A New Species of Xenosaurus (Squamata: Xenosauridae) from the Sierra de Juárez of Oaxaca, Mexico

Abstract: We describe a new species of Knob-scaled Lizards of the genus Xenosaurus from the Sierra de Juárez of Oaxaca, México. Although this new species was identified as a distinct, undescribed lineage (and sister taxon to X. grandis) by previous molecular phylogenetic studies of the genus, we documented that it also differs from all of its congeners by a unique combination of scalation and color-pattern characters. The new species also is geographically isolated from all congeners and appears to have a geographic distribution limited to the vicinity of its type locality, between 1400 m and 1800 m of elevation, in the cloud forest belt of the Sierra de Juárez. Because the new species is a terrestrial, crevice-dwelling species generally ignored by humans and has a limited geographic and ecological distribution, we calculated its Environmental Vulnerability Score at 17, which places it in the middle of the high category of vulnerability to environmental degradation.