Streptosyllis reducta Hartmann-Schröder 1960
Length 1mm; width 0.13mm without parapodia, 0.19mm with parapodia; for 16 chaetigers. Prostomium semi-circular, anterior margin slightly pointed. Median antenna filiform, basal slightly thicker than distal, inserts in middle of prostomium on small ceratophore. Lateral paired antennae insert near anterior margin of prostomium and are similar in shape to the median antenna, but one third shorter. Palps not visible, neither dorsal nor ventral, probably reduced. Four small reddish eyes, in trapezoid arrangement on posterior part of prostomium. Buccal segment not clearly seperated from prostomium, as long as the following segments, bearing two pairs of tentacular cirri which are - like the antennae - thinner at the base than at the tip. Dorsal tentacular cirri slightly shorter than lateral antennae. Following segments similar to buccal segment, clear separation between segments only from chaetiger 4 onwards. The surface of the animal is covered by tiny sphaerical papillae which are more numerous posteriorly.
Parapodia rectangular with small tip, bearing one distally knobbed acicula. Acicula similar throughout all parapodia and nowhere notably enlarged. Ventral cirri stout, digitiform, shorter than parapodium. Dorsal cirri in shape and length similar to antennae and tentacular cirri, reaching in length the tip of the chaetae.
Compound chaetae with serrated blades, blades in dorsal chaetae almost twice as long as in ventral ones. No notable differences between the compound chaetae in anterior and posterio chaetigers. Blades serrated and maybe distally bifid, it cannot be observed if the subapical tooth is part of the serration or more prominent and thus has to be regarded as a secondary tooth.
The tip of the shafts is smooth and very fine, no details visible.
A simple dorsal chaeta present from the 1st segment, slightly bent upwards, distally knobbed and serrated on lower margin.
The opening of the pharynx is located under the prostomium. The pharyngeal tooth is located at the anterior end. Pharynx from 2nd to 4th chaetiger with 38 very narrow glandular rings.
Pygidium semi-circular, the present exemplar possesses only one small appendix. Either both lateral anal cirri are broken and this one is an additional appendix or only one anal cirrus is broken.
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.
