Description: A medium-sized flat-bodied lizard with a wide oval-shaped body and scattered enlarged pointed scales on the upper body and tail. The back skin is smooth with small spines. 8 horns extend from the back of the head. The two central horns are long, slender and sharp. Long and narrow spines on the lower jaw and two rows of fringe scales on the sides of the body, the bottom row scales smaller than the upper.
Habitat: Typical habitat consists of sandy desert flatlands with sparse vegetation and low plant species diversity; occasionally the species occurs on low hills, mud hills, alkali flats, or areas covered with small pebbles or desert pavement; it is most abundant where surface soils contain some loose or windblown sand but rarely occurs on dunes. Vegetation in favourable habitat may include creosote bush, bur-sage, indigo bush, saltbush, and ocotillo; also salt-cedar. In Arizona, it is most abundant in areas with galleta grass, sandy soil, and many active black harvester ant nests. In southeastern California, abundance is positively correlated with density of perennial plants, and there is a strong positive association between lizard and ant densities. This is a cryptic lizard that generally occurs on the ground; often it is immobile and difficult to detect until it moves. Sometimes it perches on rocks or wood. Periods of inactivity may be spent burrowed in loose sand. When approached, it may attempt escape into a burrow or under a shrub. Hibernation burrows appear to be self-constructed (constructed by the lizards themselves versus using burrows constructed by other animals) and are within 10 cm of the surface. It was found that the majority of lizards hibernated within five cm of the surface. The greatest depth recorded was 20 cm below the surface.
Range: This species is known only from a limited area in extreme southwestern United States, and extreme northwestern Mexico. The range includes southeastern California, extreme northeastern Baja California, northwestern Sonora, and southwestern Arizona. In California, the species ranges southward from the Coachella Valley, including both sides of the Salton Sea and Imperial Valley, and westward into the Borrego Valley, Ocotillo Wells area, West Mesa, and Yuha Desert (Yuha Basin), and, on the east side of the Imperial Valley, to the vicinity of the Dos Palmas Bureau of Land Management (BLM) Area of Critical Environmental Concern (ACEC), but predominantly it occurs in East Mesa and in areas adjoining the Algodones Dunes (i.e., Imperial Sand Dunes, Glamis Sand Dunes) on the east side of the Imperial Valley. In southwestern Arizona, it occurs south of the Gila River and west of the Gila and Tinajas Altas Mountains in Yuma County. The range extends into Mexico from the international border in the Yuha Desert in California, south to Laguna Salada in Baja California, and from the international border in the Yuma Desert in Arizona, south and east through the Pinacate Region to the sandy plains around Puerto Penasco and Bahia de San Jorge, Sonora. The distribution of the Flat-tailed Horned Lizard is not contiguous across its range; it is fragmented by large-scale agricultural and urban development, primarily in the Imperial Valley and the Coachella Valley.
Diet: This species feeds almost exclusively on ants, especially harvester ants; sometimes also eats other insects.
Reproduction: Flat-tailed horned lizards are oviparous (egg-laying), early maturing, and may produce multiple clutches within a breeding season. Flat-tailed horned lizards produce relatively small egg clutches (N = 31; mean clutch size = 4.7; range = 3 to 7), compared to most other horned lizards. The first cohort hatches in July to August, and in some years a second cohort may be produced. Hatchlings from the first cohort may reach sexual maturity after their first winter season, whereas hatchlings born later may require an additional growing season to mature
Status: Listed as Near Threatened since the species depends on areas of wind-blown sand, and so its area of occupancy is probably not much greater than 2,000 kmē, and the extent and quality of its habitat is declining, thus making the species close to qualifying for Vulnerable under criterion B1ab.
Disclaimer: ITIS taxonomy is based on the latest scientific consensus available, and is provided as a general reference source for interested parties. However, it is not a legal authority for statutory or regulatory purposes. While every effort has been made to provide the most reliable and up-to-date information available, ultimate legal requirements with respect to species are contained in provisions of treaties to which the United States is a party, wildlife statutes, regulations, and any applicable notices that have been published in the Federal Register. For further information on U.S. legal requirements with respect to protected taxa, please contact the U.S. Fish and Wildlife Service.
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