Petaloproctus borealis Arwidsson, 1906

Synonyms:
Petaloproctus tenuis var. borealis Arwidsson, 1906
Nicomachella tenuis Levinsen, 1883
Petaloproctus tenuis borealis Hartmann-Schröder, 1971
Petaloproctus borealis Imajima & Shiraki, 1982

Distinguishing characteristics
The head without cephalic plate, prostomium anteriorly broadly rounded.
Pygidium as an asymmetrical funnel with a smooth margin, dorsally very short and ventrally much longer.

Species description
Body long and cylindrical. The head without cephalic plate. Prostomium anteriorly broadly rounded, ocelli absent. 21 chaetigers. The notopodia bear capillary chaetae with feathery tips. Three first segments with ventral spines, following segments with a row of hooks. One pre-pygidial achaetous segment. Anus terminal. Pygidium as an asymmetrical funnel with a smooth margin, dorsally very short and ventrally much longer, without cirri. Tube - flattened, fixed to stones or muscle shells, strongly meandering, with crust of sand.

Size
Up to 44-73 mm for 21 chaetigers.

Color
Anterior body half to only 3rd chaetiger more or less weakly with red-brown pigmentation, following segments or also posterior segments irregularly spotted red.

Habitat
In mud mixed with stones. From sublittoral down to about 1700 m deep.

Mobility
Sedentary.

Feeding
Surface deposit feeder.

Life cycle

Distribution
Arctic, North Pacific, North Atlantic, northern North Sea, Skagerrak, Kattegat to middle Öresund.