Phylogenetic positions of Paronychomys Jacobs and Basirepomys Korth and De Blieux relative to the tribe Neotomini (Rodentia, Cricetidae)

A recent study on the fossil history of North American woodrats and their relatives suggested that the Neotomini includes two subtribes: the Neotomina (woodrats; Tsaphanomys, Neotoma, Hodomys, Xenomys) and Galushamyina (reprats: Protorepomys, Galushamys, Miotomodon, Repomys, Nelsonia). The extinct Miocene Lindsaymys was proposed as a possible early neotominan, but not formally included in the Neotomini. In other studies, two extinct genera, Basirepomys and Paronychomys, occasionally have been treated as related to neotominans, but their ancestry had not been formally explored in detail. We performed a phylogenetic analysis on representatives of all genera with 40 dental and mandibular characters likely to be preserved in fossil material. The analysis resulted in a single most parsimonious tree supporting a neotominan-galushamyinan tribal classification of the Neotomini, and securely placed Lindsaymys within the Neotomina. None of the Basirepomys and Paronychomys species or Protorepomys bartlettensis nested within the Neotomini. The three Basirepomys species, possibly a paraphyletic group, are not closely related to Repomys, and Paronychomys (minus P. shotwelli = Tsaphanomys shotwelli) is not closely related to Onychomys, but is a possible sister group to the Neotomini. With the understanding that further study may remove it from Protorepomys, P. bartlettensis is tentatively retained within the genus, representing a relatively underived species possibly ancestral to both neotominan clades. Neotoma species of the extinct subgenus Paraneotoma and extant Neotoma may be paraphyletic at the generic level, but that determination will require further study.