FRESHWATER MOLLUSCS OF THE SINAI PENINSULA

ABSTRACT

In a revision of the freshwater species of molluscs in the Sinai Peninsula it was found that five species inhabit the entire area. Two of these: Melanoides tuberculatus O.F. Müller and Hydrobia musaensis (Frauenfeld) are, as a rule, restricted to the coastal brackish springs. Physa subopaca Lamarck is mostly limited to the foothills and low mountains of southern Sinai. Valvata saulcyi Bourguignat occupies the highest mountains of the peninsula and Melanopsis praemorsum Linné is confined to a single spring located at the northeastern corner of the peninsula ('Ein el Qudeirat = Qadesh Barnea). The scattered distribution of Melanoides in extremely isolated water bodies in the desert of Sinai suggests an ancient arrival of this species to the area. Melanopsis arrived much later (late Miocene or Pliocene) when passages further to the south were already blocked by the developing southern palaearctic desert belt. Physa and Valvata may have been dispersed through the air by insects and birds. Hydrobia musaensis is confined to the springs of Et Tur and Wadi Gharandal (southern Sinai), and probably to one spring in Dhofar (southern Arabia) from where it was described as Paludestrina glaucovirens Melvil. This species was isolated and speciated out of a marine stock of Hydrobia probably during the Neogene. Separation between the Arabian and Sinaitic populations could have occurred after the main faults of the Red Sea-Rift Valleys occurred during early Pleistocene.