SHAKING THE TREE OF CHINCHILLIDS (RODENTIA, CAVIOMORPHA) WITH A TOTAL EVIDENCE PHYLOGENY

L. RASIA; A. CANDELA; C. CAÑÓN

Jornada; 34º JORNADAS ARGENTINAS DE PALEONTOLOGÍA DE VERTEBRADOS; 2021

Chinchilloidea is a poorly understood clade of caviomorph rodents, from an evolutionary and phylogenetic perspective. It includes the extant families Chinchillidae and Dinomyidae, the extinct Neoepiblemidae and Cephalomyidae, and several extinct chinchilloids without a definite phylogenetic position. Chinchillidae include the extant Chinchilla and Lagidium, grouped in Chinchillinae, and the only living Lagostominae, Lagostomus maximus. Among extinct chinchillids, Eoviscaccia, Prolagostomus and Pliolagostomus are the only genera originally described as members of the family. We performed a combined molecular and morphological phylogenetic analysis including extinct and extant taxa of Chinchilloidea, encompassing all recognized families. Our phylogenetic analysis recovers three major lineages within Chinchilloidea. The first one is composed of Dinomyidae (Dinomys, Drytomomys, Scleromys, ?Scleromys? and Tetrastylus), recovered along with Eoincamys pascuali as sister groups of a clade composed of the second major lineage, ?Cephalomyidae? (Banderomys, Cephalomys, Litodontomys and Soriamys; not forming a clade) + Neoepiblemidae (Neoepiblema, Perimys, Phoberomys and Scotamys), and the third one, the pan-Chinchillidae. Pan-Chinchillidae includes the stem Chinchillidae, grouping taxa without a clear suprageneric group (Garridomys, Incamys, Loncolicu and Saremmys) along with Eoviscaccia. The crown Chinchillidae comprises Chinchillinae and Lagostominae, the latter including Prolagostomus and Pliolagostomus. Chambiramys sylvaticus occupies a basal position to the clade ((?Cephalomyidae?+Neoepiblemidae) pan-Chinchillidae). The analysis of new morphological characters linked with molecular evidence, as well as the addition of taxa of uncertain or unstable phylogenetic position or not considered in previous studies, allows us to resolve part of the relationships within Chinchilloidea, particularly that of pan-Chinchillidae, supporting preceding morphological hypotheses.