RESUMEN
The freshwater snails Biomphalaria straminea, B. intermedia, B. kuhniana and B. peregrina are morphologically similar; based on this similarity the first three species were therefore grouped in the complex B. straminea. The morphological identification of these species is based on characters such as vaginal wrinkling, relation between prepuce: penial sheath: deferens vans and number of muscle layers in the penis wall. In this study the polymerase chain reaction restriction fragment length polymorphism technique was used for molecular identification of these molluscs. This techniques is based on the amplification of the internal transcribed spacer regions ITS1 and ITS2 of the ribosomal RNA gene and subsequent digestion of these fragments by restriction enzymes. Six enzymes were tested: Dde I, Mn I, Hae III, RSA I, Hpa II and AluI. The restriction patterns obtained with Dde I presented the best profile for separation of the four species of Biomphalaria. The profiles obtained will all the enzymes were used to estimate the genetic distances among the species through analysis of common banding patterns.