microstomus, Cottus Heckel [J. J.] 1837:147, Pl. 8 (figs. 3-4) [Annalen des Wiener Museums der Naturgeschichte v. 2 (no. 1) (for 1840); ref. 2079] Vicinity of Krakow, Poland. Holotype (unique): NMW 98212. •Synonym of Cottus gobio Linnaeus 1758 -- (Berg 1949:1145 [ref. 20662], Neelov 1973:593 [ref. 7219], Kottelat 1997:169 [ref. 22952], Sideleva 1998:151 [ref. 23595]). •Valid as Cottus microstomus Heckel 1837 (often dated 1839 or 1840) -- (Bogutskaya & Naseka 2004:187 [ref. 28183], Freyhof et al. 2005:160 [ref. 28259], Sideleva 2009:211 [ref. 30173], Goto et al. 2014:[11] [ref. 33456], Sideleva et al. 2018:3 [ref. 36393], Sideleva et al. 2022:54 [ref. 39468], Sideleva & Shidkov 2024:492 [ref. 41080]). Current status: Valid as Cottus microstomus Heckel 1837. Cottidae. Distribution: Eastern Europe: Black Sea basin (Dniestr River system) and southern Baltic basin (Vistula River and Neman/Nemunas River basins): Poland and Lithuania. Habitat: freshwater.