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 Piscicolidae Piscicola geometra (Linnaeus, 1758) Localities: Nickelsdorf (Miklóshalma) 9. 1991 (A/H); upstream from Nickelsdorf 26. 10. 1990 (A); Kleine Leitha (Kis-Lajta) at the Albrechtsmühle 30. 7. 1991 (A); Lajta-megyei-csatorna (Komitatskanal) near Nickelsdorf (Miklóshalma) 9. 1991 (A/H); Rét-árok (Leithakanal) 30. 7. 1991 (A); Gattendorf (Lajtakáta) 30. 6.1991 (A); Rohrau 14. 5.1991 (A). The fish leech is an abundant member of the fauna of the Lajta. It is distributed throughout the whole middle and lower reaches, appearing in the mainstream and in the secondary branches. The second species of this genus, Piscicola haranti Jarry, 1960, recently found in the Rábca and Körös, was not observed in the Lajta (Nesemann 1991a). Family Haemopidae Haemopis sanguisuga (Linnaeus, 1758) Localities: Mosoni-Duna at Mosonmagyaróvár (Ungarisch Altenburg) 13. 9. 1991 (H); Rohrau, in secondary branch 27. 5.1990, 14. 5. 1991 (A); Pachfurth, in a secondary branch "Unterer Auwinkel" 2. 6.1990 (A); Pachfurth, in small, deadwater reaches 4.1990 (A). H. sanguisuga belongs to the semiaquatic fauna, preferring mud and sand of the banks near the water line (Nesemann 1990a). It is absent from the fast flowing reaches of the mainstream. Family Hirudinidae Hirudo medicinalis Linnaeus, 1758 Localities: Pachfurth, in several small deadwater reaches 4.1990, 4.1991 (A). The medicinal leech feeds on higher vertebrates. It occurs in swampy, temporarily flooded ponds of lowland rivers (Nesemann 1991b). During the activity period from April to August, the leeches can be frequently found in the submerged vegetation. Family Erpobdellidae Erpobdella nigricollis (Brandes, 1900) Localities: Mosoni-Duna, from two collections 1990, 1991 (H); Lajta at the confluence with the Mosoni-Duna 13. 9.1991 (H); Lajta-megyei-csatorna (Komitatskanal) near Nickelsdorf (Miklóshalma) 9. 1991 (A/H); Rét-árok (Leithakanal) 30. 7. 1991 (A/H); Nickelsdorf (Miklóshalma) 26. 10. 1991 (Am). E. nigricollis belongs to the fauna of potamon rivers, being strongly restricted to the lowlands and plains. The distribution area is bordered in the Kisalföld, whereas isolated relicts still exist in the Bavarian Danube. The species inhabits the Danube as far upstream as Dunaremete. The closely settled area of the Hungarian plains includes the lower reaches of the tributaries, e. g. the Lajta and MosoniDuna (Soós 1963,1967). Erpobdella vilnensis (Liskiewicz, 1925) Locality: Rét-árok (Leithakanal) 11.9.1989 (A/H). This Erpobdella species prefers streams of the mountains and hilly countries. In general, it is absent from lowland rivers. Nevertheless E. vilnensis can occasionally be found in potamon rivers, when drifted out of smaller tributaries. Erpobdella octoculata (Linnaeus, 1758) Localities: Lajta at the confluence with the Mosoni-Duna 13. 9. 1991 (H); Mosonmagyaróvár (Ungarisch-Altenburg) 3. 4. 1990 (H); Rét-árok (Leithakanal) 11. 9. 1989, 30. 7. 1991 (A/H); Lajtamegyei-csatorna (Komitatskanal) near Nickelsdorf (Miklóshalma) 9. 1991 (A/H); Zurndorf (Zurány)