(Bate and Westwood, 1861)
Body extremely robust and strongly laterally flattened, cuticle coarse and thickened, dorsal keel extending from the head to pleon segment 4, pleon segments 3 and 4 with a pronounced posterior angle; coxal plates large, plates 4 to 6 with a distinct transverse proximal ridge; epimeral plate 3 with the distal angle quadrate. Head with a small rostrum, lateral lobes strongly produced, downturned with a rounded apex; eyes large. Antenna 1 peduncle article 1 very large, anterior margin compressed with the distal angle prolonged into a large lobe, article 2 with a small anterodistal lobe, flagellum in female small, about 7-articulate; antenna 1 in male little longer than in female, flagellum about 9-articulate with article 1 elongate and setose; accessory flagellum absent. Antenna 2 in female short and slender, flagellum only about 4-articulate; in male flagellum filiform, as long as the body, peduncle robust, flagellum with calceoli. Gnathopod 1 subchelate, propodus narrowly rectangular, palm transverse and delimited by a pair of large spines. Gnathopod 2 very long and slender, weakly chelate. Pereiopods 5 to 7 robust, posterior margins densely setulose, basis and merus broadly expanded. Uropod 3 rami about equal, in female with few small spines, in male the inner margins with long plumose setae. Telson extremely long and narrow, about three times as long as wide, cleft to three-quarters of its length.
Up to about 8 mm.
Whitish, with an orange patch on each segment.
Usually in shallow water, depth range from 5 to 60 metres.
North-East Atlantic, North Sea, European coasts from southern Norway and Denmark to Portugal; western Mediterranean.