Xenosaurus grandis, commonly known as the knob-scaled lizard, is a species of diurnal, terrestrial lizard endemic to Mexico and Guatemala. It primarily inhabits tropical rainforests. It dwells in rock crevices and eats insects. Etymology The scientific name, Xenosaurus grandis, comes from the Greek words xenos, meaning “alien”, “stranger”, or “foreigner”, saurus, meaning “lizard”, and grandis, meaning “grand” or “great”. Its common name, “knob-scaled lizard”, refers to the bumpy, “knob-like” scales found on the upper portion of its body. Taxonomy There are five recognized subspecies, which are spread throughout the species’ range, and the species complex is being reevaluated. Some of the subspecies are currently in the process of being elevated to species status. The species as a whole is listed as vulnerable by the IUCN Red List and its population is currently decreasing. Physiology Appearance Xenosaurus grandis has a flattened head and body and is nearly always found in rock crevices, or at least with a portion of the body in a crevice. Its flattened physiology is most likely an adaptation to allow it to squeeze into narrow crevices. Its color ranges from dark grey to dark brown, with lighter bands or blotches. It has a forked tongue, and small, sharp, fang-like teeth. Body size On average, the snout-vent length (SVL) of Xenosaurus grandis is 6.8 - 12.9 cm. While some species of Xenosaurus do not exhibit sexual dimorphism, Xenosaurus grandis, among other species, is one that does. In Xenosaurus grandis, males and females do not differ significantly in body size, but males have proportionately larger heads (in length and width) than females. Males and females of X. grandis do not exhibit a significant difference in femur length or head shape. Body temperature Xenosaurus grandis is a diurnally active thermal conformer, meaning that its body temperature correlates with substrate and air temperatures. Its average body temperature is 22.7 C. Air and substrate temperatures may be particularly relevant in Xenosaurus grandis since they are almost exclusively ground and crevice dwellers. Temperatures seem to differ across Xenosaurus species, possibly because of environment and habitat. Xenosaurus grandis appears to inhabit more dense tropical forests, where sunlight may not reach the ground as much. While body temperature is influenced by the lizard's amount of cover and its body position in its crevice, it does not seem to be influenced by sex, month, vegetation type, or any crevice characteristics. Diet Lizards in the genus Xenosaurus