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)

Family Talitridae Orchestia cavimana Heller, 1865 Material: Sükösd, near the Danubian floodplain at the Molaván-hegy, 11. 05. 1933, leg. Dudich, E.; Római-fürdő near Budapest, in the drainage ditch of a thermal spring, 25. 02. 1934, leg. Balogh; Csillaghegy near Budapest, 14. 10. 1928, leg. Kesselyák, A.; Alsórákos near Budapest, 25. 06. 1926, leg. Vasváry, M.; Rákos near Budapest, 1927, leg. Mödlinger, G.; Vác, in a spring, 06. 10. 1934, leg. Kesselyák, A. The distribution pattern of this talitrid amphipod (Fig. 6) is best characterized as Ponto-Mediterranean and its ecological requirement as semi-aquatic (or semi-terrestric) because it is generally found just above the water's edge. It is very common and widespread in the area of the Mediterranean and Black Sea. Following French river systems, it extended its range from the western Mediterranean area far to the north and northeast in this century (Kinzelbach 1965). In the drainage system of the River Danube its distribution is restricted to the middle and lower reaches. It was never recorded beyond the mountain ridge (Bakony, Visegrádi hegység), that separates the larger Hungarian Plain (Alföld) in the east from the smaller plain (Kisalföld) in the west. O. cavimana does not inhabit the main course of the Danube, but is restricted to tributaries and lakes with approximately stable water levels, where it is found just above the water's edge. Dead plant matter washed ashore is a preferably inhabited substrate. Specimens of O. cavimana were collected in the humid edge of springs, on swampy lake shores and on the banks of lowland streams (Rákos-patak) and smaller rivers (Zala, Zagyva). Some of the Hungarian populations were examined in the 1920ies (Dudich 1927, Abonyi 1928). Until nowadays, they show no tendency to extend their range in a westward direction, although acceptable conditions would also be available in the Kisalföld plain. The way of spreading and the habitat requirements of the Eastern European populations in the Danube system seem to be quite different from those of the Western European populations. In the Rhine River, O. cavimana inhabits gravel banks and seems to be better adapted to highly variable water levels, tolerating droughts and floods of considerable duration. On the contrary, the populations of the Hungarian Danube valley are restricted to sheltered and shaded parts of banks and shores, semi-aquatic microhabitats of high atmospheric humidity. The size of the Danubian animals (up to 14 mm total body length) is considerably smaller than that of their Western European relatives (20 mm). Family Mysidae Limnomysis benedeni Czerniavsky, 1882 Material: see Wittmann (1995); further records: Danube at Dunaújváros, 05. 09. 1991, leg. Ofenböck, T. & H. Nesemann; Danube, in a secondary branch Rosskopfarm near Stopfenreuth, 15. 03. 1991; Danube, in a side-branch at Regelsbrunn, 14. 03. 1991; Danube, upstream from Regelsbrunn, 17. 03. 1991; Danube, in a deadwater reach near Fischamend, 16. 03. 1991, leg. Nesemann, H.; Danube upstream from Krems, 1987, leg. Zoufal, W. & E. Weigand; Hake Balaton at Keszthely, 21. 06. 1990, leg. Forró, L. & H. Nesemann. L. benedeni is a widely distributed Ponto-Caspian mysid species which prefers fresh or oligohaline waters. It lives in slow-flowing and stagnant waters where it lives mainly in the hyperbenthic zone among aquatic macrophytes, at flooded banksides, or associated with artificial hard substrate (Wittmann 1995).