semipellucidus, Gobius Kessler [K. F.] 1877:15 [The Aralo-Caspian Expedition; ref. 2597] Mouth of Karasu River, Astrabad Bay, Caspian Sea, Azerbaijan. Holotype (unique): ZIN (not found in 1996). •Probably a synonym of Proterorhinus marmoratus (Pallas 1814) -- (Coad 1995:31 [ref. 23608], Vasil'eva 1998:145 [ref. 23591], Ahnelt & Duchkowitsch 2002:[2] 914 [ref. 27148]). •Synonym of Proterorhinus marmoratus (Pallas 1814) -- (Pinchuk et al. in Miller 2004:72 [ref. 27853]). •Valid as Proterorhinus cf. semipelucidus (Kessler 1877) -- (Neilson & Stepien 2009:677 [ref. 30119], Neilson & Stepien 2009:98 [ref. 30487]). •Synonym of Proterorhinus nasalis (De Filippi 1863) -- (Parin et al. 2014:503 [ref. 33547], Dyldin et al. 2020:90 [ref. 37569], Jouladeh-Roudbar et al. 2020:246 [ref. 37983], Parenti 2021:77 [ref. 38603]). •Valid as Proterorhinus semipellucidus (Kessler 1877) -- (Berg 1949:1102 [ref. 20662], Kvach et al. 2021:53 [ref. 38595], Zarei et al. 2021:[6] [ref. 38799]). Current status: Valid as Proterorhinus semipellucidus (Kessler 1877). Gobiidae: Gobiinae. Distribution: Eurasia: Caspian Sea and Sea of Azov basins. Invasive in Volga River drainage and northeastern Baltic Sea. Habitat: freshwater, brackish.