ISS N 0031-0204

Transactions and Proceedingsof thePalaeontological Society of Japan
New Series

No.

166

Palaeontological Society of Japan
June 30, 1992

Co-Editors

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Trans. Proc. Palaeont. Soc. Japan, N.S., No. 166, pp. 1097-1115, 10 Figs., June 30, 1992

936.

THREE SPECIES OF KRITHE (CRUSTACEA: OSTRACODA)
FROM SURUGA BAY, CENTRAL JAPAN*
BAOCHUN ZHOU
Department of Geology and Mineralogy, Faculty of Science,
Kyoto University, Kyoto 606, JapanandNORIYUKI IKEY A
Institute of Geosciences, Faculty of Science,
Shizuoka University, Shizuoka 422, Japan

Abstract. A total of 545 specimens belonging to the genus Krithe were obtained from45 surface sediment samples collected from Suruga Bay, the Pacific side of central Japan.
These specimens were classified into three species on the basis of differences in carapace
morphology, which can be clearly traced in each species to the young larval stage (A-6).
The three species were identified as K. sawanensis Hanai, 1959, K. antisawanensis Ishizaki,
1966 and K. surugensis Zhou and Ikeya n. sp. Each species has a distinct depth range anddistributional area in Suruga Bay. Krithe sawanensis is distributed throughout the entire
bay at depths of 120-1,350 m. In contrast, the distribution of K. antisawanensis is restricted
to the vicinity of the bay mouth, and K. surugensis is limited to the eastern area of the central
trough. These two species are distributed at depths between approximately 150-650 m.
The difference in distribution pattern and the intraspecific variation of the three species iscorrelated with environmental parameters such as water depth, water temperature, anddissolved oxygen.
Two populations of K. sawanensis having distinct carapace size and vestibule shape wererecognized. The populations are separated from each other by an ostracode-barren zone
(OBZ) at depths of about 650-810 m.
Key words.
Suruga Bay.

Krithe antisawanensis, Krithe sawanensis, Krithe surugensis, Ostracoda,

hara, 1990; Ikeya and Itoh, 1991; Ikeya etal., 1992). Bathyal faunas, however, havereceived relatively little attention and only
studies conducted in such areas as the South
Korean Sea (Choe, 1984 MS), Toyama Bay,
Japan Sea (lshizaki and Irizuki, 1990), and
off the Shimane Peninsula, Japan Sea (lkeya
and Suzuki, 1992) have been investigated.
On the Pacific side of Japan, only two reports
from DSDP sites are known (Hanai et aI.,
1980; Yajima et al., 1985). Therefore, ourknowledge of bathyal ostracode taxa, their

Introduction

Recent marine ostracode faunas around theJapanese Islands, including those from suchshallow environments as inner bays and continental shelves, have been investigated indetail by several authors (lshizaki, 1968, 1969,
1971; Ikeya and Hanai, 1982; Frydl, 1982;
Bodergat and Ikeya, 1988; Tabuki and No'Received December 30, 1991 ; accepted February 12,
1992
1097

1098

Baochun Zhou and Noriyuki lkeya

ecology and geographic distribution around
the Japanese Islands is incomplete.
Several ostracode genera that are generaIly
adapted to the bathyal zone of Japan, including Krithe, Argilloecia, Bradleya, Pacambocythere, Robertsonites, Cytheropteron, etc.,
were found in the samples from Suruga Bay.
Of them, Krithe is the most abundant inspecimens, and thus we were able to conductdetailed ontogenetic studies of the species.

Suruga Bay
Surface sediment samples coIlected from
Suruga Bay provided us with an opportunity
to investigate the bathyal ostracodes. The
bay is the deepest in Japan and is also unique
because it is located at the junction of four
tectonic plates. A central trough over 2,000m deep runs along the long axis of the bay.
On the west side of the trough a basin over
900 m deep is present. The bay mouth opens
broadly to the south towards the Philippine
Sea where a strong warm oceanic current, theKuroshio Current, flows northeastward.
The hydrographic conditions within Suruga
Bay are strongly controlled by the variablebehavior of the Kuroshio Current. According to Nakamura (1982), the characteristics of
the water column near the bay mouth are as
follows. The salinity maximum is greaterthan 34.5 %0 at depth of between 50-150 m ;the salinity minimum, except for surface
water, is lower than 34.3 %0 at depths of 300500 m; and an oxygen minimum zone where
the concentration is less than 1.7 mIll isdeveloped between 700-1,000 m. The depthof the salinity maximum layer changes withseasons. It lies at around a depth of 150 m inwinter, roughly 50 m in spring, about 100 min summer, and approximately 125 m inautumn. This layer reflects the salinity maximum layer (34.9 %0) of the main Kuroshio
Water, and the water temperature is at 1416"C.
Waters above a depth of 150 m in winterhave an almost constant temperature of 14"C
because of vertical circulation. The under-

lying salinity minimum layer has a temperature of around TC.
Muddy sediments predominate throughout
the bay, especiaIly on the continental slope,in the basin, and on the trough bottom.

The genus Krithe
Krithe is a blind genus and is most common in infraneritic and bathyal environments
throughout the world (Van Morkhoven,1963). Although it is difficult to identify
species of Krithe due to the completely
smooth surface of the calcareous carapace, thespecies have recently attracted a great deal ofattention for their usefulness in estimating
paleodepth and paleotemperature. Van
Morkhoven (1972) and Bold (1971, 1981)
have correlated carapace size in Krithe withwater depth. Riha (1989) reviewed the
hypothesis of Peypouquet (1977) and correlated the trend of increasing carapace size withan increase in the silicon concentration andthe amount of dissolved nutrients In the sea

Figure 1. Map of Suruga Bay showing sample
localities and bathymetry. Dots circled are Krithebearing samples.

936.

Krithe from Suruga Bay

1099

Table 1.

List of Krithe bearing samples from Suruga Bay. St. no. = station number,
Lat. = latitude, Long. = longitude, M = mud, Sd = sand, gr= gravelly, sdy =sandy, peb=pebbly, f=fine, cly=claycy, sty=silty.

St.no.

Lat.(N)Long.(E)

Depth
(m)

Sediment
Type

Total
Ostracoda

13
20
35
36
38
40
41
45
46
48
49
57
58
87
88
89
91
92
97
102
103
105
108
109
M28
M31
M33
M41
M42
M43
M45
M46
M52
M64
M66
M69
M77
M93
M95
MI01
MI04
MI07
MI09
MI15
MI25

34'44.2'
34'42.8'
34'36.9'
34'37.0'
34'36.4'
34'42.5'
34'42.6'
34'41.0'
34'44.1'
34'47.0'
34'48.2'
35'04.5'
35'05.4'
34'37.1'
34'37.1'
34'37.1'
34'37.1'
34'37.0'
34'54.8'
34'51.7'
34'51.3'
34'53.6'
34'51.6'
34'51.5'
34'33.8'
34'36.2'
34' 36.5'
34'38.0'
34'38.5'
34'38.0'
34'37.8'
34'38.4'
34'39.5'
34'42.4'
34'44.1'
34'44.2'
34'46.0'
34'51.8'
34'52.2'
34'53.6'
34'54.0'
34'55.8'
34'55.9'
34'57.8'
34'04.1'

138'20.1'
138'28.0'
138'28.4'
138'29.7'
138'31.4'
138'32.2'
138'32.4'
138' 19.5'
138'33.1'
138'30.3'
138'30.2'
138'47.2'
138'46.8'
138'43.6'
138'42.8'
138'42.1'
138'42.7'
138'42.1'
138'32.5'
138'35.5'
138'36.5'
138'31.6'
138'35.4'
138'36.5'
138'45.9'
138'43.4'
138'35.7'
138'21.1 '138'25.6'
138'30.0'
13S038.0'
138' 41.2'
138'27.2'
138'42.0'
138'40.3'
138'28.2'
138'42.2'
138'43.6'
138'35.8'
138'29.3'
138'42.0'
138'40.3'
138' 32.3'
138'44.6'
138'44.0'

150
295
230
430
1000
195
460
185
120
435-590957-970
480
625
280
390
470
400
490
575
1040
1350
400
1065
1340
335
508
2015
418
356
180
1330
595
380
252
550
232
370
320
1115
160
630
1125
400
320
918

M
M
gr Sd
sdy M
M
sdy M
peb M
sdy M
peb M
M
M
M
M
sdy M
M
M
M
M
M
M
M
M
M
M
f Sd
sdy Silt
sdy Silt
ely Silo
ely Silof Sd
ely Silt
ely Si It
ely Silt
sty Sdsdy Silt
ely Silt
sty Sdsty Sdely Silt
sdy Silt
ely Silt
sty Clay
ely Silt
ely Silt
ely Silt

3
29
68
6
24
12
9
137
53
70
90
91
405
109
42
62
3
77
19
104
7
2
I
460
43
14
23
34
252
21
49
37
983
70
4
542
594
9
32
45
44
7
635
75

Total
Krithe
19
2
3
I
5
6
2
I
13
20
8
2
13
45
23
30
2
26
16
92
I
2
I
9
12
2
14
9
18
16
3
7
15
I
38
29
6
3
2
26
2
74
2

1100

Baochun Zhou and Noriyuki Ikeya

water. Conversely, Pokorny (1980) considered water temperature to be the primaryfactor which determines the absolute dimensions of Krithe carapaces.
Peypouquet (1979) identified the vestibule
region in Krithe and Parakrithe as the sitewhere haemoglobin regulation occurs in
response to external dissolved oxygen variation. He hypothesized that the vestibular
size in these two genera is inversely correlatedwith dissolved oxygen content of sea water,which is depth-correlated, and he developed
a method for determining paleodepth by linking vestibular size and shape.
McKenzie et al. (1989) made a partial testof Peypouquet's hypothesis, by examing living Krithe praetexta praetexta, collectedfrom about 45 m depth off the west coast of
Sweden. The relationship between vestibular size and O 2 values in early May was
shown to be basically consistent with Peypouquet's hypothesis. However, the actual O 2
values in later May and June were rather lessthan Peypouquet's prediction. They considered that the imperfect correlations between
vestibule size and O 2 values might be due tovariations in food supply and other sources of
ostracode shell calcium. This is because
unbalanced calcium distribution in the shell
can also cause an expanded vestibule.
Paleodepth estimates based on carapace or
vestibular size in Krithe have been attemptedby many authors (e.g., Donze et al., 1982;
Peypouquet et al., 1982; Benson andPeypouquet, 1983; McKenzie and Peypouquet, 1984; Riha, 1989). De Deckker et al.
(1991) found that the MgjCa ratio of Krithe
valves demonstrates a relationship with ambient water temperature. This indicates thatanalyses on the MgjCa ratios of this genus
and other taxa of ostracodes may provide avery useful tool for reconstruction of bottom
temperature.
The primary purpose of the present study is
to identify the species of Krithe living in
Suruga Bay and to describe their morphological and ecological characteristics.

We believe that these data will be importantfor understanding intraspecific morphological variation in this genus and for using
Krithe as a paleoenvironmental indicator.

Material and Methods
The material for this study was derived
from 131 surface sediment samples whichwere used for the analysis of the ostracodefauna from Suruga Bay (Ikeya and Zhou, inpress) (Fig. I). The 131 samples cover almost the entire area of the bay, ranging in
depth from 20 to 2,015 m. From 45 samples
a total of 545 Krithe specimens (78 carapaces
and 467 valves) were found. The detailed
station data and Krithe occurrence data aresummarized in Table I.
The samples were treated with solutions offormalin and Rose Bengal. Only 44 specimens of Krithe were found with the soft
chitinous parts preserved. The vestibule
morphology and the distribution pattern for
sensillum pore canals on the carapace surfaceof Krithe specimens were investigated bymeans of an optical microscope. The detailed structures of carapace surface and hinge
were observed by use of a scanning electron
microscope. The identification of species
was carried out mainly by the general micro-

HG

H AV---iI=r-

RPe

PVD

L
Figure 2. Internal structure of Krithe sawanensis (topotype of male RV). AMS = adductor muscle
scars, FS = frontal scar, A V = anterior vestibule,
PVD = posteroventral duplicature, HG = hinge,
NPC="normal" pore canal, RPC="radial" pore
canal, L = length, H = height.

936.

K rithe from Suruga Bay

scopic characters of carapace morphology.
The shell dimensions were measured using a
digital micrometer.
All specimens are deposited in the Institute1101

of Geosciences, Shizuoka University (IGSU).
A bbreviations used in this paper inel ude L =length, H = height, T = thickness of valve, V =valve, C=carapace, RV =right valve, LV =Krithe sawanensis Hanai, 1959

.;~

.

0-

0

Krithe antisawanensis Ishizaki, 1966

o

i!!
0:, 0

o •

0

Krithe surugensis n. sp.

O.5mm
Figure 3. Internal and dorsal views of male and female RV of three species in K~ithe from S.uruga Bay.
K. sawanensis is from station 103, K. anlisawanensis from station 87 and K. surugensls from station M77.

Baochun Zhou and Noriyuki Ikeya

1102

Table 2.

Comparison of some distinct characters in three species of Krithe.

K. antisawanensis(c?1 n=4)(~ n=IO)

K. sawanensis(c?1 n= 12)(~n=16)I)

Size(average L)

c?1 1.00~ 0.96

2)

Slenderness(average L/H)
Inflation(average TIL)

4)

Hinge overlap

5)Area of Anterior vestibulum
Width ofposterior duplicature

3)

6)
7)
8)

Posterovental angle (c?1)
Curvature of
dorsal margin (~)

K. surugensis(c?1 n=9)(~ n=IO)

c?1 2.09~ 1.87c?1 0.97~ 0.86c?1 2.24~ 1.92c?1 0.82~ 0.78c?1 2.22~ 1.93c?1 0.24~ 0.22c?1 0.18~ 0.21

LV<RVgenerally large

LV>RV
small

c?1 0.18~ 0.22
LV>RV

narrow, parallel toventral margin
truncatednarrow, parallel toventral margin

wide and convex

taperedtruncatedsomewhat archeda little archednearly straightleft valve, J1 = male, ~ = female, A = adult,
J =juvenile, n = number of specimens. All
measurements are in mm.
Results

Identification of species
Krithe is a genus adapted to bathyal environments and easily distinguished from otherbathyal genera by its characteristic carapace
features. Figure 2 shows internal features ofa right valve of male Krithe sawanensis, anda diagram of the measurements and descriptive terms that are used. We have found that
all adult specimens of Krithe from Suruga
Bay possess a common adductor muscle scarpattern, all have between 20-22 "normal"
sieve-type pores on the valve, and all have thesame general distribution pattern of thesepores.
Three distinct species were identified basedon differential characters that are shown in
Figure 3 and Table 2. The numbers of adultand juvenile specimens of the three species
from each station are shown in Table 3. Of
the eight characters, hinge overlap and thewidth of the posteroventral duplicature are
the most important in distinguishing thespecies. Krithe sawanensis is easily distin-small

guished from the other two by its reversed
hingement. Krithe surugensis is distinguished from the other two by its wide andarched posteroventral d u plicature.
The differences in hinge overlap, slenderness and inflation of carapace can be successively traced to young instars. This fact suggests that, despite the close resemblance ofadults, they should be considered as belonging to different biological species.
Two of the three species from Suruga Bay
were previously described as K. sawanensis
Hanai, 1959 from Pliocene Sawane Formation, Sadogashima Island, Japan Sea, and K.
antisawanensis Ishizaki, 1966 from the
Miocene Hatatate Formation, Sendai, on the
Pacific coast. The third is described below
as a new species, K. surugensis n. sp.
Growth charts of the three species areshown in Figure 4a-c. In each species, theadults do not fall on the regression line calculated from dimensions of juveniles, indicatingthat the animals take a remarkably positive
allometric growth in carapace length when
passing the last larval stages.

Distribution patterns of Krithe species
The geographical distributions of the three
species in the bay are clearly different.

936.

Krithe from Suruga Bay

1103

..

o
a)

Krithe sawanensis Hanai, 1959
(n=209)

E

-5 "0

.c

"~
Q)

I

H=O.057+0.510L

0L---~----~---oO.~3----~--~----~0.•
6----~--~--~0~.9~--~----~--~1.2
Length (mm)

..
o
b)

Krithe antisawanensis Ishizaki, 1966
(n=27)

.c

01

"iii
I

0.3

0.6

0.9

1.2

0.9

1.2

Length (mm)o'"c)

Krithe surugensis n. Sp.
(n=78)

H=O.052+0.469L

0.3

0.6
Length (mm)Figure 4. L/H diagram of three Krithe species. Dots are LV and circles RV. As for specimens ofjuveniles, only valves were measured and plotted in this figure. Regression lines are calculated from thedimensions of juveniles.

Baochun Zhou and Noriyuki Ikeya

1104

30'

r

K. sawanensis

K. suruge.sis

K. antisawanensis

t---I
10 individuals

30'

10Km

Figure 5.

Geographical distribution of three Krithe species in Suruga Bay.

Krithe sawanensis is distributed extensively
throughout the entire area of the bay. Conversely, K. antisawanensis is only found near
the bay mouth, and K. surugensis is restricted
to the east side of the central trough (Fig. 5).
With respect to their depth distributions,K. sawanensis is distributed over a wide
depth range from 120 to 1,350 m, whereas K.
antisawanensis and K. surugensis are restricted to relatively shallow depths, at about
150-650 m (Fig. 6). A few abraded valves ofK. surugensis obtai ned from a 1,350 m-deep

936.

Krithe from Suruga Bay

1105

oK. sawanensis

K. antisawanensis

K. surugensls

-E

. !:

......

Co

Q)

Cl

500

f - - - - - ...

1000
1 - - - - - ...

individuals/unit volume
1-5 5-10-10-20--201500
Figure 6. Frequency of three Krithe species across depth profile. Arrows indicate depth points fromwhich living Krithe specimens were detected. Short bars on the left side are sampling depths. The "unitvolume" represents roughly 50 cc wet surface sediment.

sample are regarded as allochthonous specimens because of their isolation from the mainoccurrence range of this species and theirpoor preservation. The depth interval of
650-810 m is barren of Krithe and other deep
water taxa, and is referred to as the ostracodebarren zone (OBZ). We found a total of 9dead ostracode specimens in 3 of the 10 samples collected from that interval. The assemblage is composed of 7 species: Aurila sp.,
Bradleya japonica Benson, Nipponocythere
bicarinata (Brady), Paracytheridea

polyspinosa Hu and Cheng, Propontocypris
sp., Sclerochilus sp., and Xestoleberis sp. We
believe these are all transported from shallow
environments.
Intraspecific variation in Krithe sawanensis
In adult specimens of K. sawanensis, twodistinct vestibule types have been recognized.
All specimens above the OBZ have an axeshaped vestibulum that shows variability inshape and size. In contrast, all specimens
below the OBZ possess a crescent-shaped

Baochun Zhou and Noriyuki Ikeya

1106

.

oI

34.5

34.0
,

1

.

4.

5,
6
~
20
10
15
5
0+0_ _-+-_~"--------;"":':"_---=t-r.,--_2..L5r----,,302

Dissolved oxygen (mVI)
Temperature (0C)'------~-------.---,-;·~-;'~r;:...... ~'w
Y i'~ ,-/

100

200
300

"

/.
/.1

K. antisawanensis,/V

S/;//{ f
f'/~s

500

//

f(-W

• ·-w
~...i..-s

OSTRACODE·BARREN ZONE

\i

\\

II
,f

\ "
\\ \\

I!h
\\
\1."

'.\ "\

.-

1000

;\

~

\ \

"\

O.5mm

1\

"I "I
I

I

"\

1500

\ I

I I
\ I
I I

I,

(m)

\I
1\
1\

T
2000

\\

s

s: summer
w: winter

Figure 7. Structure of water column near the bay mouth (La!. 34°34.9'N, Long. l38°3S.2'E) (compiled
from Nakamura, 1982), and vertical distribution of different vestibule shapes of three Krithe species.

vestibulum that is uniform in morphology(Fig. 7). The areas of the axe-shaped vestibula are smaller than or equal to those of
the crescent-shaped ones. Moreover, the volumes of the axe-shaped vestibulum are muchsmaller. In most cases, the axe-shaped vestibulum is so narrow that it is difficult topermeate it even by alcohoL Bubbles are left
in the inner part (see Fig. 10). Consequently, distinct dimorphism is found in the vestibulum of K. sawanensis inhabiting different
water depths.
Two populations of adult specimens in K.
sawanensis differ in carapace dimensions(Fig. 8). The total 28 adult valves measured
comprise 15 specimens from 8 samples above
OBZ and 13 specimens from 3 samples below
it. In Figure 8, both male and female specimens from samples above the OBZ display
wide size variati·on, whereas specimens fromsamples below that zone are characterized by
the tightly c1 ustered points.

Discussion
Waters above 200 m in Suruga Bay are
under the influence of the Kuroshio Current.
Its influence is strongest at the bay mouth,and decreases gradually from the eastern side
to the western side through the inner bay.
Krithe sawanensis is a species tolerant of avariety of environments. For example, it
occurs throughout the entire bay and has awide bathymetric range of from 120 to 1,350
m. The different distribution patterns of K.
antisawanensis and K. surugensis seem to becontrolled by the influence of the Kuroshio
Current. However, the depth ranges of thetwo species are 150-650 m, and the lower
depth limit is far below the influence of theKuroshio. The different distribution patterns of these species may reflect differences inoceanic conditions that are still not understood.
On the basis of analysis of the ostracode936.

Krithe from Suruga Bay

1107

0.6

"-:~12S-------)~

n=28,/<;~ii!~::ii /::;;;~~~'2951)-;' ~3 -5~,,,,,,_5,/'//"//"ITml"rnF;··7 0295..... .....

E
E

-

// •
/

1.60

";:,'356 . . . /-;/,/.....

~'35 .......//:;::<[""350

//

/

/

/

0550

n4~

---- _.- .....
o RV______________ ______________ ________________
~

~

1.1

1.0

~

1.2

Length (mm)Figure 8.

L-H scatter diagram of adult K. sawanensis.

Numbers beside points indicate the sample

depths in meters.

fauna from Suruga Bay, Ikeya and Zhou (inpress) recognized an assemblage composed ofKrithe spp. and Bradleya albatrossia Bensonthat has an upper depth Iimi t of between 120
and 150 m. This depth is comparable withthe lower limit of the vertical circulation
layer during winter, when a clear boundary
between the upper and lower water masses
forms. This boundary separates the ostracodes into distinct shallow and deep water
assemblages in this bay.
Ohta (1983) pointed out that in Suruga Bay
a boundary of vertical distribution of themacrobenthos is regulated by the submarine
topography of the shelf edge (about 130 m).
This boundary is, in fact, comparable withthat of the ostracodes found on the easternside. However, the depth of the shelf edge in
Suruga Bay is different in each area, i.e., it is150-200 m deep on the eastern side, about 100
m on the southwestern side, and about 50-60
m on the northwestern side. Therefore, theshelf edge in this bay might not be so important a factor in controlling the vertical distribution of ostracodes.
The boundary between shallow and deep
water ostracode assemblages is often foundbetween about ISO and 200 m (e.g., Van
Morkhoven, 1972; Peypouquet, 1980) in
many areas of the world. Van Harten andDroste (1988), on the other hand, reported
that the faunal boundary in the Mediterranean is about 250-300 m deep. They suggested that there is a relationship between
ostracode assemblages and the photic zone, as
originally proposed by Pokorny (1971). In
Suruga Bay, we consider that the mostsignificant factor controlling the ostracodefaunal boundary is the vertical circulation ofoceanic waters in winter.
One of our interests in the present study
was to clarify whether or not there is any
intraspecific variation in the vestibule morphology of Krithe, a feature that seems to be

1108

Baochlln Zholl and Noriyllki Ikeya

correlated elsewhere with environmental factors. In Suruga Bay, individuals with axeshaped vestibula occur only above the OBZ ;those with crescent-shaped vestibula occur
only below it. The OBZ corresponds withthe depth of the dissolved oxygen minimum
layer, whose known seasonal fluctuation isfrom 700 m (in summer) to 950 m (in winter),and which in summer is 1.5 mill and in
winter 1.8 mill. The axe-shaped vestibulumof K. sawanensis above OBZ, like the vestibula of K. antisawanensis and K. sllrllgensis, is narrow, and the crescent-shaped vestibulum of K. sawanensisis below OBZ iswide. These results therefore support the
hypothesis of Peypouquet (1979) that vestibule size and shape are related to dissolved
oxygen.
In the depth interval from 120 to 650 m,
where one population of K. sawanensis lives,temperature, oxygen and salinity show strong
gradients and appreciable seasonal changes(see Fig. 7). Conversely, in the depth interval of 918-1 ,350 m, which is the habitat of theother population of K. sawanensis, the environment is nearly homogeneous and shows
little seasonal change. Thus, the large variance in carapace morphology in the upper
water depths may be related to this environmental vanatlOn. This interpretation IS
supported by results of the study of K.
prodllcta from off Punta Arenas, Chile byKaesler and Lohmann (1976).
We stress that the volumes of K. sawanensis vestibula below the OBZ are greater thanthose of specimens above the OBZ. Thisshows the correlation with dissolved oxygen
minima hypothesised by Peypouquet (1977,1979), but for vol ume rather than area.

Systematic description
Class Ostracoda Latreille, 1806
Order Podocopida Sars, 1866
Superfamily Cytheracea Baird, 1850
Family Cytherideidae Sars, 1925

Subfamily Krithinae Mandelstam, 1958
Genus Krithe Brady, Crosskey
and Robertson, 1874
K rithe sawanensis Hanai, 1959
Figures 8-1, 2, 3
Krithe salVanensis Hanai, 1959, p.301-303, pI. 18,
figs. 3-7, text-figs. 3, 4; Hanai, 1961, p. 360, textfig. 48, figs. I a, b, 2a, b; Nohara, 1987, p. 39, 40,
pI. I, lig. 5; Ishizaki and Irizuki, 1990, p. 59;
Ikeya and Suzuki, 1992, pI. 6, fig. 7.
not Krithe salVanensis Hanai: Zhao, 1988, p. 243, pI.
42, figs. I, 2; Gou et al., 1983, p. 34, pI. 6, figs.
1-13, text-fig. 8.

Type.-Holotype, male LV, UMUT-CA
2908 (L= 1.16, H=0.51, T=0.25).
Type locality.-A cliff at Mano Bay,
Sawane-machi, Sado-gun, N iigata Prefecture,
Japan (Lower Pleistocene Sawane Formation).
Diagnosis.-A species of Krithe with inflated carapece. Posteroventral duplicature
narrow, parallel to ventral margin; duplicature near posterocardinal angle obscure.
Posterior margin meets ventral margin almost
making a right angle. R V overlaps LV.
Remarks.-Of all the Krithe species reported from Japan and its adjacent areas, thisspecies is the largest in carapace size. Moreover, it is quite different from the otherspecies in having reversed hingement.
In the present study, dimorphism of thevestibulum has been found in this species.
All adult specimens from depths of 120-650
m have an axe-shaped vestibulum, whereas all
those from depths of 920-1,350 m have acrescent-shaped one. The two populations
are separated by an ostracode-barren zone
(OBZ) at 650-810 m.
In the L/H scatter diagrams (Fig. 4a), theregression line for juvenile stages of thisspecies is similar to that of K. antisawanensis,
despite their distinct morphology. Sex was
distinguished by microscopic observation.
All scatter points of male are below those of
female, reflecting the distinct sexual dimorphism in this species.
Distriblltion.-Recent: About 200-1,400 m

936.

Krithe from Suniga Bay

11 09

Figure 9. 1- 3, Krilhe sawanensis Hanai , 1959. 1 : External view of male LV (IGSU-94S); 2: intern a lview of male RV (IGSU-O-949) ; 3 : a se nsillum pore of male LV (IGSU-O-94S) . 4,5, Krithe al1lisalVanensis
Ishizaki, 1966. 4 : External view of mal e LV (IGSU-O- 950) ; 5 : internal view of female LV (IGSU-O-951).
6- 12, Krithe surugensis n. sp. 6: External view of male LV (holotype, IGSU-O-942) ; 7 : external view ofmale RV of the same indi vidua l (paratype, IGSU-O- 943); 8: external v iew of female LV (paratype, IGS U-O944); 9: external v iew of female RV (paratype, IGSU-O-945) ; 10 : internal view of ma le R V (para type,
IGSU-O-946): 11 : dorsal view of male RV (p a ratype, IGS U-O-946): 12 : dorsal view of female RV (paratype , IGSU-O-947). (Magnifications are , 3: X 3,200 ; 11, 12 : x 40 ; a ll others: X 60).

Baochun Zhou and Noriyuki Ikeya

1110

Occurrence data of three species of Krithe. Number of living specimens are inparenthesis.
K. surugensis
K. antisawanensis
K. sawanensis

Table 3.

Adult
St. no.
13
20
35
36
38
40
41
45
46
48
49
57
58
87
88
89
91
92
97
102
103
105
108
109
M28
M31
M33
M41
M42
M43
M45
M46
M52
M64
M66
M69
M77
M93
M95
MIOI
MI04
MI07
MI09
MI15
MI25

C

V

I
14

I

C

V

C

V

C

Juvenile

Adult

Juvenile

Adult

Juvenile
V

V

C

C

V

2
I

I
2
I
3
4

I

2
2

2
I
10
6
6
I

3

7(5)
I

I

33

4

I
6

7(5)

22
2
13
7
16
I

2
I

I
2
2

3
3

8
7
I

I

16
I

4(2)
4(2)
26(26)

I

1(1)

1(1 )

1(1)

1(1)

I
I
2
9
2

2
3

7

I

4

I

13

I

I
4

2

10
3
3

2

3
I

4
2

I

I

2
I
4

II
I
21
3
2
2
14
I
29
2

2

I

3

I

2

4

6
2

3
25

I

I
I
4
7

32

I

936.

Krithe from Suruga Bay

2

I III

deep, Toyama Bay, Japan Sea (l shi za ki andIri z uki , 1990) ; 144 - 1, 335 m deep off
Shimane, Japan Sea (Ikeya a nd Suzuki ,1992) ; below 120 m between Suruga Bay a ndoff Tanega-shim a Island , southwest Japan ;140-268 m deep, off northeast Hokkaido , Sea
of Okhotsk. Fossil: Lower Pleistocene
Sa wane Formation , Japan Sea (Hanai , 1959) ;Plio-Pleistocene Shin za to Formation , Okinawa (Nohara, 1987).

Krilhe anlisawanensis Ishi zaki , 1966
Figures 9- 4, 5

3

Krith e antis[[lV[[nense [sic.] Ishi zaki , 1966, p. 137,
138, pI. 18, figs , 17, 24, 25.

Krith e an tis[[lV[[nensis Ishi za ki: H a nai et al. , 1977,

4

p. 26 ; Choe, 19 84 (MS) , p. 124, pI. 6, fi gs. 15 , 16,
17, tex t-fig. 10- 3.
Krith e s[[lVanensis H a na i : Zhao , 1988 , p. 243, pI. 42 ,figs. 1, 2 ; Gou et aI. , 1983, p. 34, pI. 6, figs. 1- 13 ,text-fi g. 8.

Type. - Holotype , RV , IGPS - 87016 (L =0.9 7, H = 0.50).

5

6

Figure 10. I ntraspecific variation of vestibule
morphology in Krith e species. All photographs a rein internal v iews, magnification X 49. 1: mal e LVof K.salVanensis with axe-sha ped vestibulum ; Stati on 20. 2 : Female LV of K. salVanensis with axeshaped vestibulum ; Stati o n M77. 3 : Mal e LV of
K. sawanensis w ith crescent-sh a ped ves tibulum ;Station 103. 4: Male L V of K. antiS[[lV[[nensis withcrescent-shaped vestibulum; Station M64. 5: Ma le
R V of K. surugensis with cresce nt-shaped vestibulum ; Stati on M77. 6: Male RV of K. surugensis with very sma ll semi-circular vestibulum ; Station
M115 .

Type locality.- An exposure about 1,500 m
southeast of Saboyama, Sendai City, northeast J a pan (Miocene Hatatate Formation).
Diagnosis. - Carapace laterally compressed.
Anterior vestibule narrow , restricted to thelower third of anterior marginal area. Po steroventral duplicature narrow , parallel toventral margin. Posteroventral a ngle tapered. LVoverlapsRV.
Remarks. - The holotype specimen IS a
fem a le because it has an arched dorsal margin .
Zh ao (1988) reported a Krithe species fromthe East China Sea and recogni zed it as K.
sawanensis. In our view, however, the two
specimens shown in his illu stra tion are K.
anlisawanensis becau se they have a tapered
po steroventral angle. In addition, a RV in
intern a l view shows a sharp dorsal edge thatcoincides with the hingement of K. anlisawanensis , but is the reverse of that of K.
sawanensis. Gou et al. (1983) found a
species of Krithe and referred it to K.

1112

Baochun Zhou and Noriyuki Ikeya

sawanensis. Their species may also be K.
antisawanensis because the specimen illustrated in the text-figure in internal view has
reversed hingement. Moreover, its anterior
vestibulum is narrow and restricted to thelower third of the anterior marginal area.
In four examined single valves of thisspecies from Suruga Bay, no variation investibule morphology was recognized. Thismay be due to the small number of specimens
examined.
In the LjH scatter diagrams (Fig.4b),
although the regression line for juvenilestages of this species is similar to that of K.
sawanensis, the carapace size of its adults isdifferent (Fig. 4b).
Distribution.-Recent: About 150-600 m
deep, Suruga Bay; about 50-200 m deep,South Korean Sea (Choe, 1984 MS); 15-320
m deep, East China Sea (Zhao, 1988); 116263 m deep off Shimane, Japan Sea (Ikeya
and Suzuki, 1992); below 150 m deep
between Suruga Bay and Tanegashima Island,
off the Pacific coast, southwest Japan. Fossil: Miocene Hatatate Formation, northeast
Japan (lshizaki, 1966); Pliocene deposits in
Leizhou Peninsula and Hainan Island, south
China (Gou et al., 1983); Pleistocene Chikura Formation, Boso Peninsula; Upper
Pleistocene Ninomiya Formation, Kanagawa
Prefecture.
Krithe surugensis n. sp.
Figures 9-6-12

Type.-Holotype, male LV and RV of thesame specimen (St. MI15), IGSU-O-942 (LV:
Fig. 9-6; L=0.85, H=0.38, T=0.16. RV:
Fig. 9-7; L=0.83, H=0.35, T=0.15). Paratypes, female LV (St. M 115), IGSU-O-943(Fig.9-8; L=0.76, H=0042, T=0.16); female R V (St. M 115), IGSU-O-944 (Fig. 9-9 ;L=0.81, H=Oo4O, T=018); male RV (St.
MIl5), IGSU-O-945 (Fig. 9-10, 11 ; L=0.82,
H=0.35, T=0.15); female RV (St. M77),
IGSU-O-946 (Fig. 9-12; L=0.73, H =0041,
T=0.16).

Type locality.-St. Ml15 (320 m) (34°57.8'
N, 138°44.6'E), Suruga Bay.
Diagnosis.-A species of Krithe with aslender and relatively small carapece. Posteroventral duplicature broad and convex;
dorsal and ventral margins nearly parallel.
Description.-Carapace slender and moderately small; in lateral view subrectangular.
Anterior contact margin symmetricallyrounded. Dorsal and ventral margins nearlystraight and subparallel. Posterior margin
curves gently into dorsal margin, but it meetsventral margin nearly at aright angle.
Height about one-third of length. Surface
completely smooth, having large and widely
spaced normal pore canals. Posterior end
possessing two prominent round indentations. Anterior duplicature extremely
broad; posterior duplicature broad and convex. Vestibule poorly developed in anterior
end, crescent-shaped or subcircular.
"Radial" pore canals nearly straight andwidely spaced and rare along the ventral
margin, about 16 in number. Hinge
pseudadont, dorsal hinge of left valve being
grooved to receive the edge of the right valve.
Adductor scars consist of a ventral row offour posterior scars and one heart-shaped
anterior scar.
Sexual dimorphism distinct. Male moreelongate and slimmer than female.
Remarks.- This species closely resembles
Krithe hanaii Ishizaki, 1983 in having abroad posteroventral duplicature. However,the latter has a larger and more inflated carapace, and shows a more arched dorsal margin and an axe-shaped anterior vestibule.
Intraspecific variation in vestibule size,
although not as distinct as that in K.
sawanensis, has been found in this species.
It generally has a crescent-shaped vestibulum;
but in some specimens the vestibulum
becomes extremely narrow and its shape issemicircular. This is accompanied by abroadening of the fused zone. No correspondence was found between the vestibule SIzeand environmental parameters.

936.

Krithe from Suruga Bay

The L/H regression line of this species has
a lower gradient than those of K. sawanensis
and K. antisawanensis (Fig. 4c), reflecting its
slender carapace.
Distribution.-Recent: The authors havealso found this species below 150 m between
Suruga Bay and Hyuga-nada off the Pacificcoast, southwest Japan; 730 m deep off Kerama Islands, Okinawa. Fossil: Lower
Pleistocene Nekoya Formation, Shizuoka
Prefecture, Central Japan; Lower Pleistocene
Sunakomata and Hamada Formations,Shimokita Peninsula; Plio-Pleistocene Shinzato Formation, Okinawa.
Acknowledgements

We express our deep appreciation to T.M.
Cronin (U.S. Geological Survey) and J.E.
Hazel (Louisiana State University) for reading and criticizing the manuscript; to T.
Hanai (Osaka Gakuin University) and K.
Chinzei (Kyoto University) for their critical
discussions. The first author is indebted toK.G. McKenzie (University of Melbourne)
and P. De Deckker (The Australian National
University) for their important comments on
the genus Krithe. We thank H. Okada (Kyushu University) and H. Kitazato (Shizuoka
University) for providing a part of the samples for this research.

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87, p.605-608, U.S. Govt. Printing Office, Wa-. IllS

shington.
Zhao, Q., 1988: Chapter V: Ostracoda.

In, Wang,
P. et al., Foraminifera and Ostracoda in Bottom
Sediments of the East China Sea. p.181-280,

pI. 35-58.

China

Ocean

Press,

Beijing.

Chinese with English abstract)

Chikura Tir, Hainan ita1¥!, Hamada ~EB, Hatatate :iPtll., Hyuga-nada B (ci]., Kerama~.&rJ3j, Leizhou ~HI, Mano ffi!;!IlJ, Nekoya m.tI~, Ninomiya =-'12;, Sawane iRtR, Shimane~:fR, Shinzato fJT!t!., Sunakomata rrJ;'f y, Suruga !~3tfoJ, Tanega-shima fJ:=f~, Toyama 1f!;

0.1 •• foJ~~0~lli~~Kri~.(~Bm,*%~)~3.:.M~~.8~.~M(~~;#?J ;0, G, Krithe .~~~~f)J*IJ;tfil:H~ ~ ;let.: o -: ie G ft~~ ~%~~tEl'ffj~i(i':' ~ "? -C, M
f:$:;O'GQl(:f:$:i-("3"J~/~-;q.:.5tm~h~0-:~5"0~2"JfiK.

sawanensis

Hanai,

c K. antisawanensis Ishizaki, 1966 V.:. i'1.I IE ~ h, ~ i) ~ I "J ~ K. surugensis n. sp. c
L -acmx Lt.:o3 .Ii~~,>t h-f;le!i'UJ:"? t.:1:,~,i5l!oc c ~'@'(fJ5t:;(P>a:-~~ 0 K. sawanensis fi~~:I;g1(~
120-1,350 m E{!: v.:.5t:;(P~ ~ ~ v.:.M L -C, K. antisawanensis ft~ 1=1 t.gl(, K. surugensis fi~~},If'j':'&ll~~f':' 150-650 m E{!:v':'~J,..5t:;(P-t ~o HI~ 5t:;(p/~c itat$.I:~WU ~I*l{* >a:-~i1li
c t.:oit.:, K.sawanensisfi, 650-8IOmE{!:v':'1ftE~~~)I'%~* (OBZ) v':'~"?-C2"J~@
f$:f¥f.:.5tttJi ~ h -C \" ~o ie G ~@f:$:f¥rf'ljv,:,J,.. G.h ~ ~~"'t 1" :;( c Vestibulum ~%~m:~
1959

j1 -

/'

-:

ft7.Kl1fi'tc~1f~*:;:v.:.~t!Sl~~ c~..zGh~o

Jj!iJ~~. iIll.:fi:llDz(inTrans. Proc. Palaeont. Soc. Japan, N.S., No. 166, pp. 1116-1143, 18 Figs., June 30, 1992

937.

AMYGDALOPHYLLOIDES (RUGOSA) FROM THE CARBONIFEROUS
OF THE OMI LIMESTONE, CENTRAL JAPAN*Y ASUSHI YOSHIDA and YUJI OKIMURA
Institute of Geology and Mineralogy, Faculty of Science,
Hiroshima University, Higashihiroshima 724

Abstract. The Omi Limestone Group belonging to the Akiyoshi Terrane yields
abundantly rugose coralline fossils of the genus Amygdalophylloides from its lower part.
The assemblage of Amygdalophylloides obtained from the Fukugakuchi area where the lower
sequence of the Omi Limestone Group is typically developed, comprises more than 10 forms,
from which the following eight species, including five new species and two unidentified
species, are herein described and illustrated: Amygdalophylloides denslls, sp. nov., A.
denticlilatlls, sp. nov., A. lIzurensis (Yamagiwa and Ota), A. omiensis, sp. nov., A. longiseptalliS, sp. nov., A. parVlIs, sp. nov., A. sp. A and A. sp. B. This coralline assemblage is ofNamurian A to Namurian B, Serpukhovian to early early Bashkirian age, except for theoccurrence of Amygdalophylloides sp. A referred to the late Visean age.
Key words.
Japan.

Amygdalophylloides, Rugosa, Carboniferous, Omi Limestone, central

Since then, Amygdalophylloides has been reported or described from the Upper Carboniferous rocks of the Yayamadake Limestone(Kanmera, 1961) and the Akiyoshi Limestone(Minato and Kato, 1957, 1975; Hasegawa,
1963; Yamagiwa and Ota, 1963; Haikawa,1986) in southwest Japan and from the
Ichinotani Formation of Fukuji district (Niikawa, 1981) and the north ofTarui (Furutani,1981) in Gifu Prefecture, central Japan.
Recently, one of the authors (Y.Y.) newly
collected a number of specimens of Amygdalophylloides from the lower part of the Omi
Limestone Group (Hasegawa et ai., 1969,1982) in the Fuk ugak uchi area (Figure I).
This genus appears suddenly in high frequency in the lowest Upper Carboniferous,
providing datum for understanding theboundary problem between the Lower andUpper Carboniferous of Japan.
In this paper, eight species of Amygdalophylloides including five new ones are described, and their stratigraphic distribution IS

Introduction

The genus Amygdalophylloides is a small
geyerophyllid rugose coral having a solid
columella with rare additional axial elements,a few or no lonsdaleoid dissepiments andfrequent peripheral stereozone. This genus
is widely distributed in the Lower Carboniferous to the Lower Permian of the Boreal andTethyan Provinces, such as Spitzbergen,
northern Spain, the Carnic Alps, Yugoslavia,
northeastern Egypt, the Moscow Basin, eastern Kazakhstan?, North Vietnam, North andSouth China and Japan, mostly in the Upper
Carboniferous.
Hayasaka (1921, 1922, 1924) listed anddescribed Axophyllum gracile, which waslater transferred to the genus Amygdalophylloides by Kanmera (1961), from the lower
part of the "Omi Limestone", Nishikubiki
County, Niigata Prefecture, central Japan.
'Received January 22, 1992; revised
accepted April 28, 1992

manuscript

1116

937.

Amygdalophylloides from Omi limestone

Figure 1. Topographic map of the Fukugakuchi area showing locations of the section 1 andsection 2.

analyzed.
Stratigraphy and fossil occurrence
The so-called Omi Limestone cropping out
in the Omi district of Niigata Prefecture,
central Japan near the coast of the Japan Sea,
is one of the Upper Paleozoic limestonemasses aligned isolatedly in the Akiyoshi
Terrane (Kanmera and Sano, 1986). It rests
conformably on basaltic pyroclastic rocks as
do such limestone masses in the Akiyoshi
Terrane as the Akiyoshi, Taishaku, Atetsu
and Koyama Limestones. This sequence in1117

the Omi district is called the Omi LimestoneGroup (Hasegawa et al., 1969, 1982), ranging
in age from Early Carboniferous (late Visean)
to late Middle Permian (late Guadalupian).
The lower part of the Omi LimestoneGroup is typically exposed in the Fukugakuchi area situated on the northeastern slope of
Mt. Kurohime, northern part of the Omi
district, in which two sections were measured,
namely section I and section 2 (Figure I).
The Carboniferous of this area consists ofbasaltic pyroclastic rocks on the bottom followed by massive limestone without any
stratification. The stratigraphic succession
measured along the routes shown in Figure 2
is summarized as follows in descendingorder:
I) light-gray, fine-to medium-grained bioclastic limestone (packstone) with distorted
oolitic grains and intraclasts; more than 67.8
m thick; containing abundant bryozoa andcrinoid ossicles. This limestone intercalateswith some lenticules of sponge spicular limestone in the lower part.
2) gray conglomeratic limestone (limestone breccia) and grayish, fine-grained
peloidal limestone (wackestone); 25. I m
thick, as far as exposed. The conglomeratic
limestone carries various sizes of biolithitic
limestone (boundstone) clasts, which are fossiliferous and contain abundant foraminifers,
corals, brachiopods, calcareous algae, andothers.
3) gray, fine- to coarse-grained bioclastic
limestone (packstone) of 1.4 m thick, rich inbryozoan and crinoidal fragments; being
succeeded by light-gray, fine-grained oolitic
limestone (grainstone) of 28.3 m thick.
4) greenish or purplish basaltic pyroclastic rocks with tuffaceous and bioclastic limestone (packstone) clasts of various sizes, intercalating the oolitic limestone (grainstone)layers near its uppermost part which yielded
abundant brachiopods and corals (Yoshida
et al., 1987); about 14 m thick.
The specimens of Amygdalophylloides wereobtained from the oolitic limestone at one

Yasushi Yoshida and Yuji Okimura

1118

SECTION 2

0
0

0
0

0

0

f-- OM865

0
0

0
0
0

0
0

tE8j4

0

0
0
0

~5

./OM837
OM833...L OM829

0
0

0

0
0

~6

ICD'" I7
CD

0

0
0
0

0
0

0

0
0

0

0

"T"""o
o~o
0

OM779

o~o

0

1--10

o~o

0

OM55811

0
0

o~
0
0
0
0
0

6
6

SECTION 1/,g~~~~-2

6= OM6l7-l

6

6
6
6

OM6l6

6
6

=;;:OM609
OM601

6
6

OM731
OM721
OM7ll
6
OM708
OM707
6 - OM703- OM689
6

6

6
6

j

6

OM682

6
6

6

0

0
0

0

0
0

0

0

0

0

0
0

0

0

-OM558

0
0

0

0

0

0

0

0
0

0
0

0
0

0
0
0

----------1

0
I

0
0

0
0

\

0
0

\

0

20m

0

I

~\fP_~g~f1;,~li~~!.,\~\;\'~

101);\)2:&\,',;
ICD>-:..\~..q;;>}iX/~'{J~~place in section I (Loc. OM 558), the conglomeratic limestone at six places in section I(Locs. OM 601,609, 616, 617-1, 617- 2 and619) and eight in section 2 (Locs, OM 682,
689,703, 707, 708, 711, 721 and 731) and thebioclastic limestone at five places in section 2(Locs. OM 779, 829, 833, 837 and 865). A
species list of Amygdafophylloides from theabove mentioned localities and horizons isshown in Table 1.
Biostratigraphical studies of the Omi Limestone Group have been done by Kawada(1954a, b, c), Fujita (1958), Kato et af.
(1964), Hasegawa et af. (1969, 1982) and
Watanabe (1973). Hasegawa et af. (op. cit.)
divided the pre-Moscovian formation of the
Omi Limestone Group into two zones basedon smaller foraminifera and fusulinaceans,
namely an Endothyra Zone and an
Eostaffella-Millerella Zone.
Almost all of the coral specimens in thepresent study fall within the EostaffellaMillerella Zone, except for the sole specimenof Amygdafophylloides sp. A. According toHasegawa et af. (1982), the age of the
Eostaffella-Millerella Zone ranges from thelate Visean to early Bashkirian. However,
the occurrences of Amygdafophylloides in thisZone may be limited in age as discussed
below.
Amygdafophyffoides uzurensis was originally described by Yamagiwa and Ota (1963)
from the "Uzura" Quarry of the Akiyoshi
Limestone, southwest Japan, as one of theimportant elements of the "Uzura fauna", theage of which has been regarded as early
Namurian or late Chesterian by Ota (1971)o+- Figure 2. Columnar sections of the lower partof the Omi Limestone Group in the Fukugakuchi
area, showing the stratigraphic positions of fossil
localities in section I and section 2 shown in Figure I.
I : lenticular sponge spicular limestone, 2: bioclastic
limestone, 3: conglomeratic limestone, 4: peloidal
limestone, 5: oolitic limestone, 6: bioclastic
packstone-rudite with basaltic tuffaceous matrices, 7 :clasts of limestone, 8: basaltic pyroclastic rocks, 9:covered interval, 10: fault, II : locality number.

937.
Table 1.

Amygdalophylloides from Omi limestone

1119

List of Amygdalophylloides from the lower part of the Omi Limestone Group in the Fukugakuchi
area (Numerals show the examined specimen-number). The stratigraphic positions of fossil
localities are shown in Figure 2.

~'
Species

Section 2

Section I(OM-)

558 601 609 616 617-1 617-2 619 682 689 703 707 708 711 721 731 779 829 833 837 865• Amygdalophylloides
denslls, sp. nov.

42

• A. denliclilaills,

I

sp. nov.
6• A. lIzlIrensis

I

9

2

6

(Yamagiwa and Ota)

10

• A. omiensis,
sp. nov.

3• A. /ongiseptall/s,

1

I

sp.nov.
I• A. parvlIs, sp. nov.

43

I

A. '! gracilis

3

I

2

I

I

(Hayasaka)• A. sp. A

I• A. sp. B
A. spp.

I
3

I

I

4

9

5

4

I

15
2

• Species herein described.

and Matsusue (1986), late early Namurian toearly late Namurian by Haikawa (1988) andlate Namurian or Morrowan by Igo and
Koike (1965) and Igo and Igo (1979).
Meanwhile, the lowest Amygdalophylloidesbearing limestone in the Eostaffella-Millerella
Zone in section I (Loc. OM 601) yields thefollowing smaller foraminifera, brachiopod
and calcareous sponge (red alga ?): Endothyra aff. E. hortonensis Rich, Weiningia sp.
and Komia sp. The first form closely resembles Endothyra hortonensis, originally described by Rich (1980) from the upper Chesterian of south-central Tennessee. The second form belongs to a genus known from theLower (?) to Middle Carboniferous of southwest China (Ching and Liao, 1974). The
third form is quite similar to representativesof a genus denoting a Pennsylvanian age(Wray, 1977a, b and others).
On the other hand, the fusulinid species,
Pseudostaffella antiqua (Dutkevich) is firstobserved at about 3 m above the highest
Amygdalophylloides-bearing limestone in sec-tion 2 (Loc. OM 865). This species has been
known from the Severokeltmensky Horizon(upper lower Bashkirian, C7 e2) of USSR
(Semichatova et al., 1979; Groves, 1988, andothers) and from Cf 9 (upper Namurian
B-Namurian C) of Western Europe (Conil etal., 1980).
According to the viewpoints mentioned
above, the present Amygdalophylloides assemblage in the Eostaffella-Millerella Zone can be
estimated to be of Namurian A (Serpukhovian) to Namurian B (early early Bashkirian) age.
The stratigraphic horizon of Amygdalophylloides sp. A in section I (Loc. OM 558) is
equivalent to the upper part of the Endothyra
Zone of late Visean age.
Systematic descriptions

All the specimens described and figured inthis paper are deposited in the Institute ofGeology and Mineralogy, Faculty of Science,
Hiroshima University, Higashihiroshima

1120

Yasushi Yoshida and Yuji Okimurawith prefix IGSH-YY.
Family Geyerophyllidae Minato, 1955
Genus Amygdalophylloides Dobrolyubova
and Kabakovich, 1948
Type species (by original designation).
-Amygdalophyllum ivanovi Dobrolyubova,
1937, p. 60, pI. 19, figs. 15-20.
Remarks. -The morphological relationship between the genus and the allied genera
are fully discussed by Minato and Kato
(1975) and Rodriguez (1984, 1985).
Amygdalophylloides gracilis (Hayasaka,1924) is the first species of the gen us to havebeen described from the Omi Limestone originally under the generic name of Axophyllum.
Amongst our collections a few specimens canbe compared with this species, but these specimens are excluded from the present description because they are so poorly preserved that
their assignment to it is questionable. Inview of the morphologically extremely variable nature of this species, we feel it necessary
to make its specific conception clear.
Hayasaka's (op. cit.) original definition of thespecies included forms which have a large
corallite, a large number of septa, a comparatively well developed stereozone, short minor
septa and a relatively large solid columella.
Later Minato and Kato (1975, p. 21) presented some inked figures of specimens having asmaller form with a smaller number of septa(Fig. 3), a thicker stereozone and longer
minor septa (Fig. 2) and a much larger
columella (Fig. I), compared to the typespecimens. So here we interpret the specificdiagnosis of A. gracilis as follows:
Moderately large to large-sized Amygdalophylloides having corallite diameter of 12 to
18 mm. Peripheral stereozone 1/7 to 2/5
width ofcorallite radius. Minor septa 1/5 to
3/5 length of major septa. Columella simple
and solid, 1/7 to 2/7 or more width of corallite diameter. Lonsdaleoid dissepiments
sometimes developed. Tabulae mostly incomplete, can be complete, commonly steeply
inclined and rather closely spaced.

The following is a key to the nominal
species of Amygdalophylloides from the Omi
Limestone.
I.
Stereozone very thick (> 2/5 width ofcorallite radius) and minor septa welldeveloped (> 3/5 length of major septa)
With small, spindle shaped or smoothy
elliptical columella ........ A. densus
With small, denticulate columella having septal lamellae-like projections.................... A. denticulatus
II.

Stereozone not very thick « 2/5 widthof corallite radius)IIa. Minor septa less well developed ( < 3/
5 length of major septa)
Hal. With moderately large to large
corallite (12-18 mm in diameter),and mostly incomplete andrather closely spaced tabulae.................. A. gracilis
IIa 2 •

lIb.

With small corallite (7-11 mm indiameter), and mostly complete
and distantly spaced tabulae
Columella large (1/6-1/4
width of corallite diameter)................ A. omiensis
Columella small (1/8-1/6
width of corallite diameter). ............... A. uzurensis
Minor septa well developed (> 3/5
length of major septa)
With moderately large corallite(12-13 mm in diameter) and distinct inner wall .. A. longiseptatus
With small corallite (5-7, rarely 9mm in diameter) ...... A. parvus

Geographic and stratigraphic distribution.
-As shown in Figure 3, this genus is distributed universally in the Boreal and Tethyan regions. Its stratigraphic distribution is
Lower Carboniferous (upper Visean) to
Lower Permian (Artinskian), and its maximum distribution is in the Upper Carboniferous, especially in the Moscovian.

Amygdalophylloides densus Yoshida, sp. nov.

937.

2

Amygdalophylloides from Omi limestone

1121

o~

Figure 3. Geographic distribution of Amygdalophylloides. I: Spitsbergen (Forbes et al., 1958), 2:
Asturias, northern Spain (Rodriguez, 1984),3: Palencia, northern Spain (de Groot, 1963),4: the Carnic Alps
(Heritsch, 1936),5: Bosnia, Yugoslavia (Kostic-Podgorska, 1955),6: northeastern Egypt (Herbig and Kuss,
1988), 7: the Moscow Basin (Dobrolyubova, 1937, 1940, 1948; Dobrolyubova and Kabakovich, 1948), 8:
eastern Kazakhstan (Bikova, 1974), 9: Nei Mongol Autonomous Region, North China (Guo, 1983), 10:
Shaanxi Province, South China (Ding and Yu, 1987), II : Hubei Province, South China (Xu in Jia et al.,1977),12: Jiangsu Province, South China (Yu, 1980), 13: Guizhou Province, South China (Chi, 1931 ; Ding,
1986; Wu and Zhao, 1989), 14: Yunnan Province, South China (Wang and Zhao, 1989; Wu and Zhao,
1989),15: Guangxi Province, South China (Xu and Chen in Xu el al., 1986),16: North Vietnam, (Fontaine,1961), 17: Yayamadake, southwest Japan (Kanmera, 1961), 18: Akiyoshi, southwest Japan (Minato andKato, 1957, 1975; Hasegawa, 1963; Yamagiwa and Ota, 1963; Haikawa, 1986), 19: Tarui, central Japan(Furutani, 1981), 20: Fukuji, central Japan (Niikawa, 1981), 21 : Omi, central Japan (Hayasaka, 1921, 1922,
1924; this paper).
Figures 5-la--5,6-la--7

Derivation of name. ~After the feature ofcorallum having a very thick peripheral stereozone. Latin densus~thick, dense.
Material. ~Forty-two corallites from Loc.
OM 601 in section I, which is referred to thelower part of the Eostaffella-Millerella Zone.
Holotype, IGSH- YY 10021, paratypes,
IGSH- YY 10022-10062.
From these specimens, 103 transverse and
13 longitudinal thin sections were examined.
Diagnosis. ~Comparatively small-sized

Amygdalophylloides with an extremely broad
peripheral stereozone, well developed minor
septa and a solid columella, from which a few
axial tabellae are differentiated in some cases.
Small lonsdaleoid dissepiments sometimes
developed.
Description. ~Corallum is ceratoid to subcylindrical, and small in size. Although
individuals frequently aggregate and in somecases are even flattened on one side by contiguity with other specimens, there is no evidence of branching or budding. Indeed it
seems probable that the species is invariably

Yasushi Yoshida and Yuji Okimura

1122

-

~

10

Ir-·

a

+

. .a.i. .r

UJ

I-

::::;
...J

«

a:

o

a

U

u.

o

ffi

.•

I-

UJ

:::;;

«

II

.

•

• • a
•

r

15

10

15

20

25

NUMBER OF MAJOR SEPTA

Figure 4. Relationship between number of major septa and diameter of corallite in Amygdalophylloides
densus. sp. nov. +: holotype of A. densus.

solitary. External characters are unknown.
In transverse section, corallite is round inoutline, 10.2 mm in calicular diameter in thelargest corallite. Wall is crenulated in outerconfiguration, suggesting the presence of septal grooves and interseptal ridges. The
peripheral stereozone formed by lateralfusion of dilated septa is strongly developed,
usually occupying 2/5 to 3/5 (rarely 2/3) of
the radius of the mature corallite. Dissepimentarium is completely masked by thedevelopment of the stereozone in many specimens. However, in the mature stages ofsome specimens small peripheral dissepiments
are present, which are confined to the stereozone and commonly of only sporadic orpartial occurrence; quite exceptionally in asection of the specimen IGSH- YY 10032 (Figure 6-6a), they show an almost complete
vertical. In a few specimens some of thesedissepiments become subsequently modified
to small lonsdaleoid dissepiments by theretreat of minor septa and sometimes evenmajor septa from the wall (e.g. IGSH-YY
10029, Figure 6-3). Such lonsdaleoid vesicles are also observed in the cal ice of thespecimen IGSH-YY 10033 (Figure 6-7), in
which a distinct rejuvenation takes place.
Tabularium is round in outline, comparatively wide to wide, occupying commonly 2/5 to
3/5 (rarely 1/3) of the diameter of corallite.
A few cut edges of tabulae are seen between

major septa. Septa are in two orders, major
and minor. They are somewhat pinnately
arranged in the early growth stages, but tend
to take radial symmetry in the mature stages.
Fossula is not observable. Major Septa arestrongly expanded in the stereozone, gradually attenuated towards the columella, withwhich only the cardinal septum is normally incontact. The axial ends of major septa arebluntly terminated. Minor septa alternatingwith the major septa are well developed,
attaining 3/5 to 3/4 (rarely 4/5) the length ofthe latter. They are entirely restricted within
the stereozone in general, but uncommonly
only just emerge from it. Rarely, septa areinterrupted by the development of the lonsdaleoid dissepiments, if present. Septal finestructure is diffuso-trabecular. As many as
23 major septa occur in the 9.9 mm diametercorallite. Relationship between the numberof major septa and the diameter of corallite isshown in Figure 4. Axial structure originates from the axial end of the cardinal septum, which usually expands to form a prominent columella in the early growth stage.
Generally, in the mature stages the columella
becomes independent of the cardinal septum,
their conjugation being mere abutting. Thus
formed columella is spindle-shaped orsmoothly elliptical in outline, and consists ofa solid structure with a fairly long medianlamella and radiating calcite fibres. How-

937.

Amygdalophylloides from Omi limestone

ever, in some specimens a few outwardly
convex axial tabellae are differentiated fromthe columella that is continuously connectedwith the cardinal septum except in the latest
mature stage (e.g. IGSH-YY 10029, Figure 63; IGSH- YY 10032, Figures 6-6b-c).
Width of the columella is variable, but does
not exceed 1/7 the diameter of corallite. A
few specimens have an auxiliary col umella,
which appears in the early growth stages, butdisappears in the mature stages (e.g. IGSHYY 10022, left-hand corallites in Figures 5la-b). Rejuvenescence occurs frequently
and usually it is only indicated by thedifferentiation of a new wall from calicularwall of the old corallite (Figures 5-2a,4a).
A single specimen IGSH-YY 10033(Figure 6- 7) represents a more distinct rejuvenation by secreting a new wall around anaxial portion of the old cal ice, which leads tolarge reduction of the corallite diameter and acomplete reconstruction of the morphology.
In longitudinal section, corallite surface iswavy or more commonly irregular due to thefrequency of minor rejuvenation. Wall isvery thick. Dissepiments are only sporadic,
small, weakly elongated, steeply sloping orvertical and in one or rarely two rows, butcommonly concealed by the extensive development of stereoplasmic deposits. Tabularium is comparatively wide to wide. Tabulae
are mostly complete, but may be locally incomplete. They are subhorizontal or declined axially, and include steeply or gently
inclined clinotabulae. Sometimes, they are
gently to steeply ascending to the columella.
Three to seven tabulae are present in thevertical distance of 2 mm. Only occasionally, vesicular, arched and upwardly convex
periaxial tabellae may be developed. In
some specimens a few axial tabellae aredifferentiated from the columella and aresteeply tilting or vertical. Columella is narrow to moderately wide, weakly undulated
and solid, with the calcite fibres perpendicular to the slightly sinuous median lamella
which is vertically continuous. In the early1123

growth stage of a few specimens columella issplit into two parts, one of which is soon
degenerate (e.g. holotype, Figure 5-lc).
Calice is deep and steeply sided, with a prominent columella.
Remarks. -The present new form shows
considerable variability in its skeletal elements. Some of the specimens describedabove differ from the typical form by thepresence of peripheral dissepiments and/or
lonsdaleoid dissepiments, and a few axial
tabellae (e.g. IGSH-YY 10029, 10032). Thus
they are apt to be treated as representing an
independent species. However, these morphological variations occur together at thesame locality and even in a single specimen.
Therefore they are best regarded as
intraspecific variations.
The present form closely resembles Amygdalophylloides uzurensis (Yamagiwa and Ota,
1963), but differs from the latter in having amuch thicker stereozone and stronger minor
septa. It also shows resemblance to the corallites of Amygdalophylloides gracilis(Hayasaka, 1924) illustrated by Minato andKato (1975) as Figs. 2 and 5 on p.2l in
revealing a rather thick stereozone, fromwhich it is distinguished by its smaller corallite with fewer septa and smaller columella, in
addition to much thicker stereozone andbetter development of minor septa.
Amygdalophylloides crassicolumellatus
Dobrolyubova and Kabakovich (1948) fromthe Upper Carboniferous (C~II horizon) of the
Moscow Basin, is somewhat similar to thepresent form, but is readily distinguishable bypossessing a slightly narrower stereozone,
shorter minor septa and a much larger
columella with some open holes in it.
On the other hand, the specimens withlonsdaleoid dissepiments are reminiscent of
Darwasophyllum sp. aff. D. irregu!are forma
compacta Pyzhjanov, described and figured
by Rowett and Kato (1968, p. 37, pI. 10, figs.
1-6), which was obtained from the Moscovian of the Akiyoshi Limestone, southwest
Japan. The latter is, however, said to be a

11 24

Yasushi Yoshida and Yuji Okimura

937.

Amygdalophylloides from Omi limestoneloosely fasciculate form, and is provided witha few irregular and curved septal lamellae.
Furthermore, it bears a narrower stereozone,
shorter minor septa and a slightly thicker
columella compared to the present form.

Amygdalophylloides denticulatus
Yoshida, sp. nov.
Figures 8-la-f

Derivation of name. -Based on the featureof corallum with denticulate columella.
Material. -A single corallite from Loc.
OM 601 in section I, which is referable to thelower part of the Eostaffella-Millerella Zone.
Holotype, IGSH-YY 10063.
Five transverse and one longitudinal sections have been cut from this material.
Diagnosis. -Comparatively small sized
Amygdalophylloides having a particularly
thick peripheral stereozone, well developed
minor septa and a solid, denticulate columella with septal lamellae-like projections which
are circumscribed by a few axial tabellae.
Description. -Corallum is solitary, ceratoid and small in size. Surface characters
are unknown.
In transverse section, corallite is round inoutline, attains 8.2 mm in the largest diameter. Wall has an external crenulation, showing the presence of septal grooves and interseptal ridges. The peripheral stereozone
made up by lateral contiguity of dilated septa
is strongly developed, occupying the width ofabout 1/2 the half diameter of corallite.
Dissepimentarium is entirely masked by thedevelopment of the stereozone except in one
section of the mature stage (Figure 8-le), in
which a few, small peripheral dissepiments
are to be seen. Tabularium is round inoutline, wide, occupies approximately 1/2 of1125

the corallite's diameter. A few cut edges oftabulae are seen between major septa. Septa
are radially arranged in two orders, major
and minor, in alternation. Fossula is notdiscernible. Major septa strongly expand in
the stereozone, gradually tapering towards
axis, with bluntly ended axial terminations.
They come close to the axial structure, butalmost never connect with it, except that the
cardinal septum always touches the peripheryof the columella. Minor septa are well developed, 3/5 to 3/4 the length of the major, but
do not project beyond the stereozone. Finestructure of septa is diffuso-trabecular.
Major septa are 19 in number in the corallitewith 8.2 mm diameter. Relationshipbetween the number of major septa and thediameter of corallite is shown in Figure 7.
Axial structure is irregular in outline,
occupies 1/5 to 1/4 of the diameter of corallite. It is composed of a thick, solid columella having a denticulated outline with a few,
short septal lamellae-like protuberances
which are circumscribed by a single row ofthickened, outwardly convex axial tabellae.
A fairly long median lamella and radiallydisposed calcite fibres are to be seen in thecolumella. The columella is attached to thecardinal septum, but the median lamellae of
these structural elements do not join eachother. Width of the columella is less than
1/8 of the diameter of corallite. A small
elliptical auxiliary columella is present onlyin the early growth stage. The corallite
reveals a distinct rejuvenation by secreting a
new wall around an axial portion of the oldcalice, which causes large reduction of thecorallite diameter and a repetition of younger
morphology (Figure 8-1f). Also minor
rejuvenescence occurs, which is only indicated by the differentiation of a new wall from~ Figure 5. 1-5: Amygdalophylloides densus, sp. nov. la-d, successive transverse (la-b) and longitudinal (Ie-d) sections (Ia-b, right-hand corallites and le-d, holotype, IGSH-YY 10021; la-b, left-handcorallites, paratype, IGSH-YY 10022); 2a-b, transverse (2a) and longitudinal (2b) sections (paratype,
IGSH-YY 10023); Ja-b, successive transverse sections (paratype, IGSH-YY 10024); 4a-b, transverse (4a)and longitudinal (4b) sections (paratype, IGSH-YY 10025); 5, transverse section (paratype, IGSH-YY
10026). All figures X 6.

11 26

Yasushi Yoshida and Yuji Okimura

937.

Amygdalophylloides from Omi limestone

10

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20

NUMBER OF MAJOR SEPTA

Figure 7. Relationship between number ofmajor septa and diameter of corallite in Amygdalophylloides denticulatus. sp. nov.

calicular wall of the old corallite (Figures 8Ie-f).
In longitudinal section, corallite surface is
not smooth owing to the presence of repeatedminor rejuvenescences. Wall is very thick.
No dissepiments are observable in an available longitudinal section. Tabulari urn iswide. Tabulae are subhorizontal or declined
axially, and include gently inclined
clinotabulae. They are mostly complete,
although they can be locally incomplete, andrather coarsely spaced, counting 3 to 7 in thevertical distance of 2 mm. Large, elongate,
vertical, vesicular structures (cystoseclinotabulae) are to be seen in the outermarginal part of tabularium in the mature
stage. Axial tabellae are sparsely disposed,
steeply sloping or vertical, and thickly coatedwith stereoplasmic deposits. Columella israther wide, more or less sinuous and solid,

1127

consisting of the calcite fibres perpendicular
to the feebly undulated and vertically continuous median lamella. There exists an auxiliary columella in the early growth stage, but
it is soon degenerate.
Remarks. -The present form is represented by only one specimen in our collections,but is considered sufficiently distinctive towarrant erection of a new species. Closest
similarities are shown to Amygdalophylloides
densus, sp. nov. described above. This
species has, however, a spindle-shaped orsmoothly elliptical columella, from whichsometimes a few axial tabellae may bedifferentiated, whereas the columella of thepresent form reveals denticulated outline withseptal lamellae-like projections that are circumscribed by one row of axial tabellae.
Amygdalophylloides uzurensis (Yamagiwa
and Ota, 1963) somewhat resembles the present form, but is clearly distinguished inpossessing a narrower stereozone and shorter
minor septa, together with a simpler axial
structure.

Amygdalophylloides llzllrensis(Yamagiwa and Ota, 1963)
Figures 10- I -7b

Lophophyllidium uZlIrense Yamagiwa and Ota. 1963,
p. 91, pI. I, fig. 6; pI. 2, figs. 1-5.
Amygdalophylloides lIzurense; Minato and Kato,
1975, p.7.

Material. -Twenty-four corallites: IGSHYY 10064-10069 from Loc. OM 609 and
1GSH-YY 10070-10078 from Loc. OM 619 insection I, and IGSH-YY 10079 from Loc. OM
703, IGSH-YY 10080-10081 from Loc. OM
721 and IGSH-YY 10082- 10087 from Loc.
OM 779 in section 2; all these localities areequivalent to the lower half of the
Eostaffella-Millerella Zone.

~ Figure 6.
1-7: Amygdalophylloides densus. sp. nov. la-b. successive transverse sections (paratype,
IGSH-YY 10027); 2a-b, oblique transverse (2a) and longitudinal (2b) sections (paratype, IGSH-YY
10028); 3, transverse section (paratype, IGSH-YY 10029); 4, longitudinal section (paratype, IGSH-YY
10030); 5, longitudinal section (paratype. IGSH-YY 1003 I); 6a-c, serial transverse sections (paratype,
IGSH-YY 10032); 7, transverse section (paratype, IGSH-YY 10033). All figures x6.

11 28

Yasushi Yoshida and Yuji Okimura

Figure 8. 1: Amygdalophy/loides denliculalus, sp. nov. la- f, seria l transverse (la - b, ld- f ) a nd longitudinal ( Ie) sections (holotype, IGSH- YY 10063). All figures X 6.

From these, 37 transverse and 7 lo ngitudinal thin sect ions have been prepared.
Description. -Co rallum is so litary with aceratoid fo rm and sma ll in size. Frequentl y,a few cora llites belonging to different individuals are nearly placed a nd in one case evenappressed, so as to give a fa lse impression of
a compound corall um (Figure IO- 7a). Surface characters are unobservable.
In transverse sectio n, cora llite is round inoutlin e, measures 7.2 mm in di ameter in thelargest cora llite. Externa l surface of wa ll iscren ul ated to reveal the presence of septal
grooves and interseptal ridges. A prono un ced stereozone is formed by latera lfusion of peripherally thickened septa, varies
in its width from 1/ 4 to 2/ 5 of the radius ofcora ll ite In the mature stages. D issepimentarium is comp letely fi ll ed by the development of the stereo zo ne in some spec imens.

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NUMBER

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25

MAJOR SEPTA

Figure 9. Rel ationship between number ofmajor septa and diameter of corallite in Amygdalophy/loides uzurensis (Yamagiwa a nd Ota) .

H owever, in other specimens a few sma ll
peripheral dissepiments are present, and someof them become subsequently modified tolonsda leoid di ssepiments by the withdrawal

9]7.

A mygdalophy /loides from Omi limestone

11 29

Figure 10. 1- 7: Amygda/ophyl/oides uzurensis (Yamagiw a a nd Ola ). 1, lra nsve rse secli o n (IGSH -YY
10064) ; 2, lran sverse seclion ( IGS H-YY 10070) ; 3a - b, lran sve rse (3a) a nd lo ngil udinal (3b) secl io ns (IGSHYY 10065) ; 4a - b, longitudina l (4a) a nd lra nsverse (4b) seclions (IGSH-YY 10082) ; 5, lransverse seclion(IGSH-YY 10066) ; 6, long ilu di na l secli on (IGSH-YY 10067) ; 7a - b, lra nsverse (7a) and lo ngi tu d in a l (Th)secli o ns (7a , left-h and cora llile, Th, IGS H-YY 10071 ; Th, ri ghl-h an d cora llite, IGS H-YY 10072). A ll
figures X 6.

of minor se pta a nd rarely even major septa
from the wa ll. Tabularium is ro und in o utlin e, w ide, occ upying 3/ 5 to 3/ 4 of the diameter of corallite. There are a few c ut edges oftabulae visi bl e between m ajor se pta . Septa
are of two orders, major and minor. Arrange-

ment o f se pta is so mewhat pinnate in the ea rl y
growth stages, but te nds to be radi a l in them at ure stages . N o fossu la is discernib le.
Maj or septa show strong dil ation in the stereozone a nd so metimes a lso in the tabularium .
They fall short of the co lume ll a except the1130

Yasushi Yoshida and Yuji Okimura

cardinal septum. Inner ends of major septa
are bluntly terminated. Minor septa alternate with the major septa, 2/5 to 3/5 (rarely
2/3) as long as the latter. They are normallyembedded in the stereozone, but may justpenetrate the tabularium. Only occasionally, minor septa are interrupted by the development of the lonsdaleoid dissepiments, if thelatter is present. Septa are diffuso-trabecularin their fine structure. As many as 25 major
septa are counted in a corallite of 6.3 mm indiameter. Relationship between the numberof major septa and the diameter of corallite isshown in Figure 9. Axial structure consistsof a solid columella which is a slightly thickened extension of the cardinal septum beginning in the early growth stage. In the mature
stages the columella has elliptical and smoothouter configuration, with a fairly long medianlamella and radially arranged calcite fibres.
The columella is in contact with the cardinal
septum, but the median lamellae of these two
structural elements are usually disconnected.
In a few specimens the columella is only
partly replaced by axial tabellae which are
outwardly convex (e.g. IGSH- YY 10066,
Figure 10-5). Width of the columella isusually 1/8 to 1/6 of the diameter ofcorallite.
Rare specimens have auxiliary columella (e.g.
IGSH-YY 10065, Figure 1O-3a). Rejuvenation may occur, but not frequently, and it isrepresented by the differentiation of a newwall from calicular wall of the old corallite(e.g. IGSH-YY 10072, right-hand corallite in
Figure 1O-7a).
In longitudinal section, wall is thick, andfeebly undulated or in rare cases irregular by
the presence of minor rejuvenescences. Dissepiments are only sporadic, small, a little
elongated, steeply sloping and in one or two
rows, but commonly suppressed by the stereoplasmic deposits. Tabularium is wide.
Tabulae are mostly complete, but sometimes
locally incomplete. They are subhorizontal,
slightly sagging or descending towards thecolumella, and include gently or steeply tilting clinotabulae. In a vertical distance of 2

mm, 2 to 6, commonly 3 to 5 tabulae arecounted. Only rarely axial tabellae aredifferentiated from the columella and aresteeply inclined or vertical; quite exceptionally, in the specimen IGSH- YY 10067 (Figure10-6), one or two vertically continuous rowsof axial tabellae are developed. Columella
is comparatively wide, slightly sinuous andsolid, made up of the calcite fibres perpendicular to the vertically continuous medianlamella that is a little flexuous. Cal ice isdeep with steep sides and has a prominentcolumella.
Remarks. -The present form shows nosignificant differences from the type materialof Amygdalophylloides uzurensis, which wascollected by Yamagiwa and Ota (1963) fromthe lower Upper Carboniferous of the Akiyoshi Limestone, southwest Japan. A. uzurensis was originally assigned to the genus
Lophophyllidium (Yamagiwa and Ota, 1963,
p. 91). However, Minato and Kato (1975, p.
7) transferred this species to the genus Amygdalophylloides on the grounds of its possession of lonsdaleoid dissepiments andclinotabulae. Indeed, study of the present
Omi specimens clearly reveals that thecolumella originates from the axial end of the
cardinal septum, instead of the counter one asin Lophophyllidium
A. uzurensis shows closest similarities to
Amygdalophylloides omiensis, sp. nov. described below, from which it differs in having
a less swollen columella.
Amygdalophylloides gracilis (Hayasaka,1924) resembles A. uzurensis, but the smaller
size of corallite and more complete and more
widely spaced tabulae of the latter serve to
distinguish the two from one another.

Amygdalophylloides omiensis
Yoshida, sp. nov.
Figures 12-1a--2bDerivation of name. -After the Omi
Limestone in Niigata Prefecture, Japan.
Material. -Ten corallites from Loc. OM

937

Amygdalophylloides from Omi limestone

6 16 in section I, w hi ch is assig na ble to thelower part o f the EostajJella-Millerella Zone.
H o lotype , IGSH- YY 10088, p a ra ty pe s,
IGSH- YY 10089- 10097.

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25

20

15

NUMBER

OF

MAJOR

SEPTA

Figure II. Relati o nshi p betwee n number ofm aj o r se pt a a nd di a meter of co rallite in Amygda/opIJy //oides omiensis, sp. nov. + : ho lotype o f A.
omiensis.

11 3 1

Twenty-six tra nsverse and four longitudinal thin section s are ava ilabl e for study .
Diag nosis. - Co mp a rative ly sm a ll- sized
Amygdalophy lloides with a thick peripheral
ste reo zo ne and a so lid columell a wh ich isre lative ly large for the size of cora llite.
Sma ll lo nsdaleoid di sse piments ra rely develo ped.
Description. - Cora llum is so li ta ry, cerato id a nd sma ll in size. Sometimes, twocora llites belonging to different indi vidual s
are observed to be cl ose ly situated a nd growpara llel to each other, so as to give a fal se
impression of being colon ial (Figures 12 - 1b,Id). Surface characters unkn own.
In tra nsverse secti o n, coral li te is ro und ino utlin e, the la rgest be ing 9.2 mm in ca licul a r
di a meter. W a ll is cre nul ated on its ex terna lsurface, suggest in g the prese nce of septa lgrooves a nd interse pta l ridges. A prominent
stereo zo ne is prod uced by late ra l coa lition of

Figure 12. 1- 2: A mygda/oplJy lloides omiensis, sp. nov. la - d, ser ia l tra nsverse ( Ia - b, Id) a nd lo ngitudina l (Ic) secti ons ( la, Ib, Id, left-h a nd co ra llites, Ic , ho lo type, IGSH-YY 10088 ; Ib, ld, fi ght-hand corallnes,
p ara type, IGSH-YY 10089) ; 2a - b, tran sve rse (2a) a nd lo ngitudin a l (2b) secti o ns (paratype, IGSH-YY 10090).
All fi gures

X 6.

1132

Yasushi Yoshida and Yuji Okimura

peripherally dilated septa, ranging in its
width from 1/4 to 1/3 of the radius of corallite. Dissepimentarium is entirely masked by
the development of the stereozone except in
one section of the holotype specimen (I efthand corallite in Figure l2-ld), in which afew small lonsdaleoid dissepiments interrupting the continuation of minor septa are to be
seen. Tabularium is round in outline, wide,
occupying 2/3 to 3/4 of the diameter ofcorallite. There are a few cut edges oftabulae observable between major septa.
Septa are in two alternating orders, major andminor. They are somewhat pinnately disposed in the early growth stages, but tend toshow a radial arrangement in the mature
stages. Fossula is not observed. Major
septa taper gradually towards axis from thestereozone, with bluntly terminated axialends. They are not connected with thecolumella, except for the cardinal septum.
Minor septa are ordinarily confined to thestereozone, commonly 2/5 to 1/2 as long as
the major. Septa have diffuso-trabecular finestructure. As many as 24 major septa arepresent in a corallite with the diameter of 8.4
mm. Relationship between the number ofmajor septa and the diameter of corallite isshown in Figure II. Axial structure is asolid columella that first appears as a slightaxial swelling of the distal part of the cardinal
septum. In the mature stages the columella
is smoothly elliptical in outline and fairly
large with regard to the diameter of corallite,
comprising a relatively long median lamella
and radiating calcite fibres. The columella isin touch with the cardinal septum except in
the cal ice, but the median lamellae of these
two structures are usually separated. Widthof the columella is 1/6 to 1/4 (usually 1/5) of
the corallite's diameter.
In longitudinal section, wall is thick, andweakly undulated or rarely irregular becauseof the presence of minor rejuvenescences.
Dissepiments are only sporadical, small,flattened, vertical and in a single row, but
generally concealed by the stereoplasmic

deposits. Tabularium is wide. Tabulae aremostly complete, but may be locally incomplete. They are subhorizontal or descending
to the columella, and include gently or steeply inclined clinotabulae. Two to four
tabulae are contained in a vertical distance of
2 mm. Columella is wide, a little sinuousand solid, composed of the calcite fibres
perpendicular to the median lamella which isslightly flexuous and vertically continuous.
Calice is deep and steep-sided, having aprominent columella.
Remarks. -The present new form morphologically stands in between Amygdalophylloides uzurensis (Yamagiwa and Ota,
1963) and A. gracilis (Hayasaka, 1924). It
differs from A. uzurensis in having a moreswollen columella, and from A. gracilis inproviding a smaller form and more incomplete tabulae which are more widely spaced.
Amygdalophylloides stenotabulatus Wang
and Zhao (1989) from the Upper Carboniferous Weining Formation of Huize, Yunnan,
South China, may bear some resemblance tothe present form, but is easily distinguishedfrom the latter by having a narrower stereozone, shorter minor septa, better developed
dissepiments, no clinotabulae and a muchlarger columella from which septal lamellae
are differentiated.

Amygdalophylloides longiseptatus
Yoshida, sp. nov.
Figures 14-1a-4b

Derivation of name. -After the feature ofcorallum having long minor septa.
Material. -Five corallites: holotype,
IGSH-YY 10098 and 2 paratypes, IGSH- YY
10099, 10100 from Loc. OM 707, 1 paratype,
IGSH-YY 10101 from Loc. OM 708 and I
paratype, IGSH-YY 10102 from Loc. OM 829
in section 2; these horizons are referrable to
the Eostaffella-Millerella Zone.
Nine oblique transverse and three longitudinal thin sections were obtained from thespecimens stated above.

937.

Amygdalophylloides from Omi limestone

Diagnosis. -Moderately large-sized Amygdalophylloides with long minor septa, a narrow tabularium and a solid columella, fromwhich a few irregular axial tabellae may bedifferentiated in some cases. Small lonsdaleoid dissepiments sometimes developed.
Intrathecal dilation is frequent, making theinner wall prominent.
Description. -Corallum is solitary, ceratoid and moderately large in size for the
genus. No external characters are known.
Corallite observed in obliquely cut transverse section is elliptical in outline, attaining
12.5 mm in short diameter in the largest corallite. Internally it consists of wall, dissepimentarium, tabularium and axial structure.
Wall is thick, comparatively smooth ormarked only by faint septal grooves and interseptal ridges in outer configuration. Dissepimentarium is narrow, usually occupying
1/5 to less than 1/3 of the radi us of corall itein the mature stages, and sometimes so
reduced as to be replaced by the thick peripheral stereozone formed by lateral fusion ofdilated septa in the early growth stage (Figure14-3). It is composed mainly of I to 4 rowsof irregularly arranged interseptal dissepiments which are straight, oblique or inwardly
convex. Frequently, smallionsdaleoid dissepiments are developed; they are indicated by
the discontinuation of minor septa and only
rarely even major septa. Intrathecal dilationon the septa and the internal surface of thedissepimentarium is often very distinct andinner wall is clear in that instance. Tabularium is narrow, well differentiated from thedissepimentarium, occupying 2/5 to 1/2 ofthe diameter of corallite. Cut edges oftabulae are seen between septa. Septa areradially arranged in two orders, major andminor. No fossula is observable. Septa arealmost straight in the tabularium, and areoften greatly thickened by intrathecal dilation. They may be however slightly sinuousand occasionally discontinuous in the dissepimentarium. Major septa are long, extending close to the axial structure, but only the

1133

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30

NUMBER OF MAJOR SEPTA

Figure 13. Relationship between number ofmajor septa and diameter of corallite in Amygdalophylloides longiseplalUs, sp. nov. +: holotype of
A. longiseplatlls.

cardinal septum joins its periphery. Minor
septa are almost as thick as the major ones
with which they alternate. They are also
long, attaining 2/3 to even 7/8 the length ofthe major, and are prolonged into the tabularium or terminated within the inner wall.
Axially both septa end bluntly. Fine structure of septa is of the diffuso-trabecular type.
The number of major septa is as many as 30 ina corallite with a short diameter of 12.5 mm.
Relationship between the number of major
septa and the diameter of corallite is shown in
Figure 13. Axial structure is represented bya fairly large, smoothly elliptical solid
columella which comprises a rather long
median lamella and radially distributed calcite fibres. Sometimes, a few irregular axial
tabellae can be differentiated from the periphery of the col umella. The col umella touches
the cardinal septum, but the median lamellaeof these two structures are not united. Widthof the columella is approximately 1/5 of thediameter of corallite.
In longitudinal section, trizonal arrangement of skeletal elements is clear. Wall isthick and weakly undulated. Dissepimentar-

11 34

Yasushi Yoshida and Yuji Okimura

Figure 14. 1- 4: Amygda/ophy/loides /ongiseplalllS, sp. nov. la - c, long itudin a l (Ia) an d success ive
ob lique transverse (lb- c) sections (holotype, IGS H-YY 10098) ; 2, lo ngitud in a l secti on (paratype, IGS H-YY
10099); 3, transverse section (para type, IGSH -Y Y 10100) ; 4a - b, lo ngitudinal (4a) a nd ob li que transverse (4b)section s (paratype, IGSH -YY 10101). A ll figures x S.

937.

Amygdalophylloides from Omi limestone

1135

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15

20

NUMBER OF MAJOR SEPTA

Figure 15. Relationship between number of major septa and diameter of corallite in Amygdalophylloides
parl'us, sp. nov. +: holotype of A. parvus.

ium is narrow, with 1 to 2 rows of small,steeply tilting globose dissepiments. Strong
intrathecal dilation occurs on the internalsurface of the dissepimentarium. Tabularium is narrow, well differentiated from thedissepimentarium, made up of subhorizontaltransverse tabulae and steeply sloping
clinotabulae. All the tabulae are rather distantly spaced. Columella is wide, a little
sinuous and solid, consists of the calcite fibres
oriented perpendicularly towards the slightly
flexuous and vertically continuous medianlamella. A few axial tabellae may appear in
the columella.
Remarks. -With its long minor septa, thepresent form is unlikely to be confused withany other known species of Amygdalophylloides. The type species, Amygdalophylloides ivanovi (Dobrolyubova, 1937), may
have some similarities, especially in corallite
size, n umber of septa and the general character of axial structure. The present form isdistinguished, however, by its stronger dilation of septa, much longer minor septa and anarrower tabulari urn.

Amygdalophylloides parvus Yoshida, sp. nov.
Figures J6-la-7

Derivation of name. -After small dimensions. Latin parvus-small.

Material. -Forty-four corallites:
holotype, IGSH-YY 10103 and 42 paratypes,
IGSH-YY 10104-10145 from Loc. OM 731
and 1 paratype, IGSH- YY 10146 from Loc.
OM 708 in section 2; these localities arereferred to the lower part of the EostaffellaMillerella Zone.
From these specimens, 97 transverse and 3
longitudinal thin sections were made for thesystematic study.
Diagnosis. -Small-sized Amygdalophylloides with a thick peripheral stereo zone,
fairly long minor septa and a solid columella.
Small lonsdaleoid dissepiments only rarely
developed.
Description. -Corallum is solitary with aceratoid to subcylindrical form and small insize. No surface characters are known.
In transverse section, corallite is round to
subround in outline. The largest corallite
has a calicular diameter of 9.0 mm, but this is
exceptional as the next largest one is only 6.5
mm in diameter of calice. External crenulation of wall indicates the presence of septal
grooves and interseptal ridges. The peripheral stereozone composed of dilated marginalends of septa is thick, its width being usually
1/4 to 1/3 (rarely 1/5) of the corallite radius.
Dissepimentarium is completely masked by
the development of the stereozone in many
specimens. However, in rare specimens a

1136

Yasushi Yoshida and Yuji Okimura

Figure 16. 1- 7: Amygda/ophylloides parvLls, sp. nov. la - c, longitudin a l (la) a nd success ive tran sverse(lb- c) sectio ns (holotype, IGSH-YY 10103) ; 2a - b, success ive transverse secti ons (p araty pe, IGSH -YY 10104) ;3a- c, seri a l transverse section s (paratype, IGSH-YY 10105) ; 4, tra nsverse section (p a ra type, IG SH-YY 10106) ;5a- b, lo ngitudinal (Sa) a nd tra nsverse (Sb) section s (paratype, IGSH- YY 10107) ; 6, lo ngitudinal sectio n(paratype, IGSH-YY 10108) ; 7, tra nsverse secti on (paratype, IGSH-YY 10109).

few , small interseptal di ssepiments are o bservab le. Quite exceptiona ll y, sma ll lo nsd aleo id
di ssepiments are pa rtly developed in the
calice. Tabul arium is round in outlin e,wide, occupying normall y 2/ 3 to 3/ 4 o f thediameter of corallite. A few cut edges ofta bulae a re visib le betwee n septa. Septa areof two orders, maj o r a nd minor. Septal
arrangement is somewhat pinnate in the early
growth stages, but shows a tendency to be

A ll figure s

x 6.

radial in the mature stages. No fos sul a isobserved. Major septa are very thick at theirbases, but gradual ly attenuating towards theco lumel la, with which o nl y the cardina l septum is connected. They have bluntl y termin a ted axial e nd s. Min o r septa alternating
wi th major o nes are rather lo ng comp ared
with the size of the cora ll ite, commonly
pro truded into the tabul ar ium. Length ofthe min o r se pta is 3/ 5 to even 4/ 5 of the937.

Amygdalophylloides from Omi limestone

11 37

Figure 17. 1: Amygdalophy lloides sp. A. 1a- b, longitudinal (la) and oblique tran sverse (lb) section s(IGSH-YY 10147). 2- 3: Amygdalophylloides sp. B. 2a - b, success ive transve rse sect ions (IGSH-YY 10149) ;3a - c, successive transverse sect ion s (3a - b, left-h a nd co rallites, 3c, IGSH-YY 10150; 3a - b, right-hand corallites,
IGSH-YY 10151). All figure s x 6.

major septa in the mature stages. Septa are
diffuso-trabecular In fine structure. The
number of major septa is as many as 20 in acorallite of 5.8 mm in diameter. Relationship between the number of major septa andthe diameter of corallite is shown in Figure
15. Axial structure is composed of a solid
columella which is formed by a slight expansion of the axial end of the cardinal septum atfirst. In the mature stages the columella isfusiform or smoothly elliptical in outline,
consisting of a fairly long median lamell a andradially disposed calcite fibres. The
columella is in contact with the cardinal
septum, but the median lamellae of thesestructural elements do not join each other.
Width of the columella is usually 1/ 6 to 1/ 5
(rarely 1/ 7) of the diameter of corallite.
Simple budding is discernible in the holotype(Figure 16- lc) and the paratype specimen
IGSH-YY 10109 (Figure 16- 7), in which two
small offsets arise in the axial area in themother coral Iite. A Iso in the paratype,
IGSH-YY 10106 (Figure 16- 4) , one small
offset springs out from the sidewall of themother corallite. A few spec imens show
evidence of rejuvenescence.
In longitudinal sect ion , wall is thick andfeebly undulated. Di sse piments are only
sporadical , small, flattened and vertical and1138

Yasushi Yoshida and Yuji Okimura

in one row, but commonly suppressed by thestereoplasmic deposits. Tabularium is wide,
made up of complete or incomplete tabulae
which are mostly inclined axially and include
steeply or gently sloping c1inotabulae. Two
to four tabulae are situated within a verticaldistance of 2 mm. Columella is comparatively wide to wide, slightly sinuous andsolid, with the calcite fibres perpendicular to
the median lamella which is weakly undulating and vertically continuous.
Remarks. -The small corallite size clearly
separates the present new form from the otherJapanese representatives of Amygdalophylloides.
Amygdalophylloides rareseptatus 00brolyubova and Kabakovich (1948) from theUpper Carboniferous (GIl horizon) of the
Moscow Basin, has similar dimensions to thepresent form, but is easily distinguished fromthe latter by having a narrower stereozone,
better developed dissepiments and shorter
minor septa.
Putting aside small size of corallite, thepresent form somewhat resembles A. gracilis(Hayasaka, 1924), but differs from that species
in possessing longer minor septa for the sizeof corallite, and more complete tabulae which
are more distantly spaced.

Amygdalophylloides sp. A
Figures 17-1a-b

Material. -Single fragmental corallite
from Loc. OM 558 in the section I, which
belongs to the upper part of the Endothyra
Zone. IGSH-YY 10147.
Two obliquely cut transverse and longitudinal thin sections were made from thisspecimen.
Description. -Corallum is solitary, smallin size. Externals are not available.
Oblique transverse section of a corallite inmature stage is elliptical in outline, and 6.5
mm in minimum diameter. External surfaceof corallite is crenulated, as far as preserved.

Stereowall is thick, formed by peripheral
dilation of septa. No dissepiments are observable. Tabularium is wide, where cut
edges of tabulae are seen between septa.
Septa are in two orders, major and minor.
They are somewhat pinnately arranged, but
fossula is indistinct. Major septa are 27 in
number, very thick at their bases, graduallytaper towards axis, with bluntly ended axial
terminations. They do not reach thecolumella except for the counter and cardinal
septa; the counter septum joins the columella laterally, while the cardinal one meets it
directly. Minor septa are 1/2 to 3/5 thelength of the major septa with which theyalternate, and most of them project only
slightly into the tabulari urn. Fine structureof septa is diffuso-trabecular. Axial structure is a fairly large, spindle-shaped, solid
columella that is formed by a extremely
strong expansion of the axial end of the
cardinal septum.
In longitudinal section, wall is thick.
Oissepiments are unobservable. Tabularium
is wide, with gently or steeply inclined, complete c1inotabulae which are fairly distantly
spaced. Columella is wide, smooth andsolid, comprising the calcite fibres oriented
perpendicularly to the feebly undulating
median lamella, which is vertically continuous.
Remarks. -The present unidentified form
closely resembles Amygdalophylloides omiensis, sp. nov. described above, but is distinguished by possessing a much longer counter
septum attached to the columella and slightly
longer minor septa, most of which just penetrate the tabularium, and a columella that iscontinuously connected with the cardinal
septum even in the mature stage. It also
resembles Amygdalophylloides gracilis(Hayasaka, 1924). The two forms can be
distinguished by the latter having a larger
form and more closely spaced tabulae which
are mostly incomplete, besides a counter septum separated from the columella. The
present form may represent a new species, but

937.

Amygdalophylloides from Omi limestone

1139

E10
E

w
fo-

•

::::i
....J
~

0::

5

0
0

LL

0

~
~

0
Figure 18.
sp. B.

• •

•
10

... .
I

15

•
•

•

• • • •
•
I

•

•

.

20

25

NUMBER OF MAJOR SEPTA

Relationship between number of major septa and diameter of corallite in Amygdalophylloides

the final decision is deferred pending discovery of more well preserved specimens.

Amygdalophylloides sp. B
Figures l7-2a-3c

Material. -Sixteen fragmental corallites:
IGSH-YY 10148 from Loc. OM 708 and
IGSH- YY 10149- 10163 from Loc. OM 711 insection 2, which are equivalent to the lower
part of the Eostaffella-Millerella Zone.
From these, 50 transverse thin sections havebeen examined.
Description. -Corallum is solitary, smallin size; individuals are commonly aggregated and are often in contact with each other(Figure 17-3a), but there is no indication of
branching or budding. Surface characters
are unobservable.
In transverse section corallite is round inoutline, the largest having a diameter of 7.8mm. Wall is crenulated externally with septal grooves and interseptal ridges. The
peripheral stereozone produced by lateralfusion of expanded septa is strongly developed, ranging in width from 1/4 to 3/5 (generally 1/3 to 1/2) of the radius of corallite in
the mature stages. Dissepimen tari um isentirely filled by the development of the stereozone except in a few specimens, in whichsparse, small interseptal dissepiments are vis-ible. Tabularium is wide, occupies normally
1/2 to 2/3 (rarely 2/5) of the diameter ofcorallite. A few cut edges of tabulae are
discernible between septa. Septa are in twoorders, major and minor. They are more orless pinnately arranged in the early growthstages, but become radial in the mature stages.
Fossula is not observed. Major septa arestrongly dilated in the stereozone, graduallytapering axially. They fall short of or touch
the columella. Minor septa are fairly long
and almost as thick as the major with which
they alternate. They may be confined to thestereozone, but more commonly intrude into
the tabulari um. Length of the minor septa is
usually 3/5 to 3/4 (rarely 4/5) of the major.
The axial ends of both septa are bluntly
terminated. Septal fine structure is diffusotrabecular. As many as 26 major septa arecounted in the 7.3 mm diameter corallite.
Relationship between the number of major
septa and the corallite diameter is shown in
Figure 18. Axial structure consists of a solid
columella which is a slight axial swelling of
the distal part of the cardinal septum at first.
In the mature stages a median lamella andradially situated calcite fibres form an ellipticalor spindle-shaped columella, which insome instances may have a denticulated outline with a few short septal lamellae-likeprojections. The columella is attached to1140

Yasushi Yoshida and Yuji Okimura

the cardinal septum except near the cal ice, but
the median lamellae of these structural elements do not unite with each other. Widthof the columella is usually 1/7 to 1/5 of thecorallite diameter. There may be an auxiliary columella in the early growth stage (e.g.
IGSH- YY 10150, left-hand corallite in Figure17-3a). A few specimens show rejuvenescence, which is indicated by thedifferentiation of a new wall from the oldcalicular wall (e.g. IGSH-YY 10150, lefthand corallite in Figure 17-3b, Figure 173c). No longitudinal section is available.
Remarks. -Although the material certainly represents a new species, longitudinal sections were not obtainable, so that it is not asuitable basis for a new taxon. Closest similarities can be seen to both Amygdalophylloides denticulatus and A. densus, sp. nov.
described above. These forms have, however, minor septa which are generally embedded in the stereozone, whereas most of theminor septa only just project into the tabularium in the present form. Furthermore, they
are provided with a smaller columella
compared to the present form; the columella
is circumscribed by a few axial tabellae in A.
denticulatus and it bears no septal lamellaelike projections in A. densus.
Amygdalophylloides gracilis (Hayasaka,1924) is distinguished from the present formin having a larger form, shorter minor septa
and more numerous cut edges of tabulae intransverse section.
Acknowledgements

The authors wish to express their sincere
thanks to Prof. M. Kato of Hokkaido University for his valuable suggestion and criticalreading of the manuscript. They are alsomuch indebted to Prof. Emeritus A. Hase ofHiroshima University for his cordial guidance and encouragement to one of the authors(Y.Y.), and to Prof. Y. Hasegawa and Dr. I.
Niikawa of Niigata University for theirinstructive advice and various suggestions.

Special acknowledgements are due to Prof.
W.S. Wu of Nanjing Institute of Geology andPalaeontology, Academia Sinica for her valuable advice and fruitful discussion on coral
palaeontology, and to Associate Prof. Z.T.
Liao of the same Institute and Prof. J.
Yanagida of Kyushu University for theirkindness in identifying brachiopods. The
authors are much obliged to the Myojo
Cement Co., Ltd. for every facility in the field.
Thanks are extended to the late Mr. H. Takahashi and Mr. A. Magai of Hiroshima University for preparing many thin sections. A partof this study was supported by the Grant in
Aid for Scientific Researches from the Ministry of Education of Japan.

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(in Chinese with English abstract)

Fukuji m:ttB, Gifu ~.$., Ichinotani -O)1:i'-, Kuro-937.

Amygdalophyfloides from Omi limestone

hime ~Ptt Niigata *MJ!,~. Nishikubiki iJ13%i.tb.x. Omi ww. Tarui ~#. Yayamadake ~LlJffi.

wwEIlk.!fiO)EiT<i{d I) J£'-t Q Amygdalophylloides (~M-1j- /' ::i'~): ~1~!!i!:wwEIlk.
!fi~MTj'ffi~ii'Ga:l:ffitJ':-1j- /' ,,"{r.E~J£'tl:l-tQo .:.: "C'a~m:LlJ;ft*~HmK.{~~-tQm*7 pj:i!2JiJ1Z1 I):!*~ LJ-: Amygdalophylloides 0) 5 'G. (j(0) 5 ~lI~i5'tr 811~~cmt-t Q :Amygdalophylloides densus, sp. nov., A. denticulatus. sp. nov., A. uzurensis (Yamagiwa andOla), A. omiensis, sp. nov., A. longiseptatus. sp. nov., A. parvus. sp. nov., A. sp. A, A. sp. Bo.: 0) -1j- /' ,,' {r.EMO) lIi)of~a A. sp. A ii:f&Jtfl I::" -fi - t!t"C';5 Q 0) ~~4'<l' L fi T A -/I.--t!t A ii,
G T A -/I.--t!t B (-t II.-- 7' " 7t!tii, GfrJJtfl /~:/ "" -/1.--t!tfJJJtfl) "C';5 Q .!: ~;t GA'L Q0
E 83 ~jlj. i'rrtttt=

1143

Trans. Proc. Pa1aeont. Soc. Japan, N.S., No. 166, pp. 1144-1156, 7 Figs., June 30, 1992

938. AMMONITES OF THE GENUS ACOMPSOCERAS AND SOMEOTHER ACANTHOCERATID SPECIES FROM THE IKUSHUNBETSU
VALLEY, CENTRAL HOKKAIDO(STUDIES OF THE CRETACEOUS AMMONITESFROM HOKKAIDO-LXXIII)T ATSURO MATSUMOTO
c/o Department of Earth and Planetary Sciences,
Kyushu University 33, Fukuoka 812
and

T AKEMI TAKAHASHI
28-109 Yayoi (Hanazono-cho), Mikasa 068-21

Abstract. We have recently investigated the hitherto unexplored outcrops of Lower
Cenomanian sandy rocks not far from the type section of the Mikasa Formation along theRiver Ikushunbetsu of central Hokkaido. Although bivalves predominate there, at least ten
ammonite species are identified. In this paper the following four species are described, since
they have not yet been recorded in Hokkaido: Acompsoceras renel'ieri (Sharpe), Utaturiceras vicinale (Stoliczka), Mantelliceras aff. japonicum Matsumoto, Muramoto & Takahashi
and Mantelliceras saxbii (Sharpe). Also a biostratigraphic correlation with the type section
is attempted with a suggestion that the Acompsoceras-bearing bed may represent, though
locally and with lateral change of facies, the next higher level than the Zone of Mantelliceras
japonicum in the type section of the lower Cenomanian in the Ikushunbetsu Valley.
Key words. Acompsoceras.
Cenomanian, Hokkaido

Mantelliceras.

Utaturiceras,correlation,

lower

inate there, we have identified at least ten
species of ammonoids, of which an Acompsoceras and three other acanthoceratids markthe first occurrence in Hokkaido. We
describe them in this paper and give brief
remarks on their biostratigraphic implications.

Introduction
One of us (T.T.) recently noticed hitherto
unexplored outcrops of fossiliferous sandyrocks which could be referred to the lower
part of the Mikasa Formation. This seemed
important in that the obtained material might
supplement the knowledge of Cenomanianammonite zones which were established primarily along the main course of the River
Ikushunbetsu [= IkushumbetsJ. Subsequently, we visited the outcrops frequently forfurther hunting. Although bivalves predom-

Notes on stratigraphy
The outcrops mentioned above are located1,250 m northeast in plan and 300 m higher in
altitude from the bridge called the KatsuraOhashi, i.e., loco Ik 1054, on the Ikushunbetsu
River (see Matsumoto, compiler, 1991, fig. 3).

"Received January 30, 1992; accepted April 24, 1992
1144

938.

,

Acompsoceras and some other ammonites

\, +
.)1
...... ",

,

.'

\

I

".' '

..

,

,.

Ik

, ...

/

,,,

o

1145

~

..,

,
,,

, .. .. -- ......

500m
!

I

,

,

Kl

Figure 1. Map of the Ikushunbetsu Valley (part), showing the locations of the described ammonites by
three small solid circles around Ik from NW to SE: Ik 7001, 7002 and 7003. KB: bridge called KatsuraOhashi KD: Katsura-zawa dam. KL: Katsura-zawa Lake, S: Suido-no-sawa, T: Torii-zawa, Y: Yu-nosawa.

They are on the slope of a mountain and were
cuttings along a forestry road which was
active several years ago but is now abandoned
and covered with bush -(Figure I).
The following succession of strata is observable there in ascending order:
A (Ioc. Ik 7001): A unit of dark grey silty
fine-grained sandstones or sandy siltstones, atleast 30 m in thickness, of which upper part
(10 m) is well exposed. Desmoceras kossmati Matsumoto, Mantelliceras saxbii (Sharpe) and Sciponoceras cf. baculoides (Mantell)are yielded from some nodules. Unit A isunderlain by layers of milky white to gray,compact tuff and tuffaceous sandstone.
B (Ioc. Ik 7002): Fine- to medium-grainedsandstones, bedded or laminated and filledwith molluscan shells in some layers. Turritellas are often aligned in roughly parallelorientation. Ammonites are rather few, fragmentary and scattered. Desmoceras sp.,
Mantelliceras cf. japonicum, Tun'ilites cos-

tatus Lamarck, etc. may be found. At least 7
m thick.
C (Ioc. Ik 7003): Medium- to coarsegrained sandstones, containing abundantly
Cucullaea ezoensis Yabe and Nagao andPterotrigonia(Ptilotrigonia)

mifunensis(Tamura and Tashiro). Inoceramus tenuis
Mantell and Inoceramus cf. virgatus Schluter
are collected rarely. Ammonites yielded sporadically are as follows: Hypophylloceras(Neophylloceras) seresitense (Pervinquiere),Desmoceras(Pseudouhligella)japonicum

Yabe, D. (P.) ezoanum Matsumoto, Mantelliceras aff. japonicum, Utaturiceras vicinale,
Acompsoceras renevieri, Prionocycloides cf.
proratus (Coquand), Zelandites europae
Wright and Kennedy and Turrilites costatus.
Overlying strata are not exposed here on
account of displacement by a wrench fault.
Let us attempt to correlate the above
sequence with that of the type section along
the main course of the River Ikushunbetsu

1146

Tatsuro Matsumoto and Takemi Takahashi(See Matsumoto et al., 1991 or Matsumoto,comp., 1991 for the type section). The
tuffaceous rocks below unit A are certainly a
key marker at about the Albian-Cenomanianboundary or immediately below the lowest
fossiliferous bed of the lower Cenomanian.
Unit A is correlated with the Zone of
Desmoceras kossmati in the basal member(lIa) of the Mikasa Formation in the typesection. Unit B is certainly an extension of
the Zone of Mantelliceras japonicum, i.e.
lower part of Member lIb in the type section,with lateral change of facies to a near-shore
environment, where shells were often transported by washing processes and the sediments are thinner.

Now Unit C can be regarded as an extension of the ammonite-poor sandstone withtrigoniids and other bivalves in the middle
part of Member lIb in the type section.
Noteworthy is the fact that Acompsoceras
renevieri, Utaturiceras vicinale and Man telliceras aff. japonicum (instead of undoubted
M. japonicum), which have not been recordedin Hokkaido, are found in this Unit C. A.
rene vieri , however, may have a longer range,
if its occurrence in Europe (see Wright and
Kennedy, 1987) is taken into consideration.
It should be further noted that in Hokkaido Turrilites costatus appears at a lower
level than in Europe, occurring in the Zone of
M. japonicum together with Hypoturrilites

Q

Figure 2. Acompsoceras renevieri (Sharpe).
Diagrammatic sketch ofTTC. 020415-1. Right lateral view and whorl section at Q.

---+ Figure 3. Acompsoceras renel'ieri (Sharpe).
TTC. 020415-1, phragmocone in 4 views (a-d), X I.

Photos by M. Noda.

Scale bar=IOmm.
T.M. deIin.

938.

Acompsoceras and some other ammonites

1147

Tatsuro Matsumoto and Takemi Takahashi

1148

gravesianus (d'Orbigny) and Neostlingoceras
carcitanense (Matheron), and is found also in
Unit C. (Turrilitid ammonoids from Japan
should be monographed on another occasion.) The true stratigraphic range and vertical distribution of Utaturiceras vicinale
should be worked out further, as our examples are solitary juveniles.

Systematic descriptions
The morphological terms in the following
descriptions are the same as those explainedby Matsumoto (1988, p. 4), who generally
follows those in the Treatise (Arkell et al.,1957), with a slight alteration. Abbreviations used in the measurements include D=
diameter of shell, U =width of umbilicus,
H=whorl-height, B=whorl-breadth, h=whorl-height at half whorl earlier than H,
Inv. = degree of involution, L T = lectotype,c = costal, ic = intercostal, LS = last septum.
The described and figured specimens arenumbered under the heading ofTTC (Takemi
Takahashi's Collection) and will be kept in
the Museum of Mikasa City. Their plastercasts are kept in the Type Room of the
Department of Earth and Planetary Sciences,
Kyushu University 33, Fukuoka.
Family Acanthoceratidae
de Grossouvre, 1894
Genus Acompsoceras Hyatt, 1903

Type

species.-Ammonites

bochumensis

Schliiter, 1871 by original designation, which
is a synonym of Ammonites renevieri Sharpe,
1857.
Remarks.-See Wright and Kennedy, 1987,
p. 139-140 for the diagnosis and comments.
Distribution.-Rather rare but widespreadin Europe, North Africa, the Middle East,
Madagascar, east and west Africa, Texas (U.S.
A.). This is the first record in Japan.

Acompsoceras renevieri (Sharpe, 1857)
Figures 2-4

Ammonites renevieri Sharpe, 1857, p. 44, p1. 20, fig. 2.
Ammonites bochumensis SchlUter, 1871, p. I, pl.1,
figs. 1-4; p1. 2, fig. 1.
Ammonites essendiensis SchlUter, 1871, p. 3, p1. I, figs.
5-7; pl. 2, fig. 2.
Acompsoceras renevieri (Sharpe); Wright and Kennedy, 1987, p1. 140, p1. 43, fig. 2; text-figs. 34G,
350-f, 36A-F, 37-40 (with full synonymy).

Material.- Two specimens collected by T.
Takahashi from loco Ik 7003: TTC. 020415-1(Figures 2, 3), a well-preserved phragmocone,and TTC. 030512-1 (Figure 4), a fragmentarybody-chamber.
Description.- The phragmocone is nearly
100 mm in diameter, consisting of fairly
involute whorls with a high ratio of expansion (H/h = 1.6). Its umbilicus is fairly narrow, about 20 percent of shell-diameter, surrounded by nearly vertical wall and abruptly
bent edge. The preserved last whorl ishigher than broad, keeping BIH at about 2/3.
It is subtrapezoid in cross-section, showing
gently convex and outward converging flanks,
sharp outer ventrolateral shoulder on eitherside of nearly flat but rather narrow venter,with a weak but nearly continuous train of
siphonal clavi.
The phragmocone is ornamented withnumerous ribs of unequal length on the flank,
fairly strong tubercles at the umbilical edge
and sharp-headed clavi at the outerventrolateral shoulder. On the outer flank of
the younger part, there is a row of very weaknodes, which may be called the inner'
ventrolateral.
The ornamentation of this wholly septate
specimen is regular. Between the two primary ribs, which arise from the umbilicaltubercle, normally two, though occasionallyone, secondary ribs are intercalated. The
ventrolateral clavi are thus nearly three times
as numerous as the umbilical tubercles; actually 34 of the former versus 12 of the latter inan entire volution. On the early part of thepreserved outer whorl the ribs are narrow andthe secondaries sometimes look as if branchedfrom the primary at the bullate umbilical938.

A compsoceras and some other ammonites

Figure 4. A compsoceras renevieri (Sharpe).
TTC. 030512 - 1, incomplete body-chamber in left lateral (a) and ventral (b) vi ews.

1149

Scale bar = 10 mm.
Photos by M. Noda.

Tatsuro Matsumoto and Takemi Takahashi

1150

tubercles. The ribs gradually broaden andlower as the whorl grows; the secondaries
shorten, but the sharp ventrolateral clavi
persist. On the earlier part the ribs are gently
flexuous, with some forward inclination on
the outer flank. Later some ribs are nearlyrectiradiate.
Colour patterns are discernible where thetest is preserved, with light-coloured spiralbands on the middle of the flank and a lessdistinct display along the row of inner
ventrolateral weak nodes.
The suture is that of Acompsoceras, showing the phylloid terminals of the folioles.
The stems of the lobes Land U2 and subdividing lobules are fairly narrow in thisspecimen.
The fragmentary body-chamber, with test
partly preserved, of about 150" in spiral angle
lacks the part around the umbilicus but shows
the venter, middle to outer part of the left
flank and the outer portion of the right flank.
The preserved parts of the flanks converge
outward. The venter, which is demarcatedby angular to subangular outer ventrolateralshoulders, is relatively narrow, adapically 15
mm and adorally 18 mm in breadth. The
ventrolateral clavi are well developed on theearlier 50" and much weaken later. Also thespiral elevation is traced on some part of the
mid-venter.
On the flank there are very faint rib-likeelevations, periodic shallow groove alongsome of them, weak lirae or striae, all ofwhich are gently flexuous, with a broad convexity on the middle part and a gentle projection in approaching the ventrolateral shoulder. Weak striae or lirae and also shallow
grooves may run across the venter vertically.
Dimensions.-Measurements in mm of thewholly septate TTC. 020415-1 in comparison
with the lectotype (below) are as follows:
TTC
LP

D
96.5 (I)
115.0 (I)U
H.5 (.20)
26.5 (.23)

H
49.5 (.51)
54.0 (.47)

B
32.5 (.34)
34.5 (.30)

B/H
0.66
0.64

H/h
1.6
-

Inv.
0.59
0.57

• cited from Wright & Kennedy (1987). except for Hjh and In\', by T.M

Comparison.- The two specimens fromIkushunbetsu described above are generally
similar to the types and other well known
examples of Acomposoceras renevieri (Sharpe, 1857). This species has been recently
redefined by Wright and Kennedy (1987),
who regarded Ammonites bochumensis
Schlliter, 1871 and Ammonites essendiensis
SchlUter, 1871 as synonyms of A. renevieri.
We agree with them in this point, since one ofus (T.M.) once examined SchlUter's specimensfrom northwestern Germany as well as Sharpe's and other specimens from southern England.
The wholly septate specimen from Ikushunbetsu particularly resembles in shell form theillustrated paralectotoype of A. bochumensis
Schlliter (1871, pI. I, figs. 3-4) and anotherexample from Nigeria figured by Reyment(1957, pI. 8, fig. 3, under Acomposoceras
subwaterloti Venzo), both identical with A c.
renevieri as Wright and Kennedy pointed out.
Our specimen, however, shows somedifference in ornamentation, viz. its ribs are
gently flexuous at least in younger part andmore numerous, with normally two secondaries on each interval of the primaries,
whereas in the latter two specimens and also
the lectotoype of A. renevieri (see Wright and
Kennedy, 1987, pI. 43, fig. 2) the ribs arenearly rectiradiate and less numerous with
one by one alternation of the primary andsecondary ribs.
The material from western Europe as wellas that from Japan may be insufficient toinspect precisely the extent of variation. The
paralectotype of Amm. essendiensis, refigured
by Wright and Kennedy (1987, text-fig. 13
D- F), with its still inner whorl (Schlliter 1871,
pI. 1, fig. 7), shows gently flexuous ribs withsome ventrolateral projection. Its ribs arevery fine but appear to be numerous. The
number of its umbilical bullae and that ofventrolateral clavi are respectively quite similar to that in our specimen (see Figure 2).
This suggests strongly that the difference inornamentation noted above between our specimen and representative ones of A. renevieri is938.

Acompsoceras and some other ammonites

very probably within the extent of variation.
Incidentally, the above mentioned
SchlUter's specimen, which is still septate, hasso fine and faint ornament that it looks somewhat similar to our second specimen of bodychamber.
To sum up, the two specimens from Ikushunbetsu are regarded as examples ofAcompsoceras renevieri (Sharpe, 1857) fromJapan.

Genus Utaturiceras Wright, 1957
Type species.-Ammonites vicinalis Stoliczka, 1864 by original designation.
Remarks.-See Matsumoto et al., 1966, p.
306-307 for the diagnosis and affinities of thisgenus.

Figure S. Utatul'icel'as vicinale (Stoliczka).
Diagrammatic sketches of two juveniles, A: TTC.
020415-2 (with scale bar= 10 mm) and B: TTC.
020415-3 (with scale bar=5 mm).
T.M. delin.

1151

Utaturiceras vicinale(Stoliczka, 1864)
Figure 5A, B; Figure 7C, D

Ammonites vicinalis Stoliczka, 1864, p. 84, pI. 44, figs.
1,4,5,7,8.
UWllIl'iceras vicinale (Stoliczka); Matsumoto et al.,
1966, p.297, pI. 32, fig. I ; pI. 33, figs. 1-3; textfigs. 1-4.

Material.- Two small specimens collectedby T. Takahashi from loc. Ik 7003: TTC.
0204 I 5-2 (Fig. 5A; Fig. 7C) and TTC.
020415-3 (Fig. 5B; Fig. 70).
Description.- The above two specimens are
involute, with a narrow umbilicus, which isless than 20 percent of diameter, and have acompressed whorl, with a narrow venter
demarcated by trains of outer ventrolateral
tubercles, sloping facets on outer portion offlanks, and nearly flat and parallel main partsof flanks, which can incline more or lessdistinctly toward the umbilical edge in youth.
The ornament is characterized by fairly
crowded, more or less flexuous ribs some ofwhich arise in pairs from feeble umbilicalbullae and others which are intercalated.
The inner ventrolateral tubercles are weakand can show merely as accents where ribs arebent forward toward more distinct outerventrolateral tubercles.
The ribs are asymmetric in cross-section
with adorally gentle and adapically steep
slopes. This may give apparently low andbroad ribs or rather sharp ones, depending onlighting orientation or angle of view. likewise the venter varies in appearance. Generally the ribs cross the venter between the outerventrolateral clavi, but they are lower than
the flank ribs. When the sharply clavate
tubercles are exaggerated by certain lighting,the venter looks almost smooth. The ribs on
the venter are lowered and broadened, withadorally forward curve on the extension of aclear projection on the ventrolateral facet, butthey run straight across the venter on theiradapical side. The adoral outline of the ribson the venter sometimes form an obtuse chev-

Tatsuro Matsumoto and Takemi Takahashi

1152

ron.
Sutures are discernible on the early part ofthe preserved outer whorl of the larger specimen at H = 6 mm or so. Their pattern isessentially similar to the one illustrated by
Kossmat (1895, pI. 25, fig. 2) but less intricate
because of immaturity.
Dimensions.-Our two specimens and aparalectotype (GSI. 187) are measured (inmm) as follows:
Specimen

D

U

H

8

8/H

Ribs
( ISO')

Fig.5A

25.0

4.5 (.IS)

12.3 (.49)

9.4 (.3S)

0.76

5/16

Fig. 58

18.0

2.6 (.16)

9.7 (.54)

6.5 (.36)

0.68

9/18

GSI. 187

31.8

6.5 (.20)

15.2 (.48)

11.0 (.35)

0.72

8/17
Ribs (ISO'): Number of long or primary ribs/that of all the ribs ina half whorl.

Comparison and discussion.-One of our
two specimens (Fig. 5A) closely resembles apara lectotype (GSI. 187) of Utaturiceras
vicinale (Stoliczka) (1864, pI. 44. fig. 5),
which one of us studied at the Geological
Survey of India (GS!), Calcutta (see also
Matsumoto et al., 1966, pI. 33, fig. 2; text-fig.
3). In the lectotype (Stoliczka, 1864, pI. 44,
fig. 8; Matsumoto et al., 1966, pI. 32, fig. 1),
which represents a late growth stage, but
preserves only a portion of the body chamber,many of the ribs are less flexuous and theumbilical bullae tend to weaken or become
obsolete. In its observable earlier part andalso in GSI. 189 of moderate size (Stoliczka,
1864, pI. 44, fig. 7; Matsumoto et al., 1966,
pI. 33, fig. 3) the flanks are subparallel, someribs are fairly flexuous and often paired ribs
arise from the umbilical bullae. The smaller
specimens mentioned above are thus reasonably regarded as juveniles of Utaturiceras
vicinale.
Incidentally the venter of the bodychamber in the lectotype is crossed by the ribs
which form on their adoral side obtuse chevrons along with obliquely disposed outerventrolateral tubercles.
The character mentioned above and alsothat of the immature specimens give us somedoubt about the generic distinction between

Utaturiceras Wright, 1956 and Mrhiliceras
Kennedy and Wright, 1985. This question,
however, will remain unsettled until we examine the type species of the latter, i.e. Mammites lapparenti Pervinquiere, 1907, which is
now defined very broadly to include inflated
forms with rectiradiate coarse ribs and compressed ones with flexuous fine ribs (Kennedy
and Wright, 1985).
Occurrence.-Our immature specimens
were yielded from a calcareous nodule in thesame bed which contained Acompsoceras
reneVlert. Fragmentary pieces of Turrilites
costatus were obtained from the same nodule.
The bed is allocated to the upper horizon of
the lower Cenomanian in our section.
The localities of Ammonites vicinalis wererecorded as north and west of Odium,
Utatoor [Ootatoor] Group of South India(Stoliczka, 1864, p. 85), but their precise
stratigraphic position has yet to be worked
out.
Genus Mantelliceras Hyatt, 1903

Type

species.-Ammonites

mantelliJ.

Sowerby, 1814 by original designation (Hyatt,
1903, p. Ill).
Remarks.-See Wright and Kennedy, 1984,
p. 97-99 for the diagnosis, affinities and distribution.

Mantelliceras aff. japonicum Matsumoto,
Muramoto and Takahashi
Figure 6; Figure 7 A, B

Compare.Manlelliceras japonicum Matsumoto, Muramoto and
Takahashi, 1969, p. 253, pI. 25, figs. 1-2; pI. 26,
figs. 1-3; pI. 27, figs. 1-2; text-figs. 1-2.

Material.- TTC. 030512-2 (Fig. 6; Fig.
7A) obtained by T. Takahashi from loc. Ik
7003. TTC. 030512-3 (Fig. 7B), a fragment,
may be another example.
Dimensions.- This specimen is rather small
and measures as follows:938.

Acompsoceras and some other ammonites

Figure 6. Mantelliceras aff. japoniclim Matsumoto, Muramoto & Takahashi. Diagrammatic
sketch of TTC. 030512-2. Left lateral view andwhorl section at Q. Scale bar= IO mm. T.M. delin.

Ribs

D

u

H

B

Bill

(c)

43.0(1)

12.6(.29)

18.2(.42)

13.5(.31)

0.74

6/11

(ic)

40.0 (1)12.0 (.30)

16.2 (.40)

12.3 (.31)

0.76

6/11

( 180')

Descriptive remarks.- The whorl is compressed, with BjH smaller than that of any
measured specimen of M. japonicum, andsuboval in intercostal section, with flanks
gradually inclined to the umbilical wallwithout forming an abruptly bent umbilicaledge.
Although the shell is partly broken, theobservable main whorl is ornamented withalternately long and short, fairly strong ribs,
all of which are provided with inner
ventrolateral nodes of moderate intensity andprominent outer ventrolateral clavate tubercles. The tubercles on the long ribs aredoubled around the umbilicus, those on the
inner flank being somewhat stronger thanthose at the umbilical end. The above characters of the ornamentation are essentiallysimilar to those of M. japonicum, in whichsometimes a long rib on one side extends to ashort one on the other side (see Matsumoto etal., 1969, text-fig. I). The same feature is
exhibited in the specimen from loc. Ik 7003

1153

(Fig. 6).
There are, however, unnegligible differences in ornamentation between this specimen and young shells of M. japonicum of
corresponding size. The ribs of the former
are narrow, more sharp-headed and separated
by wider interspaces than those of the latter.
The ribs are somewhat prorsiradiate in theformer, whereas they are rather recti radiate in
the latter. As to the double tubercles on thelong ribs those at the umbilical end tend to
weaken and disappear in the latter but persist
distinctly in the former, although how theornamentation would change on the presumably lost still later part of the former is notknown.
As only a single incomplete specimen isavailable, whether the above differences inshell form and ornamentation deserve specificor sub specific distinction or otherwise is hardly decided. It is hence tentatively called
Mantelliceras aff. japonicum.
Occurrence.-Rare in the bed with Acompsoceras renevieri at loc. Ik 7003, which isregarded as the next higher horizon than theextension of the bed with Mantelliceras
japonicum in the main section along theRiver Ikushunbetsu.

Mantelliceras saxbii (Sharpe, 1857)
Figure 7E

Ammonites saxbii Sharpe, 1857, p. 45, pI. 20, fig. 3.
Mantelliceras saxbii (Sharpe); Wright and Kennedy,
1984, p. 121 ; pI. 23, fig. 4; pI. 32, figs. 1-3; pI.
33, figs. 1-4; pI. 34, figs. 1-4; pI. 35, figs. 1-5 ;pI. 36, figs. 2, 3; pI. 39, fig. 1 ; text-figs. 25B-D, I ;26B; 28L-P (with full synonymy).

Material.-A single well preserved specimen, TTC. 030502-1 (Fig.7E), collected by
T. Takahashi and T. Matsumoto from loc. Ik
7001.
Dimensions.- The specimen measures:

1154

Talsuro Matsumoto and Tak emi Takahashi

D

D

U

938.

Acompsoceras and some other ammonites

H

B

IlfH

0.79

Al L (e)34.0

8.7(.26)

15.6 (46)12.4 (.36)

Behind Ls (ic)32.0

8.2 (.26)

15.2(.47)

11.5 (.37)

Ribs( ISO)

7/14

0.76
7/14
It preserves the beginning or the body~chambcr at its adoral end.

Descriptive remarks.- This specimen showsa moderately involute form, with fairly narrow umbilicus. Its whorl is higher thanbroad and subtrapezoid in costal section,with slightly convex flanks.
Ribs are of moderate intensity and density,normally alternately long and short, gently
flexuous and prorsiradiate, with some projection on the ventrolateral part; nearly straightribs occur occasionally. All the ribs haveweak inner and moderately strong clavateouter ventrolateral tubercles and run acrossthe venter, lowering and broadening. Longer ribs have bullate tubercles at the umbilical edge and faint but often perceptible small
nodes on the inner flank or slightly below themid-flank, where ribs are weakly flexed.
Based on the above characters this specimen is certainly identified with Mantelliceras
saxbii (Sharpe), recently redefined by Wright& Kennedy (1984). It is in particular similar
to the young to middle-aged part of an illustrated specimen (op. cit., pI. 35, fig. 4) fromthe Lower Chalk of southern England. It
may represent a phragmocone of a microconch but could be a juvenile macroconch.
Occurrence.- This specimen occurred rarely in the Basal Member (Sandy siltstone) of
the Mikasa Formation at loco Ik 7001, low inthe lower Cenomanian.
Acknowledgments
We thank Dr. C.W. Wright (Beaminster)for his kindness in reading the first draft withvaluable suggestions; Drs. Masayuki Noda
(Oita) and Seiichi Toshimitsu (Tsukuba), fortheir friendly help in taking the photographs

1155

and preparing the plaster casts respectively.
We owe much to Messrs. Mamoru Kera andKikuo Muramoto, the Director and the
Keeper of the Museum of Mikasa City, in
keeping the studied specimens in the custodyof the Museum; also to Miss Akiko Murakami for her assistance in preparing the typescript.

References cited
Arkell, W.J., Kummel, B. and Wright, C.W., 1957:
Mesozoic Ammonoidea. In, Moore, R.C., eds.,
Treatise on Inrertebrale Paleontology, Pari L,
Mollusca 4, Cephalopoda Ammonoidea, p. L80L465. Geol. Soc. Amer. and Univ. Kansas
Press.
Hyatt, A., 1903: Pseudoceratites of the Cretaceous.
Monogr., U.S. Ceol. Surv., vol. 44, p. 1-351, 47
pIs.
Kennedy, W.J. and Wright, C.W., 1985. Mrhiliceras
n.g. (Cretaceous Ammonoidea) a new
Cenomanian mantelliceratine. N. Jb. Ceol.
Palliont. Mh., 1985, H. 9, p. 513-526.
Matsumoto, T., 1988: A monograph of the
Puzosiidae (Ammonoidea) from the Cretaceousof Hokkaido. Palaeont. Soc. Japan, Spec.
Papers, no. 30, iii + 179 p. (incl. 88 figs.)- - , comp., 1991 : The Mid-Cretaceous ammonitesof the family Kossmaticeratidae from Japan.
Ibid., no. 33, vi+ 143 pp. (incl. 31 pIs.).
- - , Muramoto, T. and Takahashi, T., 1969:
Selected acanthoceratids from Hokkaido. Mem.
Fac. Sci., Kyushu Univ., Ser. D, Ceol., vol. 19,
no. 2, p. 251-296, pis. 25-38.
- - , Noda, M. and Maiya, S., 1991: Towards an
integrated ammonoid-, inoceramid- and formaniferal biostratigraphy of the Cenomanianand Turonian (Cretaceous) in Hokkaido. Jour.
Ceogr., Tokyo, vol. 100, no. 3, p.378-398 (inJapanese with English abstract and tables).
- - , and Sarkar, S.S., 1966: Utaturiceras vicinale(Stoliczka) from southern India. In, Matsumoto, T., Sastry, M.V.A. and Sarkar, S.S., Notes
on some Crelaceous ammonites from southern
India. Part. I. Mem. Fac. Sci., Kyushu Univ.,
Ser. D, Ceol., vol. 17, no. 3, p. 295-309, pIs. 3233.
Pervinquiere, L., 1907: Etudes de paleontologie+- Figure 7. A, B: Manlel!iceras afT. japonicum Matsumoto, Muramoto & Takahashi, TTC. 030512-2(A) and TTC. 030512-3 (8), both X 1.2. C, D: Ulaluriceras I'icinale (Stoliczka),juveniles, TTC. 0204152 (C), X 1.5 and TTC. 020415-3 (D), x2. E: Mantelliceras saxbii (Sharpe), TTC. 030502, X 1.2.
Photos by M. Noda.

1156

Tatsuro Matsumoto and Takemi Takahashi

tunlSlenne. I, Cephalopodes des terrains secondaires. Carte Geol. Tunisie, v+438 p., 27 pis. Paris.
Reyment, R.A., 1957: Uber einige wirbellose F ossilien aus Nigerien und Kamerun, Westafrika.
Palaeontographica, Abt. A, vol. 109, p.41-70,
pis. 7-11.
SchlUter, C., 1871: In, SchlUter, c., 1871-1876. Die
Cephalopoden der oberen deutschen Kreide.
Palaeontographica, vol. 21, p. 1-24, pis. 1-8(1871); p.25-120, pis. 9-35 (1872); vol. 24, p.
121-264, pis. 36-55 (1876).
Sharpe, D., 1857: In, Sharpe, D., 1853-1857.
Description of the fossil remains of Mollusca
found in the Chalk of England. I, Cephalopoda.
Palaeontogr. Soc. Monogr., 68 p., 27 pis. (p. 126, pis. 1-10 (1853); p. 27-36, pis. 11-16 (1855);
p. 37-68, pis. 17-27 (1857)J.
Stoliczka, F., 1864: Ammonoidea, with revision of

the Nautilidae etc. In, Blanford, M.F. and Stoliczka,F., 1861-66. The fossil Cephalopoda of theCretaceous rocks of southern India. Mem. Geol.
Surl'. India, Palaeontologia Indica, ser. 3,216 p.,
95 pis. (p.41-56, pis. 26-31 (1863); p.57-106,
pis. 32-54 (1864); p. 107-154, pis. 55-80 (1865);
p. 155-216, pis. 81-94 (1866)].
Wright, C.W., 1956: Notes on Cretaceous ammonites. III Utaturiceras gen. nov. and theMetoicoceratinae. Ann. Mag. Nat. Hist., ser.
12, vol. 9, p. 391-393.
- - and Kennedy, W.J., 1984: The Ammonoidea of
the Lower Chalk. Part I. Monogr., Palaeontogr. Soc. London, p. 1-126, pis. 1-40 (Publ.
No. 567, part of vol. 137 for 1983).
- - and - - , 1987: Ditto. Part 2. Ibid., p.127218, pis. 41-55 (Publ. No. 573, part of vol. 139 for1985).

Fukuoka tmlli'iJ, Hanazono-cho ftllllBJ, Hokkaido ~UfjHt Ikushunbetsu [= IkushumbetsJ~*~Ij, Katsura-Ohashi tt::*:1\li, Katsura-zawa ttiR., Mikasa -=~, Oita ::*:51-, Suido-no-sawa
7.K~0)iR., Torii-zawa ,~Jl5iR., Tsukuba ":) < Ii, Yayoi ipJ;1=., Yu-no-sawa ~0)iR..
~t#a~~*~Ij)IIvrr::l¥1i;£O) Acompsoceras .:to)ft!!0) 7 7J /' r 'T '7 Af4*.iEM: .::. 0):f;(g:l¥1i;0)-=~J!mJ3:;t¥JTffijO);l!lG:;js:vrr:iJ'GJi< t,n':frO)f.'lffij~.:., vt**~Wt':-::,f,:'UM (iU'E-tG 3:f;(g,¢,O iJ~;l!lI), .:t'::'O)1i'Ji'1t::'--IV H!o'-1i'Ji;'fiiJ'G,~t#a~t. L.-CI;tf}]IJb-CO)*.iEM (I)

Acompsoceras renel'ieri (Sharpe), (2) Utaturiceras I'icinale (Stokiczka), (3) Mantelliceras
aff. japonicum Matsumoto, Muramoto and Takahashi (:lI4~i¥Jt.( >b 0) J: I) $liiiJ~~ \,,), (4)Mantelliceras saxbii (Sharpe) :a-t!Jt.: o)-Cgc1liJ(: L. t.:o 'UMliTiJ' G A, B, C 0) 3 J!ff:IK51-:af;:;~-tGiJ~, -t""-CT$-e/7:='7/'-C;l!lG o A Ii Desmoceraskossmati*-C:' (4) :a-£L.
t.:o B Ii M. japonicum *~.:.;f§~-t G iJ~, j't~J! :a-~tJciJ,~tri"dJ¥m#a;f§-C:', *.iEMlit¥JT Jt
iJ~~tE-t G 0 C li:;js:vrr:i'fh 'O)-=~J1,1i'Ji;'fiO)~*~.:.~ G iJ~, (I )-(3) 0) vliJ,;t='fO)*.iE iJ~t!J G

nt.:o .f.jj$i¥J-eli;l!lGiJ~, M. japonicum *O)J:{ftO)]E*:a-f\;~-tGoi0:;js:~fl~ • ~1\liftt~

Trans. Proc. Palaeont. Soc. Japan, N.S., No. 166, pp. 1157-1163, 4 Figs., June 30, 1992

939.

A RECORD OF PSEUDOPHYLLITES INDRA (LYTOCERATINA,TETRAGONITIDAE) FROM THE UPPER CRETACEOUS OFHOKKAIDO AND SAKHALIN*Y ASUNARI SHIGETA
Geological Institute, University of Tokyo,
Hongo 7-3-1, Bunkyo-ku, Tokyo, 113

Abstract. A tetragonitid ammonite, Pseudophylfites indra (Forbes) is described basedon material from the Orannai Formation in the Soya area of northern Hokkaido and fromthe Krasnoyarka Formation in the Naiba area of south Sakhalin. P. indra, occurring in the
Schlueterella kawadai Subzone of the Metaplacenticeras subtilistrialUm Zone, which corresponds to the upper Campanian, has a nearly circular initial chamber in median section, asubellipsoid caecum with weakly constricted base and a ventrally located siphuncle. In
various areas of the North Pacific region, the present species first appeared almost
synchronously in the upper Campanian. From Santonian to early Campanian times, P.
indra was distributed in the Indian region. This evidence shows that this species extended
its geographical distribution from the Indian region to the North Pacific region in lateCampanian time.
Key words.
graphy.

Pseudophylfites, upper Campanian, Soya, Naiba, ontogeny, paleobiogeo-

from the upper Campanian of the Soya areaofHokkaido and from the Naiba (=Naibuti)
area of Sakhalin, as described below.

Introduction
The genus Pseudophyllites Kossmat, 1895
of the family Tetragonitidae is considered to
be one of the offshoots from Tetragonites(Kennedy and Klinger, 1977). Species of
Pseudophyllites are known to occur from theSantonian to Maastrichtian worldwide (Collignon, 1956). In Hokkaido several fragmentary specimens of Pseudophyllites were described as P. indra (Forbes, 1846) and P. cf.
teres (Van Hoepen, 1920) by Matsumoto andMiyauchi (1984) from the upper Campanianof the Soya area, but further work based on
more sufficient material is required to discuss
the taxonomy, biostratigraphy andpaleobiogeography of this genus.
Recently, I have discovered many wellpreserved specimens referable to P. indra

Paleon tological description
Order Ammonoidea Zittel, 1884
Suborder Lytoceratina Hyatt, 1889
Superfamily Tetragonitaceae Hyatt, 1900
Family Tetragonitidae Hyatt, 1900
Genus Pseudophyllites Kossmat, 1895

Type species.-Ammonites indra Forbes,
1846 by original designation.
Diagnosis.-Very involute tetragonitids
with a high whorl expansion rate and a smallumbilicus. Early whorls rounded in crosssection, later whorls becoming elliptical, witha convex venter, somewhat flattened flanks
and a steeply sloping umbilical wall. Shellsurface ornamented by fine striae, inflected'Received March 2, 1992; accepted May 18, 1992
1157

Yasunari Shigeta

1158

foward and passing radially across venter.
Constriction absent. Suture very finely
divided with asymmetrically trifid or asymmetrically bifid major saddles having subphylloid terminations.

Pseudophyllites indra (Forbes, 1846)
Figures 1-4

Ammonites indra Forbes, 1846, p. 105, pI. 11, fig. 7;
Stoliczka, 1865, p. 112, pI. 58, fig. 2; Whiteaves,
1879, p. 105, pI. 13, fig. 2.
Pseudophyllites indra (Forbes); Kossmat, 1895, p.
137, pI. 16, figs. 6-9, pI. 17, figs. 6-7, pI. 18, fig. 3 ;Whiteaves, 1903, p. 331; Woods, 1906, p. 334, pI.
41, fig. 6; Spath, 1922, p. 119; Collignon, 1938,
p. 24, text-fig. E; Usher, 1952, p. 57, pI. 3, figs. 213; pI. 31, figs. 15-17; Collignon, 1956, p. 90 ;Matsumoto, 1959, p. 134, Jones, 1963, p. 25, pI. 7,
figs. 6-7, pI. 8, pI. 29, figs. 7-12, text-fig. 10; Collignon, 1969, p. 12, pI. 516, fig. 2032; Kennedy
and Klinger, 1977, p.182, text-figs. 19-22;
Matsumoto and Miyauchi, 1984, p. 54, pI. 21, fig.
5; Henderson and McNamara 1985, p.50, pI. 2,
figs. 7, 8, pI. 3, figs. 4, 5, text-fig. 5a, d.
Tetragonites glabrus (limbo); Shigeta, 1989, p. 334,
text-fig. 12(3).

Type.- The holotype is the specimen originally figured by Forbes (1846, pI. II, fig. 7),
BMNH C51068, from the Valudayur Groupnear Pondicherry, southern India.
Material.-In addition to the specimen(MNH.231) described by Matsumoto andMiyauchi (1984, pI. 21, fig. 5) from the Soya
Harbor, 14 specimens collected from theupper part of the Orannai Formation in the
Soya area of northern Hokkaido and three
specimens from the middle part of the
Krasnoyarka Formation in the Naiba area ofsouth Sakhalin are used in the following
description: UMUT MM18991-18997 fromfishery harbor of Soya (upper Campanian);
UMUT MM 18998 from fishery harbor of
Kiyohama-I (upper Campanian); UMUT
MM 18999-19002 from new fishery harbor of
Kiyohama-II (upper Campamian); UMUT
MM19003 and MMl9004 from old fisheryharbor of Kiyohama-II (upper Campanian);
UMUT MM 19005 from locality NB3031 (=N 100 of Matsumoto's locality, upper
Campanian); UMUT MM 19006 andMM 19007 from the middle course of the
Krasnoyarka River (NB3023P) (upper
Campanian). All the specimens from theSoya area and two specimens from the Naiba
area were obtained from floated calcareous
nodules. For details of their localities andages see Matsumoto and Miyauchi (1984) andMatsumoto (1942).
All the specimens utilized herein are deposited at the University Museum, Universityof Tokyo (UMUT). The specimen (MNH.
231) described by Matsumoto and Miyauchi(1984) is now kept at UMUT (UMUT
MM19008) by courtesy of Mr. T. Miyauchi.

Dimensions.-

Shell
diameter(D)

Breadlh ofumbilicus
(U)

Whorl
heighl(H)

Whorlbreadlh
UjD
(B)

(mm)

(mm)

(mm)

(mm)

MNH.231(MMI9008)

110.0

18.0

61.0

50.0

MMI8991

185.0

30.0

100.0

MMI8998

40.6

9.0

19.7

MMI8999

33.0

7.5

MM I 8994

28.4

MM 18995

23.8

MM19003

21.3

MMI9001

17.2

BjH

0.16

0.82

75.0

0.16

0.75

19.8

0.22

1.01

14.7

15.7

0.23

1.07

6.3

14.3

14.5

0.22

1.01

5.7

11.7

12.0

0.23

1.03

5.2

9.8

10.0

0.24

1.02

4.4

8.1

8.5

0.25

1.05

Description.Early internal shell structure (Figure 1)
The initial chamber is nearly circular inmedian section. The caecum is subellipticalin lateral view with a weakly constricted base,and its adapical end connects with the initialchamber wall by a short, adorally concave
prosiphon. The siphuncIe occupies a central
position near the pro septum and then immediately shifts toward the venter within thesecond chamber. Thereafter it keeps a ventral position. Initial chamber size, ammonitella size and its spiral length in thespecimen UMUT MM 18996 in median section are 712,um, 1,550,um, and 336 respectively.
0

939.

Pseudophy llites from Hokkaido and Sakhalin

11 59

Figure 1. Scann in g electron mi crog rap hs of the ea rl y interna l she ll structure o f Pseudophy llites indra(F o rbes ) in medi a n secti o n. Sca le bar in 1, 500 jim. Sca le bar in 2, 100ji m. UMUT MM1 8996, lheupper Cam pa ni a n, fi shery ha rb o r o f Soya.

o

1

2mm

!

Figure 2. Externa l suture a l a who rl heighl o f 6.2 mm of Pseudophyllites indra (For bes ).
MM 18994, the upper Campanian , fishery ha rb o r of Soya.

Early to middle whorls (10- 60 mm in di ameter) (Figures 2 and 3)
The she ll is very involute, rapidly expanding, with a depressed w horl section . The
umbilicu s is narrow and dee p, with a n
abruptly rounded should er. The shell sur-

U MUTface is ornamented by fine striae w hi c h a ri seacross the umbilical seam , swee p slightl ybackw a rd s ac ro ss the umbilica l wa ll , fle x
backw a rd s ove r the shoulder, and pass acrossthe fl a nk s in a pro rsiradiate direction. The
striae sweep bac k wards across the ve ntrol ater-

Yasunari Shigela

1160

1a

1b

939.

Pseudophy l/iles from Hokkaido and Sakhalin

Figure 4. Pseudophyllites indra (Forbes), x O.7.
harbo r of Soya. I: latera l view, 2: ven tra l view.

al shoulder and cross the venter with a broad ,faint, concave ventral sinu s.
The suture (Figure 2) is hi ghl y subdi vid ed ,with a large irregularly trifid first latera l sa ddle (E l L) , a sm aller bifid seco nd lateral saddle (L/ U 2 ), a deepl y inci sed bifid latera l lo be(L) , and a suspensi ve lobe with a la rge bifid

11 6 1

UMUT MMI S99 1, the upper Campanian , fisheryfirst a uxilia ry sad dle .
Later whorls (over 60 mm In diameter)(Figure 4)
The largest specimen in the present material , 185 mm in diameter, lack s a majority(5 / 6) of the body chamber. The shell is very
invo lute, with compressed whorls a nd a high~Figure 3. Pseudophyllites indra (Forbes), X 1.0. l a- b. UMUT MM1 900 1, the upper Campa nian ,new fish ery harbo r of Ki yo ha ma- II. 2a - b. UMUT MMI S994, the upper Ca mpa ni an, fishery harbor of
Soya. 3a- b. UMUT MMI S995, the upper Ca mpa ni a n, fi shery harbo r of Soya. 4a- b. UMUT MM19007 ,the upper Ca mp anian , the middle co urse of the Kras noy ark a Ri ver, N aib a area. 5. UMUT MM 19005, theupper Ca mpa ni a n, NB3031 (NIOO), Naiba area . 6a - b. UMUT MMI900S (MNH . 231), the upper
Ca mpan ia n, fis hery harbor o f Soya.

Yasunari Shigeta

1162

whorl expansion rate. The umbilicus issmall and deep, with a sloping wall andabruptly rounded shoulder. It is ornamented by fine and dense striae which show agently backward curve on the ventrolateralpart.
The suture is poorly visible, but consists ofnumerous deeply incised elements, with subphylloid terminals of folioles.
Comparison.-In the juvenile stage P.
indra most closely resembles Tetragonites
glabrus, a Turonian to lower Campanianspecies known from Hokkaido, Sakhalin,
Alaska, California and South Africa in having a subellipsoid caecum with weakly constricted base, ventrally located siphuncle, ahigh whorl expansion rate and a small umbilicus, but is distinguished from T. glabrus
in having a rounded umbilical shoulder andweakly adorally concave sinuous aperture onventer. The specimens ill ustrated as T. glabrus by Shigeta (1989, UMUT MMI8636-16,
29,35,37,47,51,58) from the upper Campanian of the Soya area are regarded as ajuvenile specimen of P. indra.
Occurrence.-P. indra is a cosmopolitan
species known from the upper Santonian tolower Maastrichtian in South Africa, southern India and western Australia, and from theupper Campanian to lower Maastrichtian insouthern Alaska and Vancouver Island. In
Hokkaido and Sakhalin, this species occurs
in the Schlueterella kawadai Subzone of theMetaplacenticeras subtilistriatum Zone,
which is equivalent to the upper Campanian.

Stratigraphical significance ofthe occurrence

P. indra occurs in the Metaplacenticeraspacijicum Zone and the Pachydiscus suciaensis Zone in British Columbia (Usher, 1952),
in the M. pacijicllm Zone in California(Matsumoto, 1960), in the Pachydiscus kamishakensis Zone in Alaska (Jones, 1963), andthe M. subtilistriatum Zone in Hokkaido and
Sakhalin (Matsumoto, 1984; this study).

According to the zonal correlation of
megafossils in the Northern Pacific region,
this species is restricted to an interval fromthe upper Campanian to the lowest Maastrichtian (Muller and Jeletzky, 1970; Ward,
1978; Matsumoto, 1984). The upper limitof the occurrence of this species in Hokkaido
and Sakhalin has not yet been sufficiently
elucidated because in many areas megafossils
are rather rare in the uppermost Campanianto the lowest Maastrichtian. However, thefirst appearance of this species in Hokkaido
and Sakhalin is nearly synchronous with thatin the Pacific coast of North America.
From Santonian to early Campanian times,
P. indra was distributed in the Indian region(South Africa, Madagascar, and southern
India) (Kossmat, 1895; Kennedy and Klinger, 1977). This evidence shows that thisspecies extended its geographical distribution
from the Indian region to the North Pacificregion in late Campanian time.

Acknowledgements
I wish to thank Prof. Itaru Hayami andProf. Kazushige Tanabe, University ofTokyo, for many helpful suggestions during
the course of this study, and for critical reading of the manuscript. I am much indebted
to Prof. Emeritus Tatsuro Matsumoto, Kyushu University, for helpful suggestion, and to
Drs. Haruyoshi Maeda, Kyoto University,
Tomoki Kase, National Science Museum,
Kazuto Kodama, Koch University, Takashi
Okamoto, Ehime University, Mr. Toru Takeuchi, Nagoya University and Mr. Toshiya
Miyauchi, Natural History Collection of
Northern Hokkaido, for their help in the fieldwork and for providing specimens.

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pis. 1-9.
..--, 1956: Ammonites neocretacees du Menabe

939.

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Ward, P.O., 1978: Revision to the stratigraphy andbiochronology of the Upper Cretaceous
Nanaimo Group, British Columbia andWashington State. Canad. Jour. Earth. Sci.,
vol. 15, no. 3, p. 405-423.
Whiteaves, J.F., 1879: On the fossils of theCretaceous rocks of Vancouver and adjacentIslands in the Strait of Georgia. Mesozoic Fossils, vol. I, no. 2, p. 93-190, pis. 11-20.
- - , 1903: On some additional fossils from the
Vancouver Cretaceous, with a revised list of thespecies therefrom. Mesozoic Fossils, vol. I, no. 5,
p. 309-415, pis. 40- 51.
Woods, H., 1906: The Cretaceous fauna of Pondoland. Ann. S. Africa. Mus., vol. 4, p.275350, pis. 33-44.

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Transactions and Proceedings of the PalaeontologicalSociety of Japan

June 30, 1992

New Series No. 166

CONTENTS
TRANSACTIONS
936.

Baochun Zhou and Noriyuki Ikeya: Three Species of Krithe (Crustacea:
Ostracoda) from Suruga Bay, Central Japan ............................ 1097

937.

Yasushi Yoshida and Yuji Okimura: Amygdalophylloides (Rugosa) from the938.

Tatsuro Matsumoto and Takemi Takahashi: Ammonites of the genus

Carboniferous of the Omi Limestone, Central Japan ..................... 1116

939.

Acompsoceras and some other Acanthoceratid species from the Ikushunbetsu
Valley, central Hokkaido (Studies of the Cretaceous ammonites from Hokkaido-Lxxiii) ...................................................... 1144
Yasunari Shigeta: A record of Pseudophyllites Indra (Lytoceratina,
Tetragonitidae) from the Upper Cretaceous of Hokkaido and Sakhalin .... 1157