The freshwater molluscs of Serbia: Annotated checklist with remarks on distribution and protection status Author Marković, Vanja Author Gojšina, Vukašin Author Novaković, Boris Author Božanić, Milenka Author Stojanović, Katarina Author Karan-Žnidaršič, Tamara Author Živić, Ivana text Zootaxa 2021 2021-07-16 5003 1 1 64 journal article 218052 10.11646/zootaxa.5003.1.1 aceedc3f-3f24-490c-8046-7528c30aac10 1175-5326 5120059 8C98CC0B-18AF-418A-A794-AA3CA9CB7409 16. Bythinella opaca (M. von Gallenstein, 1848 ) Findings in Serbia . Bythinella opaca opaca : Karaman & Karaman (2007) . Bythinella schmidti schmidti : Radoman (1983) . Bythinella opaca : Jaeckel et al. (1958) . Morphology . Minute snails, up to 3.3 mm high. Shell is cylindrical-conical. Aperture is ovoid, umbilicus is slit like, or closed. For more details see Radoman (1983: 172 , pl. 12, fig. 204). Distribution and ecology . Alpine and Dinaric spring species. In Serbia , the most common representative of the genus. Reported from springs and brook systems from Ibar, Drina and Zapadna Morava catchments. Other remarks . Being the only widely distributed species of the genus, and with fairly isolated spring populations, a few subspecies of this snail were recognized ( Radoman 1983 ). On the IUCN Red List it has been assessed as LC ( Fehér 2010 a ).