A new species of Xenosaurus (Squamata: Xenosauridae) from the Sierra Gorda Biosphere Reserve of Querétaro, Mexico

AbstractA new species of Xenosaurus from the Sierra Gorda Biosphere Reserve of northeastern Querétaro, Mexico, is described. The new species differs from all of the other described species of the genus by having usually 2 postrostral scales on each side of the midline (in 84.6% of the specimens, n=26); largest supraoculars that are not, or only slightly, wider than long; postorbital and zygomatic ridges that are widely separated from each other by an intervening row of scales; labiomental rows that usually extend posteriorly from the second or third chinshield (in 92.3% of the specimens, n=26); 23–26 lamellae under the fourth toe (x¯=24.3, n=25); a venter that is immaculate or with only diffuse, scattered dark specks on the sides, and a postorbital region rounded, lacking a canthus temporalis demarcated by enlarged or well-defined scales. The new species inhabits oak forest and a transitional zone between oak forest and subperennial tropical forest at approximately 1 100–1 400m of elevation. The new species is morphologically most similar to X. platyceps from Tamaulipas, but does not appear to be its sister taxon