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

23. 6. 1991 (A); Gattendorf (Lajtakáta) 30. 6.1991 (A); Gattendorf, in a small pond near to the river bed 30. 6. 1991 (A); downstream from Hollern 26. 10.1990 (A); Rohrau 14. 5. 1991 (A); Rohrau, in a secondary branch 27. 5. 1990,14. 5.1991 (A); Gerhaus 10. 5.1991; Bruck, in a secondary branch 16. 7. 1991 (A). E. octoculata is widely spread in the western Palaearctic region. This species is a generalist in its habitat preferences, occurring in all types of permanent water bodies (Soós 1967, Sawyer 1986). Dina punctata Johansson, 1927 Localities: Mosoni-Duna near Mosonmagyaróvár (Ungarisch Altenburg) 13. 9. 1991 (H); Lajta at the confluence with the Mosoni-Duna 6. 9.1991 (H); Mosonmagyaróvár (Ungarisch-Altenburg) 3. 4. 1990 (H); Rét-árok (Leithakanal) 11. 9. 1989 (A/H); Kleine Leitha (Kis-Lajta) at the Albrechtsmühle 30. 7. 1991 (A); Lajta-megyei-csatorna (Komitatskanal) 9.1991 (A/H); Nickelsdorf (Miklóshalma) 26. 10. 1990, 23. 6. 1991 (A/H); Zurndorf (Zurány) 23. 6. 1991 (A); Gattendorf (Lajtakáta) 30. 6. 1991 (A); downstream from Hollern 26. 10. 1991 (A); Rohrau 14. 5. 1991 (A); Pachfurth 27. 5. 1990 (A); Gerhaus 3. 6.1991 (A); Bruck, in a secondary branch 16. 7.1991 (A). This rheophilic Dina species originates from the upper reaches of rivers and streams as well as Unio crassus cytherea and Leuciscus souffia souffia (Risso, 1826). It is the most abundant leech of the upper Danube basin. The distribution area is extended into easterly direction as far downstream as the middle reach of the Danube (Érd-Ófalu, Dunaújváros). The Lajta is the only Hungarian tributary of the Danube, which is inhabited by Dina punctata (Nesemann 1990a). In the Kisalföld and Alföld plains, the species is strongly restricted to the Danube, except the Lajta. Dina lineata lineata (O. F. Müller, 1774) Locality: Pachfurth, in a swampy, wooded district 27. 5.1990 (A). D. lineata occurs in the lowlands and plains along the middle and lower reaches of the Danube. It is completely absent from the upper river basin. Its western distribution range is bordered in the Vienna and Kisalföld plains. The Danubian populations belong to the nominate subspecies Dina lineata lineata. They prefer swampy areas and temporarily flooded ponds, which are poor in oxygen and filled with organic matter. Therefore, D. lineata lineata resembles Sphaerium nucleus and Segmentina nitida (O. F. Müller, 1774) in its habitat preferences. Crustacea Amphipoda Family Gammaridae In the Lajta, the composition of gammarids is typical of most lowland rivers, flowing in the Vienna plain, the Kisalföld, and the Transdanubian hill country. Gammarus pulex (Linnaeus, 1758) exists only as relict populations along the upper Danube (in Bavaria and upper Austria) and is absent from the western part of the Hungarian plains. Consequently, Gammarus roeseli Gervais, 1835 is the dominant species in the potamon. The faunal composition of the Danube and the tributaries is very different because most of the Pontocaspian gammarids (Dikerogammarus, Chaetogammarus, Obesogammarus) are strongly restricted to the Danube and do not enter the adjacent waters. Gammarus roeseli Gervais, 1835 Localities: Lajta at the confluence with the Mosoni-Duna 6. 9. 1991 (H): Lajta-megyei-csatorna (Komitatskanal) near Nickelsdorf (Miklóshalma) 9. 1991 (A/H); Kleine Leitha (Kis-Lajta) at the Albrechtsmühle 30. 7. 1991 (A); Nickelsdorf (Miklóshalma) 23. 6. 1991 (A/H); Zurndorf (Zurány) 23.