Bengalus longiductus Biseswar 2006, n. sp.

Bengalus longiductus n. sp.

(Fig. 2 E-G)

TYPE MATERIAL. — Holotype: Porcupine Abyssal Plain, BENGAL 2, Discovery 226, stn 13078#11, 48°53.19’N, 16°35.98’W, 4844 m, 1.IV.1997, sexually mature ♀.

Paratype: BENGAL 2, Discovery 226, stn 13078#06, 48°44.55’N, 16°32.77’W, 4838 m, 30.III.1997, 1 ♀.

ETYMOLOGY. — The species is named on account of the presence of a long gonoduct.

DESCRIPTION

Colour of proboscis of preserved specimen is cream, trunk is light pink. Only basal stump of proboscis is attached to trunk, distal part is missing. Junction of proboscis and trunk is stout. Lateral margins of proboscis curl inwards proximally but do not fuse to form funnel around mouth (Fig. 2E). Mouth is an oval aperture located on round muscular projection. Trunk is cylindrical. In holotype trunk measures 41 mm in length and 8 mm across broadest part. Corresponding measurements of paratype are 60 and 7 mm. Integument is thick and opaque. Papillae are microscopic, more closely aggregated at extremities of trunk. Genital pore is conspicuous transverse slit located on round eminence of body wall about 6 mm away from anterior end of trunk (Fig. 2E). Ventral setae absent.

Gonoduct single, elongated, tubular, about threequarters length of trunk, on right side of nerve cord (Fig. 2F). Gonoduct of holotype contains few round eggs. Gonostome stalked, located on one side near distal end of gonoduct, with minute lobes around margin (Fig. 2F). Except for foregut, rest of intestine and blood system damaged in holotype. In paratype, foregut is straight tube. Pharynx is somewhat dilated, clearly demarcated from oesophagus. Intestine filled with fine sand not moulded into faecal pellets. Cloacal chamber is thick and bulbous. In paratype dorsal vessel is long, passing anteriorly and entering proboscis. Neurointestinal vessel arises as single vessel and splits into two vessels which open separately into ventral vessel. Anal vesicles small, tubular, slightly distended distally, opening into cloacal bulb (Fig. 2G). Distal ends of vesicles fastened to body wall by thin mesenteric strands.

REMARKS

The new genus Bengalus n. gen. is nearest to the genus Charcotus in possessing a single gonoduct, tubular anal vesicles and in lacking ventral setae. In both genera, the anal vesicles open into a cloacal bulb. In the genus Bengalus n. gen., however, the gonoduct is long and tubular and the gonostome is located on one side near the distal end of the gonoduct. Furthermore, in the genus Charcotus the mouth is located in an oral cup formed by the inflection of the lateral margins of the proboscis proximally and the body wall is covered with thick papillae.