Biogeography, diversity and seasonality of Syrphidae (Diptera) in a Guineo-Congolian rain forest in Kenya

Abstract

Syrphidae (Diptera) were collected from different sites in Kakamega Forest, the only dry guineo-congolian rain forest relict in Kenya. In addition, literature records were compiled and old collections specimens were re-identified. In total, 74 species or 43 % of the known syrphid fauna in Kenya, were identified. The fauna indicates a biogeographical affinity with the main central and western African rain forest belt, with 12 out of the 74 species being indicator species for such a link. The alpha and beta diversity were compared at four sites, representing the main ecological habitats within the forest complex. Mostly undisturbed forest habitat shows the highest diversity. It also harbours a large proportion of the indicator species (seven out of 12). Natural glades in the forest show a low similarity with the other habitats, indicating the more exceptional fauna of the natural grasslands. The seasonal fluctuations for the more abundant species are briefly discussed. Most species reach highest abundance during the dry season. .

Journal of East African Natural History Vol. 90 (1&2) 2001: pp. 87-101