Molecular validation and redescription of Glypthelmins staffordi (Digenea: Plagiorchiidae) with an updated key to genus Glypthelmins Stafford, 1905.

Glypthelmins is a genus comprising species that parasitize anurans and has been reported in America and Asia. The taxonomic history of the genus Glypthelmins is problematic, involving the reclassification of species into other genera. Glypthelmins staffordi was consequently not considered a valid species in Glypthelmins due to morphological differences and was placed in the genus Rauschiella. Thus, the valid name of G. staffordi prior to this work is R. staffordi. Moreover, no molecular data has been published for R. staffordi. To address this gap, a morphological redescription of G. staffordi is provided, along with the confirmation of the phylogenetic placement of G. staffordi in genus Glypthelmins using three genetic markers. Morphological comparisons were conducted with eight other Glypthelmins species, and the molecular phylogeny revealed that the G. staffordi specimens form a monophyletic group with other Glypthelmins. Glypthelmins staffordi was also evidenced to be genetically distant from genus Rauschiella. Thus, G. staffordi is proposed to be reinstated as a valid species within the genus Glypthelmins, instead of in Rauschiella. Additionally, the morphological character of the excretory vesicle should not be used as a key character to distinguish among genera. Supplementing the systematics of this taxonomically complex group, we provide an updated key for the genus Glypthelmins, alongside molecular sequences of G. staffordi, to supplement the identification of Glypthelmins species.