(M. Sars, 1872)
Body long, slender and cylindrical. Prostomium elongated, pointed, without an obvious caruncle; the posterior point free and reaching the middle of the first chaetiger. 4 eyes in trapezoid arrangement.
Notopodial postchaetal lobes in the segments with gills big, triangular, leaf-like, on the first and posterior chaetigers smaller, oval.
Anterior parapodia with winged capillaries only. From neuropodium 29-35 onwards also 4-5 hooks present. From notopodium 35-42 onwards 3-5 hooks present (A. oxycephala-detail).
Gills completely separate from the postchaetal lobes, 20-30 pairs, starting at chaetiger 2.
Pygidium with 6-8 short cirri.
Up to 100 mm for 200 segments.
Anterior part yellowish or greenish, posteriorly darker.
Eulittoral to 70 m.
North Sea to Öresund, Atlantic, Mediterranean, Black Sea Pacific and Indian Ocean.