Identification and molecular characterization of digenean trematode parasites of Aylacostoma chloroticum (Gastropoda: Thiaridae) from a Neotropical Basin.

Thiarids are pantropical gastropods distributed from South America to Australia and found in lentic and lotic freshwater environments. These gastropods act as intermediate hosts for several species of digeneans. There are difficulties in the correct identification of these digeneans in certain stages of the life cycle as the larvae have a reduced size and few morphological characteristics for diagnosis. Because of this, techniques based on molecular markers have become an extremely useful tool. Our objective was to molecularly characterize the digeneans found in gastropods from the Ivaí River, Paraná, Brazil, using the mitochondrial molecular marker cytochrome c oxidase (COI) and the 28S ribosomal marker. With the molecular marker COI, gastropods showed high genetic similarity with Aylacostoma chloroticum. For the parasites, four different taxa were characterized with both markers. The 28S ribosomal marker proved to be more effective for the identification of Ivaí River parasites, being possible to suggest the identification of two species among the four groups found. Considering that there are no records in the literature of studies involving parasites and gastropods as intermediate hosts in the Ivaí River, this study is the first regarding these relationships.