Revisión de los géneros Nopachtus Ameghino y Phlyctaenopyga Cabrera (Xenarthra, Glyptodontidae, Hoplophorinae) del Mioceno tardío y Plioceno de Argentina

Abstract

Revision of the genus Nopachtus Ameghino and Phlyctaenopyga Cabrera (Xenarthra, Glyptodontidae, Hoplophorinae) from the late Miocene and Pliocene of Argentina. This work presents the first formal diagnosis for two genera of Hoplophorinae glyptodons, Nopachtus and Phlyctaenopyga, as well as for the species they incluye. In addition, a new species of Nopachtus is recognized for the Montehermosan, and a new combination is proposed: Phlyctaenopyga trouessarti. Precise geographical and stratigraphic provenance is provided for all the analyzed taxa. The most significant differences between Phlyctaenopyga and Nopachtus lie in the osteoderms, especially in the degree of convexity of the central figures and the number of peripheral figures that surround them. Although the central figure is convex in both genera, it is more “bulbous”/ “bubble-shaped” in Phlyctaenopyga compared to Nopachtus. Lastly, in Phlyctaenopyga the peripheral figures are arranged in two or three rows, with 18 to 23 figures in the first row. In the genus Nopachtus there are never more than two rows peripheral figures, and the first one comprises 12 figures.