shallow sea ofhigh-energy conditions (Ampornmaha, 1993 MS; Adachi
et al., 1993). The age of this part of the limestone is Late
Triassic (Carnian and Norian).
As already mentioned, the lower and middle parts of the
Semanggol Formation were deposited in the deeper andoft-shore pelagic environments which spread in theeastern part of the Permian-Triassic carbonate complex.
The present discovery of Upper Permian radiolarians from
Bukit Nyan suggests that the boundary between the
Permian and Triassic will be settled within the lower Chert
Member of the Semanggol in the future. Furthermore,
our other discovery of Middle Permian radiolarians from asiliceous limestone block and Carnian algal-foraminifer
limestone blocks at Bukit Barak supports our contention
that the upper part of the Chert Member is contemporaneous but is a heterofacies with both the middle Rhythmite
and upper Conglomerate Members. Allochthonous

50

Katsuo Sashida et al.

blocks of Permian siliceous limestone and Triassic limestone were derived from the paleoslope of the carbonate
complex in the west and slumped in the siliceous shale
sequence of the upper part of the Chert Member.
The middle Rhythmite Member that yields Middle andLate Triassic pelecypods is characterized by thinly bedded alternations of sandstone and shale. Various sedimentary structures observed in these alternations havebeen interpreted as turbidites (e.g., Teoh, 1992). The
source area of these turbidites was located in the east
where accretionary wedges were formed associated withthe collision of Sibumasu. The absence of carbonate
rocks as clastics in these turbidites also supports aneastern sediment source.
Toward the east the accretionary wedges are further
continued to the Semantan Basin formed in the East
Malaya block. The Semantan Formation (Jaafar, 1976)
was deposited in this basin. This formation is a flysch
sequence of alternating carbonaceous shale, siltstone,
and rhyolitic tuff with very few lenses of crystalline limestone. It locally yields Oaonella, Posidonia, and other
MiddleTriassic pelecypods (e.g., Kobayashi, 1963, Metcalfe et al., 1982). Provenance of volcanic materials wasinterpreted as acidic volcanic islands or an island chain(e.g., Metcalfe et al., 1982) aligned along the eastern
margin of the Semantan Basin (Figure 7). This modelaccords well with the scenario of tectonic evolution of
Peninsular Malaysia explained by collision of the
Sibumasu block with the East Malaya block in Early
Triassic time.
Sash ida, Igo, Adachi et al. (1993) and Sashida, Igo,
Hisada et al. (1993) pointed out the occurrence of Permianto Middle Triassic radiolarians in cherts exposed in theFang area of northwestern Thailand and also in the Sra
Kaeo-Chanthaburi areas of eastern Thailand. Theseradiolarian faunas are similar to those of Japan, thePhilippines, and southern China. This paleontologicalevidence shows that the radiolarian cherts in theseregions were deposited on the same ocean floor"Paleotethys" in the interval of Middle Permian to Middle
Triassic times (Figure 8). The Fang area is situated in
the western mountains of the Sukhothai Fold Belt
(Bunopas, 1981) or the ophiolitic areas of the Plateau Beltin the Shan-Thai Block (Mitchell, 1992). The Sra KaeoChanthaburi areas also rest in the ophiolitic areas of theLoei and Sukhothai Fold Belts. These areas are characterized by a complicated geologic structure that consists of various kinds of sedimentary rocks, ultra mafic
and mafic rocks, and volcanic and plutonic rocks of Late
Paleozoic to Middle Triassic age. This complex has
been regarded as a mobile belt or accretionary wedges
formed as a result of collision of the Sibumasu (ShanThai) and Indochina blocks. As mentioned above, theyoungest age of the deeper marine sedimentary rocks(radiolarian cherts) that constitute these folded belts is
the Middle Triassic, hence the timing of collision of thesetwo continental blocks in Thailand is considered to be notprior to the Middle Triassic. Moreover, it is well known
that the thick nonmarine strata, the Khorat Group (late.. , EURASIAN PLATE"': ::, ::::~<:.?:.>::;~\':':.:. ':;:i.;.::./:::./.:~:,/. :.:-:::

20·

TETHYS

Figure 8. Palinspastic map of the main part of Southeast Asia in Early Triassic time (modified from Hutchinson,1989).

Triassic to Cretaceous) unconformably and extensively
rests on the Indochina block. Our present study showsthat the timing of collision of the Sibumasu and East
Malaya continental blocks was slightly earlier than in
Thailand (Figure 8).
Systematic paleontology
All specimens described in this paper are deposited in
the Institute of Geoscience, University of Tsukuba withthe prefix IGUT.
Order Polycystida Ehrenberg, 1838,
emend. Riedel, 1967
Suborder Albaillellaria Deflandre, 1952,
emend. Holdsworth, 1969
Superfamily Follicucullacea Cheng, 1986
Family Neoalbaillellidae Takemura
and Nakaseko, 1981
Genus Neoalbaillella Takemura
and Nakaseko, 1981
Neoalbaillella cfr. ornithoformis Takemura
and Nakaseko
Figures 10-1-4
Compare:Neoalbaillella ornithoformis Takemura and Nakaseko, 1981, p.
211-213, pI. 33, figs. 1-6; Ishiga et al., 1982b, p. 15-16, pI. 1,
figs. 6-8, pl. 2, fig. 1 ; Nishizono et al., 1982, pl. 2, fig. 7 ;Sash ida and Tonishi, 1985, pI. 7, figs. 8-9; Ishiga, 1990,
pI. 1, fig.5; Tumanda et al., 1990, pI. 2, fig.21; Ishida etal., 1992, pI. 1, fig. 2.
Neoalbaillella sp., Kojima, 1982, pI. 2, figs. 8-9, pI. 3, fig. 1.

984.

Permian Radiolaria from Peninsular Malaysia

SI

7

4

5

6

Figure 9a, b. Thin- section microphotographs of foraminifers and pelecypod - radiolarian limestone embedded in the Semanggol Formation exposed at Bukit Barak. 9a (left figure). 1; Arenovidalina indosinica Liem.
x 60. 2, 3; Endothyra? sp.. x 60. 4; Trochammina ? sp. . x 60. 5 ; Glomospira sp.. x 60. 6; Dentalina sp .•x 60. 7 ; Aulotortus sp., x 30. 9b (right figure). Pelecypod - radiolarian limestone. x 30.

Neoalbaillella sp. cfr. N. ornithoformis, Kojima. 1982, pI. 2. fig .
10.

Albaillella sp. cf. A. triangularis, Cheng, 1989. p. 138, pI. 5, figs.
6- 9. 11 -12.

Remarks. - Although preservation of our present specimens is very poor. the shape of the apical cone and thedorsal wing are identical with that of the type species of
Neoalbaillella ornithoformis . Our specimens differ fromN. optima in lacking ladder-shaped extension of rods.

Remarks. - This species is characterized by having a
triangular shell with a ridged H- frame. Owing to ill preservation, our specimens lack the H- frame but othercharacters such as a triangular shell with horizontal
bands on the shell surface are quite identical with thetype species and the above- listed reports of this species.

Occurrence.-CHU - 43. 44.

Occurrence. - CHU - 41 , 42.
Family Albaillellidae Deflandre, 1952.
emend . Holdsworth, 1977
Genus Albaillella Deflandre. 1952,
emend . Holdsworth, 1966.
emend. Ormiston and Lane. 1976
Albaillella triangularis Ishiga, Kito and Imoto
Figures 10-18- 20
Albaillella sp. C, Ishiga and Imoto, 1980, p. 341 , pI. 5, figs. 11-16.
Albaillella triangularis Ishiga. Kito and Imoto. 1982b. p. 2. figs.
8-11 ; Wakita. 1983. pI. 6. fig. 8; Caridroit et al. , 1985. pI. 1.
fig . 1 ; Ishiga, 1985. p.13, pI. 2. figs. 13- 19 ; Yoshida and
Murata, 1985, pI. 2. figs. 9. 10 ; Caridroit and De Wever.
1986. p.58- 59, pI. 1. figs. 1- 5; Wu and Li. 1989, pI. 1, fig.
14 ; Tumanda et al. , 1990. pI. 2, fig. 18; Kuwahara et al ..
1991 . figs. 4-1- 2 ; Ando et al .. 1991, pI. 9, fig . 9 ; Kuwahara and Sakamoto. 1992. pI. 3, figs. 5- 6 ; Yao et al .•1993. pI. 1. fig . 3.

Albaillella levis Ishiga, Koto and Imoto
Figures 10-16- 17, 21
Albaillellidae gen. et sp. indet., Takemura and Nakaseko, 1981.
pI. 34. fig . 10.
Albaillella levis Ishiga. Kito and Imoto, 1982b, p.17, pI. 3, figs.
1- 4 ; Kojima. 1982, pI. 3. figs. 5- 6 ; Wakita. 1983, pI. 6,
figs. 5- 6 ; Sashida and Tonishi. 1985, pI. 7, figs. 5- 6 ;Yoshida and Murata, 1985. pI. 2. figs. 11 -12; Noble andRenne. 1990. pI. 1. figs. 12- 15; Tumanda et al .. 1990, pI. 2.
fig . 24; Ishida et al .• 1992, pI. 1. fig . 4 ; Kuwahara andSakamoto. 1992. p. 40. pI. 3, figs. 8- 9. 12 ; Yao et al., 1993,
pI. 1. figs. 6, 8.
Albaillella sp. cf. A. levis. Cheng. 1989, p. 138, pI. 1. figs. 5- 7, pI.
2, figs. 1- 4 ; Ando et al .• 1991. pI. 9. fig. 10.
?Albaillella levis . Wu and Li. 1989. pI. 1. fig. 10.

Katsuo Sash ida et al.

52

Remarks. - Our specimens assignable to the present
species lack an H- frame but the general shell shape witha ventral rod is similar to that of the original specimens.
Occurrence.-CHU - 41 , 42, 43, 44.
Albaillella excelsa Ishiga, Kito and Imoto
Figures 10- 5- 11

Albaillella exce/sa Ishiga, Kito and Imoto, 1982b, p. 17- 18, pI. 3,
figs. 5- 8 ; Wu and Li , 1989, pI. 1, figs. 8- 9 ; Kuwahara andSakamoto, 1992, pI. 39, pI. 1, fig. 8, pI. 3, figs. 1- 3 ; Yao eta/., pI. 1, figs. 2, 7.
Albaillella sp. cfr. A. exce/sa , Cheng , 1989, pI. 138, pI. 4, figs. 911 .

Remarks .-Our specimens are similar to the original

Figure 10. Permian radiolarians from Bukit Barak and Bukit Nyan. 1- 4. Neoalbaillella cfr. ornithoformis
Takemura and Nakaseko, 1 ; IGUT - KS0580, CHU- 43, x 200, 2 ; IGUT - KS0517, CHU - 44, x 170, 3; IGUTKS0579, CHU - 43, x 200, 4 ; IGUT - KS0531 , CHU- 44, X150. 5 -11. Albaillella excelsa Ishiga, Kito and Imoto, 5 ;IGUT- KS0536, CHU - 41 , x 150, 6 ; IGUT- KS0555, CHU- 41, x 150, 7 ; IGUT- KS0542, CHU - 42, X 150, 8 ; IGUTKS0547, CHU - 42, x 150, 9 ; IGUT - KS0575, CHU- 41 , x 150, 10 ; IGUT - KS0545, CHU- 42, x 150, 11 ; IGUTKS0537, CHU - 42, X 150. 12-15. Follicucullus monacanthus Ishiga and Imoto, 12 ; IGUT - KS0591 , BT -1, X 100,
13 ; IGUT- KS0578, BT- 1, X 100, 14 ; IGUT- KS0588, BT-1, x 100, 15 ; IGUT- KS0589, BT- 1, x 100. 16-17,21.
Albaillella levis Ishiga, Kito and Imoto, 16 ; IGUT- KS0518, CHU- 44, x 150, 17 ; IGUT- KS0571, CHU - 41 , X 150,
21 ; IGUT - KS0560, CHU - 41 , x 150. 18 ~20 ; Albaillela triangularis Ishiga, Kito and Imoto, 18 ; IGUT- KS0573,
CHU - 42, X 150, 19 ; IGUT- KS0533, CHU- 42, x 150, 20 ; IGUT- KS0539, CHU - 42, x 150.

984.

Permian Radiolaria from Peninsular Malaysia

and other above-listed specimens. The present species
is similar to Albaillella lauta Kuwahara, but length
between the proximal part of wing and aperture in A. levis
is longer than in A. lauta. Albaillella flexa Kuwahara isdistinguished from A. excelsa in having a diagnostic
bending in the apical portion.
Occurrence.-CHU-41 , 42, 43, 44.
Family Follicucullidae Ormiston and Babcock,1979 emend. Kozur, 1981
Genus Follicucullus Ormiston and Babcock, 1979
Follicucullus monacanthus Ishiga and Imoto
Figures 10-12-15
Follicucullus sp. A, Ishiga and Imoto, 1980, p. 340, pI. 4, figs. 1115; Ishiga et al., 1982a, pI. 2, figs. 5-6; Ishiga et al.,1982b, pI. 2, figs. 5-7.
Follicucullus monacanthus Ishiga and Imoto, in Ishiga et al.,1982c, p. 276-277, pI. 4, figs. 15-17; Suyari et al., 1983, pI.
4, figs. 1, 2; Isozaki, 1984, pI. 31, figs. 2-7-8; Tazawa etal., 1984, fig. 2-3; Ishiga, 1984, pI. 431, pI. 1, figs. 9-12;
Naka and Ishiga, 1985, pI. 1, figs. 8-11; Yoshida and
Murata, 1985, pI. 2, figs. 3-4; Ishiga et al., 1986, p. 128, pI.
2, figs. 4-11; Kojima, 1986, fig. 3-12; Uchiyama et al.,1986, pI. 8, fig. 14; Nishimura and Ishiga, 1987, pI. 1, figs.
7-10; Ishiga and Suzuki, 1988, pI. 1, fig. 1 ; Ishiga et al.,
1988, figs. 5, 13; Wang, 1991, pI. 3, fig. 4; Ando et al.,1991, pI. 9, fig. 4; Blome and Reed, 1992, p.364, figs. 9.
14-15; Ishida et al., 1992, pI. 2, fig. 2
Follicucullus sp. B, Ishiga and Imoto, in Ishiga et al., 1982c, pI.
4, figs. 18-20.
Remarks.-Follicucullus monacanthus is similar to F.
scholasticus morphotype II Ishiga in general shell shape.
The former species, however, is discriminated from thelatter in having a short hook-like spine (or wing) on thedorsal side of the apical cone. Although our specimens
are poorly preserved, shell shape with a strongly segmented pseudoabdomen in the dorsal side and a hooklike spine are identical with F. monacanthus.
Occurrence. - BT -1.
Suborder Spumellaria Ehrenberg, 1875
Superfamily Entactiniacea Riedel, 1967
Family Entactiniidae Riedel, 1967
Remarks.-Sugiyama (1992) included this family in theorder Entactinaria which was proposed by Kozur andMostler (1982). He pointed out that the family is characterized by the spherical shell and internal spicule thatsuggest phylogenetically much closer to nassellarians
than to typical spumellarians. Nazarov and Ormiston(1985) systematically listed and classified this radiolariangroup. Kozur and Mostler (1989) described many generaand species attributable to the suborder Entactinaria.
There are, however, diverse opinions on taxonomy of thiskind of radiolarians (e.g., Blome and Reed, 1992). We
tentatively classified these radiolarians as the suborder
Spumellaria.

53

Genus Entactinosphaera Foreman, 1963
Entactinosphaera pseudocimelia Sash ida
and Tonishi
Figures 11-1-3
Entactinosphaera pseudocimelia Sashida and Tonishi, 1988, p.
528-529, figs. 7-1-3, 6-8.
Remarks.-The present materials have longer major
spines compared with those of the original species described by Sashida and Tonishi (1988). As alreadypointed out by them, Entactinosphaera pseudocimelia isdistinguished from E. cimelia Nazarov and Ormiston in thenature of major spines. The latter species has thinbladed and long major spines which are triangular incross section.
Occurrence.-CHU-43,44.
Entactinosphaera sp.
Figures 11-4-6
Remarks.-This unidentified species is characterized inhaving three sturdy major spines, which are triradiate incross section. The length and width of these major
spines are variable.
Occurrence.-CHU-43, 44.
Superfamily Latentifistulidae Nazarov
and Ormiston, 1983
Family Ruzencevispongidae Kozur, 1980
Genus Octatormentum Nazarov
and Ormiston, 1985
Octatormentum ? sp.
Figure 11-20
Remarks.-The present specimens lack terminal
spines. An internal sphere cannot be observed. This
unidentified species is referred to the genus Octatormentum, which has a spongy shell of double pyramidal
form.
Occurrence. -CHU-44.
Family Ormistonellidae De Wever and Cardroit, 1984
Remarks.-This family diagnostically has four rays in atetrahedral pattern without any surrounding external shell.
Two genera, Nazarovella De Wever and Caridroit andOrmistonella De Wever and Caridroit are grouped in thisfamily. Previously, Sashida and Tonishi (1986) placedthese genera in the family Latentifistulidae, but weinclude these genera in the family Ormistonellidae in thisstudy.
Genus Nazarovella De Wever and Caridroit, 1984
Nazarovella graCilis De Wever and Caridroit
Figures 11-17,19
Nazarovella gracilis De Wever and Caridroit, 1984, p. 101, pI. 1,
figs. 14-15, 17; Ishiga, 1985, pI. 2, figs. 22-23; Naka and54

Katsuo Sash ida et al.

Figure 11. Permian radiolarians from Bukit Nyan. 1- 3. Entactinosphaera pseudocimelia Sash ida andTonishi, 1; IGUT - KS0509, CHU - 44, x 100, 2 ; IGUT - KS0508, CHU - 44, x 100, 3; IGUT - KS0553, CHU- 40, x
100. 4 - 6. Entactinosphaera sp., 4 ; IGUT- KS0506, CHU - 44, x 100, 5; IGUT- KS0507, CHU- 44, x 75. 7 -11.
Ishigaum? sp., 7; IGUT - KS0556, CHU- 41, x 100, 8 ; IGUT - KS0504, CHU - 44, x 100, 9 ; IGUT - KS0581 , CHU 43, x 75, 10 ; IGUT- KS0584, CHU - 43, 11 ; IGUT - KS0583, CHU - 43, x 75. 12-13. Triplanospongos musashiensis Sashida and Tonishi, 12 ; IGUT - KS0572, CHU - 44, x 100, 13 ; IGUT - KS0548, CHU - 42, x 100. 14. Praedeflanderella sp., IGUT - KS0559, CHU - 41, X 100. 15-16. Nazarovella inflata Sashida and Tonishi , 15 ; IGUTKS0525, CHU- 44, X 150, 16 ; IGUT- KS0514, CHU- 44, X 150. 17,19. Nazarovella gracilis De Wever andCaridroit, 17; IGUT - KS0572, CHU - 41 , x 75, 19 ; IGUT - KS0582, CHU - 44, x 75, 18; Pseudotormentus sp. ,IGUT - KS0582, CHU - 41, x 100. 20. Octatormentum? sp., IGUT - KS0510, CHU- 44, x 75.

Ishiga, 1985, pI. 1, figs. 14-15 ; Yamakita, 1986, pI. 1, figs.
12- 13 ; Ishiga and Miyamoto, 1986, pI. 64, fig. 16 ; Sash ida
and Tonishi, 1986, p. 10, pI. 3, figs. 10- 12, pI. 4, fig. 7 ;Caridroit and De Wever, 1986, p.82- 83, pI. 4, figs. 9- 15 ;Tumanda et al., 1990, pI. 1, fig . 27 ; Blome and Reed, 1992,
p. 375, figs. 13. 9- 10.
Nazarovella spp., Cheng, 1989, pI. 2, fig. 12.
Nazarovella sp., Ishiga et al., 1986, pI. 3, figs. 11 -13.

984.

Permian Radiolaria from Peninsular Malaysia

Nazarovispongus? sp. B, Ishiga and Suzuki, 1984, pI. 1, figs.

17-20.

.

Remarks.-Although all of our specimens are incompletely preserved, they may be identified with N. gracilis in
having diagnostic features of four arms, one of which, thefourth arm, is perpendicular to the plane of the otherthree.
Occurrence.-CHU-43,44.
Nazarovella inflata Sashida and Tonishi
Figures 11-15-16
Nazarovella inflata Sashida and Tonishi, 1986, p.10-11, pI. 4,
figs. 1-6, 10-12; Tumanda et a/., 1990, pI. 1, fig. 20;

Wang, 1991, pI. 4, fig. 2.
Nazorovella spp., Cheng, 1989, pI. 2, figs. 10-11.

unidentified? latentifistulid, Blome and Reed, 1992, fig. 13. 21.

Remarks.-An inflated tetrahedron shell with long cylindrical rays is a distinctive feature of this species.
Expansion of the tetrahedron shell is fairly variable inspecimens. Some specimens (e.g., Figure 10-15) have aless expanded shell compared with other ones (e.g.,
Figure 10-16). This species is easily distinguished fromN. gracilis in having a tetrahedral shell and cylindricalrays.
Occurrence.-CHU-44.

55

Remarks.-Completely preserved specimens are rare in
our collection. This unidentified species characteristically has a large shell composed of three rays, the lengthof which attains more than 500,um. Rays with coarse
spongy club-like tips are composed of a bundle of three
thin rods and have weak torsion. A conical terminal
spine protrudes from the spongy club-like tips. The
generic position of this unidentified species is tentative.
Occurrence.-CHU-43,44.
Spumellaria Incertae sedis
Genus Triplanospongos Sashida and Tonishi, 1988

Remarks.- This genus has almost the same shell structure as that of Trifidospongus Noble and Renne, 1990.
Blome and Reed (1992) considered that Trifidospongus isa junior synonym of the present genus.
Triplanospongos musashiensis Sash ida
and Tonishi, 1988
Figures 11-12-13?Paronaella sp. A, Wakita, 1983, pI. 7, fig. 7.
Angulobracchia ? sp., Yoshida and Murata, 1985, pI. 2, fig. 18.
Triplanospongos musashiensis Sashida and Tonishi, 1988, p.
536-539; Tumanda et a/., 1990, pI. 2, fig. 14.
Triplanospongos sp. cf. T. musashiensis, Cheng 1989, p.142,

pI. 3, figs. 13-16.
Genus Praedeflandrella Kozur and Mostler, 1989
Praedeflandrella sp.
Figure 11-14

Remarks.-Several poorly preserved specimens wereobtained. This unidentified species differs from otherspecies of the genus Deflandrella De Wever and Caridroitin having chambered arms.
Occurrence.-CHU-41.
Family Ishigidae Kozur and Mostler, 1989
Genus Pseudotormentus De Weverand Caridroit, 1984
Pseudotormentus sp.
Figure 11-18

Remarks.- This unidentified species slightly resembles
Pseudotormentus kamigoriensis De Wever and Caridroit
from southwest Japan. The shell of the latter species,
however, has a bulbous central portion. This unnamed
species is also similar to Latentifistula sp. described by
Sashida and Tonishi (1986) from Itsukaichi, Tokyo, but werefrain from a detailed comparison because of therestricted number of specimens.
Occurrence.-CHU-41.
Genus Ishigaum De Wever and Caridroit, 1984
Ishigaum? sp.
Figures 11-7-11

Latentifistula sp. cf. L. similicutis, Cheng, 1989, p.140, pI. 1,

figs. 13-14, 16.
?Trifidospongus dekkaensis Noble and Renne, 1990, p.388-

389, pI. 1, figs. 1-3, 6; Blome and Reed, 1992, p.376-379,
figs. 13. 13-14.
?Trifidospongus angustus Noble and Renne, 1990, p. 389, pI. 1,
figs. 4-6.

Remarks.- This species shows broad variation in raymorphology as shown by Sashida and Tonishi (1988).
The above-listed species placements may reflect different degrees of preservation.
Occurrence.-CHU-42, 43, 44.
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/ 985 1 Density and relative abundance of microsphericand megalospheric forms of Nummulites assedimentologic and taphonomic indicators
YASUO KONDO
Department of Geology, Faculty of Science, Kochi University, Kochi, 780 Japan
Received 25 July 1994; Revised manuscript accepted 5 January 1995
Abstract. The density and relative abundance of smaller (megalospheric) and larger (microspheric)forms of Nummulites provide excellent indicators of sedimentary condensation, dilution and sizesorting during the formation of fossil assemblages, using an inferred 10 : 1 original ratio of the twoforms. Various degrees of current sorting were recognized in the sandy facies of Nankinhama of
Hahajima, Ogasawara Islands; storm condensation in low-angle, cross-bedded sandstone, winnowing in sandstone beds with strongly imbricated Nummulites tests, and highly diluted occurrence indebris flow deposits. A poorly sorted, pale green, bedded sandstone is interpreted to represent theleast disturbed and perhaps indigenous preservation of Nummulites. In this sandstone, the ratio of
the two forms is roughly 10 : 1, as for other published examples.
No significant modification of density and relative abundance between the two forms occurs in
an apparently allochthonous occurrence of Nummulites in conglomeratic debris flows. Therefore,
preservation of the original ratio of the two forms of Nummulites does not necessarily exclude
transportation.
Key words: Taphonomy, sorting, biofabric, Nummulites, Ogasawara, Eocene
Introduction
Discrimination of in-situ from transported fossils of theepifaunal benthos is difficult, because epifaunal benthos
shows no definite indication of in-situ growth, such aspreserved life position commonly recognized in infaunal
bivalves. This is true of Nummulites, an epifaunal larger
foraminifer which flourished in the Eocene tropical andsubtropical sea. One of the advantages of Nummulites
in assessing its post-mortem transportation is its distinct
size dimorphism. Iwasaki and Aoshima (1970) first noted
current sorting in a Nummulites accumulation in the
Eocene of Hahajima, observing variable ratios of microspheric (larger) and megalospheric (smaller) forms.
Aigner (1982,1985) successfully applied the same idea to
the Nummulites accumulations in the Eocene of Egypt.
He recongnized four types of Nummulites accumulations
which were characterized by different biofabrics and ratioof microspheric to megalospheric forms of Nummulites in
the accumulations. In-situ and selectively transported
fossil assemblages between the two forms were inferredin the study.
In this paper, I evaluate the utility of density as well as
relative abundance of the two forms of Nummulites assedimentologic and taphonomic indicators.

I thank Kiyotaka Chinzei, Adolf Seilacher, Hiroshi
Kitazato, and Ken'ichi Kanazawa for their stimulating
discussions. I am, of course, wholly responsible for theinterpretation presented in this paper. The manuscript
was improved by Robert M. Cater. This study was carried out as part of the project "Natural history of Boso, Izu,
Ogasawara and Northern Mariana" by the Natural History
Museum and Institute, Chiba. Financial support provided
by Chiba Prefecture is acknowledged.
Stratigraphic and paleoenvironmental settingsof the Nummulites beds
Hahajima is an oceanic island consisting of Eocene
volcanic rocks, and one of the Japanese Ogasawara
Islands, located in the western Pacific more than 1,000 km
southeast from mainland Japan. The example studied inthis paper thus provides a contrasting environmental
setting of a Nummulites association to the well known
example from the Eocene of Egypt, which represents ashallow embayment basin bordering the Tethys sea(Aigner, 1982, 1985).
The island consists mainly of andesitic and basaltic
lava, and sedimentary rocks are distributed in the central
and southern part. The general stratigraphy and bio-

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Yasuo Kondo

stratigraphy has been described by Iwasaki and Aoshima(1970), Ujiie and Matsumaru (1977) and Matsumaru (1984),
following some early studies made before World War II
which are summarized in Ujiie and Matsumaru (1977) andliterature therein.
According to Ujiie and Matsumaru (1977), the sedimentary deposits of Hahajima are divided into three formations; basal conglomeratic and sandy sediments
containing Nummulites and other larger foraminifera(Yusan Formation), fine-grained sandstone with abundant
planktonic foraminifera (Okimura Formation) and Sekimon
Limestone. The age of the Nummulites-bearing strata
has been assigned to the Lutetian (middle Eocene;
Yabe, 1920, larger foraminifera; Hanzawa, 1925, larger
foraminifera; Saito, 1962, planktonic foraminifera). The
Nummulites of Hahajima was first described as Nummulites boninensis by Hanzawa (1947). Ujiie and Matsumaru (1977) and Matsumaru (1984) recognized several
other species of Nummulites, such as N. perforatus(Montfort) and N. cf. partschi de la Harpe.
The stratigraphic sequence of the Nummulites-bearing
strata in Hahajima is best exposed at Nankinhama andMiyukinohama, where a general coarsening-upwardfacies succession can be recognized above the basal
lava. The vertical facies succession is interpreted as
representing deepening-upward environmental changes(Kondo, 1993, 1995).
Sedimentary facies and their vertical succession
The basal contact of the sedimentary rock and theunderlying lava along the Miyukinohama and Nankinhama coast shows a topography with rugged relief.
The 25-m thick sequence, exposed at Nankinhama andMiyukinohama coasts, displays an overall coarseningupward trend (Figure 1). The sedimentary sequence
consists of a lower sandstone and siltstone, a middle
sandstone and an upper conglomerate. The following
facies designation, description and interpretation of thesedimentary facies are based on Kondo (1995).
Five sedimentary facies are recognized in the succession exposed at Nankinhama and Miyukinohama. Eachsedimentary facies is briefly described below in ascending order with a corresponding environmental interpretation.
The Interlaminated Sandstone and Siltstone Facies
consists mainly of interlaminated sandstone and siltstone
associated with some conglomerate and breccia at thebase. This facies is interpreted as the shallowest environment in the sequence studied. No Nummulites wasfound here.
The Cross-bedded Sandstone Facies overlies the Interlaminated Sandstone and Siltstone Facies. Paleocurrent
patterns shown by the Nummulites test imbrication are
multidirectional, representing an unusual current pattern
resulting from storm-like high-energy events (Kondo,
1993; 1995). The occurrence of Nummulites is generally
sparse, but may be very condensed locally.
The Cross-bedded Sandstone Facies changes upward

into the Parallel-bedded Sandstone Facies. This facies
contains large numbers of Nummulites, both megalospheric and microspheric forms. Pebble- and cobblesized concretionary clasts with Nummulites are occasionally contained in this facies. The upper unit of thisfacies characteristically shows a pale green colour andless common current-generated sedimentary structures,
as compared with the lower unit. The upper unit isinterpreted as the indigenous environment in which
Nummulites lived, representing an offshore environment
where water agitation was relatively uncommon.
The Interbedded Sandstone and Conglomerate Facies
is a transitional facies between the underlying Parallelbedded Sandstone Facies and the overlying Thick-bedded Conglomerate Facies. The sandstone beds in thisfacies are poorly-stratified or structureless, and the facies
is interpreted as a sediment gravity flow deposit. The
sparse occurrence of Nummulites found is consistent
with this facies interpretation.
The Thick-bedded Conglomerate Facies is a matrixsupported cobble to boulder conglomerate, with poorly
developed stratification. This clast fabric suggests a
debris flow origin. Nummulites abundance is as high as
in the Parallel-bedded Sandstone Facies.
Taphonomic processes inferred from density andrelative abundance of microsphericand megalospheric forms
The vast majority, if not all, of foraminifers are known orthought to undergo both sexual and asexual reproductive
phases. The well known morphological dimorphism of
Nummulites reflects this phenomenon. Sexual reproduction (gametogenesis) gives rise to diploid microspheric
forms, and asexual reproduction (schizogony) to haploid
megalospheric forms. Thus, two distinct size classes
are found in a single population (Figure 2). Amongmodern populations of larger foraminifera with symbiotic
algae as in Nummulites, microspheric forms are scarce(Hallock, 1982), and similarly, megalospheric forms dominate in original, undisturbed assemblages (Blondeau,
1972; Aigner, 1983, 1985). An original ratio of megalospheric to microspheric forms of approximately 10: 1 isinferred in these studies. If we assume that this ratio
applied to Nummulites boninensis and other species in
the Yusan Formation of Hahajima, the relative abundanceof the two forms can be used as a measure of the sorting
effect during transport. In this study, numbers ofmegalospheric and microspheric forms are counted, torepresent both relative abundance and also density of thetwo forms. The mode of occurrence of Nummulites andother biofabric features are described for each facies
below.
A quadrat (15X15 cm) was used to count the density
and relative abundances of the forms of Nummulites for a
vertical section of sandy beds in Nankinhama and conglomeratic beds in Miyukinohama. The measured outcrops were selected to represent all the major sedimentary facies and several different lithologies in the Parallel-

985.

Nummulites as sedimentologic and taphonomic indicators

DENSITY OF
NUMMULITESOCCURRENCECOLUMNARSECTION

61

SEDIMENTARYFACIES
Thick-bedded
Conglomerate Facies
Interbedded Sandstone &Conglomerate Facies

pale green bedded sandstone

1
!!i~

I
m
10

Parallel- bedded
Sandstone Facies----:;;;.;::ne with strongly~_~_ _- - - - imbricated tests

black silty sandstone~~ Cross-bedded Sandstone\

low-angle cross-beds{.. ----------,

I-::~~~E~-----:; wave ripple
Iconvolution

5

Interlaminated Sandstone &S;Us,on. Facl.so\"'- boulder
pebble-cobble

Figure 1. The sedimentary facies and their vertical succession at Nankinhama and Miyukinohama coast,
Hahajima. Density of Nummulites occurrence is shown on the left side of the columnar section ; black(abundant), stripe (common), white (rare or absent). Field photographs of mode of the fossil occurrence areshown for each sedimentary facies. Most of the Nummulites tests in the Cross- bedded, Sandstone Facies are
dissolved out. Measured units for density and relative abundance of the two forms of Nummulites are shownas arrows on the left side of the column.

bedded Sandstone Facies (Figure 1). Three or more randomly selected parts of each outcrop were measured.
The measurement was made in a total of 44 quadrats.
To confirm sorting phenomena indicated by this method,
the size frequency distribution of the diameter of microsph eric form was also measured directly in the field in
Nankinhama.
Figure 3 shows the abundance of the two forms of
Nummulites within the quadrats (15 x 15 cm) counted foreach sedimentary facies. This illustrates that the density and relative abundance of the two forms of Nummulites are closely related to sedimentary facies, andhence depositional environment and processes. The
measurements in different sedimentary facies and lithologies are fairly variable, but easily distinguishable fromeach other in most cases (Figure 3).
No macrofossils, including Nummulites, were found in
the Interlaminated Sandstone and Siltstone Facies.

62

Yasuo Kondo

'"E
(,)

500.-------------------------~.. -. -.- . . .. ..

an
N

N

--E 400-....Pafalle/.bed. " \:. Sandst. Facies :.. ... .... .. ... ..-

"

o

300

( ,)

".:::
Q)
.c
cUI
.2

}ed. sandS,;"

,0.-.

r·. .
..

::2'
~ 8 !~

asCl

100 ~• 011 v:; ~Q),..-.~
.~

,0 /

~

z

"

Sandst. Fac/es·..... :\o .-~ .,(•......

Thlck:~ed.

,

',.

. ae

~1' silty 's.~nd1'--..I,..·tong/o. Fac/es.tt: ~
11 /.b'l 'k~·Eci./crJ~bed.

y.
~ ~ ~~ :~O~ /",.. \\. .: ~~~

200. •. . .. -0..

pale.green~

sandst. with strongly·•...
(. Imbrleate~.': tests

O~~~~~~--~~~~'-~~

o

10

20

30

40

No. microspheric form I 225 cm

50
2

.

E

Figure 2. Field photograph of megalospheric andmicrospheric forms of Nummulites in the black silty sand in
the Parallel- bedded Sandstone Facies at Nankinhama(Upper), and its close- up view (below).

o

o

It:
CI)

.c

Co
(/)

The density of Nummulites occurrence in the Crossbedded Sandstone Facies is higher than for the Thickbedded Conglomerate Facies and the Parallel - bedded
Sandstone Facies. The numbers of megalospheric andmicrospheric forms in the Cross- bedded Sandstone
Facies are plotted within the region of the original Nummulites population or slightly microspheric-rich, winnowed region (Figure 3). This suggests that the storm
reworking and redeposition inferred for th is facies (Kondo,
1993, 1995) did not result in distinct size sorting.
The Parallel - bedded Sandstone Facies consists ofseveral different types of lithology ; pale- green parallel bedded sandstone distributed mainly in the upper unit,
and sandstone with strongly imbricated tests of Nummulites and black silty sand found in the lower unit. The
density and relative abundance of the two forms are mostvariable in this facies, and these lithologies within thisfacies differ greatly from each other (Figure 3). Palegreen, bedded sandstone beds are roughly constant intheir test ratios and similar to those of the Thick- bedded
Conglomerate Facies. The sandstone with strongly- imbricated tests shows distinct sorting, with concentrationof microspheric forms and smaller forms inferred to havebeen swept away by currents. Consistent with this, thesize frequency distribution of microspheric forms isdominated by larger specimens (Figure 4, lower). In theblack, silty sand layer, fossil density is much lower for theother sedimentary facies (Figure 3). This is interpreted
as the original low density of Nummulites in the silty

.9
cu

C)
CI)

E
o

z

microspheric

No. microspheric form
Figure 3. The density and relative abundance of
megalospheric and microspheric forms of Nummulites forvarious sed imentary facies in the Nankinhama- Miyukinohama section (upper). Interpretative diagram of post- mortem modification of density and relative abundances of thetwo forms of Nummulites (lower).

substrate.
In the Interbedded Sandstone and Conglomerate
Facies, the smaller forms are sorted away from structureless sandstone beds, though the densities are very much
reduced .
The Thick- bedded Conglomerate Facies contains
abundant Nummuli tes. The density and relative abundance of the two forms are relatively constant, withmegalospheric forms 100- 300/ 225 cm 2 , and microspheric
forms 10- 30/ 225 cm 2 (Figure 3). The ratio of megalospheric to microspheric forms is thus 10: 1. It is, therefore, concluded that there was no distinct size sorting

985.

40
30

Nummulites as sedimentologic and taphonomic indicators

pale green
beddedsandstone

Thick-bedded
Conglomerate
FaciesJ~J!la;:) 20

"0

> 10
."0

.....

0

L..

40

C

0

dJ
..0

E 30

pale green
beddedsandstone

J

~r-

;:)

Z

sandstone wi thstrongl yimbricat ed
tes ts

r-

20

10

20

30

40

50

60

Test Diameter (mm)Figure 4. Comparison of size frequency distribution of
microspheric forms of Nummulites between fossil assemblages from A) the pale green bedded sandstone in the
Parallel-bedded Sandstone Facies in Nankinhama (white)and the Thick-bedded Conglomerate Facies at the westernend of Nankinhama (black), and B) the pale green bedded
sandstone in Nankinhama (white) and sandstone beds withstrongly-imbricated tests (stripe) in the Parallel-bedded
Sandstone Facies in Nankinhama. Note the clear deviation
toward larger size in sandstone beds with strongly-imbricated tests.

during deposition of these debris flow deposits. The
larger forms show a similar size-frequency distribution(Figure 4, upper).
Which sedimentary facies represents
the habitat of Nummulites?
Both the Thick-bedded Conglomerate Facies and thepale green bedded sandstone in the Parallel-bedded
Sandstone Facies contain large numbers of Nummulites
tests, and show approximately the expected natural ratio
10: 1. The former, however, is interpreted as debris flow
deposits, and must be excluded as a candidate of Num'
mulites' natural habitat.
The pale green, bedded sandstone, therefore, probably
represents the habitat of Nummulites. This facies is little
affected by substrate disturbances, although some do
occur including well-developed test imbrication and63

small-scale ripple bedding. The presence of the concretionary clasts containing similar ratios of Nummulites
tests may perhaps indicate reworking of prefossilized
Nummulites. Aigner (1982) called attention to the natureof Nummulites tests as a sedimentary particle, statingthat the Nummulites test must have been originally very
porous (up to 54%) and light (down to 1.28 g/cm 3 ), andtherefore very susceptible to being reworked. A similar
idea has been suggested by Seilacher (personal communication), who noted the importance of prefossilization inmodifying hydrodynamic behavior of crinoid remains(Seilacher,1973). This suggests that undisturbed preservation of Nummulites occurs only rarely in shelteredenvironments, and that in-situ reworking and small-scaletransportation are involved even in indigenous fossil
assemblages.
Nevertheless, the evidence of common reworking foundin this facies is not necessarily inconsistent with thisfacies representing the habitat of Nummulites. Considering that the animal had almost none or very little
locomotive and escape ability, incessant and rapid dumping of sediments into their habitat would greatly hinderthese animals from establishing continuous colonization.
In contrast, transportation of the living tests by current or
wave may not harm them so long as the tests remained on
the sea floor to receive adequate water circulation andsufficient light to sustain the growth of the inferredsymbiotic algae (Lee et al., 1979).
As discussed above, in-situ deposition of Nummulites
is inferred, based on the comparison between observed
and postulated ratio (10: 1) of the megalospheric andmicrospheric forms of Nummulites. The roughly constant ratio of the two fossil forms in the pale-green
bedded sandstone is, in turn, strong evidence for theconclusion that the sandstone represents the original
habitat of Nummulites. Also, this implies that the postulated original ratio of 10: 1 for the megalospheric andmicrospheric forms of Nummulites is independently
supported by the present study.
Summary(1) The density and relative abundance of megalospheric and microspheric forms of Nummulites is a
powerful tool for estimating sedimentary condensation,
dilution and current sorting during formation of fossil
assemblages. Attention must be paid to other features,
however, such as biofabric, sedimentary structures andtheir vertical succession for an accurate interpretation of
the origin of the fossil assemblage, because transportation can occur without significant size sorting, as in debris
flows.
(2) The ratio of megalospheric and microspheric formsof the original population of Nummulites boninensis andother species is inferred to be roughly 10: 1, similar to theratio reported for Nummulites gizehensis studied by
Aigner (1982, 1983, 1985).
(3) The natural habitat of Nummulites from the volcaniclastic sequence of Hahajima is inferred to haveYasuo Kondo

64

been transitional to an offshore sandy bottom where
current activities causing rapid burial or reworking wererelatively uncommon. Evidence of In-situ reworking,and a small amount of transport nevertheless does occur
in this facies.

References
Aigner, T., 1982: Event stratifications in nummulite accumulations and in shell beds from the Eocene of Egypt.
In, Einsele, G. and Seilacher, A. eds., Cyclic andEvent Stratification, p. 248-262., Springer Verlag,
Berlin.
Aigner, T., 1983: Facies and origin of nummulitic buildups: an example from the Giza Pyramids Plateau(Middle Eocene, Egypt). Neues Jahrbuch fur
Geologie und Palaontologie, Abhandlungen, vol. 166,
p.347-368.
Aigner, T., 1985: Biofabrics as dynamic indicator in
Nummulite accumulations. Journal of Sedimentary
Petrology, vol. 55, p.0131-0134.
Blondeau, A., 1972: Les Nummulites: Vuibert ed., Paris,
254p.
Hallock, P., 1981 : Algal symbiosis: a mathematical analysis. Marine Biology., vol. 62, p. 249-255.
Hanzawa, S., 1925: Notes on some foraminiferous rocks
from Okinawa-jima and the Ogasawara Islands.
Journal of the Geological Society of Tokyo, vol. 31, p.
10-24. (in Japanese)
Hanzawa, S., 1947: Eocene foraminifera from Haha-jima(Hillsborough Island). Journal of Paleontology, vol.
21, p.254-259.
Iwasaki, V. and Aoshima, M., 1970: Report on geology of
the Bonin Islands. In, The nature of the Bonin andthe Volcano Islands, p. 205-219. Higher Edncationand Science Bureau, Ministry of Education andCultural Properties Protection Division, Agency for
Cultural Affairs, Japan. (in Japanese with English
abstract)
Kondo, V., 1993: Sedimentary facies and depositional

environment of the Eocene volcaniclastic sequence,
Hahajima, Ogasawara Islands, western P~cific, withdiscussion on taphonomy of Nummulttes. Programme and Abstracts, Geological Society of New
Zealand Inc., 1993 Annual Conference, p. 102, Victoria University of Wellington.
Kondo, V., 1995: Paleocurrent reconstruction, using imbricated tests of Nummulites in the Eocene of Hahajima, Ogasawara Islands. Journal of the GeologicalSociety of Japan, vol. 101, p.228-234.
Lee, J.J., McEnery, E.G., Kahn, E.G. and Schuster, F.L.,
1979: Symbiosis and the evolution of larger foraminifera. Micropaleontology, vol. 25, p. 118-140.
Matsumaru, K., 1984: Larger foraminiferal associations
useful for the correlation of the Eocene andOligocene sediments in the Ogasawara Islands,
Japan, and an examination of Nummulites boninensis
Hanzawa. Benthos '83; 2nd International Symposium on Benthic Foraminifera, p. 415-422.
Seilacher, A., 1973: Biostratinomy: the sedimentology of
biologically standardized particles. In, Ginsburg,
R.N. ed., Evolving concepts and method in
sedimentology. Johns Hopkins Univ. Press., p.159177. Baltimore and London.
Saito, T. 1962: Eocene planktonic foraminifera from
Hahajima (Hillsborough Islands). Transactions andProceedings of the Palaeontological Society of Japan,
New Series, No. 45, p.209-225.
Ujiie, H. 1985: Microfossils from the Ogasawara andMariana Arcs and history of formation of thePhilippine Sea. Gekkan Chikyu (Earth Monthly), vol.
7, p. 657 -663. (in Japanese; title translated)
Ujiie, H. and Matsumaru, K. 1979: Stratigraphie outline of
Hahajima (Hillsborough Island), Bonin Islands. Memoirs of the National Science Museum, No. 10, p.5-18,
4 pis. (in Japanese with English summary)Vabe, H. 1920: Japanese Tertiary rocks with larger foraminifera (2). The Journal of the Geological SOCiety
of Japan, vol. 27, p.293-300. (in Japanese)

Hahajima -ff.J:Jlfh, Nankinhama i¥iJi(~, Miyukinohama 1JfIJ* / ~.

Trans. Proc. Palaeont. Soc. Japan, N.S., No. 177, pp.65-78, 7 Figs., April 30, 1995

Early Middle Miocene ostracodes from the
Suenomatsuyama Formation, Ninohe City, Northeast
Japan and their paleoenvironmental significanceTOSHIAKI IRIZUKI and TAKASHI MATSUBARA
Department of Earth SCiences, Aichi University of Education, Kariya, 448 Japan
Department of Geoenvironmental Science, Faculty of SCience, Tohoku University, Sendai, 980-77 Japan

Received 11 October 1994; Revised manuscript accepted 15 December 1994
Abstract. Sixty-six species in 44 genera of fossil ostracodes are reported for the first time from thelower Middle Miocene Suenomatsuyama Formation, distributed in Ninohe City, Iwate Prefecture,
Northeast Japan. Dominating species throughout the formation are E/ofsone//a cf. concinna (Jones),
Neomonoceratina japonica (lshizaki), Pectocythere daishakaensis Tabuki and Schizocythere kishinouyei (Kajiyama). Vertical changes of species composition of ostracode faunas and Q-mode
cluster analysis reveal that the lower part of the Suenomatsuyama Formation is dominated by cooland sublittoral species, while the middle to upper part is marked by sublittoral temperate-water
species. Thus, cool to temperate water ostracode species, which appeared abundantly in the middle
part of the underlying Kadonosawa Formatiton, lingered on until the deposition time of the Suenomatsuyama Formation, whereas warm-water species became dominant in the upper part. One new
species, Laperousecythere ishizakii, is described herein.
Key words: Miocene, circumpolar and cryophilic ostracodes, cluster analysis, mid-Neogene Climatic
Optimum, Laperousecythere

Introduction
Late Early to early Middle Miocene rocks are well
exposed in the vicinity of the Mabechi-gawa River,
Ninohe City, in the northernmost part of Iwate Prefecture,
Northeast Japan. Previous geological andpaleontological studies pointed out that only for a shortperiod (ca. 16.5-15 Ma), tropical to subtropical faunas andfloras spread widely from southern Kyushu to southern
Hokkaido in Japan (e.g. Oyama, 1950; Chinzei, 1986;
Itoigawa and Yamanoi, 1990). This event is called the
mid-Neogene Climatic Optimum, which was followed by
an abrupt cooling occurring ca. 15 Ma (e.g. Tsuchi, 1986).
In the study area, tropical to subtropical molluscan faunas
called the Kadonosawa Fauna (Otuka, 1939; Chinzei,1963) have been reported from the Lower Miocene Yotsuyaku Formation (the Koiwai Mudstone, Sandstone andConglomerate Member) and the lowest part of theKadonosawa Formation (the Tate Conglomeratic Sandstone Member) (Otuka, 1934; Chinzei, 1963, 1979). They
are thought to have lived in intertidal to upper sublittoral
areas under the influence of a warm-water current (Chinzei, 1978). According to Chinzei (1979), the upper part of
the Kadonosawa Formation yields the Shiobara-typemolluscan fossils: cool to temperate shallow-water andendemic Japanese molluscan faunas from the Middle toLate Miocene (Chinzei, 1963,1978; Chinzei and Iwasaki,
1967; Iwasaki, 1970,1981). Thus, the overlying
Suenomatsuyama Formation, which is the object of thepresent study, must be deposits of post-mid-Neogene
Climatic Optimum.
Studies on faunal changes of ostracodes during these
periods, however, have been superficial. Hence, it isimportant to investigate vertical changes of ostracodefaunas spanning from the Kadonosawa Formation to theoverlying Suenomatsuyama Formation and search forancestors of Japanese endemic ostracodes. Recently,
Irizuki and Matsubara (1994) studied ostracode faunas
from the Kadonosawa Formation and proved the existence of a succession of depositional environments in the
Kadonosawa Formation: warm inshore, deep offshore
and cool inshore in ascending order. They emphasized,
moreover, the significance of circumpolar-cryophilic
ostracode species first appearing around the base of the
diatom Denticulopsis praelauta Zone (the middle part of
the Kadonosawa Formation): the appearance of coolwater ostracodes predates that of cool to temperatewater molluscs belonging to the Shiobara-type Fauna.

Toshiaki Irizuki and Takashi Matsubara

66

The aim of this study is to report Middle Miocene
ostracodes for the first time from the Suenomatsuyama
Formation and to show vertical changes of cool to temperate ostracode faunas after the mid-Neogene Climatic
Optimum.
Geological settings
The geology of Ninohe City has been studied by many
workers (e.g. Otuka, 1934; Chinzei, 1958a, b; Samata,1976). The Suenomatsuyama Formation overlies conformably, partly disconformably, the Kadonosawa Formationand is conformably, partly disconformably, overlain by theTomesaki Formation (Figure 1). Since the Suenomatsuyama Formation has a great variety of rock types, it
comprises seven members (Chinzei, 1958a, 1966): 1)
Shinden Sandstone (volcanic medium sandstone), 2)
Nakuidake Andesite (andesitic volcanic breccia and tuff
breccia), 3) Anaushi Conglomeratic Sandstone (conglomerate and coarse sandstone), 4) Itsukamachi Sandstone (tuffaceous medium sandstone), 5) Aikawa Andesite (andesitic volcanic breccia and lapilli tuff), 6)
Maisawa Sandstone (medium to coarse sandstone) and 7)
Tsukidate Sandstone (pumiceous coarse sandstone) from
NNE to SSW. The fossil-bearing rock samples used in
the present study were collected from the Itsukamachi
Sandstone and Maisawa Sandstone Members.
Many molluscan fossils have so far been reported fromthe Suenomatsuyama Formation (e.g. Aoki, 1960; Chinzei, 1966,1979). They are assigned to the cool to temperate Shiobara-type Fauna mentioned above. Some
datum planes of planktonic microfossils have also been
identified around the study area (Samata, 1976; Akiba,
1977; Koizumi, 1979,1986; Oda et al., 1983,1984;
Maruyama, 1984). According to the diatom biostratigraphy by Koizumi (1979,1986) and Maruyama (1984), theAge Ma P.F.

DiatomFormation

14 N.tO D. husledtii

Tomesaki---- -D.-hyalma
15'"----w:2 15 N.9

z:::!:w

r-- D./aula

t)

0
:::!:

r- 16

Samples obtained from the lower Itsukamachi Sandstone and upper Maisawa Sandstone Members of the
Suenomatsuyama Formation were selected for investiga-

MemberJumonjisan~Malak;
Shall~uenomatsuyamal

nTSn <-z. AI ~ MA (NA

Kadonosawa

Shikonai Siltstonef-- - - -N.7

Materials and Methods

Sandstone

N.S r--_---D. prae/aula

r---

~
m
w

base of the Denticulopsis lauta Zone is present in thelower part of the Suenomatsuyama Formation and thebase of the Denticulopsis hyalina Zone is in the lower partof the overlying Tomesaki Formation (the Jumonji Sandstone Member). Samata (1976) and Oda et al. (1983,1984) indentified fossil planktonic foraminifers assignable
to Zone N.8 of Blow (1969). The Suenomatsuyama
Formation was deposited consequently during the early
Middle Miocene (ca. 15.7+ to 14.85+ Ma, according toKoizumi, 1985) (Fig. 1).

r---?
A. ingens-17

TS: Tsukidate Sandstone
AI: Aikawa Andesite
AN: Anaushi Coarse Sandstone
IT: Itsukamachi Sandstone
MA: Maisawa Sandstone

Yotsuyaku~IT/SHe onalomeratic andstone~ SUgOh~a A.M.S.C.
Keiseitoge
Andesite
Koiwai M.S.C.

SH: Shinden Sandstone
NA: Nakuidake Andesite
A.M.S.C.: Alternation of Mudstone.
Sandstone and Conglomerate
M.S.C.: Mudstone. Sandstone
and Conglomerate

Figure 1. Litho- and biostratigraphy of the studied
area. Biostratigraphy is based on the chronology of Oda(1986) and Koizumi (1985). Compiled after Samata (1976),
Maruyama (1984) and Koizumi (1986).

Figure 2. Map showing the studied area (arrow head)and ostracode fossil localities (a part of 1 : 50,000 map of"Ichinohe" published by Geographical Survey Institute ofJapan). HK: Hokkaido, HN: Honshu, S: Shikoku, K :Kyushu.

986.

Miocene ostracodes from Suenomatsuyama Formation

tion of ostracode faunas (Figures 2 , 3).
The Itsukamachi Sandstone Member exposed well in
so- called Basenkyo (large cliffs on the right side of theMabechi - gawa River) is composed entirely of about 150m- thick tuffaceous fine to medium massive sandstone
with many calcareous nodules and siltpipes, and isconformably covered w ith andesitic volcanic breccia of
the Aikawa Andesite Member (BAS in Figure 3). The
lower part of this member (around samples BAS 1 and 2)
yields abundant molluscan fossils such as Mizuhopecten
kimurai nakosoensis (Masuda) and M. ninohensis(Masuda). The relationship between the Itsukamachi
Sandstone Member and the underlying Kadonosawa
Formation can not be recognized along the samplingroute.
The Maisawa Sandstone Member distributed on thelower Jumonji - gawa River can be divided into threeparts : the lower consisting of cross- bedded dark gray to
black, medium to coarse sandstone with many volcanic
rock fragments reworked from the Aikawa Andesite
Member and calcareous fossil fragments of molluscs andbarnacles ; the middle composed of a random mixture of
medium to coarse sandstone as in the lower and darkgray silty sandstone (slumping deposits) ; the upper consisting of siltstone and black mudstone, which are disconformably covered with medium sandstone of the
Metoki Shell Sandstone Member of the overlying
Tomesaki Formation. The entire thickness is about 100
m along the Jumonji- gawa River (JMJ in Figure 3).
A total of 36 samples were collected from both members : 20 from the Itsukamachi Sandstone Member and 16
from the Maisawa Sandstone Member. Eighty grams ofdried sediments were disaggregated making use of asaturated sodium sulfate solution and naphtha for rockmaceration (Maiya and Inoue, 1973), washed through a
200 mesh sieve screen, and dried again. These procedures were repeated until the whole sediment sample
disintegrates. A fraction coarser than 125 J1m (115 mesh)
was sieved and all the specimens present were picked.

67

@

n

BAS

c:
0

~

E

14

~

13
12
11

ra
rn
E
Q)

0

@

10

f-

...
Q)

.c
E
Q)

9
8

~

n

Q)

c:
0

en
"l:l

n
n
n

c:

ra

(/)

n
n
Q5
.c
E

6
5

Q)

~
Q)

4
3

c:

@

0

en

"l:l

c:

ra

(/)

:E
(.J

ra
E
ra

I 8I
~

Figure 3. Columnar sections of the Suenomatsuyama Formation. BAS : samples from the Itsukamachi
Sandstone Member exposed in Basenkyo; JMJ; samples from the Maisawa Sandstone Member along theJumonji -gawa River. - - n shows samples barren of
ostracodes. ____ shows samples used for Q-mode
cluster analysis. Ka : the Kadonosawa Formation.

9

:i:

:::J

Four groups of ostracodes from the
Suenomatsuyama Formation
Sixty- six species in 44 genera of fossil ostracodes
were obtained from 14 samples of the Itsukamachi Sandstone Member and nine of the Maisawa Sandstone
Member (Table 1).
Ostracodes from the Suenomatsuyama Formation canbe divided into four different categories of species : 1)
circumpolar, 2) cryophilic, 3) temperate (including
species common in Middle to Late Miocene deposits of

n

~

10m

®

20m

~I

10m

Ka

Q

molluscan fossil

t-:-:-J siltstone= calcareous nodule •fine sandstone

U sandpipe~ slumping deposits

wmmamedium sandstonet':-:1fine tuff

t:,:·.:::.:-.;·I cross-bedded sandstone~ mudstone

R~~ coarse sandstoneToshiaki Irizuki and Takashi Matsubara

68

Table 1. List of ostracode species from the Suenomatsuyama Formation. BAS: samples fromthe Itsukamachi Sandstone Member; JMJ: those from the Maisawa Sandstone Member. * shows
species and samples used for Q-mode cluster analysis.

~
sample, Acantnocyt~erelS !lunelmensls
Acanthocythereis aff. munechikai
Ambtonia sp.
* Aurila sp.
Australimoosella cl. hanaii
t:lytnocerallna. sp.
* Callistocythere reticulata
Cluthlasp.
* Cornucoquimba aff. alata* Cornucoquimba monlwensls· cornucoqulmba sanol
Cornucoquimba? sp.
* Cythere omoienipponica* Cythere cl. omotenlpponlca* Cythere sp.
c;ytheropleron sawanense
Cytheropteron sp. 1* Cytheropteron sp. 2* Eiolsonelia cl. conclnna
Eucythere sp.
• Eucyt.nerura neoalae
Falsobuntonia taiwanlca* Finmarchinelia hanali* Finmarchinelia japonlca* Hemlcythere cf. gu~anovae· Hemlcytnere kHanlpponlca* Hemlcythere ochotensls* Hemlcytherura clathrata* HermanHes? posterocostatus
Hlrsutocythere? sp.
• Kotoracythere cf. abnorma
Kotoracythere sp.
Krlthe sp.
* laperousecythere Ishlzakli
laperousecythere cf. robusta• laperousecythere yamsensls* laperousecythere sp.
loxoconcha pulchra
loxoconcha subkoloraforma
loxoconcha aff. uranouchlensls, Loxocomlculum kotoraformum* Munseyelia hatatatensls
Munseyella hokkaidoana* Munseyella sp. 1
Munseyella sp. 2
Neocymen<lels sp.
* Neomonoceratina japonlca* Normanlcythere sp.
* Paljenborchella hanall* Palmenella Iimicola
I'almoconcna sp.
* Paracytherldea neolonglcaudata* Pectocythere daishakaensls
Pontocythere sp.
Propontocypris? sp.
• Hooensonlles retlCulfforma
Rolundracythere? sp.
* Schlzocythere klshlnouyel
Sclerochilus sp.
* Semlcytherura henryhowei
SemlCymerura CT. sklppa
Semlcytherura sp.
Spinlleberls cl. rhomboldalis
Typhlocythere sp.
Urocytherels gorokuensls
XestOleoens sp.
No. of spec mens
No. of spec es

JMJ

BAS
*1

*2 *3 *4 *5 *6 *7

2

7

3

6

8 *9 *10 *11 *12*13 *14

3

2

2

5

7

4

*2 *3 *4 *5 *6

7

8

3

2

1

1
1

1
2

1

6
1

1
1

3

1

1

3
2
11

1
3
7

1
4
2

6
9
11

6
6
9

3
2
2

3
1
3

3
1
4

1

1

1

1

3

3

1

1

8

18

1
1
7
2
2
2
1
1

1

3

2

1
2

1

1
1
7
12

1

2

1

1

2

6

9

1
2
1
1
1

1

2
3
1
1
7

1
2
5

4
2

2
4
4

10

5

8

15

1

1

1
1

2

1
16

1
2 16

1

2

3
4

3
6

4
5

3

1

4

4
6
1
3

2

4

10

5

2

2

1

1

4
1

2

1

3

1

1
26

26

35
1

1
1
2
1
4

1
1

1

2

1

1

2
1

17

1
2
1
1
1
2

2
6
1
5
5
3
1

5

4

1
1

2

1

1

15
1
2
1
3
3

9
1
1
3

3
8

1
4

4

3

4
3
1

2
3

5

7
1
2

1

1
2
1
2
1
1

5

2
2

1
1

1
8

4
2

1
2

3
1

1
1

3
2

1
3

2

1

1

1

1

3

1

1

5

2

2

4

17

3

6

1

1

7
2

3
1

2

3

5
3
1
20

2

7

1
1

18

8

3

2
2
3

1

6
4

9
1

3

4

4

2
1

1
1

1
5
27

2
1
2

1
3

2

7

2

7

7
1
7

1
1

1
1
3

4

2
2

5

1
6

1
1
4

9
2
5

3
2
5

3

8

1

12
1
1

1
1

1

1
1

3

4

5

4
1
2

2
4
12

2

3
11
1

1
1
5

1

1
1
2

7
2

3
1

1
1
1

1

6
1
1
1

3
4

6
6

1
2

5

3

4

2

7

12

5 27

31

2

3

1

1

8 16
4
1
3
3
2
1
5 13
9 11
1

1
1

2
6

1

1
1

1

3

9
1
1
2

7 18
3 11
2
1
1
2
1 4
5
4 10 12

2

7
2

19
3

1
14
1

2
1
2
2

3

2

6
6

1
2
6 11

4

13
2

6
4

2
3

1
1

2
2

1
35
10

15
12

19
9
1

9
9

9
7

2
5

29
9
1

8
11

3

1

1

1
1

1
2
2
2

1
1

1

3
2

12
3
1
4

1
1

3
6
1
1
1
1

7
1
3

3
1
2

10

1

1
1 20

14

2
1
2

1

1
2

7

13

1

1

1

4
1

1

2
81
13

64 97105
13 22 30

36135189
21 32 371
2
38 61 134 74123 82 85
15 20 31 30 29 29 24

39206 128 58189
18 35 30 19 32

57 31 30
16 12 13

5
4

986.

Miocene ostracodes from Suenomatsuyama Formation

69

Table 2. Circumpolar, cryophilic and temperate ostracodes from the Suenomatsuyama Formation.

CIRCUMPOLAR SPECIESTEMPERATE SPECIESAcanthocythereis dunelmensis (Norman, 1865) Callistocythere reticulata Hanai, 1957
Elotsonella ct. concinna (Jones, 1857)
Cornucoquimba moniwensis (Ishizaki, 1966)
Hemicytherura clathrata (Sars, 1865)
Cornucoquimba saitoi (Ishizaki, 1963)
Munseyella hatatatensis (Ishizaki, 1966)
Cythere omotenipponica Hanai, 1959
Palmenella limicola (Norman, 1865)
Hermanites? posterocostatus Ishizaki, 1966
Kotoracythere ct. abnorma Ishizaki, 1966
CRYOPHILIC SPECIESFinmarchinella hanaii Okada, 1979
Laperousecythere ishizakii, sp. nov.
Finmarchinella japonica (Ishizaki, 1966)
Laperousecythere sp.
Hemicythere ct. gurjanovae Schornikov, 1974 Loxoconcha pulchra Ishizaki, 1968
Hemicythere kitanipponica (Tabuki, 1986)
Neomonoceratina japonica (Ishizaki, 1966)
Hemicythere ochotensis Schornikov, 1974
Paracytheridea neolongicaudata Ishizaki, 1966
Schizocythere kishinouyei (Kajiyama, 1913)
Laperousecythere ct. robusta (Tabuki, 1986)
Laperousecythere yahtsensis Brouwers, 1993 Semicytherura henryhowei Hanai and Ikeya, 1977
Robertsonites reticuliforma (Ishizaki, 1966)

northern Japan), and 4) others. Many workers haveidentified cold-water ostracodes from Plio-Pleistocene
formations in northern Japan (Hanai, 1957,1970; Hanai
and Ikeya, 1991; Hanai and Yamaguchi, 1987; Ishizaki,
1966; Ishizaki and Matoba, 1985; Ishizaki et a/., 1993;
Okada, 1979; Tabuki, 1986; Cronin and Ikeya, 1987;
Hayashi, 1988; Irizuki, 1989,1993). Cronin and Ikeya(1987) recognized 26 circumpolar and 21 cryophilic
species from some formations yielding the Omma-Manganji Fauna, a term proposed by Otuka (1939) for theJapanene Pliocene cold water molluscan assemblage.
They referred ostracodes known from Recent and/or
fossil deposits of the North Atlantic and adjacent Arctic
seas to "circumpolar species", and those typically occurring with circumpolar species in Japanese deposits and,in most cases, being members of high-latitude genera to"cryophilic species." It would not be true that in the
Miocene circumpolar-cryophilic species ever experienced such subfrigid to frigid environments as in the
Recent. It is probable that they have adapted to colder
environments during the Late Cenozoic. They are, however, reckoned to be cool water indicators in the present
study since they are expected to have preferred living incolder water than other species even in the Miocene.
Thus, the present study concerns only relative watertemperatures during deposition of the Suenomatsuyama
Formation.
Five circumpolar and eight cryophilic species wereidentified in the Suenomatsuyama Formation (Table 2).
Elofsone/la cf. concinna (Jones) is comparable to a reticulate form, E. concinna, reported from Plio-Pleistocene
formations yielding the Omma-Manganji Fauna (Tabuki,
1986; Cronin and Ikeya, 1987; Irizuki and Sasaki, 1993)
by its similar but weaker patterns of reticulation andridges. It is a representative species also in the middle
to upper part of the underlying Kadonosawa Formation(Irizuki and Matsubara, 1994). Laperousecythere yahtsensis Brouwers (=Patagonacythere dubia of Cronin and

Ikeya, 1987) is abundant in Pleistocene to Holocene
deposits in the Gulf of Alaska (Brouwers, 1993) and PlioPleistocene formations distributed on the Japan Sea sideof northern Japan (Cronin and Ikeya, 1987). It should not
be a circumpolar species but a cryophilic one since it has
not been recorded from the Arctic to northern Atlanticareas. All specimens of such hemicytherin ostracodes
as E. cf. concinna, L. yahtsensis and L. cf. robusta (Tabuki) have weaker and thinner ornamentations than theircounterparts from younger formations containing theOmma-Manganji ostracodes. This may reflect that thissetting was in higher water temperatures than depositional sites for other younger formations.
Thirteen species belong to a temperate species group(Table 2): they are assumed to have preferred inhabiting
warmer waters than the above-mentioned indicators.
Ca/listocythere reticulata Hanai, Laperousecythere ishizakii sp. nov. (=Hermanites sp. of Irizuki and Matsubara,1994) and Loxoconcha pulchra Ishizaki are also recognized in the lowest part of the underlying Kadonosawa
Formation (the Tate Conglomeratic Sandstone Member),which was deposited at the time of the mid-Neogene
Climatic Optimum. Thus, they are thought to have beenwarm-water species. Cythere omotenipponica Hanai
and Semicytherura henryhowei Hanai and Ikeya live
dominantly in coastal areas influenced by the Kuroshio
Current (Hanai, 1957,1959; Hanai et a/., 1977; Tsukagoshi and Ikeya, 1987). The other eight species are common in such Middle to Late Miocene deposits in Northeast Japan as the Hatatate and Tsunaki Formations in
Sendai City (Ishizaki, 1966; Ishizaki et a/., in press), theTogi Formation in the Sekinohana area (Yajima, 1988) andthe Fujikotogawa Formation in Kamikoani Village (Yajima,
1988; Irizuki, 1994). Some of these formations contain
Shiobara-type molluscan fossils. These eight species
are, moreover, minor constituents in Pleistocene formations deposited under subfrigid to frigid environments innorthern Japan.

Toshiaki Irizuki and Takashi Matsubara

70

Among others are bathyal to lower sublittoral
ostracodes reported from mudstone of the Kadonosawa
Formation such as Falsobuntonia taiwanica Malz, Hirsutocythere? sp. and Propontocypris? sp., which are allrare throughout the Suenomatsuyama Formation.
The above four groups are qualitatively assorted at the

JMJ4
JMJ 5
JMJ3

1113

JMJ 2
BASS

discretion of the present study, pending more data on thespatial and temporal distribution of ostracodes are gathered.
Q-mode cluster analysis
Q-mode cluster analysis was used to examine verticalchanges of ostracode faunas, which could be in association with varying depositional environments of the
Suenomatsuyama Formation. This analysis was conducted by using 17 samples, containing more than 50
individuals, and 35 species represented by three or moreindividuals in anyone of the samples. The used similarities are Horn's overlap indices (Horn, 1966), and clustering is practiced by the unweighted pair group method witharithmetic averages (UPGMA). The result reveals threeclusters (I, II, III) bounded by a similarity value of 0.6(Figure 4).
Cluster I: This cluster is represented by only one sample(JMJ 6; silty sandstone) from the upper part, showing thestrongest slump structures, of the Maisawa Sandstone

BAS 13
Table 3. Values of species diversity (H(S)) andequitability (Eq.) calculated by the method of Buzas andGibson (1969) for ostracode assemblages obtained fromsamples used for Q-mode cluster analysis. CI. meansclusters.

BAS 12
BAS 11
BAS 141112
BAS 10
BAS?

2.02
1.88
2.45

EO. CI.
0.58
II
0.50
0.53 1111

BAS 6
2.96 0.60 1112
BAS 7
3.03 0.56-------------------------------_.
BAS 9
2.78 0.81 111.3

BAS 4

1111

BAS-:{0----3 ~ ij1- ---o~ 65 ------

II

BAS 11
BAS 12
BAS 13
BAS 14

3.09
3.14
3.01
2.83

0.74
0.80 1112
0.70
0.71

JMJ 3
JMJ 4
JMJ 5
JMJ 6

2.99
2.69
3.02
1.92

0.66 1113
0.78
0.64
0.43

BAS 2
BAS 1
JMJ 6
0.4 0.5 0.6

H(S)BAs-4--- --3~60 ---6:6-"- --- --

BAS 6

BAS 3

Sample
BAS 1
BAS 2
BAS 3

o.? 0.8 O.S 1.0

Horn's overlap index
Figure 4. Dendrogram resulting from Q-mode cluster
analysis based on the index of overlap of Horn (1966). I to1113 refer to clusters.

jrvfj-2------3~64 ---6:60 ---- --986.
Member.

Miocene ostracodes from Suenomatsuyama Formation

It contains poorly preserved specimens ofAcanthocythereis dunelmensis (Sars), Elofsonella cf. concinna and Kotoracythere cf. abnorma Ishizaki. The faunain this cluster has low values both of diversity (1.92) andequitability (0.43) as calculated by the method of Buzas
and Gibson (1969) (Table 3).
Cluster II: This cluster is composed of two samples (BAS
1,2,; medium sandstone) from the lower part of the Itsukamachi Sandstone Member. It is characterized by thedominance of E. cf. concinna, Laperousecythere sp. andPaijenborchella hanaii Tabuki, and faunas having low
values both of diversity (1.88-2.02) and equitability (0.500.58).
Cluster III: This cluster comprises ten samples (BAS 3, 4,
6,7,9-14; fine to medium sandstone) from the middle
part of the Itsukamachi Sandstone Member and four
samples (JMJ 2-5; medium sandstone) from the lower
part of the Maisawa Sandstone Member. It is characterized by faunas having high diversity (2.45-3.14) andequitability values (0.53-0.80). Three subclusters (III"1112, 1113) bounded by a similarity value of 0.8 can berecognized in this cluster. Neomonoceratina japonica(Ishizaki), Paracytheridea neolongicaudata Ishizaki, Laperousecythere ishizakii and Pectocythere daishakaensis
Tabuki occur commonly throughout the cluster.
Discussion
1) Depositional environments of the Suenomatsuyama
Formation
The Suenomatsuyama Formation contains entirely
diversified sublittoral ostracode species; bathyalostracodes such as Falsobuntonia taiwanica, Hirsutocythere? sp., Krithe sp. and Propontocypris? sp., which arecommon in the deep water-facies of the underlying
Kadonosawa Formation, are rare or absent. It does notyield shallow embayment species either. Many samples
show high values of diversity and equitability. The
Suenomatsuyama Formation treated in the present study(the Itsukamachi Sandstone and the Maisawa Sandstone
Members) is, therefore, reckoned, as a whole, to havebeen deposited in open sublittoral environments. It is
probable that the lowest part of the Itsukamachi Sandstone Member (around BAS 1 and 2) and the Maisawa
Sandstone Member were deposited in upper sublittoral
areas because of common occurrences of some large
Pectinidae such as Mizuhopecten spp.
Figure 5 shows vertical changes both of percentages offour species groups (circumpolar, cryophilic, temperate
and others) and clusters (I, II and III). Most formations
bearing the Omma-Manganji Fauna contain abundantly
circumpolar and cryophilic species, representing around
50% of the total (see Table 2 of Cronin and Ikeya, 1987).
In particular, circumpolar and cryophilic ostracodes fromthe Plio-Pleistocene Setana, Tomikawa and Shibikawa
Formations, distributed in northern Japan, comprise about
70% of the total assemblages. The Upper Miocene
Fujikotogawa Formation in northern Japan also contains
large numbers of circumpolar and cryophilic ostracodes71

representing about 40% of the total (Irizuki, 1994). Samples from the lower part of the Suenomatsuyama Formation contain large numbers of cool-water indicators, representing about 40-50%, and are assigned to clusters II
and 111 1 • It is certain that surface water temperatures
were also low in that time because of the absence oftropical to subtropical planktonic foraminifers at thishorizon (Samata, 1976). The middle part of the
Suenomatsuyama Formation (subclusters 1112 and 111 3) isdominated by temperate species; circumpolar and cryophilic species represent around 30% of the total assemblages. All samples from the lower part of the Maisawa
Sandstone Member (JMJ 2 to 5) belong to cluster 1113 andcontain predominantly temperate-water ostracodes, coolwater indicators are less abundant (less than 30%). It isconcordant with the occurrence of tropical to subtropicalplanktonic foraminifers at this horizon (zone III of Samata,1976). The results of Q-mode cluster analysis and vertical changes of percentages of each species group indicate that paleotemperatures were lowest in the lower partof the Suenomatsuyama Formation (cluster II), increasing
toward the highest in the Maisawa Sandstone Member(cluster 1113).
Cluster I (JMJ 6) and sample JMJ 7 contain poorly
preserved specimens of Acanthocythereis dunelmensis(Norman), E. cf. concinna and Kotoracythere cf. abnorma.
Sample JMJ 8 also bears poorly-preserved Hirsutocythere ? sp., Kotoracythere sp. (= Kotoracythere sp. 2 of Irizuki
and Matsubara, 1994) and Acanthocythereis aft. munechikai Ishizaki, which are representative species of the black
mudstone facies of the lowest part of the Shikonai
Siltstone Member in the underlying Kadonosawa Formation (lrizuki and Matsubara, 1994). All these samples
were obtained from strata exhibiting signs of subaqueous
mudflows, and thus possibly containing some specimens
reworked from underlying strata, upheaved due to volcanic activity associated with the Aikawa Andesite
Member, as well as those displaced from shallower water.
2) Comparison between ostracode faunas of the
Suenomatsuyama Formation and those of the Kadonosawa Formation
Fifteen of the 66 species from the Suenomatsuyama
Formation do not occur in the Kadonosawa Formation.
These species are low in abundance except for species
belonging to the genus Laperousecythere (L. cf. robusta,
L. yahtsensis and L. sp.), which are discussed in the
Systematics section. Laperousecythere species arecharacteristic of the Suenomatsuyama Formation, but
most of the other ostracodes from the Suenomatsuyama
Formation, for example A. dunelmensis, E. cf. concinna,
Finmarchinella spp., Neomonoceratina japonica, Norman icy there sp. and S. kishinouyei, are common to the
middle and upper parts of the underlying Kadonosawa
Formation (clusters 0 and E of Irizuki and Matsubara,1994). In the upper part of the Suenomatsuyama Formation (the Maisawa Sandstone Member, cluster Ills), suchwarm-to-temperate-water ostracodes as Hermanites ?
posterocostatus Ishizaki, Paracytheridae neolongicaudata

Toshiaki Irizuki and Takashi Matsubara

72

n

BAS

n

9
1112
10

8
1113

9
8

7

D

others•temperate~ cryophilic•

circumpolar

n

n
n
n
n

n

n

R

n

7

5

6
5

4

1113

3

4
3
2

I

2
1

n
n

(%)

10m

(%)

1
10m

Figure 5. Diagram showing vertical changes of clusters and percentages of each group of ostracodes.
to 111 3 stand for clusters. Columns are the same as in Fig. 3.

and Laperousecythere ishizakii increase in number. Thisis concordant to the occurrence of warm-water planktonic foraminifers reported by Samata (1976) around thishorizon. However, ostracode faunas containing theabove- mentioned species are different from faunas characterized by such shallow- and warm- water ostracodes
as Loxoconcha pulchra, Spinileberis sp. and Trachyleberis
spp. recognized in the lowest part of the Kadonosawa
Formation (the Tate Conglomeratic Sandstone and thelowest Shikonai Siltstone Members ; clusters A and B of
Irizuki and Matsubara, 1994) and those in the Lower

Miocene Akeyo Formation (the Shukunohora Sandstone
Member) in the Mizunami area (Yajima, 1992), which were
deposited at the time of the mid - Neogene Climatic
Optimum. They are similar in containing the Shiobaratype Fauna to those reported from Middle to Late
Miocene formations in northern Japan. Therefore, thecooling event (from subtropical to cool temperate) occurring at about 16 Ma in Ninohe district continued to thetime of depOSition of the lower part of the Suenomatsuyama Formation. After that water temperatures
became higher during depOSition of the middle to upper

986.

Miocene ostracodes from Suenomatsuyama Formation

part of the Itsukamachi Sandstone Member, Maisawa
Sandstone Member and the overlying Tomesaki Formation, and suggested by the dominance of warm-waterplanktonic foraminifers (Samata, 1976) and diatoms(Maruyama, 1984,1993) as well as by temperate
ostracodes.
Concluding remarks

The following four conclusions were obtained from thestudy of ostracode faunas from the Suenomatsuyama
Formation.
1. Sixty-six ostracode species were found for the firsttime to occur in the lower Middle Miocene Suenomatsuyama Formation.
2. Q-mode cluster analysis and vertical changes ofpercentages of species groups reveal that the depositional environment of the lower part of the Suenomatsuyama Formation was cool and shallow water and that of
the upper sandy facies temperate and shallow water.
3. Slumping deposits in the middle to upper part of the
Maisawa Sandstone Member may include some fossil
ostracodes reworked from parts of the underlying strata
as well as those displaced from shallower water.
4. Many ostracodes from the lower to middle part(sandy facies) of the Maisawa Sandstone Member are
warm-water species, but these are different from those indeposits yielding the Kadonosawa Fauna.
Acknowledgments

We would like to express our deep gratitude to Professor Kunihiro Ishizaki of the Department of Geoenvironmental Science, Faculty of Science, Tohoku University,
for critical reading of the manuscript.
Systematics

Four species under the genus Laperousecythere aredescribed and/or discussed in this section because they
are representative species of the Suenomatsuyama Formation. All the illustrated and measured specimens aredeposited in the collections of the Department of
Geoenvironmental Science, Faculty of Science, Tohoku
University (IGPS).
Suborder Podocopina Sars, 1866
Superfamily Cytheracea Baird, 1850
Family Hemicytheridae Puri, 1953
Subfamily Hemicytherinae Puri, 1953
Genus Laperousecythere Brouwers, 1993
Laperousecythere ishizakii Irizuki
and Matsubara sp. nov.
Figures 6.1-4
Hermanites sp.

Irizuki and Matsubara, 1994, p. 140, 141, table

1.

Etymology.-In honor of Professor K. Ishizaki

73

Materials. -34 specimens.
Diagnosis.-Characterized by quadrate valve shapeand some oblique and hook-shaped robust ridges.
Description.-Carapace large, quadrate in lateral view,highest at anterior cardinal angle. Anterior margin
broadly rounded and slightly extended below. Dorsal
margin sinuate in left valve, slightly convex in right valve.
Ventral margin slightly sinuate. Posterior margin triangular: upper half concave but lower half convex. In dorsal
view, carapace subhexagonal. Surface ornamented withregularly arranged coarse reticulation, prominent ridges,
eye and subcentral tubercles. Sinuate lateral ridge starting from subcentral tubercle and terminating at midheight of anterior margin. In posterior area, four robust
ridges obliquely developed. Dorsal ridge starting above
eye tubercle and turning downwards at posterodorsal end
to form hook-shaped rims. Subcentral tubercle distinct.
Eye tubercle large and prominent. Pores scattered on
valve. surface, moderate in numbeL Marginal pores
straight, about 35 in anterior margin. Marginal infold
broad along anterior and posterior margins. Vestibule
present along entire free margin, but narrow along ventral
and posterior margins. Hinge holamphidont. Muscle
scars consist of three frontal scars (middle one is smaller
than the others) and a row of four adductor scars: subdivided dorsal and dorsomedian scars, an elongatedventromedian and ventral scars. Sexual dimorphism
distinct: males more slender than females.
Types and Dimensions.-Holotype: Figs.6-3a-c,
female LV, Loc. JMJ 3, IGPS 102547, L=0.878 mm, H=
0.529 mm; paratype: Fig. 6-1, male LV, Loc. BAS 12,
IGPS 102548, L=0.813 mm, H=0.428 mm; Fig. 6-2,
female RV, Loc. BAS 9, IGPS 102549, L=0.831 mm, H=
0.450 mm; Fig. 6-4, female carapace, Loc. JMJ 5, IGPS
102550, L=0.894 mm, H=0.525 mm, T=0.511 mm.
Type locality.-Lower Middle Miocene Suenomatsuyama Formation (the Maisawa Sandstone Member),Loc. JMJ 3.
Occurrence.-BAS 9,11-13, JMJ 1-5.
Remarks.-This species is also present in the Tate
Conglomeratic Sandstone Member in the Kadonosawa
Formation. It is similar to Laperousecythere yahtsensis
and Laperousecythere sp. in this study with respect to thereticulation patterns, but differs from them in having more
prominent and robust ridges, hook-shaped rims in posterior portion and quadrate valve morphology. It is alsosimilar to Hermanites? posterocostatus, but differs fromthe latter in having a different ridge pattern and more
inflated carapace.
Laperousecythere cf. robusta (Tabuki, 1986)
Figure 6. 5-7c
Compared with.Patagonacythere robusta Tabuki, 1986, p. 77, 78, 116, text-fig.
20, pI. 9, figs. 4-12; Cronin and Ikeya, 1987, p. 81, 82, pI. 3,
fig. 13; Irizuki, 1993, p. 189, fig. 2-20.
Laperousecythere robusta (Tabuki); Brouwers, 1993, p. 25, 26,
pI. 10, figs. 6-12, pI. 11, figs. 2, 3.

74

Toshiaki Irizuki and Takashi Matsubara

Figure 6 . 1- 4 , Laperousecythere ishizakii sp. nov. 1 : lateral view of male LV, Loc. BAS 12, IGPS 102548 ;2: lateral view of female RV, Loc. BAS 9, IGPS 102549 ; 3a-c : lateral and internal views and muscle scars offemale LV, holotype, Loc. JMJ 3, IGPS 102547 ; 4 : dorsal view of female carapace, Loc. JMJ 5, IGPS 102550.
5 - 7c, Laperousecythere cf. robusta (Tabuki, 1986). 5 : lateral view of male LV, Loc. JMJ 3, IGPS 102551 ; 6 :lateral view of male RV, Loc. JMJ 3, IGPS 102552 ; 7a-c: lateral and internal views and muscle scars of female
RV, Loc. JMJ 1, IGPS 102553. Scale bars are 0.1 mm : A for 1- 3b, 4- 7b ; B for 3c, 7c. LV : left valve. RV :right valve.

986.

Miocene ostracodes from Suenomatsuyama Formation

Figure 7. 1a- 3, Laperousecythere yahtsensis Brouwers, 1993, 1a- c : lateral and dorsal views of male
carapace, Lac. BAS 12, IGPS 102554 ; 2a- c : lateral and internal views and muscle scars of female LV, Lac.
BAS 10, IGPS 102555 ; 3 : lateral view of female RV, Lac. BAS 10, IGPS 102556. 4a - 8 , Laperousecythere sp.,
4a- c : lateral and internal views and muscle scars of male LV, Lac. BAS 1, IGPS 102557 ; 5 : Lateral view ofmale RV, Lac. BAS 1, IGPS 102558 ; 6 : lateral view of female LV, Lac. BAS 1, IGPS 102559 ; 7 : dorsal view offemale carapace, Lac. BAS 1, IGPS 102560 ; 8 : lateral view of female RV, Lac. BAS 1, IGPS 102561. Scalebars are 0.1 mm : A for 1a- 2b, 3- 4b, 5- 8 ; B for 2c, 4c.

75

Toshiaki Irizuki and Takashi Matsubara

76

Materials. -11 specimens.
Dimensions.-Fig.6-5, male LV, Loc. JMJ 3, IGPS
102551, L=0.879 mm, H=0.465 mm; Fig. 6-6, male R.V.,
Loc. JMJ 3, IGPS 102552, L=0.869 mm, H=0.456 mm;
Figs.6-7a-c, female RV, Loc. JMJ 1, IGPS 102553, L=
0.925 mm, H = 0.500 mm.
Occurrence.-BAS 4,11,13,14, JMJ 1-3.
Remarks.- The present form has less prominent ridges
in posterodorsal, posteroventral and anterior areas, andless elongate valve morphology as compared with thetype specimens from the Plio-Pleistocene Daishaka
Formation, northern Japan (Tabuki, 1986). Its reticulation
and ridge pattern are similar to those of the type specimens.
Laperousecythere yahtsensis Brouwers, 1993

Figures 7. 1-3
Patagonacythere dubia (Brady); Cronin and Ikeya, 1987, p.81,
82, pI. 2, fig. 10 (non Patagonacythere dubia (Brady, 1868)).
Laperousecythere yahtsensis Brouwers, 1993, p. 26, 27, pI. 10,
figs. 13-18, pI. 11, figs, 4, 5.
Materials. -70 specimens.
Dimensions.-Figs.7-1a-c, male carapace, Loc. BAS
12, IGPS 102554, L=0.875 mm, H=0.413 mm; Figs. 72a-c, female LV, Loc. BAS 10, IGPS 102555, L=0.878
mm, H=0.455 mm; Fig. 7-3, female RV, Loc. BAS 10,
IGPS 102556, L=0.856 mm, H=0.453 mm.
Occurrence.-BAS 4-12,14, JMJ 1-5.
Remarks.-This species was reported from such PlioPleistocene formations as the Setana, Sawane, Junicho
and Omma Formations yielding the Omma-Manganji
Fauna of northern Japan (Cronin and Ikeya, 1987) andPleistocene deposits of the Gulf of Alaska (Brouwers,
1993). This species is closely related to Patagonacythere
dubia recorded from the Pleistocene to Recent sedimentsin the Arctic and North Atlantic areas (e.g. Hazel, 1967),
but the former has an elongate and quadrate valve
outline, fine muri, wide anterior rim and slightly different
distributional patterns of the reticulation. It is also similar to Patagonacythere sasaokensis Irizuki, but differs fromthe latter in being smaller in size, having less inflated
valves and lack of antero-marginal ridges.
Laperousecythere sp.

Figures 7. 4-8
Materials.-38 specimens.
Dimensions.-Figs.7-4a-c, male LV, Loc. BAS 1, IGPS
102557, L=0.829 mm, H=0.455 mm; Fig. 7-5, male RV,
Loc. BAS 1, IGPS 102558, L=0.829 mm, H=O.444 mm;
Fig. 7-6, female LV, Loc. BAS 1, IGPS 102559, L=0.829
mm, H=0.494 mm; Fig. 7-7, female carapace, Loc. BAS
1, IGPS 102560, L=0.850 mm, H=0.500 mm, T=0.456mm; Fig. 7-8, female RV, Loc. BAS 1, IGPS 102561, L=
0.863 mm, H=0.506 mm.
Occurrence.-BAS 1-4,6,7, JMJ 7.
Remarks.-Ishizaki et al. (in press) described species

similar to this form from the Upper Miocene Tsunaki
Formation, northern Japan, as a new species. Its typespecimens are more quadrate valves than the present
specimens. This form is closely related to Laperousecythere robusta with respect to its reticulation pattern, but differs from the latter in having no anteromarginal
ridges and thin valves in the anteromarginal area.
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/

Suenomatsuyama
tlllJ, Ninohe =p, Kadonosawa r~ iR, Mabechi-gawa f.!i,iJljflll, Yotsuyaku IZB 'Y f~, Koiwai 'Nst" Tate ti'i, Shiobara :f;\[ffi(, Tomesaki ljWl1j, Shinden li'!f83, Nakuidake ~7..:j:j: ttr, Anaushi 1\ 4, Itsukamachi Ii B IBT, Aikawa i?t III, Maisawa iR, Tsukidate F3 ti'i,
Basenkyo f.!i,{wll!lf.::, Jumonji-gawa +Jt::t}II, Metoki §Ilif, Omma-Manganji *~-7J}jj~, Hatatate
mt:v:, Tsunaki ~*, Sendai {wt:J, Togi M*, Sekinohana ~!f., Fujikotogawa ~~}II, Kamikoani_ttN"Ii::, Setana li¥.fjfJl)j, Tomikawa Mill, Shibikawa 1m}11, Shikonai JJL-r-J*j, Akeyo ~i!!, Shukunohora 1"NilRJ, Mizunami fffil~.

*Trans. Proc. Palaeont. Soc. Japan, N.S., No. 177, pp.79-83, 2 Figs., April 30,1995

SHORT NOTESo

On the occurrence of Upper Paleozoic conodontsfrom central Spitsbergen

HISAHARU IGO
Department of Astronomy and Earth SCiences, Tokyo Gakugei University, Koganei, Tokyo, 184 Japan
Received 18 November 1994; Accepted 15 December 1994

Introduction
In the summer of 1990, I jojned the international
collaboration field survey in Spitsbergen of the Svalbard
Archipelago in the Arctic region. This project wasplanned by Koji Nakamura of Hokkaido University ofJapan in collaboration with staff of the Norwegian Polar
Research Institute and financed by a grant under theInternational Scientific Research Program-Field Research(Project No. 01041005) of the Ministry of Education, Science and Culture, Government of Japan.
During this field survey, I collected many limestone
samples for a conodont study from the Nordenski61dbreen
and Kapp Starostin Formations exposed near Skansbukta
and Trygghamna in west-central Spitsbergen. Unfortunately, however, most of these samples are barren of
conodonts, and only three of them yield a few elements
indicating Late Carboniferous and Late Permian ages.
Although these conodonts are not numerous, the occurrence provides additional data to discuss the geologic
age of both formations.

association with fusulinaceans. Limestones at F-2 andF-3 are thickly bedded and yield abundant fusulinaceans,rugose corals, and crinoids.
The other occurrence of conodonts was confirmed in
the Upper Permian Kapp Starostin Formation exposednear Trygghamna about 40 km west of Longyearbyen(Loc. 2, Figure 1). We measured a 450-m thick sequenceof this formation subdivided into 11 units (Nakamura et al.,in Nakamura, 1992). Unit 1, the lowest unit of the formation, is 11.5 m thick and consists of bioclastic coquinoid
limestone which contains abundant brachiopod shells.
Hence, this limestone is conventionally called "Spiriferlimestone." Conodonts are recovered from two levels

Geologic setting
The Nordenski61dbreen Formation (Carboniferous-Permian) is extensively exposed near Skansbukta about 35
km northeast of Longyearbyen (Loc.1, Figure 1) in westcentral Spitsbergen. We measured a 135-m thicksequence of this formation exposed on the shore cliff
along a valley south of a 478-m peak in the Billefjord(Bille fiord). This measured section was designated as
the Skansen (478 Peak Valley) section. The Nordenski61dbreen Formation consists mainly of limestone intercalating with a dolomitic facies, and subdivided into 23
lithologic units; A to G and 1 to 16 in ascending order(Nakamura et al., in Nakamura, 1992). I recovered
conodonts from Unit F, 3.2 m in thickness, and the baseof which is 25.7 m above the base of this formation. In
the field, we collected samples from three different levels(F-1, F-2, and F-3) of this unit. F-1 is the base of Unit F,
and F-2 and F-3 are 80 cm and 160 cm above the base,respectively. Samples collected from F-1 are gray, bedded, and dolomitic limestone and yield conodonts in

Figure 1. Map showing the conodont localities fromthe Skansen (478 Peak Valley) section of the Nordenskioldbreen Formation (Loc.1) and Trygghamna section of theKapp Starostin Formation (Loc. 2).

Hisaharu Igo

80(Tr-1 and Tr-2) of this unit. Tr-1 is the base of UniH and
Tr-2 is 8.5 m above the base. Limestone collected from
Tr-2 includes fish teeth and scales, small gastropods,
holothurian sclerites, and foraminifers.
Conodont elements and their geologic age
Conodont elements such as Igiognathodus magnificus
Sauffer and Plummer, Ozarkodina sp., and some otherunidentified ramiform elements were recovered from F-1of the Nordenski61dbreen Formation. Idiognathodus
magnificus is known from the Lower and Upper Pennsylvanian (Sweet, 1988). Recently, however, Grayson etal. (1989, 1990) proposed a new phylogenetic classification for the Idiognathodus-Streptognathodus plexus.
According to them, Idiognathodus magnificus evolved
from I. claviformus Gunnell at the end of the Desmoinesian, and has a range in the Missourian. In Russia,
the occurrence of I. magnificus has been recorded in the
Podol'sk and lower Myachkovo Horizons of the Moscovian of the Moscow Syneclise (e.g., Goreva, 1984). A
number of species belonging to the genus Idiognathodus
have been known in the Kasimovian of Russia (Barskov
and Alekseev, 1975; Barskov et al., 1980; Kozitskaya,
1983; Goreva and Isakova, 1993), but Idiognathodus
magnificus has not been recorded in the Kasimovian bythese Russian workers. Grayson et al. (1989), however,synonymized several Kasimovian species assigned to thegenera Streptognathodus and Idiognathodus to their I.
magnificus complex.
Based on the occurrence of I. magnificus, Unit F of theNordenski61dbreen Formation can be correlated with theMissourian of North America and the Kasimovian of
Russia. This correlation is supported by the occurrenceof fusulinaceans in Unit F. Igo and Okimura (in Nakamura, 1992) reported the following importantfusulinaceans from the unit to consider the detailed
geologic age: Quasifusulinoides fusiformis (Rozovskaya) , Protriticites aff. pseudomontiparus Putrja,
Pseudofusulinella tempelensis Ross, and others. Q.
fusiformis and Protriticites pseudomontiparus are representatives of the lower Kasimovian and known from CaAI
Zone of the Krevyakino Horizon in the stratotype sectionsof the Russian Platform and the Pre-Urals (e.g., RauserChernousova et al., 1979). These two species are also
known to occur in another standard section of the Carboniferous of Russia. The former species is reported in
the Isaevian of the Kalinova section of the Donetz Basin.
The latter occurs in the lower part of the Kalaikukhna
Formation of southwestern Darvas (Davydov, 1990).
These levels are correlated with Klo the lower Kasimovianof the type section in the Moscow Syneclise.
The other conodont locality from which Neostreptognathodus svalbardensis Szaniawski and some fragmented ramiform elements were rocovered, is near
Trygghamna (Tr-1 and Tr-2). Unfortunately, they are few
in number and poorly preserved, but the occurrence of N.
svalbardensis is worthy of note.
Malkowski and Szaniawski (1975) first reported theoccurrence of Permian conodonts in the "Spirifer-limestone" of the Kapp Starostin Formation in Polakkfjellete,
Spitsbergen. Subsequently, Szaniawski and Malkowski(1979) documented the study in detail and described thespecies belonging to the genera Sweetognathus, Sweetocristatus, Neostreptognathodus, Neogondolella, andothers. According to them, these conodonts are similar
to those reported from the Meade Peal Member of the
Phosphoria Formation of Idaho, Wyoming, and Utah, andthe Victorio Peak and Bone Spring Formations of West
Texas. From these paleontological data, they assigned
the Svalbardian (=the Kapp Starostin Formation) to theUpper Leonardian of the North American standard.
Neostreptognathodus svalbardensis obtained from Tr-1
and Tr-2 in the present study is known to occur inassociation with Neogondolella idahoensis (Youngquist,
Hawley and Miller) in Polakkfjellete. In North America,
N. idahoensis ranges from the middle Leonardian to theRoadian (Wardlaw, 1986; Wardlaw and Collinson, 1984).
The presence of N. svalbardensis in our collection may
indicate that the basal part of the Kapp Starostin Formation at Trygghamna is at least younger than the middle
Leonardian.
Recently, Nakrem (1991) reported Permian conodontsfrom the Kapp Duner and Hambergjellet Formations of theGipsdalen Group and the Miseryfjellete Formation of theTempelfjorden Group exposed in Bjornoya, the southernmost island of the Svalbard Archipelago. The conodont
faunas in these formations are similar to those documented from other Arctic regions and correlatable to thosereported from the Asselian-Sakmarian to KungurianUfimian of Russia and the Wolfcampian-Leonardian toRoadian-Wordian of U.S.A. N. svalbardensis does notoccur in the formations, but the occurrence of N. idahoensis is confirmed almost entirely to the Miseryfjellete
Formation. He correlated this formation with theRoadian-Wordian. These new conodont data from Bjornoya suggest that our N. svalbardensis-bearing levels ofUnit 1 can be correlated with the lower Roadian of North
America and the Kungurian of Russia. This age assignment was already supported by preliminary studies ofbryozoans (Sakagami, in Nakamura, 1992) and brachiopods (Nakamura et al., in Nakamura, 1992).
Paleontological note
In the present study, only two species, Idiognathodus
magnificus Stauffer and Plummer and Neostreptognathodus svalbardensis Szaniawski, are worthy of note.
SpeCimens treated herein are housed in the
paleontological collection of the Department of Astronomy and Earth Sciences, Tokyo Gakugei University.
Genus Idiognathodus Gunnell, 1931
Idiognathodus magnificus Stauffer
and Plummer, 1932
Figure 2-1-6

31 .

Upper Paleozoic conodonts from Spitsbergen

For detailed synonymy refer to Grayson et al. (1989, 1990).

Description. - Platform is slender and curved inward
and has a sharply pointed posterior end. Posterior half
platform is ornamented by distinct transverse ridges. In
lateral view, oral surface of platform is slightly arched.
Surface of platform is ornamented by discontinuous trans~e~se rid~es. Two or three accessory lobes are present
In Inner side of anterior end of platform. One or two outer
accessory lobes appear in a few specimens. The free blade consists of sharply pOinted denticles and continues
to a low central carina which extends to one- half ofanterior platform. Near anterior end of platform, a shallow trough appears on each side of carina. An adcarinal
ridge appears on both sides of carina near the anteriorof81

terminal of platform. The blade is almost the samelength as the platform.
Remarks. - Since Gunnell's (1931) study, many species
belonging to the Idiognathodus - Streptognathodus transition series have been erected in the Pennsylvanian
System of the U.S.A. Grayson et a/., (1989, 1990) discussed the phylogenetic basis for species recognition within
Idiognathodus, and proposed a new taxonomic concept.
They proposed that Idiognathodus should be subdivided
into unadulterated polymorphic species that consist ofsimilar recurring morphotypes. According to them, I.
magnificus is an entirely Missourian complex of thisgenus that is distinguished by the precipitous terminationof its anterior platform margin and adcarinal ridges.
Occurrence. - F-1 of the Skansen (478 Peak Valley)

Figure 2. 1- 6, Idiognathodus magnificus Stauffer and Plummer, Oral views, Reg. nos. TGU 94101, 94102,
94103,94104, 94105,94106,1- 4, X100, 5,6. x 150. All specimens occurred in F-1 of the Skansen (478 Peak
Valley) section, the Nordenski61dbreen Formation. 7-9, Neostreptognathodus svalbardensis Szaniawski, 8, 9
occurred in Tr-1, and 7 occurrred in Tr- 2 of the Trygghamna section, the Kapp Starostin Formation. Oralviews, Reg. nos. TGU 94107, 49108, 94109. All x 200. 10,11, unidentified ramiform elements. All specimens
occurred in Tr-1 of the Trygghamna section, the Kapp Starostin Formation, lateral views, Reg. nos. 941010,
941011 . All X150.

Hisaharu Igo

82

section, the Nordenskioldbreen Formation.
Reg. nos. TGU 94101, 94102, 94103, 94104, 94105,
94106.
Genus Neostreptognathodus Clark, 1972

Neostreptognathodus svalbardensis
Szaniawski, 1979
Figures 1-7-9
Neostreptognathodus aff. pequopensis Behenken; Szaniawski, 1976, p.82-83, pI. 1, figs. 6-8, 10 (only).
Neostreptognathodus svalbardensis Szaniawski, 1979, p. 250251, pI. 6, figs. 2-6 (only), pI. 7, figs,1a-5c.
Neostreptognathodus pnevi Kozur and Movshovich; Nakrem,
1991, p. 245, fig. 3E.

Remarks.- The anterior part of the present specimens
is lost but the characteristic platform is preserved andassignable to this species. The platform has deep
median trough, and each carina has five or six large
nodes. This species resembles Neostreptognathodus
sulcoplicatus (youngquist, Hawley and Miller) but theformer is easily distinguished from the latter by numerous
transverse ridges. N. svalbardensis, however, is difficult
to distinguish from the immature stage of N. sulcoplicatus.
This species is also similar to N. pnevi Kozur andMovshovich, but it differs from the latter in a few denticles
on the anterior free-blade.
Occurrence.- Tr-1 and Tr-2 of the Trygghamna section,
Kapp Starostin Formation.
Reg. nos. TGU 94107, 94108, 94109.

Acknowledgement
I thank Prof. Koji Nakamura of Hokkaido University, theleader of this research project, and all research membersof the Japanese and Norwegian teams. Prof. Hisayoshi
Igo of the University of Tsukuba read the manuscript andgave me invaluable comments.

References cited
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Middle and Upper Carboniferous from the vicinity of
Moscow. Akademiya Nauk Izvestiya SSSR, Seriya
Geologicheskaya, Moscow, no. 4, p.84-99. (in Russian)Barskov, loS., Alekseev, A.S. and Goreva, N.V., 1980:
Conodont stratigraphical scale of the Carboniferous.
Akademiya Nauk Izvestiya SSSR, Seriya Geologicheskaya., Moscow, no. 3, p.43-45. (in Russian)Clark, D.L., 1972: Early Permian crisis and its bearing on
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Davydov, V.I., 1990: Zonal subdivision of the Gzhelian
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Goreva, N.V., 1984: Moscovian conodonts from Moscow

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H., Kumon, F., Kawamura, T., Kano, A. and Hilde B.
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University, Sapporo.
Nakrem, H.A., 1991 : Conodonts from the Permian succession of Bj¢rn¢ya (Svalbard). Norsk Geologisk Tidsskrift, 71, p. 235-248, figs. 3a-p, figs.4a-k.
Rauser-Chernousova, D.M., Ivanova, EA, Grozdilova, L.P.
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pis. 1-6. Published by Hokkaido University, Sapporo.
Stauffer, C.R. and Plummer, H.J., 1932: Texas Penn-31.

Upper Paleozoic conodonts from Spitsbergensylvan ian conodonts and their stratigraphic relations.
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Phosphoria Formation. Contributions to Geology,
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83

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87

Palaeontological Society of Japan (PSJ) Council Actions
During its meeting on Februaly 1,1995, the Council enacted the following changes to PSJ
membership.
New members elected;
Hiroshi Amemiya,
Masahiro Gouda,
Koji Kameo,
Tarou Kiso,
Hitoshi Nakagawa,Shigehiro Nukatsuka,
Takayuki Oguchi,
Minoru Sum ita,
Toshiyuki Tanaka,
Tomoko Usui,
Apson Ampornmaha.

Mutsumi Fujimoto,
Hiroshi Hase,
Toshio Kawamura,
Kouji Makino,
Hideo Nagato,
Akira Obata,
Michiko Saito,
Masanori Suzuki,
Hideto Tsutsui,
Morio Yabuki,

Osamu Furuie,
Shiyunpei Ishikawa,
Fumihisa Kawabe,
Hiroshige Matsuoka,
Ayumu Nojo,
Kiichi Obata,
Tamaki Sato,
Eiichi Takagi,
Morihiro Usami,
Tatsuo Yamazaki,

New Fellows approved;
Rie Hori,
Tetsuro Ueda.

Akihiko Suzuki,

Minoru Tsukagoshi,

New patron member;Museum Park Ibaraki Natural Museum
Deceased member;
Masanobu Kikuchi
Resigned members;(Fellow)
Norio Fuji,
Satoru Uozumi.
(Ordinary Member)
Takao Ito,
Kyoichiro Numano,

Keiichi Ono,

Toshio Saito,

Shoichi Kiyokawa,Toshio Nishio,
Fukumatsu Sugita, Shigeyuki Suzuki,
Ricardo Franco-Nietro.

(Patron member)
Mitsui Sekiyu-Kaihatsu Company.

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Transactions and Proceedings of the PalaeontologicalSociety of Japan
April 30, 1995

New Series No. 177
CONTENTS
TRANSACTIONS
982.

Yukio Yanagisawa : Cenozoic diatom genus Rossiella Desikachary et Maheshwari :An emended description .... . ....... .. .. ..... . .. .......... . ........ .. ..... ......... .

983.

Yukio Yanagisawa: Cenozoic diatom genus Bogorovia Jouse: An emended description
21

984.

Katsuo Sash ida, Shuko Adachi, Hisayoshi Igo, Toshio Koike, and Ibrahim B. Amnan :Middle and Late Permian radiolarians from the Semanggol Formation, northwest
Peninsular Malaysia.. .. .. .. . . .. .. .. .. . . . . .. .. .. .. . . .. .. .. .. .. .. .. .. . . .. .. .. .. .. .. ..

985.

forms of Nummulites as sedimentologic and taphonomic indicators .... ; . .. .. .. . . .. .. ..
986.

43

Yasuo Kondo: Density and relative abundance of microspheric and megalospheric
59

Toshiaki Irizuki and Takashi Matsubara : Early Middle Miocene ostracodes fromthe Suenomatsuyama Formation, Ninohe City, northeast Japan and their
paleoenvironmental significance.. . . .. .. .. .. .. .. .. .. . . .. .. .. .. .. .. .. .. .. .. . . .. .. .. ..

65

SHORT NOTES

31.

Hisaharu Igo: On the occurrence of Upper Paleozoic conodonts from central
Spitsbergen... . .. .... .... . . .. .... .. . . . . .. .. ............. :. . ..... .... ........ . .... .

79

PROCEEDINGS .. . . . . .. . . . . .. . . .. . . .. . . .. .. .. . . .. .. .. .. .. .. . . .. . . .. .. . . .. .. .. .. .. . . .. .. ..

84