A REVISION OF AFROTROPICAL AGABUS LEACH (COLEOPTERA, DYTISCIDAE), ANDTHE EVOLUTION OF TROPICOALPINE SUPER SPECIALISTS

The thirteen species of Agabus Leach, 1817, of the Afrotropical Region are revised and classified into four species groups: the dibasic ambu lator-group endemic to Ethiopia, ragazzii-group with five species in E thiopia, raffrayi-group with five species in East and South Africa, an d A. discicollis Ancey, 1882, endemic to Ethiopia, is placed in the Ne arctic cordatus-group. Agabus perssoni sp.n. and Agabus galamensis sp. n. are described from the highlands of Ethiopia. Agabus ruwenzoricus G uignot, 1936, stat.n. is given specific rank. Agabus ferrugatus Regimb art, 1905, is synonymized with Agabus ragazzii Regimbart, 1887, and Ag abus limbicollis Regimbart, 1905, is synonymized with Agabus raffrayi Sharp, 1882, syn.n. Lectotypes are designated for the following nomina l species: Agabus discicollis Ancey, 1882, Agabus raffrayi Sharp, 1882 , Agabus limbicollis Regimbart, 1905, Agabus pallidus Omer-Cooper, 193 1, Agabus ruwenzoricus Guignot, 1936, Agabus sjostedti Regimbart, 1908 , Agabus dytiscoides Regimbart, 1908, Agabus ragazzii Regimbart, 1887, Agabus ferrugatus Regimbart, 1905, and Gaurodytes abessinicus Zimmerm ann, 1928. Reconstructed phylogenies are presented for the raffrayi- a nd ragazzii-groups. The following adaptations to tropicoalpine habitat s are suggested: (1) body and especially pronotum narrow, (2) head bro ad anteriorly, (3) hindwing small, and (4) hind leg long and slender. Biogeography and evolution of the studied species are discussed. Four different invasions of Holarctic lineages to the East African mountain s are suggested. Recurrent periods of cold and dry climate are conside red the chief driving force in the evolution of high altitude super sp ecialists.