Round-tailed horned lizard

Roundtail Horned Lizard

The roundtail horned lizard, scientifically known as Phrynosoma modestum, is a diminutive species belonging to the Phrynosomatidae family. It is recognized as one of the smaller members of the horned lizard genus, Phrynosoma. The species name, 'modestum,' is Latin for 'modest' or 'calm,' reflecting a characteristic of the lizard.

Habitat and Distribution

This lizard is native to arid regions of the southwestern United States, with documented populations in western Texas, New Mexico, eastern Arizona, and southeastern Colorado. Its range extends into eight states in northcentral Mexico, where it is locally referred to as tapayaxtin. The roundtail horned lizard thrives in rocky and sandy semiarid environments characterized by sparse vegetation. Crucially, it is often found in proximity to colonies of harvester ants and especially honeypot ants, which form the primary component of its diet.

Physical Characteristics

The roundtail horned lizard is characterized by its short, flat, and round body, complemented by short limbs and a small head. A distinctive feature is its cranial crest, composed of horns of nearly equal length. Unlike some of its relatives, it lacks a prominent fringe of lateral scales. Its coloration typically harmonizes with the soil of its surroundings, commonly appearing in shades of gray, light brown, or pale yellow. Darker markings may be present around the neck and groin, and occasionally, stripes adorn the tail.

Behavior and Reproduction

When seeking camouflage, the roundtail horned lizard employs a unique strategy. Instead of flattening itself to reduce its shadow, it hunches its body into a shape resembling a rock, boldly casting a shadow that further aids in its concealment. This species is oviparous, reproducing by laying eggs. The breeding and egg-laying season typically occurs in early summer.