nonultimus, Gobius Iljin [B. S.] 1936:337 [Doklady Akademii Nauk SSSR, Ser. A (Comptes Rendus de l'Académie des Sciences de l'URSS), Leningrad v. 4; ref. 15280] 24 miles southwest of Ulsky Bank, Caspian Sea, depth 24 meters over bottom depth of 54 meters, Turkmenistan. Holotype (unique): No types known. •Synonym of Mesogobius batrachocephalus (Pallas 1814), but a valid subspecies -- (Miller in Whitehead et al. 1986:1055 [ref. 13677]). •May be a subspecies of Mesogobius batrachocephalus (Pallas 1814) -- (Coad 1995:30 [ref. 23608]). •Valid as Mesogobius nonultimus (Iljin 1936) -- (Berg 1949:1097 [ref. 20662], Pinchuk 1977:595 [ref. 8999], Coad 1995:30 [ref. 23608], Reshetnikov et al. 1997:755 [ref. 24702], Vasil'eva 1998:137 [ref. 23591], Pinchuk & Miller in Miller 2004:132 [ref. 27853], Bogutskaya & Naseka 2004:226 [ref. 28183], Neilson & Stepien 2009:97 [ref. 30487], Freyhof 2011:284 [ref. 31742], Jouladeh-Roudbar et al. 2015:898 [ref. 34062], Esmaeili et al. 2017:83 [ref. 35254], Esmaeili et al. 2018:65 [ref. 36089], Jouladeh-Roudbar et al. 2020:236 [ref. 37983], Parenti 2021:72 [ref. 38603], Zarei et al. 2022:173 [ref. 39576], Çiçek et al. 2024:306 [ref. 40789]). Current status: Valid as Mesogobius nonultimus (Iljin 1936). Gobiidae: Gobiinae. Distribution: Eurasia: Caspian Sea basin. Habitat: brackish.