Phylogeny, morphology, and haplotypic distribution of Biomphalaria straminea populations from the five geographic regions of Brazil.

Biomphalaria straminea is one of the three snails that act as the intermediate hosts of Schistosoma mansoni and is responsible for maintaining high rates of schistosomiasis in some areas of northeastern Brazil. The principal morphological characteristic of B. straminea is the marked vaginal wrinkling, although it is also present in congeneric species, a group known as the B.