Folia Historico-Naturalia Musei Matraensis - A Mátra Múzeum Természetrajzi Közleményei 9. (1984)

Kinzelbach, R. K.–Roth, G.: Patterns of distribution of some freshwater molluscs of the Levant region

coastal rivers of Palestine, the Nahr al-Kabir (S) through the Gate of Horns and finally into the lower courses of the Orontes and the Ceyhan rivers. 5. Leguminaia saulcyi (BOURGUIGNAT, 1852] (Fig. 4). The pathway of dispersal of this species, which represents a Pliocene immigrant from the Euphrates system, cannot yet be reconstructed accurately. On its way along the coast it spread as fas as southern Palestine down to Jaffa (MODELL 1951). During the Pleistocene it lived for a short period of time within the Jordan valley ( = L.chantrei according to TCHERNOV !973)/ which it probably reached through the Yisrce'l plain. 6. Leguminaia wheatleyi (LEA, 1862) (Fig. 4). This species dispersed from the Euphrates system towards the southwest into the Orontes river. By invading the lower Orontes and the Nahr alKabir (S) it reached areas already colonized by its neighbouring species L. saulcyi. Both taxa coexist there without hybridizing. 7. Potomida littomlis delesserti (BOURGUIGNAT, 1852) (Fig. 5). According to MODELL (1951) Potomida littomlis came from the Lower Danube region to southern Anatolia during the Pliocene by way of the Vardar depression and the Egean lakes. In that region the subspecies P. I. tracheae (KOBELT, 1895) occurs down to Iskenderun. It is only slightly different from the subspecies delesserti, which lives in the rivers of the coastal plain between the lower course of the Orontes and Haifa. 8. Potomida littoralis semirugata (LAMARCK, 1819) (Fig. 5). Still during the Pliocene Potomida littomlis invaded the Levantine rift valley and further the Gabbiil basin. Here a particular subspecies, semirugata, developed. As the result of the Pleistocene fusion of the central Orontes with its present lower course semirugata reached the Amik Gölü. It immigrated further through the Gate of Horns into the Nahr al-Kabïr (S), which was already occupied by P. I. delesserti. The existence of shells with intermediate characters in both of these areas confirms their subspecific status. 9. Margaritifera homsensis (LEA, 1864) (Fig. 6). 1864 Unio homsensis LEA, Proc. Acad. nat. Sei. Philad. 8: 285. 1865 Unio episcopalis TRISTRAM, Proc. Zool. Soc. London iS6y. 544. 1893 Unio barroisi DROUET, Rev. Biol. Nord France 5: 285, F. i

; J. de Conch. 41: 36. 1929 Margaritana syriaca PALLARY, Mém. Inst. Egypte 12; 34. 1951 Potomida littoralis homsensis, — MODELL, Rev. Fac. Sei. Instanbul (B) 16: 357, 361. 1964 Margaritifera cf. auricularia, — MODELL, Arch. Moll. 83: 97. A very large mussel (up to 15 cm in length) is found in the Orontes river mainly at the same localities as P. J. semirugata. It is absent from the Qu117