'*5 ERAL ' \ * f U3&AftY A taxonomic revision of the genus Oedaleus Fieber (Orthoptera : Acrididae) J. Mark Ritchie Centre for Overseas Pest Research, College House, Wrights Lane, London W8 5SJ Contents Synopsis .......... Introduction .......... History of the genus Oedaleus ....... Materials, methods and terminology ...... Depositories .......... Oedaleus Fieber ......... Taxonomic affinities and diagnostic characters .... Keys to the species of Oedaleus ...... African species ........ Non-African species ........ Descriptions of the species ....... Biogeography of the genus Oedaleus ...... Relationships within the genus ...... Geographical origin of the genus ...... The Pleistocene in Africa ....... The southern African Oedaleus fauna ..... The Oedaleus fauna of the Somali peninsula .... The Oedaleus fauna of the subsaharan latitudinal belt The non-African Oedaleus fauna ...... Problems of analysis of distribution patterns .... East African acridid diversity ....... The Brachystegia woodland and 'trans-equatorial' speciation The woodland barrier and the 'arid corridor': evidence from other groups Conclusions ......... Acknowledgements ......... References .......... Index 83 83 84 85 86 86 87 90 92 93 94 153 153 153 154 154 159 159 163 168 169 169 171 174 174 175 182 Synopsis The economically important grasshopper genus Oedaleus is revised. Twenty species and three subspecies are described, keyed and illustrated. O. nadiae, O.plenus browni and the male of O. miniatus are described as new to science. Four species and five subspecies are synonymized and two species are reduced to subspecies, one being transferred from the genus Gastrimargus. All available primary types have been examined and four neotypes have been designated. Five lectotypes for senior synonyms and seven for junior synonyms have been designated. The biology and economic importance of the species are reviewed and their distributions are mapped. The biogeography of the genus is discussed in the light of past and present geological, vegetational and climatic factors. The fluctuations of the equatorial Brachystegia woodland zone in Africa during the Pleistocene are advanced as an explanation of the observed trans-equatorial speciation in Oedaleus and some other dry savannah organisms. Introduction In recent years members of the genus Oedaleus have increasingly been designated as crop pests in Africa, India and South East Asia. The most serious damage has been caused by Oedaleus Bull. Br. Mus. not. Hist. (Ent.) 42 (3): 83-183 Issued 30 April 1981
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