Head with the lateral lobes rounded; eyes small, oval. Coxal plate 1 in male acutely prolonged, in female rounded; epimeral plate 3 with a small posterodistal tooth and a seta, posterior margin convex; epimeral plate 2 posterior margin concave. Antenna 1 peduncle article 2 a little longer and more slender than article 1, article 3 small, flagellum very slender, up to about 30-articulate; accessory flagellum 5 or 6-articulate with the terminal article minute. Antenna 2 much shorter than antenna 1 and more robust, moderately setose, flagellum shorter than the peduncle article 5, about 5 to 7-articulate. Male gnathopod 1 extremely large, sparsely setose, basis long and robust, merus with an enormous pointed process reaching to the end of the elongate carpus, propodus long and narrow, dactylus broad and robust; in small male merus and carpus much shorter, propodus oval, moderately setose, palm convex, minutely toothed, delimited by a slender spine, dactylus with the inner margin toothed. Female gnathopod 1 propodus oval, longer than the carpus, palm oblique, convex, minutely toothed, delimited by a slender spine, dactylus inner margin toothed. Male gnathopod 2 basis oval, propodus subrectangular, palm oblique, straight, minutely toothed, delimited by a slender spine, posterior margin weakly concave distally. Female gnathopod 2 a little smaller and more slender than gnathopod 1, propodus rectangular, longer than the carpus, palm oblique, straight, minutely toothed, delimited by a slender spine. Basis of pereiopod 6 and 7 in male with a posterior lobe emarginate distally, merus weakly dilated distally; basis of pereiopod 6 and 7 in female without emarginate posterodistal angle. Pereiopod 7 very long and slender.
Up to about 9 mm.
Whitish or greenish, speckled with brown.
Locally common, intertidal to a depth of about 50 metres, amongst algae and hydroids.
All North Sea coasts; Atlantic from west Norway to Senegal; Mediterranean.