ISSN 1063-0740, Russian Journal of Marine Biology, 2009, Vol. 35, No. 6, pp. 474–478. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © S.Yu. Gagaev, 2009, published in Biologiya Morya.
The recent and most complete review on polycha-
etes of the Arctic Ocean  presents characteristics of
two species of the
Sars, 1835 and
Jirkov, 1987. In June–July
2005, several specimens of polychaetes of the genus
were collected in the Canada Basin; they
differed by several traits from the Arctic species men-
tioned above and from the other known species of the
genus. This allowed us to distinguish one more inde-
. Holotype: Canada Basin, 73
W, Station 15, the US CGC (WAGB-20)
July 24, 2005, depths of 2570–2678 m (no. 1/50553).
Paratypes: Canada Basin, 73
tion 15, the US CGC (WAGB-20)
, July 24, 2005,
depths 2570–2678 m (no. 2/50554, 2 spec.); Canada
W, Station 5, US CGC
, July 6, 2005, depths 3847–3880 m
(no. 3/50555, 2 spec.).
The holotype and four paratypes (all specimens
intact) are deposited in the Laboratory of Marine
Research of the Zoological Institute (ZIN) of the Rus-
sian Academy of Sciences, Saint Petersburg.
The ventral branchial lobes, in contrast to the dorsal
lobes, are underdeveloped: from a half of the size of
dorsal lobes to small cones that are hardly visible under
a microscope at a great magniﬁcation (Fig. a, b). The
branchial lobes are free for more than three quarters of
their length, fused only basally, at the branchial stalk.
The ventral surface of the ﬁrst thoracic setigerous seg-
ments is pale yellow in color, similar in its coloration to
the rest of the body surface. The body is elongate and
slender: the relation of the body length (L) to body
width (S) is 23.3
0.5. The maximal size of the species
is not above 15 mm. Egg cells 120–130
m in diameter.
: female with body length of 14.4 mm,
body width 0.6 mm. The mouth segment has a large
ventrolateral collar at the anterior edge, the next seg-
ment is formed ventrally as a half-moon (see Fig. a).
Eyes absent. Lateral lobes on ﬁve segments insigniﬁ-
cantly diminish in size from the 3rd to the 7th setiger-
ous segment. Two branchial lobes borne on thin stalks
and free along their entire length project dorsally from
the 1st and the 2nd setigerous segments; two rudimen-
tary ventral lobes behind the dorsal lobes are visible
under microscope only at a great magniﬁcation (see
Fig. a). The stalk is 0.6 mm high, the branchial lobe tip
is 1 mm (one third of the lobe length), formed as a long
thin feeler. Each of two anterior lobes bears 13 triangu-
lar projections. The thorax fringed from one side has
18 segments with hair-like notopodial setae; the setae
are long, somewhat longer than body width of the worm
and collected in bundles of 5 to 10 setae, with an excep-
tion of the ﬁrst setigerous segment bearing 4 setae only.
Neuropodial setae (neurochaetes) begin from the 6th
setigerous segment; the ﬁrst neuropodium has 7 acicu-
lar setae bent at a right angle, with a long hair-like tip
(see Fig. d). The neuropodial setae of the following tho-
racic segments are hoe-shaped, sitting on long thin
sp. n., a New Species of
(Polychaeta: Terebellidae) from the Arctic Basin
S. Yu. Gagaev
Zoological Institute, Russian Academy of Sciences, St. Petersburg, 199034 Russia
Received May 21, 2009
—A new polychaete species of the family Terebellidae,
sp. n., has been described
from materials collected in the Canadian Basin by the international Hidden Ocean 2005 expedition on board
the US Coast Guard icebreaker (WAGB-20)
. The new species differs from other closely related species
by its underdeveloped ventral branchial lobes that are at least two times shorter than the dorsal ones, sometimes
reduced to barely noticeable cones and in that the aciculum-like neurochaetes of the 6th setigerous segment are
curved at a right angle and have a thin capillaceous tip. Specimens of this polychaete worm are small, no more
than 15 mm long.
sp. n., polychaete, morphology, taxonomy, distribution.