Phrynosoma modestum Girard, 1852

Common Name & Base Coloration

Phrynosoma modestum, commonly called the roundtail horned lizard, typically has coloration that matches the color of the soil in its native habitat. Most individuals are uniformly gray, but they may also be light brown or pale yellow.

Marking Patterns

Darker markings often appear around the neck and groin, and faint striping can sometimes occur on the tail.

Body Shape

This species is a short, flat, round-bodied lizard with short limbs and a small head.

Head Horn Structure

The head bears a distinctive crest of horns that are all nearly equal in length.

Scale Morphology

Unlike other horned lizards, the roundtail horned lizard has no fringe of scales along the sides of its body.

Camouflage Behavior

It also does not flatten itself against the ground to eliminate shadow; instead, it hunches its body into a rock-like shape for camouflage, which leaves a distinct visible shadow.

Size Measurements

The maximum snout-to-vent length (SVL) for this species is 7 cm (2.7 in), and the maximum total length including the tail is 10.5 cm (4.3 in).

Habitat Preferences

The roundtail horned lizard favors rocky, sandy semiarid habitats with sparse vegetation.

Diet Associations

It tends to live near harvester ant colonies, and especially near honeypot ant colonies, which are the source of its primary diet.

Reproduction

It is oviparous, meaning it lays eggs, and breeds and lays eggs in early summer.