The egg capsules of Bythinella austriaca (Frauenfeld, 1856) with observations on the veliger and embryonic shell

Abstract

The world-wide distributed Hydrobiidae are the largest family of freshwater gastropods. The systematics of these small or minute gastropods remains unclear and little is known about their biology. This is particularly true of the genus Bythinella, minute inhabitants of springs in South and Central Europe. For instance, no data on their egg capsules can be found in the literature. In 1993-1994, while collecting material for another study, in St. Elias Spring, Eliasz6wka Valley, Krzeszowice, South Poland, I found egg capsules of Bythinella austnaca (Frauenfeld, 1856), containing eggs and embryos. The capsules, veligers and embryonic shells were found worth examining.