(Costa, 1851)
Description:
Pereion and pleon segments with a low dorsal keel; pereion segment 7 and pleon segments 1 to 3 each with a tooth on the posterior margin. Coxal plates 1 and 2 narrow, tapering slightly, setose; plates 3 and 4 broad. Epimeral plates 1 to 3 distal angle with a small tooth, posterior margin convex with a few small setules. Head with a short slender rostrum, lateral lobes sinuous, upper angle produced; eyes moderately large in female, very large in male. Female antenna 1 one-third of the body length, reaching to the mid-point of the flagellum of antenna 2, peduncle article 1 with a very small, distoventral tooth, flagellum up to about 25-articulate. Female antenna 2 peduncle article 5 longer than article 4, flagellum up to about 25-articulate. Antenna 1 and 2 peduncle articles robust in male, confronted margins with groups of fine short setules, flagellum slender, longer than in female. Gnathopod 1 basis robust, margins setose, propodus longer than the carpus, oval, palm oblique, weakly convex, delimited by two or three slender spines; merus, carpus and propodus very strongly setose. Gnathopod 2 longer and more slender than gnathopod 1, propodus equal or slightly longer than the carpus, propodus narrowly oval to subrectangular, palm oblique, weakly convex, delimited by three or four long spines; merus, carpus and propodus moderately setose but less dense than in gnathopod 1. Pereiopods 3 and 4 merus equal to the length of the carpus and propodus together, carpus very short especially in pereiopod 4 and much shorter than the propodus; in male pereiopods 3 and 4 with many long plumose setae. Pereiopod 5 basis with the posterodistal margin triangularly produced. Pereiopod 6 basis not produced at the distal angle, posterior margin setose. Pereiopod 7 basis posterior margin broadly rounded, weakly toothed, setose. Coxal gills deeply and distinctly pleated. Uropod 3 rami three times the length of the peduncle, margins spinose and setose. Telson longer than wide, cleft to three-quarters of the length, each lobe with an apical spine and setule.
Size:
Up to about 10 mm.
Colour:
Reddish white, with small brown markings on the dorsal surface and the coxal plates.
Habitat:
Depth range from the lower intertidal to about 75 metres.
Distribution:
Mediterranean; Atlantic coast of Europe and North Africa from Senegal to the Irish Sea and southern North Sea.