Overview
The Spot-tailed Earless Lizard (Holbrookia lacerata) is a rare, ground-dwelling reptile endemic to the rocky limestone plateaus and shortgrass savannas of Texas and northern Mexico. Easily distinguished from all other earless lizards by the distinct rows of round black spots running along the underside of its tail, it is an increasingly rare symbol of native Texas prairie ecosystems.
Biology and Physical Characteristics
The Spot-tailed Earless Lizard has a compact, flattened body with smooth dorsal scales and a blunt, rounded head completely lacking external ear openings or tympanic membranes. Its dorsal ground color is light tan to greyish-brown, adorned with four rows of dark brown jagged or comma-shaped blotches. Its defining anatomical marker is a series of 4 to 9 bold, pitch-black spots on the bright white underside of its tail.
Behavior and Ecology
A diurnal ground runner, this species relies on cryptic coloration to escape notice, flattening its body against bare limestone gravel and caliche soil where it becomes virtually invisible. When startled, it curls its tail upward over its back, displaying its bold black-and-white tail spots before darting into an abandoned rodent burrow or crack in the limestone bedrock.
Conservation and Human Impact
Assessed as Near Threatened by the IUCN and currently under review for listing under the US Endangered Species Act, the Spot-tailed Earless Lizard has suffered significant population declines. The primary causes include large-scale conversion of native shortgrass prairie to monoculture cropland, intensive residential development on the Edwards Plateau, and widespread invasive coastal Bermuda grass that chokes open soil.
Interesting Factoid
When frightened, the Spot-tailed Earless Lizard arches its tail high over its back like a scorpion, flashing a row of stark black polka dots underneath to startle predators before sprinting away.