This species occurs in northwestern Mexico, extending into southwestern United States. The range encompasses central and southern Arizona, extreme southwestern New Mexico (Guadalupe Canyon, Hidalgo County; Painter 1993, Herpetological Review 24: 155), Sonora, portions of southwestern Chihuahua, and northern Sinaloa. It is also present on Isla Tiburon in the Gulf of California (Parker 1974, Degenhardt et al. 1996, Grismer 2002, Stebbins 2003). Stebbins (2003) mapped the range as extending through southern Sinaloa to at least Nayarit, but this appears to be an error. Elevational range extends from sea level to about 1,460 m (4,800 feet) (Stebbins 2003).

Phrynosoma solare is restricted to the Sonoran desert in

south-central Arizona, east to extreme southwestern New Mexico, south through most of Sonora (including Isla Tiburon) and into northern Sinaloa, Mexico (Hodges 1998).

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) The range encompasses central and southern Arizona, extreme southwestern New Mexico (Guadalupe Canyon, Hidalgo County; Painter 1993), Sonora, portions of western Chuhuahua, and northern Sinaloa, Mexico; also Isla Tiburon in the Gulf of California (Parker 1974, Degenhardt et al. 1996, Grismer 2002, Stebbins 2003). Stebbins (2003) mapped the range as extending through southern Sinaloa to at least Nayarit, but this appears to be an error. Elevational range extends from sea level to about 4,800 feet (1,460 meters) (Stebbins 2003).

Continent: Middle-America North-America
Distribution: USA (S Arizona, New Mexico),  Mexico (Sonora, N Sinaloa, Baja California)  
Type locality: California. Restricted to Yuma, Arizona by SMITH & TAYLOR 1950.

The Regal Horned lizard is characterized by one row of lateral abdominal fringe scales upon a wide, flattened, toad-like body. The tail is short and broad at the base. Four large occipital horns at the base of the head continuous with six temporal horns, form a large crown of ten sharp, pointed horns along the base of the head. Another distinguishing characteristic of the horned lizard is that the ventral portion of its body is composed of rows of keeled scales. The squat form, head armor, and dragon-like appearance has given rise to the name "hornytoad", "horned toad", and "horned lizard", which is the nickname commonly used for this particular genus. The Horned lizard is typically soft desert gray along the back and head. It is composed of pastel shades of tan, brown, red, and yellow. The underparts are pale, yellowish gray. Color change occurs within minutes, changing from light to dark or vice versa depending on the environment. Phrynosoma solare are on average about 5 inches in length (Seymour and Royo 1999).

Length: 17 cm

Syntype for Phrynosoma solare
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Sierra De La Nariz, near Zuni, Sonora, Mexico

Syntype for Phrynosoma solare
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Sierra De La Nariz, near Zuni, Sonora, Mexico

Habitat and Ecology

Systems

• Terrestrial

The Regal Horned Lizard prefers hot, dry, sandy environments.

Terrestrial Biomes: desert or dune

Comments: This lizard occupies generally level or gently sloping terrain with openly spaced desert vegetation (e.g., creosotebush, mesquite, saguaro), including rocky and gravelly habitats of arid and semiarid plains, hills, canyons, and lower slopes of mountains (Degenhardt et al. 1996, Stebbins 2003). Three females laid eggs in 35-cm-deep holes dug in fine soil within 1 m of shrubs (Van Devender and Howard 1973).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

The Regal Horned lizard is diurnal. The lizard eats spiders, sowbugs, and other insects, especially ants. Their favorite is Harvester ants, which occupy about 88% of their stomach volume (Hodges 1998). Horned lizards do not take their food methodically, but instead take it in a toad-like fashion, with a flick of their long, sticky, tongue. After feeding, when ground temperatures become too hot, they seek the shade of a shrub, partially concealing themselves.

Comments: Ants comprise most of its diet.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 - 300

Comments: This species is represented by well over 100 collection sites that represented at least several dozen distinct occurences (e.g., see Parker 1974).

10,000 - 1,000,000 individuals

Comments: Total adult population size is unknown but certainly exceeds 10,000 and likely exceeds 100,000.

Usually not found in the same habitat with other species of horned lizards (Stebbins 1985).

Comments: Inactive in cold temperatures or extreme heat. Most active in the early morning and just before sunset (Behler and King 1979).

Mating for the Regal Horned lizard begins in late April, peaks in June, and stops abruptly in July. Egg laying starts a few weeks later, usually in late July and early August. The eggs are laid in the sand where they require several weeks for further development before the eggs hatch. The egg shells are white and flexible and average about one-half inch in diameter. The number of eggs varies anywhere from 10-30 eggs, with an average of about 15. The young are called hatchlings. They are about 7/8 to 1-1/8 inches long, snout to vent (Seymour and Royo 1998). The hatchlings receive no parental care upon hatching and immediately bury themselves in the sand. They are now responsible for finding and hunting for their own food. There is no evidence that the young reproduce within their first year, but they are classified as young adults by the end of the second summer and probably reach full growth in three years.

Mates in summer. Eggs laid July-Aug. Clutch size 7-33. In southern Arizona, eggs laid mid-July hatched by late August (Van Devender and Howard 1973).

The Regal Horned lizard populations are not protected. Four individuals may be collected in Arizona with a hunting license. However, habitat destruction and ant extermination are depriving the horned lizard not only of their homes, but of their only source of a dependable diet.

US Federal List: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Intrinsic Vulnerability: Moderately vulnerable

Population

Population Trend

Global Short Term Trend: Relatively stable (=10% change)

Comments: Extent of occurrence appears to be stable, and area of occupancy and population size probably are relatively stable or slowly declining.

Global Long Term Trend: Increase of 10-25% to decline of 30%

Major Threats

Comments: No major threats have been identified. Locally, some populations probably have been reduced or eliminated as a result of urbanization, agricultural development, and other human activities, but the species is unthreatened in most of the range.

Conservation Actions

Global Protection: Several to many (4-40) occurrences appropriately protected and managed

Comments: This species exists in several national parks, monuments, and wilderness areas.

Comments: Reeder and Montanucci (2001) examined phylogenetic relationships of horned lizards (Phrynosoma) based on mtDNA and morphology.