New remains of Cephalomys arcidens (Rodentia, Caviomorpha) and a redefinition of the enigmatic Cephalomyidae

BUSKER, FELIPE; DOZO, MARÍA TERESA; SOTO, IGNACIO MARIA

JOURNAL OF SYSTEMATIC PALAEONTOLOGY

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2020

1477-2019

Cephalomys is the best-known cephalomyid, recorded in five localities in Argentina and known by well-preserved mandibles, fragments of skull, and alarge number of isolated teeth, both juveniles and adults. Despite this, none modern description was realized and the validity of some species of Cephalomys was questioned in the last few years. New material of the Deseadan locality of Cabeza Blanca (Chubut, Argentina), including some skull fragments unknown for the species so far and excellentpreserved juvenile teeth, were added to a large number of specimens from collections in Argentina. This allows us to propose a more complete description of thegenus and a new taxonomic arrangement for the Cephalomys species. We also analyzed some dubious records of Cephalomys from Quebrada Honda and PicoTruncado. We considered C. plexus as asynonym of C. arcidens, the combination previously proposed to C. bolivianus as valid,and C. ceciae as a valid species. We performed a phylogenetic analysis including for the first time all cephalomyids (Cephalomys, Litodontomys, Cephalomyopsis, Soriamys, and Banderomys) and possibly related genera (Perimys, Scotamys, Asteromys) to test theposition of the family Cephalomyidae among the other caviomorph rodents, as well as its validity and internal relationships. The results recovered Cephalomyidaeas a clade, including Cephalomys, Cephalomyopsis and Litodontomys. The monophyly of Cephalomys could not be probed. Soriamys and Banderomys were recovered within Cavioidea. Perimys, Scotamys and Asteromys were recovered within Chinchilloidea, and we analyzed the implication of their position. The implications in terms of the biochron, distribution and evolutionary history of the family considering this new definition were discussed, as well as its implications regarding the caviomorph evolution at the scale of the entire group.