New contributions to the systematics of the Plohophorini (Mammalia, Cingulata, Glyptodontidae) from Uruguay

The Plohophorini (Late Miocene - Pliocene of South America) constitute one of the more taxonomically complex groups within Glyptodontidae, with a monophyly questioned in recent phylogenetic analyses. The tribe is characterized by a poor representation of most of its species, several of which are described upon very fragmentary type specimens, with few referred specimens, even none, besides a remarkable shortage of recent systematic reviews. In addition to some fragmentary materials dubiously attributed to the Argentinian genera Plohophorus and Parahoplophorus, in Uruguay the record of the tribe traditionally offers a complex of endemic genera mostly known by partial remains of exoskeletons (mainly fragments of carapaces and/or caudal tubes). This complex basically presents a geographic distribution bounded to the Southwest of the country (San Jose and Colonia Departments), and a stratigraphic distribution bounded to the Camacho Formation (Huayquerian Stage/ Age, Late Miocene). In light of the presence of new unpublished Uruguayan specimens referable to the tribe, a comparative analysis of them was made on the basis of qualitative and quantitative criteria (multivariate analyses of skulls and caudal tubes), using the Plohophorini from Uruguay and Argentina, and some Argentinian Hoplophorini, as a comparative group. The results obtained firstly show a greater similarity of the Uruguayan Plohophorini among themselves and to certain Hoplophorini, rather than to most of the Argentinian 'Plohophorini, which show a large morphological variability. Secondly, the analysis of all specimens allows postulating that several of the Uruguayan taxa involved were established under a purely descriptive morphotypical criterion, typical of an Ameghinian methodology popular at least through the first half of the twentieth century. A reduction of the list of Uruguayan genera up to two is herein proposed: Stromaphoropsis and Pseudoplohophorus (the latter including Teisseiria, Trabalia, Berthawyleria, and Asymmetrura), while provisionally maintaining the identity of the species involved until new findings enable a better understanding of the probable intraspecific variability present in the taxa studied.