Body relatively small, broad, with up 64 segments.
Prostomium almost rectangular with a straigth edge anteriorly, without an obvious caruncle. Four eyes in a trapezoid arrangement.
Notopodial postchaetal lobes rectangular, high and broad, posteriorly becoming smaller.
Neuropodial postchaetal lobes rectangular to oval, smaller than notopodial ones.
Gills from chaetiger 1 to near end of body; only in anterior segments partially fused with postchaetal lobes. The first gill only half as long as the other ones.
All parapodia with finely winged capillary chaetae, from chaetiger 16-21 also 7-10 bidentate hooded hooks in neuropodia (S. goniocephala-detail).
Pygidium with two oval cirri, situated ventrally.
Up to 13 mm for 64 segments.
In alcohol colourless.
On sand, 8-16 m deep.
Not common, Kattegat, Öresund, the Netherlands.