Prostomium rounded pentagonal. Acicular lobes triangular. Prechaetal lamellae rudimentary, more or less obviously bilobed. Postchaetal lamellae of the notopodia unequally bilobed: the upper lobe rounded and much bigger than the acicular lobes. Postchaetal lamellae of the neuropodia simple, oval to triangular, about as long as the acicular lobe. Neuropodia with accessory cirrus on the dorsal face. Gills start at chaetiger 2-3 and continue to the end of the body (A. rubella-detail). Proboscis with 14 longitudinal rows of 22-40 papillae.
Up to 80 mm for 120 segments.
Dorsum reddish or pink to flesh-coloured. Ventral side bluish.
Lower sublittoral to 1100 m.
Arctic, North Atlantic to Mediterranean, Adriatic, whole North Sea, Skagerrak and Kattegat.