L. Forró - É. Murai szerk.: Miscellanea Zoologica Hungarica 6. 1991 (Budapest, 1991)

Nesemann, H.: Zoogeography and composition of leech fauna of Danubian lowland rivers in the Kisalföld compared with some molluscs (Hirudinea, Gastropoda)

ches on floating aquatic plants (Danube, March), sometimes in swampy dead-water pools (Leitha), in bulrush areas and flood plains (Zala) near the main stream. Elsewhere the species is a remarkable member of the Potamon biocoenosis in lowland rivers with warm water in summers. A lot of records are known from the plain of the upper Rhine (Germany, France) and the Hungarian Great Plain (Austria, Hungary). G. concolor was found frequently in the lower reaches of the rivers Danube, March, Leitha and Zala. Its distribution is not only restricted to this part of the Danube Basin. Several isolated populations exist in tributaries along the upper Danube, especially in effluents of large exorheic lakes. Batracobdella algira (Moquin-Tandon, 1846) (Fig. 5) Localities: Danube near Vienna (A), in a temporary pond in the Prater-area (dead-water reaches of the Danube), 12. Nov. 1989, May 1990. The species was found for the first time in Central Europe and is one of the present members of the Ponto-Mediterranean fauna. As far as the published information goes, B. algira has a wide range of distribution in the Mediterranean countries including Northern Africa. The leech was found also in the southern parts of the European Soviet Union (LUKIN 1976). Populations are known from different kinds of standing and slowly flowing water bodies. In the northern parts of the settled area, the species seems to be restricted to flood plains of large rivers. Its alleged occurrence may be possible in the Yugoslavian reach of the Danube (SKET 1968). Another occurrence of Batracobdella paludosa's (EPURE 1947), might be that of B. algira, considering the author's description. Until now, it is not possible to confirm the complete range. Placobdella costata (Fr. Müller, 1846) (Fig. 4) Localities: Danube in Baranja (YU) see MIKUSKA & GEC (1970); Balaton-area (H), Kiskunság (H) see SOÓS (1963); Bátorliget (H), in a pond, 28. Sept. 1990, leg. FORRÓ & NESEMANN (near to a tributary of the River Tisza). The species is a temporary ectoparasite on the fresh-water turtle (Emys orbicularis) and on other vertebrates. Its range of distribution has centres in the Ponto-Mediterranean and Baltic area, but P. costata occurs sporadically elsewhere in Central- and Western Europe. This is one of the most common leech species in the eastern Mediterranean area (RÜCKERT 1985). Also it is known from several localities in the Hungarian Great Plain (SOÓS 1963, MIKUSKA & GEC 1970), the northern lowlands of Central Europe (DRESSCHER & ENGEL 1960, AGAPOW 1975, HECHT 1930) and from the British Isles (ELLIOTT, MUGRIDGE & STALLYBRASS 1979). Further alleged records, listed in limnological papers, seem to belong to Hemiclepsis marginata (O.F. Müller, 1774). This leech found frequently in large rivers too is often confused with P. costata (Autrum, 1958). Actually the present material gives a picture of the disjunct range in Central Europe. In the Danube Basin R costata is naturally restricted to the plains. We have no certain proof about its original existence in the upper Danubian reach. Fam. Piscicolidae Piscicola haranti Jarry, 1960 (Fig. 3) Locality: Rábca near Győr (H), near the confluence of the Rábca and the Mosoni Duna, 19. Jan. 1991, leg. MÖSSMER & NESEMANN. The fish leeches have developed several endemic taxa in the drainage area of the Ponto-Caspian Sea. P. haranti is new to the Hungarian fauna and the Danube