Two new species of the family Hydrobiidae (Mollusca: Caenogastropoda) from Austria

Two new species of the family Hydrobiidae from Austria are described. One belongs to the genus Belgrandiella A. J. Wagner, 1928, the second is allocated to Bythiospeum Bourguignat, 1882. The crenobiontic Belgrandiella species is characterized by one autapomorphic character state of the genital system and by a unique combination of states which are shared with other species. The second species, a stygobiont, is tentatively attributed to Bythiospeum, because its description is based only on shell characters. Both species are known from very restricted ranges corresponding to the distributional pattern of their congeners. In addition, data of 13 abiotic parameters measured over a period of more than 5 years in the springs where the new species were found are presented. The Values of these parameters are characteristic for natural, carbonate brooks. Contamination with fecal bacteria suggests influence through agriculture or may be caused by feces of mammals. Chemically, agriculture and forestry appear to have no significant impact on the springs investigated.