The blackflies (Diptera: Simuliidae) of Bioko (Republic of Equatorial Guinea) and the Gulf of Guinea with a description of the larvae of the ‘Pomeroy’ form of<i>Simulium cervicornutum</i>

Like many other organisms, Simuliidae often show a high degree of endemism on oceanic islands, and the Gulf of Guinea, including its islands, is a region of general biogeographical interest in view of the uniqueness of its flora and fauna. This paper presents a comprehensive review of the Simuliidae in the region, and is the first faunistic record of blackflies from Bioko. Simuliidae (larvae, pupae and neonate adults) were collected from Bioko and from around Mount Cameroon and compared with previous findings from Mount Cameroon, Principe and Sao Tome. Twenty-seven species are known from the region. Twenty-five species have been recorded around Mount Cameroon, eight species on Bioko, three species on Sao Tome and one species on Principe. Two taxonomic 'forms' (one on Bioko alone, and one on both Bioko and around Mount Cameroon) and one species (found only on Sao Tome ) are endemic to the region. A study of the variation in the morphology of Simulium cervicornutum revealed two morphotypes, one from Bioko and around Mount Cameroon and the other from the rest of Africa. The speciation and biogeography of the Simuliidae in the Gulf of Guinea are discussed.