Genuine Africans or tertiary immigrants? -: The genus Hydropsyche in the afrotropical region (insecta, trichoptera: hydropsychidae)

The distinctive character of the Afrotropical fauna has developed during a long period of isolation. About 30 million years ago the African and Eurasian plates collided and numerous groups migrated in and out of Africa. Successful colonizers adapted and became part of the endemic communities. Based on a biogeographic and phylogenetic analysis, the African species of the genus Hydropsyche were identified as belonging to this group of early immigrants. The genus now contains 17 aftotropical species all belonging to the propinqua-group which is endemic to Africa. The ranges of the related groups are in the Holarctic Region (angustipennis-group), and India to South East Asia (newae-group). This area contains the diversity centre of the genus. The African species are rather homogenous in their morphology, and their great similarity is indicative of a single immigration event. The species are unevenly distributed over the continent, with a concentration in the central African Rift system. A continental species colonised Madagascar, and subsequently Mauritius and Reunion. In an attempt to reconstruct the expansion routes, the phylogeography of the group is examined and briefly discussed.