Chaetogammarus, MARTYNOV, 1924

Copilaș-Ciocianu, Denis, Palatov, Dmitry, Rewicz, Tomasz, Sands, Arthur F., Arbačiauskas, Kęstutis, Haaren, Ton Van, Hebert, Paul D. N., Grabowski, Michał & Marin, Ivan, 2023, A widespread Ponto-Caspian invader with a mistaken identity: integrative taxonomy elucidates the confusing taxonomy of Trichogammarus trichiatus (= Echinogammarus) (Crustacea: Amphipoda), Zoological Journal of the Linnean Society 198, pp. 821-846 : 833-834

GENUS CHAETOGAMMARUS MARTYNOV, 1924

Type species: Gammarus ischnus Stebbing, 1899 .

I n c l u d e d s p e c i e s: C h a e t o g a m m a r u s h y r c a n u s Pjatakova 1962, C. pauxillus ( Sars, 1896) , C. placidus ( Sars, 1896) , C. aearpachoaeskyi (Sars, 1894) and C. trichiatus Martynov, 1932 .

Non-included species: Echinogammarus karadagiensis Grintsov, 2009 and E. mazestiensis Marin & Palatov, 2020 will be transferred to a new genus (I. Marin, D. Palatov, and D. CopilaȘ- Ciocianu, unpub. obs.).

Amended diagnosis: Small- to large-sized species (≤ 15 mm); females smaller than males. Head with oblique anteroventral lobe, sometimes distally produced. Eyes large, reniform, well pigmented. Body non-carinate. Antenna 1 feebly setose, accessory flagellum two- to eight-segmented; antenna 2 usually shorter that antenna 1, without calceoli, deeply setose in males and less setose in females. Lower lip (labium) with mostly reduced inner lobes. Gnathopod 1 smaller than gnathopod 2, sexually dimorphic, stronger in males, propodus generally teardrop shaped; gnathopod 2 sexually dimorphic, stronger in males, propodus trapezoidal with oblique palmar margin. Basis of pereopods 5–7 without or with weak posteroventral lobes, dominated by spines. Uropod 3 with exopod about four to six times as long as wide, generally dominated by spines. Urosomites 1 and 2 without elevations, armed with clusters of spines; urosomite 3 with a pair of submedian spines. Telson deeply cleft into suboval lobes, bearing clusters of spines distally and submedially.

Synonymized genera: Trichogammarus Hou & Sket, 2016 .

Distribution: The native range of the genus is restricted to the Ponto-Caspian basin. Its species occur in the Caspian Sea at up to 500 m depth, and in lagoons, estuaries and lower stretches of rivers that drain into the Black, Azov and Caspian seas.