Sphaerodorum Örsted, 1843
Sphaerodorum olgae Moreira & Parapar, 2011
Voucher specimen. SEA LION: stations 13MFA, 18MFA and 28MFC.
Diagnosis. Small-sized species; the largest voucher (13MFA) is a complete specimen with elongated, distally tapering body; voucher specimen 3.5mm long, 0.5 mm wide, for about 40 chaetigers. Body elongated, tapering; body surface papillated; yellowish in ethanol. Prostomium bluntly rounded, fused to peristomium; with median antenna and three pairs of lateral prostomial appendages; all very short, digitiform.
Two macrotubercles per chaetiger; each dorsal to parapodia; spherical to pear-shaped, provided with terminal papilla. From chaetiger 2 posteriorly two microtubercles per chaetiger, dorsal to macrotubercles, with a basal collar and a long terminal papilla. Papillae on all body surfaces. About four irregular rows of about 10 small papillae per each row covering dorsum, relatively densely distributed, additionally about 2 papillae per row between macro- and micro tubercle; in venter about 10 small papillae in about 2-3 irregular rows.
Parapodia uniramous; conical. Parapodia of first chaetiger in ventral position; following parapodia lateral. Parapodia with about 10 digiform papillae on all surfaces. Strongly curved hooks in first chaetiger (one per parapodium), visible in ventral view. Chaetae about 4 per fascicle, many broken off, and those remaining clearly simple, appearing somewhat spear-shaped with small subdistal boss, distal end falciform, pointed.
Remarks. The specimens are consistent with genus Sphaerodorum Örsted, 1843 as it possesses 2 rows of macortubercles, large hook on chaetiger 1 and simple chaetae, unlike similar genus Ephesiella Chamberlin,1919 which has compound chaetae. This genus is represented in the region by two species Sphaerodorum indutum Fauchald, 1974 known from Scotia Sea to Peter I Island and S. olgae Moreira & Parapar, 2011 from Bellingshausen Sea. Falkland Islands specimens correspond well to S. olgae in the form of recurved hooks on chaetiger 1, form and number of simple chaetae and pattern of papillation on dorsum and parapodia. Full description of S. olgae and comparison with other known species is given by Moreira & Parapar, 2011.
