東北大学機関リポジトリTOUR

(1)

Report of the Biological Survey of Mutsu

Bay_3. Notes on the Protozoan Fauna of Mutsu

Bay. I. Peridiniales.

著者

ABE Tohru Hidemichi

journal or

publication title

The science Reports of the Tohoku Imperial

University, 4th Series(Biology)

volume

2 number

4 page range

383-438

year

1927

URL

http://hdl.handle.net/10097/00131753

(2)

Report of the

B~ological Survey of Mutsu Bay.*

3. Notes on the Protozoan Fauna of Mutsu Bay.

I. Peridiniales

.

BY

ToHR

U

Hm.EMITI

An:E.

(Zoological Institute, Faculty of Science, Tokyo Imperial University, Tokyo, }apan.)

383 The investigation of

the

plankton of Mutsu-Bay carried on

last

August at

the

Asamushi Marine Biological

Station

has

brought to

light

a

rich

protozoan fauna

in

which

the

Dinoflagellates

are

abundant.

The material, as will

be

surmised

from

the

conditions

of

the

oceanic

currents in

the Tsugaru

Strait,

is comprised

partly of a number

of

warm temperate water

s

pecies

and partly of those of

cold temperat

e

seas.

The

present

paper

include

s

only

the

majority

of

the

Peridiniale

s

observed

during

my

sojou

rn

at the station

last

August.

The

rest of

them

and

of

other

cla

sses

·will

be given in

later

papers. Not

only th

e

new

forms which came to

light in my investigation

s

, but also the

other species which

have

already been

r

epo

rted from

warm

and cold

temperate

sea~'

jn

.

qther parts

..

.

of the world are

figur

e

d,

and

so

m

e

of

them are fully_

re-de

s

cribed

here. The difficulty

in

getting adequate

literatures

fn

"

this country forc

ed

me,

to my

great

regret,

to

leave

s

om

e,

which seen1

to me

recommendable,

unidentified. The references under

each

speCies

iri

this

paper are

those f

o

r

which I

have been

able

t

o

see some

figures

concerning the species even

though the

original papers

f

o

r the

species

' whether I

could or could

not

get. Of

late

years se

veral

differ

e

nt methods

of

d

es

ignating the

plates of

the

genus

Pcridinium

have been proposed.

The

designating

method

used

in thi

s

paper

is

BRacH's

(1910)

which

-

was partly

mo"

dified by

ROVlG)(O

and

PA

ULSEN

(1911)

(Fig.

14).

F~r the

necessity

of

denoting

the antapical

inter-calary plates of another

ge

nus, I

used

in thu

s

paper

cp,

1. and

w,

and

(3)

T. H. Al31i

the first figure

denoting

each-

s~ries

of plates was

put on the

right

shoulder of

numerals,

as,

7"

or

3'Y to indicate

the number

of plates

comprised in

the

series.

Grateful

acknowledgement is

here made

to

Professor

S. GoTO,

of

Tokyo Imperial University, for his kind

advice

to commence

and

-continue

this

work,

to Professor

S. Hoz.-

\\V.

-

\,

of

Tohoku Imperial

University, for collecting

material and supporting this work,

and

also

to

Professor S.

1-IAT.U,

of Tohoku Imperial

University,

the Director of

the

Institute, for

the permission to use the

research table and

for

.getting

some reagents

and

apparatus from

Sendai.

My

sincere thanks to

Profe~so;-

M. KomzuM

r,

of Keio University,

to Professor

T. KABURAKI, of

Tokyo Imperial University,

and to

Professor

K. OKAMU

RA and

H. M.-\RUKAWA, of the Marine Fisheries

Bureau

for advice

and

kind help in

getting

literature,

and also

to

Assintant

Professor

S. KoKUBO,

to Assistant

S. TAKATSUKI,

and to

Assistant Y.

K~~IADA, of the Asamush

i

Marine

Biological Station, for

-

collecting

material.

Asterisks

(*)

were

used through

out

the

entire

pages

to

refer to

those

works which

I could not read the

original

papers.

DINOPHYSIS

EHRE::-<BERG.

1) Dinophysis intermedia

PA

VILLARD

(?).

Fig. 1. Dinophysis intermidia P.-\VILt. (?) (X 60.0)

-:+ PAV!Ll.AlW 1916, P· 58, Pl. HI, Fig. 4. FURTI 1922, p. 110, P.L VII, Fig. 119.

An elongated egg

-

shaped species

with

deep

cups

composed

of

singular lists, and a

rounded

.

posterior

end.

The ratio

of the

length

to the breadth is 0.32,

~nd

the wides

_

t

part is

~bout 2

J

?>

from the

~~terio,r

end.

Dimen

~

i~ms: Len~h,

57 p.;

transdiarpeter,

31,11.

Loc.

Yunoshima, Aug.

16, Hl26.

PER!DIK!ALE

S

OF

MUTSU

BAY

2)

Dinophysis rotundata

CLi\P.-\REDE et

LACHMANK. ¥.·D. rotuudata ClAI'. et IActDL, ]859, p. 409, Pl.

XX, Fig. 16.

SCI-I urr 1 895, Pl. 1, Fig. 5.

I'AUJ.SEN 1908, P· 17, Fig. IS.

Body is broad

oval 'in side

v

iew,

with

bilateral flattening.

The ratio of the length

to

the breadth is

0.9. The plasma

is

light

brO\mish yellow in colour.

Dimensions

:

Length,

53p;

transdia-meter,

48p.

L

oc

.

Off

Hadakaiwa,

Aug-.

14,

1926.

Fig. 2. Dinophysis rotundata

C1.A 1'. et LACII. (X 600}

PHALACROMA

STEil\.

3)

Phalacroina mitra

ScH

urr.

ScnU"n 1895, Pl. IV, Fig. ] S.

ScnuTT 1896, p. 26, Fig. :18.

O"AMURA 1907, p. 134, Pl. "-Fig. 43.

FORTI 1922, P· 105, Pl. \'II, Fig. 109.

Dimensions:

Length,

64p;

transdiameter,

55;1;

dorsoventral

dia-meter,

44;1.

L

oc

.

Yunoshima,

Aug. 8,

1926.

Fig. 3. a. Phrz/acnmta mifra ScHliTT.

(4)

386

T.

n.

ABE

D F

Fig. 3. b. D, ventral view. E, Dorsal view. F, Side view of another smaller specimen with a somewhat deformecl contour. (X 600)

DIPLOPSALIS BERGH.

4)

Diplopsalis lenticula

BERGH. BERGH 1881, p. 244, Figs. 60-62. ScHUTT 1895, Pl. XV, Fig. 50. ScaUT'r 1896, p. 21, 17_i_g_._31. OKAMURA 1907, p. 131, Pl. v, Fig. 44. PAUL5F.N 1908, p. 35, Fig. 44.

The

ve

ntr

a

l

a

rea

is short,

fl

a

ring

s

lightly

posteriorly,

guar

d

ed

with

a

well

de

ve

lope

d

li

st o

n

its

l

e

ft

and posterior rims.

A B

Fig. 4. Dip!opsalis lmticula BERGH.

A and B, Diagrams of plates on .the hypotheca and the epitheca. (X 600)

PERIDINIALES OF ;I'[UTSU llAY

Dimension: Transdiameter, 43p.

Loc.

Off

H

ad

akai

wa,

Aug.

10 ,

1926.

5)

Diplopsalis lenticula

BERGH

var.

(?).

38

7 Thi

s

differ

s

from th

e

preceding

spec

ie

s

in having

on

ly

one

an

t

a

pical

plate

a

nd in

it's

s

mall

e

r

size.

The

ve

ntral

area

i

s so

mewhat l

a

r

ge

r

than the

type spec

ie

s

and

is elo

ngat

ed

obliquely

and

posteriorly

to the

l

e

ft

,

along

whic

h l

e

ft rim

exh

ibits

a

bro

ade

r li

st,

but not

exte

nding to

the

p

os

terior

· rim.

Dimensions:

L

e

n

gt

h,

51p;

tran

s

diam

c

ter, 45p.

Loc.

Off Asamushi, Aug.

10,

1926.

B

A

c

D

Fig. 5. Dip!opsalis lmtim!n BERGH var?

A and B, Pattern of the plates the hypotheca and the epitheca. C, Ventral

(5)

388

T. H. ABE'

GONYAULAX DIESING.

6) Gonyaulax polygramma

STEIN.

'!.·STEIN 1883. Pl. IV, Fig. 15.

ScHUTT 1895, Pl. IIX, Fig. 33.

OKAMURA 1907, p. 132, 1'1. III, Fig. 13.

PAULSEN 1908, p. 29, Fig. 36. .

KoFOID 191l(a), p. 229, Pl. X, Figs. 6-7, l'l. XVII, Fig. 47.

A medium

-

sized, somewhat

e

l

onga

t

ed s

pecie

s w

ith l

o

ngitudinally

striated and

reticulated

surfa

ce. Bcdy is ru

g

ged

oval w

ith both

sho

ul-ders angled

at

th

e

ap

ica

l-pr

e

cin

gular

and postcingular-an

t

apical

s

utur

es,

c

E _A

D F B

Fig. ·6. Conyaitlax polygmmma STEIN.

A, Ventral view. B, Dorsal view. C, Dorsal right-side view. D, Ventral left-side

~iew. E and F, Apical and antapical view of a :-<pecimen showing the arrangement of the longitudinal ribs. ( x 600)

J'EIUDINIALES OF MUTSU BAY

389 be

a

rin

g o

n

e

or

t

wo sma

ll antapical

s

pin

es

. The l

o

ngitu

di

nal rib

s va

ry

in

number

and a

rran

g

em

e

nt, but

so

me

of

th

e

m are

more or

l

ess

exactly

on

th

e

sutu

r

e

lines,

so

that

it is possib

le

t

o

distinguish the thecal

o

rd

er

from the

a

rran

gemen

t

of the

rib

s

.

The

pla

s

m i

s

dark

y

e

ll

ow

i

sh green.

Dimens

i

ons

:

Length,

5

7 t1;

transdiameter,

45p;

dorsoventral

dia-m

e

t

er,

42fl

.

L

oc

.

Off

H

a

da

ka

i

wa

,

Aug.

10,

Hl26

.

7)

Gony

aulax

s

pi

n

ife

ra

(CLAP

.

et

LACullr)

.

PAULSEN 1908, p. 29, Fig. 37.

KoFC•ID J91J (a), p. 209, Pl. X, Figs. 8-10, l'l. XVf, Fig. 31), Text-fig. A.D.(') C. 111m~r;ini FAUKf:-FRE~liET HJOS, p. 230, Fig. ]6.; Pl. XVI, Fig. HI.

·» Peridinium spiniferum CI.,\l'. ct L11CJDI., 1895, p. 405, Pl. XX. Figs. 4, 5.

A

minute species with a broad

s

piral

g

irdle

and an antapical

horn,

closely

correspo

n

ding

t

o

G

.

mangi7li

F. F. judging from

the

figure

and

descriptions g

iven

by

the

a

ut

hor

.

B

od

y is

so

m

ewhat short

and

egg-sha

p

ed

.

The epitheca is

subconical

11·ith

a short

apical

h

o

rn

. Th

e g

irdle is

very

b

r

oad

and

median,

with

well d

e

veloped lists

of

the

body wall.

The

furrow is deeply

impres

se

d,

and

d

es

c

e

nding,

and

is

dis

placed distally

3 girdle widths

,

and overla

p

s

one of

its

widths

.

The

g

r

oove connecting

its two

ends is

narrow

but

i

s

d

eeply

impressed. Th

e

ventral

a

r

ea

is

a

n

a

rrow furrow,

curv

ed

so

m

e1

d1at obliquely to the

right.

Th

e

hypoth

eca

i

s

a

flat

hemisphere

,

with

a

s

hort

but

d

i

s

tinct

a

ntapical spine on its

apex at

th

e

r

i

g

h

t

post-mar

g

in

of

the

longitudinal

groove.

I

t

is qu

it

e

probable

that

G. mo11oacaut/ta

PA \'ILL

is

closely rela

t

ed

to

th

i

s species

in

its

g

eneral

fea

t

ures

except in

i

t

s

lar

ge

, distinct,

a

pical ho

rn

.

Dim

e

nsions: L

en

gth,

27tL;

tran

s

diameter,

22fl.

.

L

oc

.

Off

Asa

mu

shi,

Aug

.

21,

1926.

Fig. 7. Conyaula.r sjinifem

D:r~~II\G. \·entral view. (X 600)

8 ) Gonyaulax polyedra

STErK.

·::·STEI~ JS83, p. 13, Pl. IV, Figs. 7-!J. PAt;LSE'.' 1908, p. 31, Fig. 40.

(6)

390

T. II. ABE

KoFoiD 1910, p. 23o, PI. XU, Figs. 16-20; Pl. XIV,

Figs. 28, 29, 31; PI.

xvn, F

ig. 43. CoNRAD 1926,. p. 95, PI. U, Fig. 37.

A

medium-sized

spec

ie

s.

The

b

ody

i

s

pentago

n

al with a

truncat

e

d

poste

ri

o

r

e

nd.

Dim

e

n

sio

n

s

:

Length

,

34,u;

transdiameter

3 Gt'

· Loc

.

Off

F

utagoj

i

ma, Aug.

23 ,

1926.

Fig. 8. Gonyaulax po!yedm

STEIN. (X 600)

9)

Gonyau

l

a

x

turbynei

lVIUHRAY ~md vVII!TTIKG.

1lt;RR. and \\"mn. 1899, P· 323-~24, Pl.

xxrrx,

Fig. 4.

KoFOID HJll(a), p. 225, Pl. X\~[[, Fig. 44. Ft)RTI 1922, p. 80, Pl. VT. Fig. 67.

A

sm

all

, ovo

id

spec

i

es

without

a d

i

s

tinct

apical horn.

Th

e su

r-face is

s

tri

a

ted

with

po

re

s

which

a

re

spa

r

sely

but

mo

r

e

o

r

Jess

longitudinally

scat

t

e

r

ed

,

and the

inter-stria

e

r

eg

i

o

n

s

are marJ.::edly

reticulated.

A B

Dim

e

n

s

i

ons

:

Length, 40,t';

transdiameter,

3 4p.

Fig. 9. C"nyaulax turbymi i\lUIL and

\YHJTL

Loc.

Yunoshima, Aug.

16 ,

1926.

A and B, Ventral views of two specimens. (X 600)

PYROPHACUS STEIN.

10)

Pyrophacus horologicum

STEIN. «·STEI:-1 1883, Pl. XXIV, Figs. 1-13. Pl. XXV, Fig. ].

BuTsciiu 1885, Pl. LIV, Fig. 3. ScHuTT 1895, Pl. XVII, Fig. 51.

Scni.)rT 1896, p. 13, 15, Figs. 17, 21. l'AULSEN 1908, p. ?7, }<ig. 89.

A

lar

ge,

flatten

e

d

spec

i

es.

The

numb

e

r

o

f pl

a

t

es a

r

e

rou

ghly

pr

o

p

o

rti

o

nal t

o

it

s s

iz

e

,

lar

ge

r

ones

havin

g a

lar

ger

n

umber of plates,

PERIDINIALES OF MUTSU BAY

391 a

nd

smaller ones a

s

maller numb

e

r

of

plates. The

specimen shown

in

Fig. 9, A and B

is

one

ha

v

in

g

probably a minimum

numb

e

r

of plates

.

Dimen

s

i

ons:

Length,

10 3-

134,u;

tran

sdiameter,

94-124p.

Loc.

Off Asamushi, Aug. 16, 1926.

Fig 10. Pyrophacus lwro!"gimm STEIN.

A and B, Arrangement of the plates on the epitheca and the hypotheca of one

specimen, having probably a minimum number of plates. C, The hypotheca of

another larger specimen showing a larger number of plates. ( x 280)

SPHAERIDINIUM WOLOSZYNSKA.

11)

Sphaeridinium

asymmetria,

n

.

sp.

A minute,

sp

her

oidal species

with a

so

mewhat curved

ve

ntral

area,

a relatively wide

g

irdl

e,

and

no

apica

l

nor

an

tapical

process

es.

The

body

is

spherical.

The epitheca and

the

hypotheca are both

hemispherical.

Th

e

most conspicuous character of this

species

i

s a

distinct diagonal

s

uture ridge on

the

ep

itheca

from the left ventral to

the right

dor

s

al, cro

ss

ing the apical pore.

It

is

incompl

ete

as

it i

s

o

nly

within the area of

the

apica

l

and

th

e

intercalary plates, not

extending into the pr

e

cingular

se

ri

es wh

ich

is on

l

y poorly developed

.

(7)

392

T. H. ABE

It,

th

e

n,

divides the plates, though incompletely,

into two

gro

up

s

, th

e

ap

ical

I, 2,

and

4•

and the

int

e

rc

alary

r

in

the

ventral, and

the

apical

3 and

the intercalary

fJ,

e,

in the

dor

sa

l

half.

H

av

in

g

some relation

with the

ob

l

iqu

ity

of

the ridg

e,

th

e

plates of the

ri

g

ht

ve

ntral and th

e

left

dorsal regions are larger

o

r

more extended than

tho

se

of

th

e

left

ve

ntral

a

nd

the

right d

o

r

sa

l

parts so that the apical plate

2

i

s

smaller

than the plate

4

• and the precingulars

a a

nd

b

are much

sm

alle

r than

th

e

c

orrespond

ing plates

g

a

nd

f.

Of these the first

sure

ly i

s

the

s

m

alles

t in

the epitheca. The intercalary plate

l3

i

s

the

lar

gest

one,

and the others,

r

and

e,

s

h

ow a s

li

g

ht

differe

nce

in s

i

ze

, but they

are

markedly displaced to the

l

ef

t

s

id

e

of the body by

the

asymmetrical

development of

the

apical

a

nd

the precingular plates.

Th

e

precin

gular

c

is a very low but

w

id

e

quadrangular plate.

The

apical pore is

relatively large

wit

h

a little

s

maller

po

r

e-like

ventral

s

lit.

The

s

lit is

not

accu

r

ately

in

th

e

ventral

m

edia

n

side,

but is deflected

abou

t

45°.

to

th

e

right

s

id

e

of the body from

th

e

dorso-ventral median plane.

It

also

m

akes

an angle of about

60°

.

w

ith

the diagonal suture

rid

ge.

The

gird

l

e

i

s

broad

a

nd

median.

Th

e

furr

ow

i

s

n

ot

deeply

impr

essed,

a

n

d

i

s very slig

htl

y

ascending

w

ith

o

ut marked

side-l

i

s

ts

.

The

· ventral

area

cu

r

ves to

the

l

e

ft

and then

t

o

th

e

ri

ght

in

sa

u

sage shape

, bearin

g

a

sem

i-lunar

list on

it

s

posterior

ri

ght side.

It

is deeply impressed

in

the

anter

ior

pa

rt

and along the

r

i

g

ht

e

d

ge o

f

the post-girdle part

of

the area,

of which

th

e

middle portion

i

s

covered wit

h

the

hyaline

semi

-l

unar list.

Th

e

hyp

otheca is

h

emisp

h

e

ric

al,

as sta

t

ed above.

Its

plate formula is

5A,

2'.

and

2'?.

As will

be clearly recognized in the

text figures, one

s

mall,

e

l

ongated p

l

ate,

7..,

i

s seen a

t th

e

right of

th

e

incurved right ri

.

n,

an

d

a

minut

e se

mi-lun

ar

plate,

<p

,

at

the rear

of

th

e

,

posterior

ed_;e

of the ventral

area

.

These

sma

ll,

hypothecal,

intercalary plates, with the epithecal

diagonal

ridge, keep

thi

s species

a

l

oo

f

from

any

other

species o

f

P

e

ridinium.

Th

e surface

is

smoot

h

and

the plasm

i

s

colourless. The

s

utur

e

lines,

excludi

n

g the

rid

ge,

a

re

very

narrow

a

nd indi

st

i

nct, being

r

ecogn

i

zed

in

so

m

e spec

im

ens

o

nl

y wit

h

the

o

il

immersion.

This

species

is distinguished

at once

fr

om

P

e

ridinium globulus a

nd

P. minutum,

by its rounded

apex.

The curved ventral area

and

the

irregularly displaced

t

heca

l

plates serve to separate

it

from

P. splzericum

MuRR.

&

WHITT.

The, ve

n

tral area of

this species has some similarit

i

es

PERIDINJALES OF MUTSU BXI:

393

A B

c

D

Fig. 11. Sphaeridim"wn a.rymmeHia, n. sp.

. A, Somewhat oblique ventral view. ll, Oblique apical view. v1ew of the hypotheca. D, Right side view. (x600)

C, Oblique dorsal

B

Fig. 13. S. asymmdria, n. sp. Oblique antapical view of the surface of the hypotheca. (x 1500)

ventral

wi

th

Goniodoma

sp!terimm

MURR.

&

vVmrr

.

,

wh

ich

differs in

hav

in

g a

smalle

r

ventral ar.:a, a

listed

girdle with

its proximal

arc

h

,

and

a

different plate

pattern.

This

species

is remarkable

both in having two antapica

l

intercalaries

and

in the

development of

the

apical

Fig. 12. S. asy11tmdrin, n. sp.

d"

_tagona

I b

_{an , as}

d

_well

_{as in}

_{the st}

_ru

c-A and B, Diagrams of the plate t

_u

_r

_{e o}

f

_t

h

_{e ventral area.}

It

is not

arrangement of the epitheca and the

hypo theca.

(x

1

500)

closely re

l

ated s

t

ructurally

to any ot

her

.

species

in

t

h

e genus

Peridinium,

and

(8)

394

T. H. ABE

ground of

it

s

spherical

body

without gird

l

e

li

s

t

s

or

a

ny app

e

ndages

except

th

e

ven

tr

al

fin,

and

a

l

so

on

it

s

antapical

int

e

rcalary plates

.

The

anterior antapical

intercalary plate

oug

ht

not t

o

be regard

e

d

as a

post-cin

g

ular plate, but

mu

s

t

be

se

p

a

rated into

another series,

the

antapical intercalary

series, with

th

e

minute posterior plat

e

,

from the

view

point

of

it

s

deve

l

opment, so

th

a

t

the

plates

of

the hypotheca

consist

of 5

precingular,

2 antapical, and 2

int

e

rcalary plates. The

ab

se

nce

of one

apical int

e

rcalary

plate and

th

e

xcess

of one plate

in

the

antapical

intercalaries mak

e

it

doubtful as

to

whe

th

e

r

this

spec

i

es

re

a

lly d

ese

rves

to

be

separated in

th

e

g

e

nu

s

Sp!tacridinium

or

not.

Dimensions

:

Len

g

th

3 6,u

; transcliameter, 34p.

Loc.

Off As

a

mushi,

Aug

.

15, 1926.

Very

rare.

PERIDli'liUM

EHRENBERG.

Fig.

14-BRocn's modified method of

cleno--ting the thecal plates.

Up

o

n attemptin

g

to

arrange the

vast

diverg

e

ncies

of

the morphological

variations

in the

ge

nus, early observers,

ScHurr,

BERGH,

and

Gl{AN

div

i

ded

the

genus

into

two

sub

s

peci

es

,

Pr

o

t

o

-peridiuium

and

E

uperi

di

nittm,

accordin

g

to the

anter

i

or

di

s

plac

e

ment of the

gi

rdle

,

cour

Jted

with

the

so

lid antapical

horns for the former

,

and the

poster

i

or

displacement of the

g

irdl

e

to

ge

th

et-with

th

e

hollow

an

t

apical

horns f

o

r

the !alter. But in

later yea

r

a

nother

system was

prop

ose

d by

J

¢RGENSEN.

(

1912)

on

th

e

basis of plate

relation-ships, which was

c

o

nfirm

e

d by

BAR-_ ROWS

(1918),

though

cr

iti

cized

and

somewhat

modified by

PAVILLARD

(1

916).

BARROWS

d

iv

id

e

d

th

e

g

enus

into

thr

ee

groups, g

i

ving

th

e

name

Orl!wperidinium t

o

those

s

p

ec

ies havin

g

th

e

ventral

plat

e

pattern

of

P. aclwo-maticmn,

J

ltf

e

t

apet'i

di

nium

to the

se

PERIDINIALES OF l\IUTSU BAY

395 having that

o

f

P. pelluczdum,

a

nd

Paraperidinium

to

th

ose

h

av

in

g

the

plate

pattern of P.

sph

er

oidea,

In

the

f

o

rm

e

r

system the

main

emphasis

is

placed

upon th

e s

tructur

es

of

the

girdle

a

nd

the

a

nta

p

ical horn, but

in th

e

latt

e

r

it

i

s

bas

e

d

only on

the

plate

patt

e

rn

without considering

any

of

the characters

o

f

the appendages

a

nd

the girdle.

It

would

be

conven

i

ent

if the two

syste

m

s

were used together

t

o

denote

the

_c

har

ac

t

e

r

s

of

the

s

pecies,

an

d the two

are

n

ot

unimportant

in dividin

g

th

e

genus

,

ea

ch

designating

the

d

iff

erent

s

tructur

al

characters.

12)

Peridinium orbiculare

(PAULSEN)

var.

temaris, n.

var.

A small

,

sp

h

e

ri

cal

spec

i

es

wit

h

o

ut

e

levati

o

n

of

the

apic

al

horn,

o

r

a

ntapical

s

pin

es.

The

e

pitheca i

s subhem

i

sp

heric

al.

Th

e

plates

a

r

e o

f th

e

Or

t

lzo

-peridiuium

type.

Th

e

plates

o

f th

e

apical

are well

developed.

The

· g

irdle is median, i

s

relatively wide

and asce

ndin

g,

and

is displaced

d

i

s

tally

half

its

width.

Th

e

furro

w

i

s

n

o

t impr

essed

,

bearing

l

ow

side-lists.

The

section

a

t

th

e

girdle

i

s

circul

a

r.

Th

e

ve

ntr

a

l

area

i

s

narr

o

w

and

short, gua

rd

e

d by

a

broad,

hyalinou

s

,

crescent fin on

its l

e

ft

s

id

e

, n

ot

extending

t

o

the

post

e

rior

ext

r

emity.

Th

e

hypoth

e

ca i

s

al

so

sub-hemi

s

pherical

without

post-ind

e

ntation,

o

r

antap

i

cal

spines.

The antapical

p

l

ates

are

lar

ge

.

A

s

mall,

so

me-what

trian

gular,

intercalary

plate

is

o

n the right

s

ide

of the

ventral a

r

e

a

as

well

as

five

postcingulars.

Th

e

surface

i

s smooth.

The

in

tercalary

band

s

are wide

and

are

pro

v

id

e

d

with

di

st

inct tran

sve

r

se s

triati

o

ns.

D E

Fig. 15. Peridiniwn orbicularel (PAULSEN) var. trmaris, n. var.

A, ventral view. 13, Oblique ventral view. C,

Dorso-~pical view. D, Antapical view. E, Antapical view of the epitheca. ( x 600)

(9)

396 Th

e

l

acking

o

f

one

dorsal

intercala

r

y

plat

e

in thi

s va

ri

ety

se

r

ves

t

o

sepa

r

ate

th

is f

r

om

the

a

tl

a

nti

c species.

Dimensions

:

Length,

35f1 ;

transdiameter,

34p.

Loc.

Off

Futagojim

a

,

Aug

. 2

3,

1~26.

13)

Peridinium nipponi

ca,

n

. sp

.

A

small, sp

h

e

r

ical

species

with a short apica

l

h

o

rn

a

n

d

fou

r

de

li

cate

a

ntapi

cal spi

n

es.

Th

e

body is

spherical without any ve

n

tral

flattening. Th

e

gi

r

d

l

e

sect

i

on is

circular

and

is perpendicular to

th

e

body

axis.

Th

e apical

pore

i

s at

th

e

termi

n

al of the

sma

ll

apical

h

o

rn

wit

h

a

short ventra

l

s

lit

.

Th

e theca

l

plat

es

are of

the

Paraperidiuium

t

ype wit

h

three

int

e

r

cala

r

y

plat

es

. T

he ep

i

theca

i

s

hemis

ph

erical, spmmetrica

l with the

· hy

potheca. T

h

e

apica

l

plate

I

i

s

a

lar

ge

hexagonal.

T

he prec

in

gu

l

ars

b

and

f

are

th

e

l

argest

in th

e

se

ri

es, while

th

e

dorsal

d

is

a

flat

plate.

Th

e

dorsal, h

exago

nal.

intercalary

o

i

s

as

l

a

rge

as

the

pla

t

e

h,

but

th

e othe

r

two

pentagonals,

r

an

d

e

,

are

t

he s

m

allest

in

the epitheca.

Th

e intercala

r

y b

an

ds a

r

e

wide.

T

he g

irdl

e

is

m

edian and

i

s

r

ela

tiv

e

l

y

narrow,

w

ith

hyaline

s

ide-li

sts.

Th

e

furro

w

is

ci

r

cu

l

ar and

i

s fain

tly

im

pressed.

T

he vent

r

al area

is

s

p

oo

n-

s

haped,

comprising

n

a

rr

ow

and posterior

wider po

rti

ons.

Th

e

fl

age

llar

por

e

is

in th

e

l

ef

t

corner

of

th

e

p

os

terior

wide

r

portion,

th

e ventral

and the dorsal rims

of

which

h

ea

r t

wo s

hort

spi

n

es

. T

wo other

lon

ger

spines are see

n

on

th

e

postero-lat

e

r

al edges o

f

the a

r

ea,

all

of

th

e

m

having

n

o

si

de-fin

s

exc

ept

the

sho

rt

ventr

al

o

n

e

.

A

longitudinal

fin i

s

on

the left

s

i

de of

th

e

ventra

l

area con

n

e

ct

i

n

g

t

he

s

h

o

rt,

d

o

r

sa

l

spi

n

e a

nd th

e proxi

m

al

part

of the

p

osterio

r

girdle

li

s

t.

Th

e

longer

sp

in

e

i

s 0

.

33 tim

es

that

of

tran

s

d

i

ameter.

Th

e su

rf

ace

is

smoo

th exc

ept

th

e

int

e

rc

ala

r

y

b

an

ds,

wh

ich

ar

e

faintly

st

ri

ated transve

r

sely.

Th

e

pla

s

m

i

s

co

lourl

ess. A

closely

r

esembling species

,

P. splterimm, was

reported

o

ff th

e

coast of

Tosa,

Shikoku

,

by Okamura, but differs

fr

om

thi

s

spec

i

es

in i

ts

l

arger

s

i

ze,

s

lig

htl

y ascendi

n

g g

ir

dle, and

two finned antapical

spi

n

es.

It

i

s

closely related

t

o

P.

Oil7t7/t

in

general,

but

diff

e

r

s

in thecal

plates

and some st

ru

ctures

i

n

th

e

p

oste

rior

reg

i

on o

f th

e vent

r

a

l

are

a

.

Dimension

s:

Le

n

gth,

40f1;

transdiam

e

ter,

36p.

Loc. Off

Asam

ushi

,

A

u

g.

16 ,

1926

.

PER!DIN!ALES OF MUTSU 13-AY

397

A

D

Fig. 16. Petidiniu>n nipp.mica, n. sp.

A and B, Diagrams of the plates on the epitheca and the hypotheca. C, Side

view. D, Dorsal view of another specimen. E, OLlique polar view of the specimen

C. F, Ventral view of another one. G, Side view of the longitudinal fin of the

ventral area. H, Oblique antapical polar view of the posterior ventral area, showing

the four spines. (X 600)

14)

Peridinium spheroidea,

n.

sp.

A

small

,

spherical

spe

cies

with two

finn

e

d

antapical

spi

n

es a

nd

broad

g

irdl

e

lists. The body

i

s s

ph

e

ric

a

l without ventral

flatt

e

nin

g

,

so

that both the

ep

ith

eca a

nd the hy

po

th

eca

are

hemi

spherica

l.

The

a

pic

a

l

h

o

rn

is

sma

ll

and

fl

a

t, hard to d

e

t

ect.

The apical pore i

s sma

ll

w

ith

a

s

hort

ve

ntral furro

w.

There

see

m

s

t

o

b

e a

v

e

ntral

sl

i

t,

but

close

obse

rv

a

ti

o

n

pro

v

es it to be

n

ot a sl

it but

a groo

v

e.

The

int

e

rcalar

y

bands

a

re br

oad

and

t

r

a

n

sve

r

sel

y

st

ri

ated.

The

pl

a

t

es

are

o

f

th

e

Metap

erid

inium

t

y

p

e wi

th thr

ee

in

tercalaries.

Th

e ap

ic

a

l

I

i

s a

l

arge

he

xagonal

plate

,

but

the dm·sa

l

pl

ate

3 i

s sma

ll.

Th

e

l

ateral intercalary

plates

r

and c are small, and

the

dorsal

a

is

so

m

ew

hat lar

ge

r.

The

ventral

pr

ec

in

g

ul

a

r

a

and

g

a

r

e

minute

,

tria

n

g

ul

ar

plates.

Th

e

girdle

(10)

398

T. H. ABE

is ascending and

is

displaced

'

distally

1.5 it

s

width, with a proximal

arch.

The

furrow is relatively narrow, faintly depressed,

wi

th

broad

s

ide

lists bearing abundantly

ribb

ed

fins

on their

inner

sides

.

Short,

numerous, perpendicu

l

ar wrinkles, their

len

gth

being

shorter

than

one-third

of the girdle

breadth,

are

obse

rved

along both

s

id

es

of

the

groove,

which are

o

nly the trac

es of

the

rib's

bas

es

in

the lists.

The

girdle

pl

a

ne

is

n

ot

perpendicul

ar

to

th

e

body ax

i

s,

but

i

s

inclined

about

15 °.

from

the perpendicular plane.

The

ventral

a

r

ea

is a narrow

g

roo

ve

guarded

with

side

fins

.

The

right

side

fin is a

little

narrower

than

th

e le

ft,

while the left one

is

broad and curves inwardly, spreading

over and

nearly

covering

th

e

left half of the area.

Th

e

fla

ge

llar

pore

is in the

l

e

ft

si

de, near

the truncated posterior

m

a

rgin,

of

the

area.

Two

long,

antapical sp

in

es

,

eac

h

w

i

th

thr

ee

latera

l

fins are on the

antapex

of

the

hypothec

a,

one

o

n

the right corner of

the

truncated

post-ma

r

gi

n

of the ventral are;:t,

and

the otl;ler on

i

ts

l

eft

edge a

little

distance from its

left

corner. The left spine

incline

s vent

rally.

The left

antapical plate

1 is

smaller than

the right

one.

Th

e su

rf

ace

is

s

mooth

.

Three

spine

-like

processes are

observed

at the antapex

in

ventral

view, but the shorter

l

e

ft

one

is

n

o

t r

eally

a

spine,

but

merely

an

image caused by the lengthwise view of

th

e

posteriorly

thickened part

o

f

the side fin at

the inters

ec

tion

of this with the left

median

fin of

the spine, whic

h

is not

noticed in

si

d

e

view.

Thi

s species

is distinguished at once

fr

o

m

P. g!obulus,

by its

different theca

l

arrang

e

meilt

and in having antapical

spi

nes.

Peridinizt

1Jl

.cerasus

,

and

P. orbiculare

· are dist

i

ngu

i

s

hed from

this

by

their

s

maller

size, and its antapical

s

pin

es serves

to separate this from

P. orbiculare

.

P

e

ridiniu1Jl. spltericum

OKAMURA

i

s

one of the best

r

elated species

, but

differs

in it

s

muc

h

smaller

s

ize, in

haviug the

equato

ri

a

l

girdle

pl

ate

p

e

r

pe

ndicular

to the body axis

a

nd in having

a distinct apical

h

orn

.

On the other

hand, the distal di

sp

l

ace

ment

of

the girdle,

t-lH~

...

shorter

but spreading left antapical spine and

the broad

side

list

on the

left

edge of

th

e

ventral area show the close re

l

ation of

the two.

OKAMURA's

non-d

e

tail

e

d

figures and descriptio

n

s

make it

difficult

to

identify

it

with

this

species,

and

it is

quite

probable that they

are

tw

o

different

speci

e

s.

Dim

ensio

ns: Length,

62,u; transdiameter, 58p;

dor

so

-ventral

dia-meter,

54p.

Loc.

Off Futagojima, Aug. 28,

1926.

PE

RIOINIALES

OF

MUTSU

BAY

399 c

D

Fig. ] 7. Peric.'inium sj>heToiden, n. sp.

A, r\ntapical ventral view. ll, Side view. C and D, Pattern of the plates of the epilheca and the hypotheca. E, Ventral view of another smaller specimen. ( x 600)

15)

Peridinium hirobis,

n.

sp.

A

minute

s

p

ecies

w

i

th

an

extraordinarily wide girdle and

two

antapical

spi

nes. Th

e

ep

i

theca

is

s

ubhcmispherical,

t

h

e anterior surface

of which

is

contracted to a short apical

horn

.

The

plates are of the

Metaperidinium

type with three dorsal intercalaries.

Its

cross-section

at the gird

l

e

i

s

broad

oval.

The

g

ir

dle

i

s

post-median, and

i

s ve

ry

(11)

400

T. H. ABE

wide,

with ribbed li

sts.

Its proximal part

t

s

far

wider

than

the distal

part.

The furrow i

s

not

deeply

impres

se

d,

and is slig

htl

y ascending

distally.

The

ventral area

is

also wide, widening posteriorly, guarded

with a

broad

fin on

its left

side.

Th

e

fla

ge

llar

pore of this species

is

very

l

arge,

is

elongated

along its left

side and

ex

t

e

nd

s

anteriorly to

the

po

s

t-margin

of

the

proximal girdle end.

The

hypotheca

i

s

a

flat

subhemisphere with a shallow

post-ind

e

ntati

o

n

at the post-margin of

the

ventral area. ln addition to

the two l

o

n

g a

ntapical

spines, slightly

diverging

posteriorly, a short spine

i

s see

n

on

the

inner

si

de

of the

left

spine

in the

ventral view.

It i

s

n

ot a

spine, but an

image

formed

by the

posterior extension of

the

side

li

st.

The

s

urfac

e

is

smooth and

th

e

intercalary bands

are narrow and indistinct.

Dimensions : Length, 26,u ;

tran

sdiameter,

24,u

; d

o

rso

ve

ntral di

a-meter,

22p.

Loc. Off Futagojima, Aug. 23,

1926.

c

D

Fig. 18. Peridinium hirobis, n. sp.

A, Ventral view of a smaller specimen with a brol<en apical par1. B, Antapical view. C, Dorsal view of another larger one. D, Oblique ventral view. (x600) E, Ventral view of a different, imperfect specimen. (X 1500)