Review of the Taxonomic Status of the Chelid Turtle Parahydraspis paranensis Wieland 1923 from Late Miocene at Parana, Entre Rios Province, Argentina: with Comments on the Paleoenvironmental Settings from the lower Levels of Ituzaingó Formation

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The panchelid turtles (stem chelid + crown chelid), one of the pleurodiran clades, display a disjunct distribution in Australasia and South America. Panchelids appeared in the fossil record during South America's Early Cretaceous (Aptian-Albian) and Late Cretaceous (Cenomanian) in Australasia. Among the crown Chelidae, the Chelinae include genera such as Acanthochelys, Mesoclemmys, Platemys, Phrynops, Ranacephala, and Rhinemys characterized by a restricted, poor or null fossil record in South America. Among this chelid clade, Parahydraspis paranenesis is a carapace-based species described by Wieland in 1923 from upper Miocene Ituzaingó Formation outcrops along the Parana river cliffs, Parana city, Entre Rios Province, Argentina. Wieland referred to this new species as a different genus from the extant Hydraspis (an old synonymous genus of the genus Phrynops), depending upon a misinterpretation of the plastral bridge. Although a recent phylogenetic analysis nested this Miocene species with stem chelid species, in this contribution based on anatomical evidence on the holotype and referred specimens, we consider Parahydraspis paranensis as a fully valid species of the Phrynops genus. The continental terrestrial and aquatic fauna of the "Conglomerado osifero" lower levels of the Ituzaingó Formation where the holotype and specimens referred to as “Parahydraspis” paranensis were recovered, indicate a warmer climate and suggest the presence of forested areas along river’s shores where these levels were deposited.

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