AFFINITIES BETWEEN THE WEST PALAEARCTIC AND ETHIOPIAN BUTTERFLY FAUNAS by R. DE JONG Rijksmuseum van Natuurlijke Historie, Leiden With ten figures Abstract A survey is given of the species and genera common to the West Palaearctic and Ethiopian Regions. The possibilities of a faunal exchange in the past, especially during the Pleistocene, are analysed and related to the present distribution of West Palaearctic species in the Ethiopian Region and vice versa. It is demonstrated that faunal exchange across the Saharo-Arabian desert zone was not infrequently possible, but most invading species died out subsequently. Palaearctic species in the Ethiopian Region had a better chance to survive than Ethiopian species in the Palaearctic Region. Although the bare condition of the desert zone at present keeps the Palaearctic and Ethiopian Regions apart, it is concluded that the main factor inhibiting large-scale faunal exchange during the Pleistocene has been the repeated change of climate. Contents 1. Introduction General 166 The Palaearctic-Ethiopian boundary 167 2. Range, ecology and relationship of genera and species of butterflies common to the West Palaearctic and Ethiopian Regions 168 3. The affinities between the West Palaearctic and Ethiopian butterfly faunas 181 Direct affinities Palaearctic influence in the Ethiopian Region 182 Ethiopian influence in the Palaearctic Region 183 Indirect affinities Indo-Ethiopian and eremic species 184 Remaining genera 185 Summary and conclusions 185 4. Historical aspects 186 Ecological history of the northern half of Africa and the Arabian peninsula 186 Tertiary 186 Pleistocene 188 The direct West Palaearctic-Ethiopian affinities The southward traverse 191 The northward traverse 197 The indirect West Palaearctic-Ethiopian affinities The Indo-Ethiopian species 203 The eremic species 204 Remaining genera 205 165
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