ISSN 1063-0740, Russian Journal of Marine Biology, 2008, Vol. 34, No. 5, pp. 296–300. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © A.P. Kasatkina, 2008, published in Biologiya Morya.
Four new species of the family Sagittidae were
found in the plankton samples collected in the coastal
shallow waters of Peter the Great Bay. Horizontal
catches along the coasts over the bottom surface in the
period of spawning were most successful: the samples
contained individuals of the fourth and, rarely, of the
ﬁfth stages of sexual maturity. Remarkably, from 14
species of the genus
, only two species
were earlier recorded:
in the open waters of
the Sea of Japan  and
in the southern
Okhotsk Sea . All other species of the genus were
found in the coastal, mostly shallow waters of the north-
western part of the Sea of Japan [4, 5]. The holotypes and
paratypes are deposited in V.I. Iljichev’s Paciﬁc Institute of
Oceanology, FEB RAS (Vladivostok).
Kassatkina, 1973 .
. Intestinal diverticula of the midgut are
absent. The ciliary loop (
) begins behind
the level of eyes. The posterior pair of lateral ﬁns is sit-
uated on the tail part rather than the trunk portion. The
ﬁns are rayed. The central nuclear portion of the eye is
pigmented and distinctly separated from the peripheral
zone. Setae are not serrated. The body is rather muscu-
lar, rigid, not ﬂagging from the forceps. The head is
wider than the trunk, so the general appearance of the
animal resembles a pin.
All the 14 species of the genus are known for the far-
eastern seas: Sea of Japan and the southern Sea of
Okhotsk. These arrowworms occur in the Paciﬁc
Ocean, at the South Kuril Islands, where they are bioin-
dicators of the currents from the Sea of Okhotsk.
Kassatkina sp. n.
Fig. 1B, D
Plankton samples were collected with the
use of the standard method (Juday net with openings
37 cm in diameter) in the shallow waters of Vostok Bay
(Peter the Great Bay, Sea of Japan). Coll. S.I. Kiyashko.
Reference number is LP-4/1, found in the
sample taken on December 8, 1999 in the surface water
layer at a negative temperature.
: Ten specimens found in the same sam-
ple with the holotype.
Description of the holotype
. The body is rigid,
muscular, slender, without constriction in the region of
seminal vesicles. The head is somewhat wider than
trunk. The specimen is at the 3rd stage of maturity.
Body length is 7.8 mm. The tail portion constitutes
27.4% of the body length. The ventral ganglion has an
unusual localization nearly at the center of the trunk
portion. The ganglion is relatively short for the species
of the genus
, about 5% of the body length
(the ventral ganglion of immature individuals is rela-
tively longer, about 6–7% of the body length). Intesti-
nal diverticula are absent. The trunk gut is not vacu-
olated, not ﬂattened in dorsoventral direction, is nearly
so wide as the pharynx. The ciliary loop is long, begins
signiﬁcantly behind the eye level, somewhat above the
neck and extends onto the trunk, not reaching the ven-
tral ganglion at a distance that is nearly equal to four
lengths of the ganglion. The loop has two pairs of well
pronounced median protuberances. The anterior end of
the ﬁrst pair of ﬁns begins behind the level of the pos-
terior end of the ventral ganglion at a distance that is
1.6 times shorter than the length of the ventral gan-
glion. The ﬁns of the ﬁrst pair are 1.5 time shorter than
Composition of the Genus
of the Family Sagittidae
(Chaetognatha) with Descriptions of Four New Species
from Coastal Waters of the Northwestern Sea of Japan
A. P. Kasatkina
Paciﬁc Institute of Oceanology, Far East Division, Russian Academy of Sciences, Vladivostok, 690041 Russia
Accepted: March 26, 2008
—Keys for the identiﬁcation of the presently known species of the genus
dae) are presented. Four new species of this genus found in shallow waters of Vostok Bay, Amursky Bay (Peter
the Great Bay), and Kievka Bay (all of the Sea of Japan) are described in detail:
sp. n., and
Chaetognatha, Sea of Japan,