Six morphologically indistinguishable but genetically and behaviorally distinct mosquito species comprise theAnopheles gambiaeGiles complex (1 ,2 ). All occur in Africa and in some localities three and possibly even four of these species occur in sympatry. The two most widespread species,A. gambiaeandA. arabiensis, both of which are found throughout most of sub-Saharan Africa, are major vectors of human malaria parasites. The speciesA. melasandA. merusare locally significant vectors on the east and west coasts of Africa, respectively, where each breeds primarily in brackish coastal waters.A. quadriannulatus, which is abundant in southern Africa and also reported from Zanzibar and Sudan, feeds almost exclusively on domestic and wild animals and thus is not a malaria vector. The sixth and most recently described member of this complex, the halophilicA. bwambae, has a very restricted distribution, occurring only within a 20-km radius of the Barunga hot springs in the Bwamba county of Uganda, where it may be a locally important vector of malaria. Some species in theA. gambiaecomplex, particularlyA. gambiaeandA. arabiensis, have also been shown to be vectors of the filarial wormWuchereria bancroftiin tropical Africa (3 ).
