Protobonellia mitsukurii Ikeda 1908

Protobonellia mitsukurii Ikeda, 1908 (Fig. 5A, B)

MATERIAL EXAMINED. — East Equatorial Atlantic Ocean. BIOZAIRE 2, KGS 39, stn D, 05°50.985’S, 008°21.805’E, 3950 m, 25.XI.2001, 1 ♀.

DESCRIPTION

Proboscis is cream, trunk is beige in preserved specimen. Proboscis is 4.5 mm long, broad, truncate with a constriction at distal end (Fig. 5A). Lateral margins of proboscis unite at base forming narrow lower lip ventral to mouth. Trunk is ovoid (Fig. 5A), 3.5 mm long and 2.6 mm across broadest part, damaged at posterior end. Integument is thick and opaque. Elongated papillae are transversely aligned over entire surface of trunk more prominent and densely aggregated at anterior end. Ventral setae golden-yellow, 3 mm in length with straight cylindrical shaft and flattened, curved terminal blade, terminating in a pointed tip (Fig. 5B).

Only small, proximal fragment of gonoduct is present on left side of nerve cord. Gonostome not seen, probably damaged due to poor preservation Anal vesicles missing.

REMARKS

The genus Protobonellia is distinguished by the presence of a truncated proboscis, a pair of ventral setae and a single gonoduct with a basally located gonostome. The species P. mitsukurii was originally described by Ikeda (1908) from a single specimen from Sagami Bay, Japan. This species was later recorded and redescribed by DattaGupta (1975, 1981). Except for some minor differences,the present specimen approaches the descriptions given by the above authors. Unfortunately, the anal vesicles and other internal organs are damaged in the specimen on hand. According to Ikeda (1908), the anal vesicles are two slender tubes that bear numerous long-stalked funnels.

Protobonellia mitsukurii has been recorded in the North Atlantic by DattaGupta (1981). Its discovery in the east Equatorial Atlantic Ocean is a new record for this region which extends its range of distribution.