Carapace suboval, much broader than long, dorsal surface relatively flat with numerous small transverse, setose carinae or tubercles; frontal region produced anteriorly, median and submedian lobes usually equally developed, acute or subacute; outer ventral margin of orbit with broad U to V-shaped incision. Antero-lateral margins of carapace setose ventrally and with spinous curved teeth. Chelipeds equal in size and stout, dactylus and propodus with longitudinal carinae, carpal spine broad and acute; pereiopods relatively thin, dactylus-carpus of the second to fourth with longitudinal carinae, propodus with one longitudinal ventral carina (setose on second pereiopod) extending length of margin and a secondary inconspicuous distal carina extending at the most half the length of propodus; dactylus of second to fourth pereiopods styliform, of fifth broadly lanceolate without a median carina.
Carapace length up to 22 (40) mm.
Depth range from 5 to 150 metres, on sand, muddy sand and gravel. Ovigerous January-October, larvae every month.
Carapace and pereiopods reddish-brown to mauve, epibranchial regions with band of white spots curving into mesogastric regions; dactylus of fifth pereiopods bright blue.
Shetland, Orkney, Viking, Moray Firth, Aberdeen, Firth of Forth, Northumberland, Dogger, Yorkshire, Wash, Thames, East Channel, Wight, Portland, Channel Isles, Plymouth, Scilly Isles, North Cornwall, Bristol Channel, Liverpool Bay, Isle of Man, Dublin, Belfast, Clyde & Argyll, Minch, Lewis, Mayo, Galway Bay, Fastnet, Cork.