Biogeography of the Oniscidean fauna of Somalia

At present, the oniscidean fauna of Somalia is the best known of the entire African continent. It includes 52 species (mostly endemic) belonging to 22 genera (none endemic) and 11 families. From a biogeographical point of view, this fauna belongs to the Afrotropical region, and in particular to the East African subregion, even though it exhibits peculiar characteristics. No elements of Palearctic origin are present. The distribution of the Oniscidea in Somalia appears to be strongly influenced by ecological factors. In fact, most species occur in the southern part of the country, west of the Webi Shebeli River, and to a lesser extent in the northernmost part (ex-British Somaliland). These areas have the most favorable climates. The conspicuous presence of eremic elements (species of the genera Tura, Xeroniscus, Periscyphis, Somalodillo, Somaloniscus); the absence of the eubelid genera typical of tropical Africa (Eubelum, Synarmadilloides, Hiallum); and the scarcity of Armadillidae and Philosciidae (well represented in the neighboring East African areas) suggest a relatively recent origin of the oniscidean fauna of Somalia.