Prostomium bluntly conical, with two or four eyes, without antenna. Two long palps present.
First segment with a ventral ‘lip’ and two dorsal, cylindrical gills, quite similar to the palps. Second chaetiger with a dorsal collar between the notopodia.
7th or 9th and following neuropodia with capillary chaetae, 4-10 hooded hooks with 4 distal teeth and a bigger subdistal tooth, and a spine. Notopodial chaetae capillaries (S. benedicti-parapodium).
Pygidium weakly bilobed.
Up to 10 mm for 50 segments.
White or reddish.
Brackish waters around the North Pacific, North Atlantic to Mediterranean, Black Sea, North Sea and Baltic Sea.