Jakobia similaris DattaGupta 1981

Jakobia similaris DattaGupta, 1981

(Fig. 1C, D)

MATERIAL EXAMINED. — Porcupine Abyssal Plain, BEN- GAL 5, Discovery 231, stn 13368#53, 48°49.98’N, 16°33.53’W, 4842 m, 19.III.1998, 1 ♀.

DESCRIPTION

Colour of preserved specimen is grey. Only basal stump of proboscis is still attached to trunk, rest is missing.Mouth opens on round muscular projection (Fig. 1C). Anterior half of trunk is considerably distended, posterior half is narrow about 5 mm in diameter. Trunk is 53 mm long and 10 mm across broadest part. Integument is thin and transparent. Papillae microscopic at anterior end, rest of trunk is smooth. Gonopore is located a few millimetres away from anterior tip of trunk (Fig. 1C). Ventral setae absent.

Internally, single gonoduct is located on right side of nerve cord. Gonoduct consists of two sharply bent sections with gonostome directed anteriorly (Fig. 1D). Neurointestinal vessel is single throughout. Segment of gut between mouth and point of attachment of neurointestinal vessel is very long. Cloacal chamber is thick and bulbous.

Anal vesicles missing, probably damaged.

REMARKS

The specimen could be easily recognised as a species of the genus Jakobia by the nature of the gonoduct which consists of two sharply bent sections. The species J.similaris was described originally by Datta- Gupta (1981) from a single specimen collected in the North Atlantic at a depth of 3000 m. According to this author, the proboscis is long and flat with a disc-like tip and the anal vesicles are branched.

Despite significant differences in the dermal papillae and the structure of the gonoduct, the present specimen has been placed in J. similaris. Additional material in the future from that region might reveal that the specimen on hand is new to science.