L. Forró szerk.: Miscellanea Zoologica Hungarica 10. 1995 (Budapest, 1995)

Nesemann, H., Pöckl, M.; Wittmann, K. J.: Distribution of epigean Malacostraca in the middle and upper Danube (Hungary, Austria, Germany)

Cliaetogammarus ischnus (Stebbing, 1898) Material: Danube at Mohács, 18. 09. 1930, leg. Dudich, E.; Danube at Dunakömlöd, 11. 09. 1947, leg. Loksa, I.; Danube at Harta, 05. 09. 1991, leg. Ofenböck, T. & H. Nesemann; Danube at Dunafödvár, 11. 09. 1947, leg. Loska, I., 05. 09. 1991; Danube at Dunaújváros, 05. 09. 1991, leg. Ofenböck, T. & H. Nesemann; Ráckevei Duna at Szigethalom, 06. 1991, leg. Nesemann, H.; Danube at Budapest, 30. 09. 1932; Danube at Budafok, 27. 09. 1930, leg. Dudich, E.; Szentendrei Duna near Leányfalu, 04. 09. 1991, leg. Ofenböck, T. & H. Nesemann; Danube at Vác, 30. 09. 1930, leg. Dudich, E.; Danube at Nagymaros, 04. 06. 1926, leg. Unger & Szabó-Patay; Danube at Dömös, 30. 07. 1927; Danube at Szőny, 17. 09. 1930; Danube at Zebegény, 14. 11. 1946, leg. Dudich, E.; Danube at Esztergom, 17. 09. 1947, leg. Loksa, I.; Danube at Dunaalmás, 29. June 1941, leg. Soós, Á.; Danube at Komárom, 19. 09. 1947, leg. Loksa, I.; Danube at Ásványráró, 11. 09. 1991; Danube at Lipót, 11. 09. 1991; Danube at Dunaremete, 13. 09. 1991; Danube at Hainburg, 08. 09. 1991; Danube at Regelsbninn, 11. 02. 1991; Danube near Korneuburg, 8. Febr. 1991, leg. Schay, G. & H. Nesemann; Danube at Zwentendorf, 20. 04. 1991; Danube from numerous collecting sites between Altenwörth and Krems, 1985 - 1990, leg. Pöckl, M. In 1993, Pinkster synonymized the generic name Chaetogammarus with Echinogammarus. In our opinion, it would have needed a higher degree of necessity to change the name commonly used in literature for many decades. As it is unclear whether the use of the trinominal name for the freshwater- (or inland-) form sowinskyi Behning, 1914, is justified (Jazdzweski 1980), the authors retain the name Chaeto gammarus ischnus for the riverine form. C. ischnus belongs together with Corophium curvispinum, to the Ponto-Caspian crustaceans that have advanced farthest northwestwards arriving in the river basins of the North and Baltic seas. In most of the larger Ponto-Caspian rivers C. ischnus was found highly upstream. In the River Danube, it advanced as far as the Slovakian reach up to Jarovce (rkm 1856, Brtek 1953, Straskraba 1953, 1959, 1962, Brtek & Rothschein 1964), with recordings along all lower reaches of this river (Dudich 1927, 1967, Carausu et al. 1955, Russev 1966, Karaman 1953, Karaman 1974). It also entered the large affluent Tisza upstream to Szeged (Dudich 1927) and Martfű (Botos et al. 1990) and lower courses of Dráva and Száva (Karaman 1953). However, it has not been found in Lake Balaton (Muskó 1989) and was not listed by Vornatscher (1965) and Dudich (1967) for the Austrian Danube. Since about 1970, C. ischnus must have greatly extended its distribution area in upstream direction. It was first recorded in Austria at Hundsheim near Krems (rkm 2005, Pöckl 1988), where it occurred together with D. haemobaphes. C. ischnus prefers large potamon rivers where it is chiefly found in the gravel. Obesogammarus obesus (Sars, 1894) Material: Danube at Harta, 05. 09. 1991; Danube at Dunaújváros, 05. 09. 1991, leg. Ofenböck, T. & H. Nesemann; Danube near Szalkszentmárton, 01. 02. 1991, leg. Wimmer, R. & H. Nesemann; Szentendrei Duna near Leányfalu, 4. 09. 1991, leg. Ofenböck, T. & H. Nesemann. O. obesus (Fig. 4) is a Ponto-Caspian gammarid species of wide distribution in the Caspian, Azov's and Black seas as well as in the lower and middle courses of the large rivers flowing into these basins. However, it does by far not advance as high upstream as the other recorded crustaceans of Ponto-Caspian origin. In the Danube, this species was distributed originally only in the lower parts. It was collected by Carausu (Dudich 1947) and Karaman (1953) in the Kazan-pass, which separates the Eastern Pannonian lowlands from the lower Danube. In the present study, O. obesus was found as high upstream as the Szentendrei Duna (rkm 1672), approximately 30 km northwards from Budapest. Downstream the Hungarian capital, at Dunaújváros and Harta, O. obesus was collected rather frequently. New records by Csányi (1994) indicate further expansion. Therefore, this species must have intensively extended its distribution in the middle Danube in the last few decades. It also seems to be restricted to the