Freshwater Molluscs of the Nile Basin, Past and Present

摘要: The malacofauna of the Nile is poor compared to that Congo and its degree endemicity lower. While highest species richness Basin in stenotopic taxa live rivers lakes, diversity occurs eurytopic living fringe habitats such as temporary pools. paucity endemics need perennial waters well Lower White confirms geological evidence indicating instability discontinuity water supply during Plio-Pleistocene times. fauna predominantly Afrotropical exclusively south junction Blue Nile. Of all sub-basins, (either zero or two species) lowest Equatorial Nile, aquatic environment this sub-basin young (probably Holocene) lending support idea Bahr el Arab Transcontinental Rift System were hydrologically unstable, with endorheic, alkaline lakes most (Salama, 1997). In (Egyptian) Ethiopian Highlands palaearctic faunal components occur, consisting widespread a limited number origin, related Levantine species. Most these first appear fossil record around 2.5 Ma. There no functioned an invasion route for Eurasiatic prior time. Only Theodoxus niloticus possibly Paratethyan origin may have invaded Late Miocene. main freshwater molluscs into Africa appears occurred via Horn Middle Miocene East African Rift, diversified only shares fraction north Albert (> ∼5° N). equato- rial headwaters, some from southern reach their northern limit, but community consists are either endemic one rift region stretching Turkana Kivu Basins. hence exists distinct bio-province, was already recognisable