Taxonomic status of Wiedomys marplatensis, an enigmatic fossil cricetid (Rodentia, Sigmodontinae): Neither Wiedomys nor Wiedomyini

Abstract

The generic placement and tribal affiliation of Wiedomys marplatensis Quintana, 2002 are revised based on the study of its holotype and a single known remains from San Andrés Formation (Early Pleistocene; Buenos Aires Province, Argentina). The anatomical traits selected as indicators belonging to Wiedomys Hershkovitz, 1959 are interpreted here as general similarities. Wiedomys marplatensis is removed from Wiedomys and is considered as a junior synonym of Cholomys pearsoni Reig, 1980. The affiliation of the latter to Wiedomyini is discussed and the alternative hypothesis to allocate Cholomys Reig, 1980 in Oryzomyini is advanced. Although further research and more fossils are necessary to solve this issue, the placement of Cholomys as Sigmodontinae incertae sedis and the avoidance of using it as a point of calibration in molecular phylogenies are suggested.