Most easily confused with Gammarus locusta ; urosome segments 1 to 3 with prominent angular dorsal humps, spine groups with a few short setae. Epimeral plates 2 and 3 with the distal angle acutely produced, plate 3 posterior margin without or with one small setule, plate 2 with two or three small setules. Head with the lateral lobes sloping forwards, upper angle produced, post-antennal sinus shallow; eyes moderately large, kidney-shaped. Antenna 1 peduncle sparsely setose, article 1 without or with one ventral setal group, article 2 with one or two setal groups, article 3 without or with one setal group (excluding apical setae); accessory flagellum elongate, about twice the length of the peduncle article 2, up to about 12-articulate. Antenna 2 peduncle setose, setae on the inner surface of the peduncle and flagellum often curved or curled distally; calceoli absent. Mandible palp article 1 devoid of setae, article 3 with two setal groups on the outer surface, ventral setae comb-like, graduated, becoming shorter proximally. Male gnathopod 1 propodus with a large truncated median palmar spine well separated from the graduated angle spines, palmar margin weakly sinuous, proximal posterior margin with only three to five setal groups. Male gnathopod 2 propodus much broader than gnathopod 1 and the palm less oblique, a large truncated spine well separated from the graduated angle spines. Female gnathopod 1 propodus suboval, palm oblique; gnathopod 2 propodus elongate rectangular, palm transverse. Pereiopod 3 merus anterior margin with two setal groups each with a spine, posterior margin with about eight setal groups; carpus without anteromarginal setae, posterior margin with setae increasing in length distally. Pereiopod 4 merus with a single anteromarginal spinule. Pereiopod 5 basis more than one and a half times as long as wide, distal angle freely produced. Pereiopod 6 basis with posterior margin weakly concave. Pereiopod 7 basis much more than one and a half times as long as wide, distal angle not freely produced but with a pair of slender spines, posterior margin almost straight distally, setae on the merus and carpus not more than twice as long as the associated spines. Uropod 3 inner ramus slightly shorter than the outer one, margins with spines and plumose setae. Telson lobes with one to three lateral spines, three apical spines, one subapical spine, each group with a few short setae.
Up to 19 mm.
In the Mediterranean found in fully marine habitats, depth range about 0 to 15 metres, tolerates reduced salinities.
Mediterranean, locally common, Black Sea; Atlantic coast of Europe to English