Carapace convex longitudinally, dorsal surface smooth with numerous club-shaped setae, sub-median lobes very broad, margins sometimes minutely serrate or tuberculate. Second and third peduncular segments of antenna not touching margin of front. Antero-lateral margins of carapace with five spinose teeth, first and second smaller than rest. Chelipeds stout, carpus tuberculate or spinose, larger cheliped with propodal surface tuberculate, smaller with spiniform tubercles; second and fifth pereiopods moderately stout and setose, usually with numerous club-shaped setae, upper margin of carpus often with a distal spine. Female chelipeds less robust and less spinose than in male.
Carapace length up to 9 (15) mm.
Depth range from low water mark to 75 metres. Ovigerous April-August, larvae May-September.
Carapace reddish brown, sometimes purple, chelipeds brownish to purple, inner surfaces orange to cream; pereiopods with alternating bands of purple and white or grey.
Yorkshire, Wash, Thames, East Channel, Wight, Portland, Channel Isles, Plymouth, Scilly Isles, Bristol Channel, Cardigan Bay, Anglesey, Liverpool Bay, Solway, Isle of Man, Dublin, Belfast, Clyde & Argyll, Minch, Galway Bay, Fastnet, Cork.