Antenna basally somewhat swollen. Nuchal slits oblique.
Notopodial postchaetal lobes in the first chaetigers small and oval, posteriorly becoming long and filamentous.
Neuropodial postchaetal lobes papilla-like.
Modified neuropodial chaetae with a distinct hood and terminal prolongation (that often falls off), starting at chaetiger 19-70.
Up to 25 pairs of gills, starting at chaetiger 4.
Pygidium with two long and one short cirrus.
Up to 8 mm for 75 segments.
Living animal yellowish, with dark green pigmentation. In alcohol prostomium, gills and dorsolateral part of anterior segments with brown pigmentation.
Arctic, North Pacific, Atlantic to Paraguay, Mediterranean, northern North Sea to Skagerrak.