SPECIES-SPECIFIC PRIMERS DISCRIMINATE SCHISTOSOME INTERMEDIATE HOSTS - UNAMBIGUOUS PCR DIAGNOSIS OF BULINUS-FORSKALII GROUP TAXA (GASTROPODA, PLANORBIDAE)

The morphological definition of taxa has proved difficult within the B ulinus forskalii group, which includes intermediate hosts of medically important Schistosoma species in West Africa. Although B. forskalii a nd B. senegalensis transmit different schistosome species they are con chologically similar and their distributions overlap. Randomly amplifi ed polymorphic DNA (RAPD) allows differentiation of sibling species in the genus Bulinus, but RAPDs are difficult to standardize, impairing their value as a taxonomic tool. Hence, RAPD products diagnostic for e ither B. senegalensis or B. forskalii from West Africa were cloned, se quenced and a panel of species-specific primers designed. Sequencing o f RAPD products identified a homology in two apparently independent RA PD loci, a problem where RAPDs are indiscriminately scored for phyloge netic analyses. Specificity of primers was confirmed by widespread sam pling throughout each species' range. This approach produced a simple, robust, unambiguous PCR-based species identification strategy for thi s difficult group.