Coxal plate 1 more strongly produced in male than in female, acute. Eyes small, rounded-oval. Antenna 1 peduncle article 1 robust, article 2 long and slender, article 3 small, flagellum up to about 15-articulate: accessory flagellum 4-articulate. Antenna 2 little shorter than antenna 1, peduncle articles 4 and 5 about equal, flagellum very short, 5-articulate. Male gnathopod 1 robust, basis broad with a small hook-like process on the inner proximal margin, carpus and propodus broad, densely fringed with long setae, palm with a large tooth-like process and a stout spine. Female gnathopod 1 propodus much larger than the carpus, palm oblique, convex, delimited by a large spine. Male gnathopod 2 basis, anterodistal angle with a curved tooth, propodus shorter than the carpus, both densely setose, palm short, convex. Female gnathopod 2 basis with a small distal process, propodus longer than the carpus. Pereiopods 3 and 4 dactylus only about half to three-quarters of the length of the propodus. Pereiopod 7 extremely elongate. Uropod 2 inner ramus longer than the outer one; uropod 3 rami about equal.
Up to about 6 mm.
Whitish, with transverse brown bands.
Intertidal and shallow subtidal, amongst algae, especially the holdfasts of Laminaria , and sponges.
North Atlantic, American and European coasts; from south and west Norway to the Mediterranean.