Jesogammarus (Jesogammarus) ikiensis sp. n., holotype, male, 13.1 mm, NSMT-Cr 24107, Ishida, Iki, Nagasaki Prefecture, Japan. A peduncular articles 1–3, accessory flagellum, and flagellar articles 1–4 of antenna 1, medial view (posterio-marginal setae on peduncular articles 2 and 3 indicated by arrowheads) B peduncular articles 1–5 and flagellar articles 1–3 of antenna 2, medial view (posterio-marginal setae on peduncular articles 4 and 5 indicated by arrowheads) C calceolus of antenna 2, medial view D upper lip, anterior view E lower lip, ventral view F left mandible except palp, medial view G incisor and lacinia mobilis of right mandible, lateral view H palp of right mandible, medial view I maxilla 1, dorsal view J outer plate of maxilla 1, dorsal view K Maxilla 2, dorsal view.