Aquatic Insects of the Nile Basin, with Emphasis on the Odonata

Abstract

Much work has been done on the Diptera of the Nile, because many species are vectors of disease of man and cattle. Some biogeographic work has been done on the Heteroptera, but the group that is known best is that of the Odonata. With c. 250 spp. out of an estimated 900 for Africa, the Nile is not particularly rich. Unlike the Congo basin, it lacks a high degree of endemicity. Relatively most endemic species are found on the faunistically depauperate Ethiopian plateau, followed by the East African lake zone. Quite a few wide-ranging Afrotropical species have used the Nile valley as a pathway to reach the Mediterranean shores, while in Lower Egypt some Palaearctic species of Irano-Turanian extraction occur. There has been exchange, across Sinai with the Levant, and perhaps across the Bab-el-Mandeb passage with Arabia. Some of these exchanges have been recent, others are older, and (sub) speciation has occurred since. Old endemics of Arabia and The Levant (at genus level) may not have had anything to do with the Nile. Their ancestors may have used the Red Sea valley as a pathway for dispersal before the opening of Bab-el-Mandeb. Not only the Afrotropical fauna of the Levant is a pluvial relict of Pleistocene age; also in West Sudan, relicts of an African forest fauna are found in a mountainous Sahel environment (Jebel Marra). Oriental elements in the Nile fauna are extremely rare.