Resolution of the long-standing controversy over the type species of the genus Pseudotypotherium (Mesotheriidae, Notoungulata)

FERNÁNDEZ-MONESCILLO, M.; CROFT, D. A.; PUJOS, F.; ANTOINE, P.-O.

Buenos Aires

Congreso; 12 CAPA; 2021

APA

Mesotheres (Notoungulata: Typotheria) are among the most common mammal remains found in late Miocene to Pliocene deposits of central Argentina, including the classic type locality of the Montehermosan South American Land Mammal “Age”. Nevertheless, the correct name for the mesothere species from Monte Hermoso has been shrouded in uncertainty for well over a century due to questions of taxonomic priority, specimen provenance, and ontogenetic changes in dentalformula. In the application of the International Code of Zoological Nomenclature, we conclude that Pseudotypotherium pulchrum (holotype MACN-A 10299, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Ameghino Collection), is the type species of mesotheriid notoungulate genus from Monte Hermoso. Article 67.2 of the International Code of Zoological Nomenclature indicates that only species considered as nominal species are eligible to set the type, in the caseof Pseudotypotherium these are: P. pulchrum, P. carlesi, P. hystatum and P. carhuense. Among these species, F. Ameghino fixed the type by original designation in 1904 when he described P. pulchrum, and included “n. g., n. sp.”, according to Article 68.2. Other species that were named later (Typotherium maendrum, T. [= P.] bravardi, or T. [P.] exiguum) are invalid according to Article 70.2, as they ignore the previous type fixation. This puts an end to a historical debate that has been going on for more than a century regarding this well-represented late Miocene–Pliocene mesotheriine from Argentina.