Taxonomy
Descriptions
Anterior part with 22 chaetigers, probably only few chaetigers missing. Length 1.9mm; width 0.27mm with parapodia, 0.17 without. Prostomium semi-circular, anterior margin slightly pointed. Median antenna at base thinner than at tip, inserted in middle of prostomium on small ceratophore. Lateral antennae near anterior margin, similar in shape, slightly shorter. Palps not visible from dorsal, ventrally small filiform appendices, in diameter less than the eyes, which can be regarded as palps. 2 small eyes behind the lateral antennae, the 6 main eyes at the posterior margin of the prostomium. The buccal segment is merged with the prostomium and not as clearly seperated as in S. reducta. Tentacular cirri inserted next to the eyes. All appendices are weakly annulated. The separation of the segments is in the anterior part only visible from the sides, from 9th chaetiger more clearly separated -here the segments are filled with sperm or spermatocytes and therfore more pronounced.
Parapodia digitiform, bearing a distally knobbed acicula, acicula in chaetigers 2-5 slightly enlarged. Dorsal cirri similar in length throughout, about half as long as segments are wide, becoming thinner towards the posterior end. Ventral cirrus in the 1st segment short, the following becoming longer, more or less clearly annulated, in the last parapodia longer than chaetae and almost as long as dorsal cirri.
 Compound chaetae with distal spur at the tip of the shafts. Blades serrated, distally slightly bifid, dorsally longer than ventrally. |
 Dorsal simple chaeta present from chaetiger 1, similar to that of S. reducta (slightly bent upwards, knobbed tip). |
Pharynx with papillae, tooth at anterior end. Proventriculum from 2nd to 6th segment with 40 fine glandular rows.
Differs from other species mainly by the reduced palps. Furthermore the aciculae are not as much enlarged as in other species. Nevertheless the species is placed into the genus Streptosyllis, because the shape of the appendices, the shape of the aciculae and the shape of the dorsal simplae chaetae are very similar to other Streptosyllis species. The small filiform palpi of S. bidentata Southern are likewise not visible from dorsal and can be regarded as reduced.
Sources
Distribution
Ecology
fine sand
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