Body short, dorsal surface convex.
Prostomium with a pair of antennae without cirrophores, a pair of bi-articulate palps of approximately the same length as the antennae; 2 pairs of eyes in a trapezoid arrangement.
First dorsal tentacular cirri slightly longer than first ventral dorsal tentacular cirrus, second dorsal about twice as long as second ventral, reaching back to chaetiger 4.
Pharynx with a pair of denticulate jaws; paragnaths entirely absent; oral ring with single papillae in each group Vl and a row of 5-9 papillae in group Vll-Vlll; maxillary ring smooth, papillae absent .
Parapodia of the first 2 chaetigers uniramous with 3 lobes. Remaining parapodia all biramous, with 4 lobes. Notopodial lobes of similar size and shape, bluntly pointed in anterior chaetigers, becoming more finely pointed in mid-body and posterior chaetigers; notopodial acicular lobe bilobed, with poorly developed upper lobe. Neuropodial lobes shorter than notopodial ones; neuropodial acicular lobe with prominent postchaetal lobe on all chaetigers, ventral neuropodial lobe becoming thinner posteriorly. Dorsal cirri in the anterior region approximately as long as dorsal notopodial lobe, in the posterior region they are shorter; ventral cirri all shorter than ventral neuropodial lobe. Notopodial chaetae homogomph spinigers neuropodial chaetae homogomph spinigers and heterogomph falcigers above the acicula, heterogomph falcigers with or without heterogomph spinigers with short blades. Chaetae are more abundant anteriorly, becoming fewer in number posteriorly (W. glauca-detail).
Up to 35 mm for 65 chaetigers.
Body reddish, brownish or greenish with dark spots or transverse bands on each segment.
Body divided into three regions, an anterior region of 14-15 chaetigers in males and 15-18 in females, followed by a region with modified parapodia of 16-45 chaetigers in males and 16 in females, and finally an unmodified tail region. The dorsal cirri of the first 7 chaetigers of males are modified, as are the ventral cirri of the first 7. In females, no modification of anterior cirri has been noted. Metamorphosed parapodia in males develop accessory flaps at the base of the dorsal cirrus, on the posterior surface of the neuropodial acicular lobe and at the base of the ventral cirrus. In females, the parapodia of the middle region show no accessory flaps. In males, the dorsal cirri of the middle region remain smooth, and no pygidial rosette is present. In both sexes chaetae develop in the middle region, completely replacing the ordinary chaetae in males, but occurring alongside the ordinary chaetae in females. In the tail region of males the parapodia are uniramous, the notopodial lobes being entirely absent, whilst the dorsal cirri are enlarged and one or 2 simple acicular chaetae are present in each parapodium.
In mucous tubes amongst algae and sedentary invertebrates, in the intertidal or shallow subtidal zone.
Northern Atlantic to Mediterranean and Black Sea.