Protobonellia Ikeda 1908

Protobonellia sp. (Fig. 5C)

MATERIAL EXAMINED. — East Equatorial Atlantic Ocean. West African continental margin, ZAIANGO-BIOL 2, KGS 16, 07°28.75’S, 11°32.43’E, 1362 m, 28.VIII.2000, 1 ♀.

DESCRIPTION

Colour of proboscis and trunk of preserved specimen is cream. Specimen is extremely small, total length including proboscis is 8 mm. Proboscis is truncate, 3 mm in length; lateral margins curl inwards and unite at base forming narrow lower lips ventral to mouth (Fig.5C). Trunk is oval (Fig. 5C), 5 mm long and about 2.5 mm across broadest part. Integument is thick and opaque. Anterior end of trunk covered with small, elongated papillae aligned roughly in transverse rows, remainder of integument is smooth. Genital pore not visible externally. Single ventral setae found in same vial is from the left side of animal as only basal cylindrical part of right seta was present in setal sac of specimen.Setae golden-yellow, consisting of cylindrical shaft with slightly curved terminal end tapering towards tip.

Single, minute, tubular gonoduct located on left side of nerve cord with basally located gonostome. Rest of internal organs missing probably damaged due to poor preservation.

REMARKS

Distinguishing features of the genus Protobonellia include the presence of a truncate proboscis, two ventral setae, a single gonoduct (left) with a basally located gonostome and anal vesicles that are elongate and dendritic.

Five species are currently known in the genus Protobonellia. The specimen on hand resembles P. mitsukurii in the structure of the proboscis but differs in lacking an interbasal muscle.

As the present specimen is extremely small with most of the internal organs missing, its taxonomic position is uncertain and will have to await the collection of additional material from that region.