Study of Biomphalaria tenagophila tenagopnila, B. T. guaibensis and B-occidentalis by polymerase chain reaction amplification and restriction enzyme digestion of the ribosomal RNA intergenic spacer regions

Biomphalaria tengaphila tenagophila, B. tenagophila guaibensis and B. occid entalis are indistinguishable on the basis of shell morphology and the majo rity of organs of the genital system. Only B. i. tenagophila is susceptible to infection with Schistosoma mansoni. The identification of this species is important for epidemiological studies of schistosomiasis. Snails from di fferent sites in Brazil, Argentine and Uruguay were studied using the Polym erase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism (RF LP) of the Ribosomal RNA Internal Transcribed Spacers (ITS) using seven enz ymes. Profiles resulting from digestion with AluI showed some invariant spe cies-specific products allowing correct identification of B. i. tenagophila , B. occidentalis and B. i. guaibensis. Profiles obtained with other enzyme s did not permit species identification as extensive intraspecific polymorp hism or invariant RFLP profiles were observed. Restriction profiles obtaine d with all enzymes were used to calculate the percentage of band sharing be tween all individual snails and these data were used for a cluster analysis . A closer relationship between B. occidentalisis and B. t. guaibensis,lsis than B. t. tenagophila and the subspecies B. i. guaibensis was observed. B ased on previous morphological data and these molecular data, we propose gr ouping B. i. tenagophila, B. occidentalis and B. i. guaibensis into a B, te nagophila complex.