Body wide, tapering posteriorly, integument smooth.
Prostomium with a pair of short antennae without cirrophores, a pair of biarticulate palps with short styles; 2 pairs of eyes in a trapezoid arrangement.
Dorsal tentacular cirri longer than ventral ones, second dorsal tentacular cirrus reaching back to chaetiger 6.
Pharynx with a pair of denticulate jaw; oral and maxillary rings with paragnaths in all groups; group I 1 and 2 conical, groups ll 8-12 conical, group III 6-9 conical, groups IV 12-19 conical, group V 2-3 conical, groups Vl single elongate bar, group VII-VIII approximately 40 cones of similar size in 2 distinct rows.
Parapodia of the first 2 chaetigers uniramous with 3 lobes.
Remaining parapodia biramous, with 4 lobes. In anterior chaetigers all lobes are of similar length, by mid-body dorsal notopodial lobe distinctly longer than the others, neuropodial acicular lobe being the shortest. Notopodial acicular lobe bilobed by chaetiger 6, with a distinct prechaetal lobe above the acicula, becoming smaller posteriorly. Dorsal cirri of similar length to dorsal notopodial lobe, ventral cirri shorter than ventral neuropodial lobe. Notopodial chaetae homogomph spinigers, neuropodial chaetae homogomph spinigers above the acicula with heterogomph spinigers and falcigers below.
Up to 190 mm for 125 chaetigers.
Body brownish green, parapodia reddish.
Body divided into 2 regions, an anterior region of 12-14 chaetigers in males and 17 in females, followed by chaetigers with modified parapodia. The dorsal cirri of the first 7 chaetigers in males and the first 5 in females are modified, as are the ventral cirri of the first 5 chaetigers in both sexes. Metamorphosed parapodia from the posterior part of the body develop accessory flaps at the base of the dorsal cirrus, below the notopodial acicular lobe, posterior to the neuropodial acicular lobe and at the base of the ventral cirri. The accessory flaps are better developed in males than in females. In males, crenulation develop along the lower edge of the dorsal cirri and a pygidial rosette is found. In both sexes, the ordinary chaetae are replaced by paddle chaetae in the modified parapodia.
An intertidal species, inhabiting rocky shores under stones and boulders, usually where there is an accumulation of sediment.
N.E. Atlantic, Mediterranean, N.W. Pacific, Indian Ocean.