Alomasoma, Zenkevitch, 1958

Biseswar, Ramlall, 2006, Additions to the deep-sea echiuran (Echiura) fauna of the North-East Atlantic, Zoosystema 28 (4), pp. 853-864 : 862-863

Alomasoma sp.

( Fig. 4B )

MATERIAL EXAMINED. — Porcupine Abyssal Plain, BEN- GAL 5, Discovery 231, stn 13368#48, 48°49.64’N, 16°30.12’W, 4841 m, 17.III.1998, 1 ♀.

DESCRIPTION

Colour of trunk cream, proboscis white in preserved state. Proboscis truncate, 0.75 mm long, flattened and rounded distally; lateral margins curl inwards and unite proximally forming narrow lower lip ventral to mouth ( Fig. 4B ). Trunk oval ( Fig. 4B ), 2.5 mm long and 2 mm across broadest part. Integument smooth, thin and transparent. Ventral setae absent.

Gonoducts one pair, sac-like with eggs which unite proximally and open to exterior by single genital aperture. Gonostomes basal in position. Intestine filled with fine sand not moulded into faecal pellets. Rest of internal organs damaged.

REMARKS

The present specimen has been assigned to the genus Alomasoma Zenkevitch, 1958 on account of the presence of two gonoducts which unite proximally and open to the exterior via a common gonopore. This sexually mature specimen with a trunk length of 2.5 mm is extremely small in comparison with all the other species described in the genus. Therefore, it seems very likely that the specimen on hand represents an undescribed species. However, it is undesirable to erect a new species on the basis of single, incomplete individual. Additional material in the future will probably shed more light on its taxonomic position.

Figures

FIG. 4. — A, Prometor sp., lateral view of anterior part of female; B, Alomasoma sp., ventral view of female; C, Bruunellia sp., ventral view of female. Abbreviations: pr, proboscis; se, seta. Scale bars: A, C, 0.5 mm; B, 1 mm.