A Guide to the Amphibians
and Reptiles of California

Desert Horned Lizard - Phrynosoma platyrhinos

Southern Desert Horned Lizard - Phrynosoma platyrhinos calidiarum

Cope, 1896

(= Doliosaurus platyrhinos calidiarum)

Click on a picture for a larger view

Description • Taxonomy • Species Description • Scientific Name • Alt. Names • Similar Herps • References • Conservation Status

Red: Range of this subspecies in California
Phrynosoma platyrhinos calidiarum -
Southern Desert Horned Lizard

Range of other subspecies in California:

Dark Blue: Phrynosoma platyrhinos platyrhinos -
Northern Desert Horned Lizard

Click on the map for a topographical view

Map with California County Names

Baja California Page

Adult, Inyo County

Adult, San Bernardino County

Adult, Inyo County

Adult, San Bernardino County

Adult, Inyo County

Adult, Kern County

Adult, San Bernardino County

Adult, Kern County

Adult male, Kern County

Adult, San Diego County

Adult, Kern County

Mono County © Keith Condon

Horned Lizards in lava rock habitat tend to have dark coloring to match the dark soil, as you can see on this adult from San Bernardino County. (Both are the same lizard; the picture on the right was taken with flash.) © Filip Tkaczyk

Adult, Kern County
© Todd Battey

Striped adult, Kern County
© Todd Battey

Adult, San Bernardino County © Jeff Ahrens

Adult, Kern County © Lou Silva

Close-ups of adults found in San Barnardino County © Sean Barefield

Adult female in yellow/orange color phase, Mono County
© Adam G. Clause

Adult, Riverside County © Huck Triggs

Adult, Inyo County © Ryan Sikola

Adult, eastern San Bernardino County desert © Joel A. Germond

Adult, Inyo County © Grigory Heaton

Adult, San Bernardino County
© Zeev Nitzan Ginsburg

Close-up of the front of the head of an adult, San Bernardino County, with closed nasal valves.

Horned lizards can close their nasal valves to keep soil from entering their nostrils and lungs when they bury themselves. The closed valves leave a small crescent-shaped opening through which the lizard can still breathe when it is buried. © Filip Tkaczyk

Desert Horned lizards are covered with small granular scales interspersed with larger pointed scales on the dorsal surfaces.

Juveniles

Juvenile, basking on a low rock in the early morning, Kern County

Juvenile, Kern County

Juvenile, eastern Riverside County
© Geoff Fangerow
When threatened, horned lizards will sometimes squirt blood from the eyes to deter predators, as this one did.

Neonate, Kern County. © Todd Battey

Juvenile, San Bernardino County
© Jeff Ahrens

Breeding Behavior

Jay Snow shot this series (left to right, top to bottom) of a mating pair of Desert Horned Lizards one day in late May in Death Valley National Park. © Jay Snow

Male vent on left
Female vent on right © Lacey Sampson

Predators

Jay Snow took this series (left to right, top to bottom) of a Red Racer trying to eat a live Southern Desert Horned Lizard over a period of 44 minutes. The snake failed to swallow the lizard and crawled away. In the last picture you can see that the lizard lay prone for several minutes after the coachwhip left then took up to 15 minutes to clean the saliva off its face before slowly walking away, no doubt thankful for the row of horns behind its head.
© Jay Snow

Comparison of Blainville's Horned Lizard with Desert Horned Lizard (from Stebbins, 2003)

Blainville's Horned Lizards have 2 rows of pointed fringe scales on the lower part of each side of the body.

Desert Horned Lizards have only 1 row of fringe scales on each side of the body

Blainville's Horned Lizards have 2 or 3 rows of enlarged pointed scales on each side of the throat.

Desert Horned Lizards have only 1 row of slightly enlarged scales on each side of the throat.

Habitat

Adult in situ basking on a rock,
San Diego County

Habitat, Kern County

Habitat, Inyo County

Habitat, San Bernardino County

Habitat, Riverside County

Lizard in habitat, Kern County

Short Video

I found this horned lizard basking on a rock on a cool morning in the Mohave Desert. It only had two speeds - sit still and hide, and run away as fast as you can.

Walking around the Mohave Desert in Kern County one spring day I spotted several Desert Horned Lizards so I slowly followed them with my video camera hoping for some action. They did what they're designed to do - they ran in quick bursts a short distance, often under a bush, then they sat still hoping that their camouflage would make them invisible.

Description

Size

2.5 - 3.75 inches long from snout to vent (6.4 - 9.5 cm). (Stebbins 2003)

Appearance

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.
The snout is blunt.
Horns extend from the back of the head, with the two central horns longest.

Each side of the body has one row of well-developed fringe scales. (Stebbins, 2003)
Each side of the throat has one row of slightly enlarged scales. (Stebbins, 2003)

Color and Pattern

Color can be reddish, tan, dark gay, beige, brown and even black in areas with dark lava. Background coloring usually matches the local soil and rocks. A pair of large dark blotches mark the neck. Wavy dark blotches mark the back.
The belly is white with smooth scales and black spotting at the vent opening.

Male / Female Differences

Males are smaller than females, and have postanal scales, femoral pores, and a wider tail base.

Life History and Behavior

Activity

Diurnal.
Adapted to hot and barren habitats.
Remains underground during hot or cold weather, but can be active on the surface at any time of the year.
Most active from April to July.
Can be seen basking on rocks and road berms in the morning.

Horned lizards roam a home range, which may overlap with others and change seasonally, but male horned lizards do not defend their territory aggressively like other kinds of lizards. They don't have patches of brighly-colored scales to display to other males. Because they don't combat other males during the breeding season, their bodies are smaller than the bodies of female horned lizards, which lets them use their energy in searching for females instead of maintaining a large body size.
(Sherbrooke, 2003)

Defense

When threatened, this lizard is capable of running away quickly for only a short distance.
It will often run under a low bush or into a rodent burrow to escape, or shuffle sideways to bury itself partly in the sand.
Its main defense is remaining motionless using its cryptic coloring to blend into the background and make it difficult to see.
It will crouch down low to prevent shadows that could make it easier to see, and sit still to avoid detection.
When grabbed, it will inflate with air, hiss, threaten to bite, and move the head from side to side to jab with its horns.
This species of horned lizard rarely defends itself by squirting blood from the corners of its eyes.

Diet and Feeding

90 percent of the diet consists of ants. The remainder consists of other small invertebrates, including flies, and some plant material such as berries.

Although horned lizards may be desirable pets, captive animals normally do not live very long due to the difficulties of feeding them a proper diet of ants.

Reproduction

Mates April to May.
Females lay 1 - 2 clutches of 2 - 16 eggs from June - July.
Hatchlings appear usually in August to mid September.

Hybrids

Know to hybridize with P. mcallii around Ocotillo and SE of Yuma. (Natureserve)

Habitat

Found in arid lands including sandy flats, at the edges of sand dunes, alluvial fans, and dry washes.
Patches of sand are generally present. Associated plants include creosote, salt bush, cacti, other small shrubs.

Geographical Range

In California, this subspecies is found throughout the Colorado and Mojave deserts, east and north of the southern mountain ranges to the Colorado River and Baja California border, and north through the Owens Valley to near the Nevada border.

Intergrades with P. p. platyrhinos in the White-Inyo mountains region. (Macey & Papenfuss 1991)

Found south of California along the eastern side of Baja California, and east through the eastern part of Arizona, the southern tip of Nevada, and extreme southeast Utah, and along the northern coast of Sonora, Mexico.

The species Phrynosoma platyrhinos occurs in southern California and northeastern Baja California, throughout most of Nevada, along the extreme northeastern edge of California, in southeast Oregon and southern Idaho, in western Utah and a couple of isolated spots in northeastern Utah, and western Arizona.

Elevational Range

From below sea level to 6,500 ft. (1,980 m). (Stebbins 2003)

Notes on Taxonomy

Three subspecies of P. platyrhinos have been recognized:

P. p. calidiarum
P. p. platyrhinos
P. p. goodei

Mulcahy et al. (2006, Mol. Ecol. 15:1807-1826) demonstrated that P. p. goodei is a full species, P. goodei, and showed that it occurs in the United States.

Leache and McGuire (2006, Molecular Phylog. Evolution 39:628-644) named four subclades of Phrynosoma - 3 in our area: Anota, Doliosaurus, and Tapaja.

Alternate and Previous Names (Synonyms)

Commonly called: "Horny Toad," "Horned Toad"

Phrynosoma platyrhinos calidiarum - Southern Desert Horned Lizard (Stebbins & McGinnis 2012)
Phrynosoma platyrhinos - Desert Horned Lizard (Stebbins 2003, 2018)
Phrynosoma platyrhinos calidiarum - Southern Desert Horned Lizard (Stebbins 1954, 1966, 1985)
Phrynosoma platyrhinos calidiarum - Desert Horned Lizard (Smith 1946)
Phrynosoma platyrhinos - Desert Horned-toad (Anota calidiarum; Phrynosoma calidiarum; Doliosaurus platyrhinos; Anota plathrhina; Phrynosoma coronatum, part. Desert Horned Lizard; Ashy Horned Toad; Smooth Horned Lizard; Smooth Horned Toad; Broad-nosed Barrel Lizard; Broad-nosed HOrned Toad. (Grinnell and Camp 1917)

Conservation Issues (Conservation Status)

None

Taxonomy
Family	Phrynosomatidae	Zebra-tailed, Earless, Fringe-toed, Spiny, Tree, Side-blotched, and Horned Lizards	Fitzinger, 1843
Genus	Phrynosoma	Horned Lizards	Wiegmann, 1828
Species	platyrhinos	Desert Horned Lizard	Girard, 1852
Subspecies	calidiarum	Southern Desert Horned Lizard	Cope, 1896
Original Description
Phrynosoma platyrhinos - Girard, 1852 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 6, p. 69 Phrynosoma platyrhinos calidiarum - (Cope, 1896) - Amer. Nat., Vol. 30, p. 833 from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
Meaning of the Scientific Name
Phrynosoma - Greek - phrynos - toad and soma - body - refers to the squat, toad-like appearance platyrhinos - Greek -platys - flat and- rhinos - nose - referring to the flat nose calidiarum - Latin - calidus - hot, warm and -arum - pertaining to, of the nature of - refereing to this lizard's habitat in hot areas from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
Related or Similar California Lizards
Phrynosoma platyrhinos platyrhinos - Northern Desert Horned Lizard Phrynosoma mcallii - Flat-tail Horned Lizard Phrynosoma blainvillii - Blainville's Horned Lizard Phrynosoma douglasii - Pygmy Short-horned Lizard
More Information and References
California Department of Fish and Wildlife Horned Lizard Conservation Society Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012. Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972. Flaxington, William C. Amphibians and Reptiles of California: Field Observations, Distribution, and Natural History. Fieldnotes Press, Anaheim, California, 2021. Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018. Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003. Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992. Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998. Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Turtles and Lizards of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009. Jones, Lawrence, Rob Lovich, editors. Lizards of the American Southwest: A Photographic Field Guide. Rio Nuevo Publishers, 2009. Smith, Hobart M. Handbook of Lizards, Lizards of the United States and of Canada. Cornell University Press, 1946. Sherbrooke, Wade C. Horned Lizards, Unique Reptiles of Western North America. Southwest Parks and Monuments Association, 1981. Sherbrooke, Wade C. Introduction to Horned Lizards of North America. University of California Press, 2003. Lemm, Jeffrey. Field Guide to Amphibians and Reptiles of the San Diego Region (California Natural History Guides). University of California Press, 2006. Macey, J. Robert and Theodore Papenfuss."Herpetology." The Natural History of the White-Inyo Range Eastern California. Ed. Clarence Hall. University of California Press, 1991. Joseph Grinnell and Charles Lewis Camp. A Distributional List of the Amphibians and Reptiles of California. University of California Publications in Zoology Vol. 17, No. 10, pp. 127-208. July 11, 1917.

Conservation Status
The following conservation status listings for this animal are taken from the April 2024 State of California Special Animals List and the April 2024 Federally Listed Endangered and Threatened Animals of California list (unless indicated otherwise below.) Both lists are produced by multiple agencies every year, and sometimes more than once per year, so the conservation status listing information found below might not be from the most recent lists. To make sure you are seeing the most recent listings, go to this California Department of Fish and Wildlife web page where you can search for and download both lists: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals. A detailed explanation of the meaning of the status listing symbols can be found at the beginning of the two lists. For quick reference, I have included them on my Special Status Information page. If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can also go to the NatureServe and IUCN websites to check their rankings. Check the current California Department of Fish and Wildlife sport fishing regulations to find out if this animal can be legally pursued and handled or collected with possession of a current fishing license. You can also look at the summary of the sport fishing regulations as they apply only to reptiles and amphibians that has been made for this website. This animal is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.
Organization	Status Listing	Notes
NatureServe Global Ranking
NatureServe State Ranking
U.S. Endangered Species Act (ESA)	None
California Endangered Species Act (CESA)	None
California Department of Fish and Wildlife	None
Bureau of Land Management	None
USDA Forest Service	None
IUCN

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