The cytotaxonomy of Simulium sanctipauli sensu stricto (Diptera : Simuliidae) in Ghana and the Cote d'Ivoire

The status of the different cytological variants of Simulium sanctipauli se nsu stricto Vajime & Dunbar (sensu Post, 1986) found in Ghana and Cote d'Iv oire is cytotaxonomically evaluated in view of recent revisions of the S. s anctipauli subcomplex. Three geographical variants designated as 'Pra','Com oe' and 'Sassandra' forms of S. sanctipauli are described. The 'Pra' form i s genetically differentiated from the other two forms by a distinct sex-det ermining system. The 'Comoe' and 'Sassandra' forms are considered as the tw o ends of an interspecific stepped dine with the River Bandama basin as the zone of contact. The possibility that the 'Comoe' form populations breedin g in southwestern Ghana could serve as reinvading S, sanctipauli into the O nchocerciasis Control Programme (OCP) area in West Africa is discussed.