L. Forró szerk.: Miscellanea Zoologica Hungarica 7. 1992 (Budapest, 1992)

Nesemann, H.: Species composition and zoogeography of the invertebrate fauna at the lower reaches of the Lajta River

Family Valvatidae Valvata piscinaüs (O. F. Müller, 1774) Localities: Mosoni-Duna near Mosonmagyaróvár (Ungarisch Altenburg) 13. 9.1991 (H); Bruck, in secondary branches 16. 7.1991 (A). Vpiscinalis was infrequently screened from secondary branches. Valvata cristata O. F. Müller, 1774 Locality: Mosoni-Duna near Mosonmagyaróvár (Ungarisch Altenburg) 13. 9.1991 (H). This prosobranche snail occurs in the submerged vegatation zone of deadwater reaches. It is widely spread in Central and East European lowlands (Falkner 1989). Family Viviparidae Viviparus contectus (Millet, 1813) Localities: Rohrau, in secondary branches 1990,1991 (A); Rét-árok (Leithakanal) 1987 (A/H). The largest member of the Viviparidae family (Figs 20-21) was collected abundantly in several, slowly running branches of the Lajta. In contrast to Vacerosus, it prefers the stagnant water and mud bottom. Viviparus acerosus (Bourguignat, 1862) Localities: Mosoni-Duna at Mosonmagyaróvár (Ungarisch Altenburg) 13. 9. 1991 (H); Lajta at the confluence with the Mosoni-Duna 6. 9.1991 (H). This species is endemic to the Danube basin (Zilch & Jaeckel 1962). It is abundant throughout the whole Kisalföld and all large tributaries of the Danube, e. g. the neighbouring Rábca, Rába, Morava and Thaya rivers. In general, this Viviparus species is absent from the upper reaches of the Danube. Consequently, it occurs as far upstream as Vienna. Relicts of the warm, postgacial period still exist in the Bavarian reaches of the Danube (Schulte & Weinzierl 1989). V, acerosus does not enter the Lajta. Its occurence is restricted to the confluence with the Mosoni-Duna. Hirudinea Family Glossiphoniidae Glossiphonia complanata (Linnaeus, 1758) Localities: Mosoni-Duna at Mosonmagyaróvár (Ungarisch Altenburg) 13. 9. 1991 (H); Lajta at the confluence with the Mosoni-Duna 6. 9. 1991 (H); Nickelsdorf (Miklóshalma) 26. 10. 1991 (A/H); Rét-árok (Leithakanal) 11. 9. 1989, 30. 7. 1991 (A/H); Kleine Leitha (Kis-Lajta) near the Albrechtsmühle 30. 7.1991 (A); Brack, in secondary branches 16. 7.1991 (A). G. complanata has no special habitat preferences. It is a predator of small specimens of Mollusca and settles various types of permanent water bodies of lowlands as well as of the mountainous regions. Glossiphonia verrucata (Fr. Müller, 1844) Localities: Lajta at the confluence with the Mosoni-Duna 6. 9.1991 (H); Mosonmagyaróvár (Ungarisch-Altenburg) 3. 4. 1990 (H); Nickelsdorf (Miklóshalma) 23. 6. 1991 (A/H); Zurndorf (Zurány) 23. 6. 1991 (A); upstream from Nickelsdorf 26. 10. 1991 (A); Gattendorf (Lajtakáta) 30. 6. 1991 (A); downstream from Hollern 26.10.1991 (A); Brack, in secondary branches 16. 7.1991 (A). This rheophilic species prefers the gravel bottoms of fast flowing rivers of the hill country (Nesemann 1990b). It is an abundant member of the fauna of the mainstream and distributed throughout all regions of the Lajta.