Trematode diversity in freshwater pulmonate snails from the St Lawrence Wetlands, Canada

This study applies a molecular approach addressing the identification of trematode larval stages (sporocysts, rediae and cercariae) parasitising four freshwater pulmonate snails (Stagnicola elodes, Radix auricularia, Planorbella trivolvis and Physella gyrina) collected in the wetlands of St Lawrence River in Canada. A total of 20 genetically distinct species or species level lineages were identified via phylogenetic analyses based on, depending on the taxonomic group, mitochondrial (cox1 and nad1) and nuclear (ITS-5.8S-ITS2 and 28S rDNA) sequences integrated with data from the recently generated sequence libraries for the European and some North American trematodes. Phylogenetic analyses and distance-based approaches allowed molecular identification of six described/named and 14 putative new species. These included species of six digenean families (Clinostomidae, Derogenidae, Echinostomatidae, Plagiorchiidae, Schistosomatidae and Strigeidae)