A new cryptic species of (Trematoda: Echinostomatidae) closely related to found in Brazil.

, described in Brazil at the end of the 1960s and used as a biological model for a range of studies, belongs to the ‘’ complex of comprising species with 37 collar spines. However, molecular data are available only for a few isolates maintained under laboratory conditions, with molecular prospecting based on specimens originating from naturally infected hosts virtually lacking. The present study describes Valadão, Alves & Pinto n. sp., a species cryptically related to found in Brazil. Larval stages (cercariae, metacercariae and rediae) of the new species were found in the physid snail in the State of Minas Gerais, Brazil, the same geographical area where was originally described. Adult parasites obtained experimentally in were used for morphological (optical microscopy) and molecular [28S, internal transcribed spacer (ITS), 1 and 1] characterization. The morphology of larval and adult parasites (most notable the small-sized dorsal spines in the head collar), associated with low (0–0.1%) molecular divergence for 28S gene or ITS region, and only moderate divergence for the mitochondrial 1 gene (3.83%), might suggest that the newly collected specimens should be assigned to . However, higher genetic divergence (6.16–6.39%) was found in the mitochondrial 1, revealing that it is a genetically distinct, cryptic lineage. In the most informative phylogenetic reconstruction, based on 1, n. sp. exhibited a strongly supported sister relationship with . , which may indicate a very recent speciation event giving rise to these 2 species.