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Regal Horned Lizard (Phrynosoma solare)

[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”1283″ img_size=”large” alignment=”center” style=”vc_box_rounded”][vc_column_text]Regal Horned Lizard, Cochise Co., AZ. Photo by Jim Rorabaugh[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”1823″ img_size=”medium” alignment=”center” onclick=”img_link_large”][vc_column_text]Regal Horned Lizard. Photo by Cecil Schwalbe[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”1824″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Regal Horned Lizard. Photo by Adrien Pesque[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”1829″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Regal Horned Lizard. ©2013 Dancing Snake Nature Photography[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”1826″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Regal Horned Lizard, Santa Cruz Co., AZ. Photo by Jim Rorabaugh[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”1825″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Regal Horned Lizard, Photo by Young Cage[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”1827″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Regal Horned Lizard, Photo by Young Cage[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column width=”1/6″][/vc_column][vc_column width=”2/3″][vc_column_text]

Description

The Regal Horned Lizard (Phrynosoma solare) is a large horned lizard (< 117 mm SVL) with the typical horned lizard body configuration – flat and wide. The tail is relatively short among Arizona’s six species of Phrynosoma.  The back of the head is armed with a crown of 12 horns, including 4 central occipital horns and 4 temporal horns on each side; the bases of the occipital horns are all in contact with each other.  No other horned lizard in Arizona has a similar crown of horns; that character is diagnostic.  The dorsal scales are strongly keeled and spiny. The ventral scales are also keeled, particularly in the anterior chest region.  At the margin of the abdomen and dorsum is one row of fringed scales. The dorsum is tan, brown or rust with dark blotches. A mid-dorsal light stripe may be present as well as broad, dark lateral stripes curving around the mid-dorsum. The ventral surface is white or cream with small dark spots.  Males have enlarged post-anal scales (Degenhardt et al. 1996, Sherbrooke 2003, Rorabaugh and Lemos-Espinal 2016).

Using mitochondrial and nuclear DNA analysis, Leaché and McGuire (2006) placed the Regal Horned Lizard into the Anota clade along with the Flat-tailed Horned Lizard (Phrynosoma mcallii), the Coast Horned Lizard (P. coronatum), Blainville’s Horned Lizard (P. blainvillii), and two Mexican species (P. wigginsi and P. cerroense).  All of these species possess prominent cranial horns and are oviparous. The phylogenetic relationships of the horned lizards has often been controversial, with others identifying different associations (e.g. Reeder and Montanucci 2001, Hodges and Zamudio 2004). No subspecies of the Regal Horned Lizard are recognized (reptiledatabase.org, Crother 2017).

In the United States, the Regal Horned Lizard occurs from southern Mohave and northeastern La Paz counties, Arizona east and south through the Sonoran Desert region to the valleys of southeastern Arizona and the Guadalupe Mountains of southwestern Hidalgo County, New Mexico (Painter 1993, Degenhardt et al. 1996, Sherbrooke 2003, Brennan and Holycross 2006).  In Mexico, it occurs throughout much of Sonora south to northern Sinaloa (Hardy and McDiarmid 1969, Rorabaugh and Lemos-Espinal 2016).  In Arizona and the 100-Mile Circle, Regal Horned Lizards are primarily a species of the upland subdivision of Sonoran desertscrub. But they extend to the west into the Colorado River subdivision, and northwest into Mohave desertscrub in Mohave County in (Jones 1981, Brennan and Holycross 2006).  In southeastern Arizona, they also occur in Chihuahuan desertscrub and semi-desert grassland, but also range upslope into the edge of the oak woodland or savanna at Oracle (UAZ 56225), along Highway 82 (CUMV 3540), and at the Florida Canyon Workstation (CMS 4449).  It has been collected in Plains grassland in the Sonoita Valley (UAZ 54786), and is sometimes found in urbanized areas of Tucson (Germaine and Wakeling 2001).  In Sonora the species occurs in Sonoran and Chihuahuan desertscrub, foothills and coastal thornscrub, tropical deciduous forest, semi-desert and Plains grasslands, and oak or oak-juniper savanna at elevations from near sea level to 1400 m (Rorabaugh and Lemos-Espina 2016). Elevational range in the 100-Mile Circle is approximately 340 to 1460 m.

William S. Parker (1971) studied the ecology of the Regal Horned Lizard at South Mountain Park in Phoenix during 1964, 1965, and 1966.  He captured these lizards on creosote flats and adjacent north and south Sonoran desertscrub slopes, as well as a disturbed area with some riparian characteristics.  Most activity by Regal Horned Lizards occurred from 0600 to 0900 and 1700 to 1900 hrs from May to September.  Activity from October to April occurred primarily from 0800 to 1000 hrs.  First year lizards were active from late February through early November. Older lizards were active from April through September.  However, during a telemetry study in the Phoenix area, some adult Regal Horned Lizards basked or made short movements during December and January.  These adult horned lizards wintered just below the surface under creosote or bursage shrubs (Sullivan and Sullivan 2016).  A few have been found active in Sonora during December (Rorabaugh and Lemos-Espinal 2016). Most active lizards have body temperatures of 34-38⁰ C (Heath 1965). This is primarily a diurnal species, but Lara-Resendiz et al. (2016) found a Regal Horned Lizard active at 0049 hrs near Hermosillo, Sonora.  At least some nest construction and egg deposition occurs at night (Wade Sherbrooke, pers. comm.).

Parker (1971) found five females with 17-25 oviductal eggs from 17 July to 3 August.  These females ranged in size from 98-107 mm SVL.  Males are mature at >70 mm SVL (Howard 1974). Gates (1957) found a pair in copulation near Wickenberg on 24 July. Clutch size ranges from 7 (Stebbins 1954) to 33 (Howard 1974) and probably only one clutch is laid per season by a female (Parker 1971). A clutch of eggs hatched during 10-12 September and the hatchlings ranged in size from 28-31 mm SVL with tails 6-9 mm in length (Parker 1971).  Van Devender and Howard (1974) described the nest chamber. Sullivan and Sullivan (2017) described courtship and mating behavior.

Parker (1971) had three of 65 captured Regal Horned Lizards squirt blood from the orbital sinuses around the eyes.  If handled roughly or if their heads or bellies were rubbed, lizards would sometimes go into a condition Parker called “tonic immobility” in which the animal would flip on its back with its legs extended and the lungs deflated.  If righted, the animal would flip onto its back again.

At Parker’s South Mountain study site, a home range of a female Regal Horned Lizard was only 0.013 hectare.  Lowe (1954) working near Tucson suggested Regal Horned Lizards were relatively sedentary, based on recaptures of three individuals, none of which moved more than 39 m from the original point of capture over a two year period.  However, radio telemetered adult male Regal Horned Lizards near Phoenix made occasional movements of up to a kilometer in five days (Sullivan and Sullivan 2017).  One male returned to his normal home range five days later.  Adult females also made forays out of their usual home ranges, but the distances were less. No female moved more than 150 m from the original point of capture.

At South Mountain, Parker (1971) thought from one third to one half of the population turned over each year.  Baur (1986) reported a male Regal Horned Lizard that lived for eight years and nine days in his care.  It was “half grown” when he acquired it, suggesting its actual age was likely 9-10 years.

Parker and Parker (1975) found that 88.8% (by volume) of the diet of the Regal Horned Lizard consisted of harvester ants.   Near Phoenix, Regal Horned Lizards feed on Rough Seed Harvester Ants (Pogonomyrmex rugosus, Sullivan and Sullivan 2017). These lizards are sometimes found in the vicinity of harvester ant nests (Rorabaugh and Lemos-Espinal 2016, Sullivan and Sullivan 2016). Goldberg et al. (1993) investigated gastrointestinal helminths in Regal Horned Lizards.

The Regal Horned Lizard is listed as a species of least concern on the IUCN Red List.  It has no status in Mexico.  In Arizona with a valid hunting license, four can be captured per year or held in possession, except that no collection is authorized without special permits on certain lands, such as Organ Pipe Cactus National Monument and the Tohono O’odham Nation.

Suggested Reading:

Baharav, D. 1975. Movement of the horned lizard Phrynosoma solare. Copeia 1975(4):649-657.

Baur, B.E. 1986. Longevity of horned lizards of the genus Phrynosoma. 1986. Bulletin of the Maryland Herpetological Society 22(3):149-151.

Bezy, R.L. and C.J. Cole 2014. Amphibians and reptiles of the Madrean Archipelago of Arizona and New Mexico. American Museum Novitates (3810): 1-24.

Blount, R.F. 1929. Seasonal cycles of the interstitial cells in the testes of the horned toad (Phrynosoma solare). Journal of Morphology 48:317-344.

Brennan, T.C., and A.T. Holycross. 2006. A Field Guide to Amphibians and Reptiles in Arizona. Arizona Game and Fish Department, Phoenix.

Crother, B.I. 2017. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding.  8^th Edition.  Society for the Study of Amphibians and Reptiles, Herpetological Circular 43.

Cutter, W.L. 1959. An instance of blood-squirting by Phrynosoma solare. Copeia 1959(2) :176

Degenhardt, W.G., C.W. Painter, and A.H. Price. 1996. Amphibians and Reptiles of New Mexico. University of New Mexico Press.

Flesch, A.D., D.E. Swann, D.S. Turner, and B.F. Powell. 2010. Herpetofauna of the Rincon Mountains, Arizona. Southwestern Naturalist 55(2):240–253.

Gates, C.O. 1957. A study of the herpetofauna in the vicinity of Wickenburg, Maricopa County, Arizona. Trans. Kansas Acad. Sci. 60):403-418.

Goldberg, S.R., C.R. Bursey, and R. Tawil. 1993. Gastrointestinal helminths of five horned lizard species, Phrynosoma (Phrynosomatidae) from Arizona. Journal of the Helminthological Society of Washington 60(2):234-238.

Hardy, L.M., and R.W. McDiarmid. 1969. The amphibians and reptiles of Sinaloa, Mexico.  University of Kansas Publications, Museum of Natural History 18:39-252.

Heath, J.E. 1965. Temperature regulation and diurnal activity in horned lizards. University of California Publications in Zoology 64(3):97-133.

Ivanyi, C. 2009. Regal Horned Lizard, Phrynosoma solare Gray, 1845. Pages 194-197 in L.L.C. Jones and R.E. Lovich (editors). Lizards of the American Southwest. Rio Nuevo Press, Tucson, Arizona.

Lara-Reséndiz R.A., D.M. Arenas-Moreno, E. Beltrán-Sánchez, W. Gramajo, J. Verdugo-Molina, W.C. Sherbrooke et al. 2015. Selected body temperature of nine species of Mexican horned lizards (Phrynosoma) Rev. Mex. Biodiv. 86(1): 275-278.

Lara-Resendiz, R.A., R. Garcia-Figueroa, and R.F. Ochoa-Jara. 2016. Phrynosoma solare. Nocturnal activity. Mesoamerican Herpetology 3(4): 1010–1011.

Leaché, A.D. and J.A. McGuire 2006. Phylogenetic relationships of horned lizards (Phrynosoma) based on nuclear and mitochondrial data: Evidence for a misleading mitochondrial gene tree. Molecular Phylogenetics and Evolution 39 (3): 628-644.

Lowe, C.H., Jr. 1954. Normal field movements and growth rates of marked regal horned lizards (Phrynosoma solare). Ecology 35(3):420–421.

Mayhew, W.W.  1968. Biology of desert amphibians and reptiles. Pages 196-356 in G.W. Brown (ed.) Desert Biology: Special Topics on the Physical and Biological Aspects of Arid Regions, Volume 1. Academic Press, New York.

Painter, C.W. 1993. Phrynosoma solare (Regal Horned Lizard). USA: New Mexico. Herpetological Review 24 (4): 155.

Parker, W.S. 1974. Phrynosoma solare (Gray): Regal horned lizard. Catalogue of American Amphibians and Reptiles ( 162: 1-2.

Parker, W.S. 1971. Ecological observations on the regal horned lizard (Phrynosoma solare) in Arizona. Herpetologica 27 (3): 333-338.

Pianka, E.R., and W.L. Hodges. 1998. Horned Lizards. Reptiles Magazine June:48-63.

Pianka, E.R., and W.S. Parker. 1975. Ecology of horned lizards: a review with special reference to Phrynosoma platyrhinos. Copeia 1975 (1):141-162.

Rorabaugh, J.C., and J.A. Lemos Espinal. 2016. A Field Guide to the Amphibians and Reptiles of Sonora, Mexico. ECO Herpetological Publishing and Distribution, Rodeo, NM.

Schonberger, C.F. 1945. Oviposition by Phrynosoma solare. Copeia 1945(1) :53-54.

Sherbrooke, W.C. 2003. Introduction to Horned Lizards of North America. University of California Press, Berkeley.

Stebbins, R.C. 1954. Amphibians and Reptiles of Western North America. McGraw-Hill, New York.

Sullivan, B.K., and E.A. Sullivan. 2016. Late fall and early winter activity by hatchling and adult Regal Horned Lizards, Phrynosoma solare. Sonoran Herpetologist 29 (1):5-6.

Sullivan, B.K., and E.A. Sullivan. 2017. Life and death in the Regal Horned Lizard (Phrynosoma solare) in central Arizona. Sonoran Herpetologist 29 (1):5-6.

Sullivan, B.K., E.A. Sullivan, K.O. Sullivan and H. McCall. 2014. Geographical Distribution: Phrynosoma solare (Regal Horned Lizard). Herpetological Review 45 (4): 660-661.

Van Devender, T. R., and C.W. Howard. 1973. Notes on natural nests and hatching success in the regal horned lizard (Phrynosoma solare) in southern Arizona. Herpetologica 29(3) :238-239.

Author:  Jim Rorabaugh

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