gradiens, Hypsagonus Herzenstein [S. M.] 1890:116 [26] [Mélanges Biologiques, tirés du Bulletin physico-mathématique de l'Académie Impériale des Sciences de St. Pétersbourg v. 13; ref. 2149] Avacha Bay, Petropavlovsk, Kamchatka. Syntypes: ZIN 1430 (1), 1483 (2), 1484 (2), 5468 (1, dry, missing), 8723 (2). On p. 26 of Bull. Acad. Imp. Sci. St. Petersbourg (n. s.) v. 2. •Synonym of Hypsagonus quadricornis (Cuvier 1829) -- (Lindberg & Krasyukova 1987:295 [ref. 15964], Kanayama 1991:17 [ref. 19261], Sheiko 1993:75 [ref. 21227], Parin et al. 2002:S98 [ref. 28300]). •Synonym of Hypsagonus quadricornis (Valenciennes 1829) -- (Sheiko & Mecklenburg 2004:3 [ref. 27591], Parin et al. 2014:289 [ref. 33547]). Current status: Synonym of Hypsagonus quadricornis (Valenciennes 1829). Agonidae: Hypsagoninae. Habitat: marine.