Sierra Curlytail Lizard

L. onaneyi can reach snout–vent lengths of up to 77 mm (3.0 in), medium size for a Leiocephalus. The back has a chocolate-brown line going down the middle of it, surrounded by slightly darker chocolate brown line on each side, and after these there are another seven lines going on each side of the back, alternating between chocolate brown and a light brownish grey in colour. Only the throat colouration differs between males and females, being white for males and grey for females, and this colouration extends down towards the belly, which is white. The colourations of the throat and belly are solid, with no discernible markings.

L. onaneyi is only known to live in the vicinity of its type locality, at elevations of 150–200 m (490–660 ft). The area is located near the coast and has a xeric habitat, with limestone karst topography and vegetation primarily consisting of grasses, agaves and bushes. The quality and extent of its habitat is threatened by goat grazing and by fires being intentionally lit to clear land so that it may be turned into pasture. Due to these threats, and the fact that the area is estimated to have an extent of less than 100 km2 (39 sq mi), led to it being listed as critically endangered on the IUCN Red List after its 2016 assessment.