In Brazil, there are three intermediate snail vectors and two potential hosts of Schistosoma mansoni. Previous studies showed three variant molecular profiles to B. amazonica and evidenced intraspecific variations using sequence data. In this context, the aim of this study was to verify whether such differences would correspond to either B. amazonica or B. cousini. The snails were morphologically identified; PCR-RFLP and sequencing were carried out. Besides, B. cousini were submitted to susceptibility experiments to S. mansoni. Noteworthy, morphological data of Brazilian specimens predominantly showed the morphology described for B. amazonica. Nevertheless, PCR-RFLP results exhibited three variant molecular profiles for the specimens previously identified as B. amazonica and the phylogenetic analyses showed two groups one to B. amazonica and another to B. cousini. Furthermore, B. cousini showed to be susceptible to S. mansoni. These results confirm the occurrence of B. cousini in Brazil and points to the risk of introduction of schistosomiasis mansoni into new areas.