Exogoninae Langerhans, 1879
Genus Sphaerosyllis Claparède, 1863
Sphaerosyllis lateropapillata Hartmann-Schröder, 1986
Voucher. LOLIGO station L2FA
Diagnosis. Voucher is a complete specimen (some damage as dorsal cirri on many anterior and mid chaetigers are missing); small, slender species; 5.5 mm long, 0.3mm wide for 54 chaetigers; colour in alcohol pale yellow. Body integument, palps and parapodia papillated; papillation relatively sparse, dorsum more densely papillated then venturm; dorsally a distinct arrangement appears (best observed when Shirla-stained) with 2 longer, slender papillae positioned laterally on each segment, forming regular longitudinal rows across the body; small rounded papillae in between and across the dorsum.
Prostomium about twice as wide as long bearing three antennae and two palps. Palps short, fused along their length, short, slightly ventrally folded, with small papillae. Antennae smooth, flask-shaped, of equal size, with median antenna positioned posteriorly to the lateral ones. Two pairs of large, red eyes in trapezoid arrangement. Pharyngeal tube extending through 4 chaetigers, with proventricle extending through chaetigers 5-7, with about 12 large muscular bands. First segment achaetous laterally with a pair of smooth, short, flask-shaped tentacular cirri (similar to antennae).
Parapodia uniramous, distinct, papillated, with one of the longer lateral papilla positioned near the paprapodial base. Dorsal cirri often missing (missing in most anterior chaetigers), where present flask-shaped (similar to antennae and dorsal cirri) becoming progressively elongated in posterior chaetigers; ventral cirri first clearly observed from chaetiger 20, long thin, cirriform, inserted near parapodial base.
Chaetae of essentially two different types: type 1 simple dorsal chaeta; unidentate, spine-like, present in all chaetigers, anterior one with more acute tip, posterior ones with rounded tip, usually one per fascicle, two observed in mid body segments; simple ventral chaetae not observed (likely broken off); type 2 compound, heterogomph, falcigers with curved, unidentate, falcate blades, blades reduce in length in dorsoventral gradation in anterior parapodia; present in all chaetigers; 7 anteriorly, 5 posteriorly per fascicle. Acicula solitary, distally bent at right angle as typical for the genus. Pygidium wide, round lobe provided with two, lateral, elongated flask-shaped anal cirri (similar to dorsall cirri, but much longer).
Remarks. Falkland Island specimens agree well with Sphaerosyllis lateropapillata (Hartmann-Schröder & Rosenfeldt, 1992) described from Antarctic Peninsula (63°16.40'S, 63°42.78'W), 300m. As the name suggests papillae are most distinct laterally, where they are longest. San Martín (2005) also reported this species from Australia, although palps seem longer in those specimens compared to those from the Southern Ocean, Falklands Islands.