Taxonomic status and phylogenetic position of Oxymycterus juliacae Allen 1900 (Rodentia: Cricetidae)

The phylogenetic position of the “Upper yungas inca hocicudo” Oxymycterus juliacae, one of the lesser-known species of the genus Oxymycterus, is still unresolved. Several authors considered it a subspecies or synonym of Oxymycterus inca, but more recently, it was recognized as a valid species based on morphometric analysis and morphological traits. The objectives of this study were then to substantiate the morphological distinction of O. juliacae and evaluate its phylogenetic position using cytochrome b sequences. We evaluated the morphology of O. juliacae and compared it with congeneric species. In addition, a Cytochrome b gene matrix was subjected to analyses of maximum likelihood and Bayesian inference. Our results support the morphometric and morphological distinction of O. juliacae and found that this species is more closely related to Oxymycterus willkaurco than to O. inca. Therefore, the recognition of O. juliacae as a full species is supported and a rediagnosis is provided. In addition, we found O. inca is more related to other lowland species from Argentina, Brazil, and Uruguay, than to central Andean species. More efforts are needed to secure genetic material of Oxymycterus species, mainly the Andean species, for a better understanding of their phylogenetic relationship.