Izolované populace praménky Bythinella austriaca (Frauenfeld, 1857) (Gastropoda: Hydrobiidae) v okolí Prahy Isolated populations of Bythinella austriaca (Frauenfeld, 1857) (Gastropoda: Hydrobiidae) in Prague surroundings (Czech Republic)

This paper completes the knowledge of an occurrence of Bythinella austriaca (Frauenfeld, 1857) (Gastropoda: Hydrobiidae) in surroundings of Prague – capital of the Czech Republic. However, this species is not rare in the eastern part of the Czech Republic, sites on north-western otskirts of Prague are isolated far from the main distribution area. Altogether, 63 sites potentially suitable for B. austriaca were investigated in this area, and occurrence of this species was confirmed in 11 of them. B. austriaca was found in springs, rivulets and small brooks, more numerous populations were found in springs. Historical occurrence data in this area were compared with results of research done in 2003, 2006 and 2010. Actual situation of this species in Prague surroundings is problematic and survival of some populations is not guaranteed.