Molecular and morphological support for the synonymy of Nephrostomum and Patagifer: discovery of new species and broad geographic connections

In this study, DNA was sequenced from adults of Patagifer Dietz, 1909 and Nephrostomum Dietz, 1909 (Digenea: Echinostomatidae) collected from avian definitive hosts in Nearctic, Neotropic, Palearctic and Afrotropic regions. Phylogenetic analyses of entire mitochondrial genomes, nuclear rDNA operons, and partial 28S, ITS2, cox1 , and nad1 all indicate that Nephrostomum is synonymous with Patagifer , which is given priority, and that head-collar characters formerly used to separate these genera represent traits that vary among closely related congeneric species. Low interspecific divergence in partial 28S (0–0.41 %) in Patagifer has contributed to misidentifications, while mitochondrial markers provided greater resolution and revealed greater species diversity. Six species were included in the present study: P. ramosum , P. bilobus , P. vioscai , P. limai , an unidentified species known only from cercariae, and a new species with distinctive head collar morphology, from Theristicus caerulescens in Argentina. In both P. ramosum and P. bilobus , mitochondrial markers show intercontinental distributions that can be plausibly linked to historical transatlantic expansions of their Old-World avian hosts.