A late Miocene pipine frog from the Urumaco Formation, Venezuela

THE PIPIDAE currently hosts about 35 species, with a disjoint Gondwanan distribution that only in the last decades, due to human introduction of the African Xenopus in four continents, expanded into Laurasian countries where this frog is often regarded as a pest (Tinsley et al., 2015). The extant pipid genera can be grouped into two clades, Pipinae and Xenopodinae, whose content varies according to different phylogenetic analyses. The molecular approach favours in most cases the inclusion of the sole Pipa in the Pipinae whereas the Xenopodinae host Xenopus (and, if not considered a synonym of the former, also Silurana) plus the Hymenochirini: Hymenochirus and Pseudhymenochirus (see literature cited in Cannatella, 2015). Conversely, the morphological approach generally suggests the inclusion of Pipa and the Hymenochirini in the Pipinae and Xenopus (plus Silurana) in the Xenopodinae (Gómez, 2016, and literature therein). Pipa is South American whereas both the Hymenochirini and the Xenopodinae are currently exclusive (not considering the above mentioned human introductions) of sub-Saharan Africa (Frost, 2017). The pipid fossil record, rather rich and with a much broader geographic range than that currently shown by extant species (Báez, 1996; Sanchiz, 1998; Gómez, 2016), consists mostly of Cretaceous and Paleogene remains that play a relevant role in the analysis of the earlier history of such disjoint—but at the same time possibly intertwined—distribution. South America hosted several taxa related to the crown Xenopodinae from the Cretaceous to the Late Pleistocene, but no Hymenochirini are recorded there (Gómez, 2016). The South American post-Paleogene record is remarkably scarce and Pipa has virtually no fossil record, except for the mention by Liais (1872) of an entire ‘head’ from the Pleistocene or Holocene of Rio das Velhas in Brazil (Rio Dal Belhas in Sanchiz, 1998). The material was reported to be identical in size and aspect to Pipa bimaculata (a species name that is currently not valid and not listed among the synonyms of Pipa by Frost, 2017). However, the fossil has not been further described or figured and was simply listed as Pipa sp. by Sanchiz (1998). Here we report on a pipid fossil from Corralito, a late Miocene locality in the Urumaco Basin, Venezuela. The Neogene localities in the Urumaco Basin have so far yielded a large number of marine and continental vertebrates belonging to several major clades (Sánchez-Villagra et al., 2010; Carrillo-Briceño et al., 2015) but amphibians had not been reported to date. Most of the continental taxa retrieved are large sized, some being ‘gigantic’, such as the crocodiliansGryposuchus and Purussaurus, the turtle Stupendemys and the rodent Phoberomys (among others, SánchezVillagra et al., 2010; Scheyer et al., 2013). Prospection in the Urumaco Basin carried out in November 2013 yielded few continental vertebrates of small size, including the single amphibian remain that is here described and discussed.