Added 24 November 2024.
Horned Lizards, also known as Horned Toads, are found in the arid parts of the southern US and Mexico. They are hard to mistake for any other genus of lizard, being in appearance something of a cross between the Australian agamid lizards Moloch horridus, the Moloch, and the bearded dragons of the genus Pogona, and are about the same size as both. Spines and raised scales feature prominently on their bodies, not only as a defence but also as a contribution towards their cryptic camouflage [check this]. They can run, although not as fast as most iguanids, and if all else fails some species have the capability of squirting a jet of blood from underneath the eyelid into the open mouth of a predator. This blood may furthermore taste unpleasant to the predator (usually in this case a canine of some type), and while it is thus distracted the lizard can make good its escape.
Although interesting, these lizards do not make suitable pets on account of their diet, which is largely or overwhelmingly (50%-90% dependent upon species, with up to 100 consumed per day [Bosch and Werning]) based on ants, particularly harvester ants, something that most keepers would find difficult or not impossible to provide. For that reason most Phrynosoma can only survive in the wild. Even the less challenging species are probably best left to specialists. Sadly some people refuse to take this advice - Conant and Collins note that tourists and visitors to the south still persist in trying to take a horned lizard home with them, which is usually illegal. Bosch and Werning also note that captive specimens tend to be less colourful than those encountered in the wild. For conscientious keepers who wish to specialise, Rogner has captive care advice on P. asio, P. cornutum, P. coronatum, P. ditmarsi, P. douglasii, P. mcalli, P. modestum, P. platyrhinos and P. solare.
In appearance horned lizards are rather flattened and somewhat round or oblong when viewed from above. They tend to bury into the ground to avoid extremes of temperature, to which semiarid and desert areas are prone. However they are not restricted to dry plantless wastes, some species also being found in scrubland, grassland and open forest.
Boulenger gives the characteristics of the genus as follows: tympanum more or less distinct. Body depressed, without dorsal crest; dorsal lepidosis heterogeneous. Head covered with small scales, bordered posteriorly by osseous spines. A transverse gular fold. Digits with keeled lamellae inferiorly. Femoral pores. Tail short. Lateral teeth subcorneal or indistinctly tricuspid; no pterygoid teeth. A large sternal fontanelle. No abdominal ribs.
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QUICK INDEX |
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P. asio, Giant Horned Lizard |
P. blainvilli, San Diego Horned Lizard |
P. braconnieri, Short-Tailed Horned Lizard |
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P. cerroense, Cedros Island Horned Lizard |
P. cornutum, Texas Horned Lizard |
P. coronatum, Coastal Horned Lizard |
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P. ditmarsi, Rock Horned Lizard |
P. douglassii, Pygmy Short-Horned Lizard |
P. goodei, Goode's Horned Lizard |
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P. hernandesi, Mountain Short-Tailed Lizard |
P. mcalli, Flat-Tailed Horned Lizard |
P. modestum, Round-Tailed Horned Lizard |
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P. orbiculare, Mountain Horned Lizard |
P. platyrhinos, Desert Horned Lizard |
P. sherbrookei, Guerreran Horned Lizard |
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P. solare, Regal Horned Lizard |
P. taurus, Mexican Horned Lizard |
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Scientific Name |
Common Name |
Distribution |
Size |
Notes |
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Phrynosoma |
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Giant Horned Lizard [D: Riesenkrotenechse] |
SE Mexico, Guatemala |
TL approx 19 cm; SVL approx 11.5 cm |
Found in cooler Mexican and Guatemalan grassland areas. Description: head a little broader than long; nostril somewhat within the extension of the supraciliary ridge; tympanum naked; the headspines large, subequal in size; on each side one postorbital, one occipital, and two temporals; the occipital spines almost perfectly vertical. A series of very large projecting scales below the lower labials; several longitudinal series of enlarged, subequal, keeled, pointed gular scales separated by granular intervals; gular folds several, irregular; a group of spines on the side of the neck. Back with very large distant tubercles, those on the sides of the vertebral line flat, strongly keeled, and as broad as long; a dorsolateral series of very large spines; two lateral series of spines, upper largest; pectoral and ventral scales keeled. Six to eight femoral pores on each side. Male without distinctly enlarged postanal scales. Tail about three times as long as the head. Coloration: olive-grey above, with large, transverse, oblique, brown, black-edged spots on each side of the back; lower surfaces immaculate. [SOURCE: Boulenger] |
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San Diego Horned Lizard |
USA (California), Mexico (Baja California) |
SVL 10 cm, TL approx 15 cm, max. approx 16 cm |
Found in valleys, mesas and foothills. Capable of ejecting blood from its eyes: Smith writes that dogs and cats readily provoke this phenomenon and appear to find it unpleasant. Description: ??. Coloration: dorsally yellowish or reddish grey, usually darker laterall; large dark brown patch on sides of neck, the two patches not widely separated medially, each with sharply defined border that fades laterally into ventral colour; 3 dark brown spots on either side of middorsal line; ventrally white or cream, and mottled to some degree with dark brown; . [SOURCE: Smith] |
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Short-Tailed Horned Lizard |
Mexico (Oaxaca) |
TL approx 4.5 cm, SVL approx 3.5 cm |
Description: head broader than long; nostrils pierced within the canthi rostrales; tympanum naked; head-spines small, six on each side, viz. a supraorbital, four temporals, and an occipital; latter a little larger than the others. A series of enlarged scales, a little larger than and parallel with the lower labials; gular scales equal [or with a longitudinal series of slightly enlarged scales on each side], keeled; gular fold strong, forming a deep pouch on each side of the neck; a dermal thickening, with two series of spinose scales, on each side between the gular fold and the tympanum. Back and limbs with scattered large spinose keeled scales which, on the back, are about as broad as long; a lateral series of spines; pectoral and ventral scales keeled. Twelve or thirteen femoral pores on each side, not extending on the preanal region. Male with enlarged postanal scales. Tail shorter than the head, as long as broad at the base. Coloration: sandy-coloured above, tinged with red on the head and limbs; a large blackish spot on each side of the nape; belly spotted with blackish. [SOURCE: Boulenger] |
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Cedros Island Horned Lizard |
Mexico (Cedros Island off Baja Californa) |
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This species now (2024) includes those individuals formerly assigned to P. wigginsi (the Gulf Coast Horned Lizard), itself formerly considered the subspecies P. cornatum jamesi. Description: nostrils excessively large, pierced in the line of canthus rostralis; gular scales enlarged, in several longitudinal rows; ventral scales smooth; along and slender spine between the sublabial rictal spine and the lower end of the ear; medium occipital spine reduced to a tubercle; no row of spines between eye and temporal spines; lower peripheral spine row obsolete and only indicated by a few scattered small spines. [SOURCE: Stejneger 1895] |
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Texas Horned Lizard [D: Texas-Krötenechse] |
USA, W Canada |
TL 12.5 cm, SVL 8.5 cm |
Typically found in flat open terrain with sparse plant cover, often found in areas of rocky, sandy or loamy soil: habitats include desert flats and washes, and arid and semi-arid plains with shrubby vegetation [Conant & Collins]. Description: head as long as broad, or a little broader than long; nostrils within the canthi rostrales; tympanum naked; five spines on each side of the head, viz. a postorbital, three temporals, and an occipital; a more or less distinct small median occipital; the large occipitals much longer than the temporals, obliquely directed upwards and outwards. A series of very large projecting scales below the lower labials ; gular scales keeled, with a longitudinal series of enlarged pointed ones on each side; two or three groups of spines on each side of the neck ; gular folds several, irregular. Back with very large erect spinose tubercles, the largest of which form a series of three or four on each side of the vertebral line; two lateral series of spines, upper largest; pectoral and ventral scales more or less distinctly keeled. Femoral pores four to twelve on each side, not extending on the preanal region, sometimes very indistinct. No enlarged postanal scales. Tail once and a half to twice and a half as long as head and body. Coloration: greyish or brownish above, with a more or less marked light dorsal streak and dark brown spots at the base of the larger dorsal spines; a large dark brown spot on each side of the nape; two cross streaks between the supraciliary ridges, a band from the eye to the angle of the mouth, and another from the eye to the middle temporal spine, dark brown; lower surfaces yellowish, uniform or with a few small brownish spots. NB var. planiceps was described by Boulenger as “hardly distinguishable” from P. cornutum but with ventrals and gulars smooth. [SOURCE: Boulenger] |
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Coastal Horned Lizard [D: Kronen-Krötenechse] |
USA (California), Mexico (Baja California) |
TL 12.5 cm, SVL approx. 8.5 cm |
Description: head broader than long; nostril pierced in the line of the canthus rostralis; tympanum naked; the head-spines large; on each side one postorbital, one occipital, three temporals; a more or less distinct additional small spine between the occipitals; latter as large as or a little larger than the largest temporals, directed obliquely upwards and extending posteriorly as far as or beyond the largest temporals. A series of very large projecting scales below the lower labials; three or four longitudinal series of enlarged, pointed, smooth or very feebly keeled scales on each side of the middle of the throat, the outer series the largest; gular folds several, irregular; two short series of spines on each side of the neck. Back with large, keeled, flat, triangular or trihedral scales, which are mostly as broad as long; two lateral series of spines, upper much stronger than lower; pectoral and ventral scales perfectly smooth. Thirteen to sixteen femoral pores on each side, the series not joining medially. Male with slightly enlarged postanal scales. Tail about twice as long as the head. Coloration: brownish above, with large dark brown or reddish spots arranged regularly; a very large dark spot on each side of the nape; or spotted or marbled with brown. [SOURCE: Boulenger] |
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Rock Horned Lizard [D: Felsen-Krötenechse] |
Mexico (Sonara) |
7.5-9 cm SVL |
Found in rocky habitats within oak and oak-pine woodlands and short-tree deciduous forest. Description: head wider than long; single row of lateral abdominal fringe scales which are bluntly pyramidal; high postorbital ridge extending from the tip of the orbital boss to the outer enlarged temporals; postocular boss present as a broad pyramid in which three edges are formed by the continuation of the superciliary, supraocular, and orbitotemporal ridges; occipital and temporal horns are reduced to rounded, flaring expansions on either side of the head, which has a deep and narrow occipital notch; nares are in the line of the canthus rostralis. Postlabials slightly enlarged, convex, and triangular; the keeled edge of the row directed nearly horizontally. Mandibles greatly expanded posteriorly, exceeding the diameter of the orbit. 5-8 rugose sublabials separate chinshields from infralabials, which increase in size and are keeled posteriorly. Gular scales small and keeled. Tympanum bare, residing in the anterior neck fold posterior to a vertical row of four small spines. Posterior and dorsal surfaces of the hind legs and tail have large, scattered, bluntly keeled scales, the larger scale bases surrounded by rosettes of smaller scales. Males have enlarged postanal scales. Coloration: red, brown, gray, or yellow dorsal ground color and dark crossbands posteriorly; venter whitish. [SOURCE: Hodges] |
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Pygmy Short-Horned Lizard [D: Nordamerikanische Kurzhorn-Krötenechse] |
W Canada, W USA, Mexico |
TL 9.5 cm; SVL 6.5 cm |
Description: Head broader than long, with the spines very small; nostril pierced in the line of the canthus rostralis; tympanum naked; the head-spines, which are subequal, not or but slightly larger than the largest spinose scales on the body, and turned upwards; they number on each side one postorbital, one occipital, and three temporals; in very young specimens the spines are not distinguishable. Lower labials terminating in a series of four or five large, compressed, obtuse or pointed scales; a series of enlarged scales, as large as or a little larger than, and parallel to, the lower labials; gular scales equal, smooth; gular fold strong ; a dermal thickening, bearing a few small erect spines, on each side between the gular fold and the tympanum. Back and limbs with scattered, large, erect, keeled, spinose scales, which are longer than broad; a regular lateral series of spines; pectoral and ventral scales perfectly smooth. Fifteen to twenty-one femoral pores on each side in the male, twelve to fifteen in the female, the series not joining medially. Male with enlarged postanal scales. Tail twice to twice and a half as long as the head. Coloration: Yellowish, greyish, or brownish above, with more or less distinct large, dark, light-edged spots forming longitudinal and transverse series; lower surfaces whitish, uniform or scantily dotted with grey. [SOURCE: Boulenger] |
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Goode's Horned Lizard |
USA (Arizona), Mexico (Sonora) |
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Formerly considered a subspecies of P. platyrhinos. Found in coast deserts. Description: nostrils pierced within the canthi rostrales; one series of enlarged spines around the periphery of the body; tail more than twice the length of the head; tympanum entirely concealed by scales; 7-10 femoral pores; 3 temporal horns only on each side, the posterior one nearly on a line with and of the same size as the occipital horns; only three posterior inframaxillary plates spinous. [SOURCE: Stejneger 1895] |
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Mountain Short-Tailed Lizard |
W USA, Mexico |
SVL approx 9.5 cm |
Formerly considered a subspecies of P. douglassii. Found in mountains and plateaus across its range. Scalation: similar to that of P. douglasii but spines on head larger, and occipital spine parallel to the temporals, seldom erect. 11-19 femoral pores on either side. Coloration: ground colour variable, sometimes reddish or yellowish; 3-4 irregularly outlined dark blotches on either side of middorsal line; sometimes, especially in young, a similar though less well defined outer series, sometimes more or less continuous with them; posterior edges of median blotches lightly edged, anterior edges blending gradually with ground colour; head often pinkish or yellowish, temporal regions reddish; large distinct dark blotch on either side of neck immediately behind head; lateral fringe of spines whitish; venter usually light but frequently mottled or suffused with grey; gular region usually mottled with gray. [SOURCE: Smith] |
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Flat-Tailed Horned Lizard [D: Flachschwanz-Krötenechse] |
SW USA, Mexico |
TL approx 10.5 cm, SVL approx 7 cm |
Description: head as long as broad; nostrils within the canthi rostrales; tympanum covered with scales; six spines on each side of the head, viz. a postorbital, four temporals, and an occipital, the latter much longer than the longest temporal, quite as long as the horizontal diameter of the orbit, obliquely directed upwards and slightly outwards. A series of very large projecting scales below the lower labials; gular scales smooth, uniform; two short series of small spinose scales on each side of the neck; gular folds several, irregular. Back with irregularly scattered, large, flat, keeled tubercles, which are mostly broader than long; a single lateral series of small spines; pectoral and ventral scales perfectly smooth. Seven femoral pores on each side. Tail nearly twice and a half as long as the head. Coloration: Greyish above, with rather indistinct darker spots; lower surfaces white, with a few scattered blackish dots. [SOURCE: Boulenger] |
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Round-Tailed Horned Lizard [D: Rundschwanz-Krötenechse] |
SW USA, Mexico |
TL 7.5 cm |
Description: nostrils within the canthi rostrales; tympanum naked; head-spines of moderate development, five on each side, viz. a very small postorbital, three temporals, and an occipital ; latter not larger than the largest temporal. A series of very large scales below the lower labials; gular scales uniform, smooth, exceedingly small. Enlarged dorsal scales very small and flat; no lateral series of spines; ventrals smooth, larger than in any other species. Series of femoral pores meeting on the preanal region. Tail about twice and a half as long as head and body, tapering very suddenly, perfectly cylindrical beyond the dilated portion of its base. Coloration: Uniform yellowish brown above, with a patch of black on each side of the nape. [SOURCE: Boulenger] |
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Mountain Horned Lizard |
Mexico |
TL 13.5 cm, SVL approx 8 cm |
The subspecies durangoensis, Description: head (spines not included) as broad as long or broader than long; nostril pierced in the line of the canthus rostralis; tympanum naked; the head-spines of moderate size, nearly horizontal or obliquely turned upwards ; there are on each side a low postorbital, an occipital, and three temporals; the occipitals are the largest, and their extremities on a line with or beyond the line of the longest temporal ; the length of the occipital spines equals about the diameter of the eye. Lower labials terminating in a series of three or four large, compressed, pointed scales ; a series of enlarged scales, as large as or a little larger than, and parallel with, the lower labials ; gular scales equal, smooth; gular fold very strong, forming a deep pouch on each side of the neck, which bears two short parallel longitudinal series of erect spines. Back and hind limbs with scattered large spinose keeled scales, which are longer than broad and obliquely directed upwards and backwards; a regular lateral series of spines ; pectoral and ventral scales perfectly smooth, fifteen to twenty-one femoral pores on each side in the male, ten to eighteen in the female, the series sometimes meeting in the middle. Male with enlarged postanal scales. Tail twice to thrice as long as the head. Coloration: brownish, yellowish, or reddish above, with one or two series of large blackish spots on each side of the back; these spots sometimes pale-bordered posteriorly; a large black spot on each side of the nape is constant; lower surfaces yellowish white, spotted or marked with black. [SOURCE: Boulenger] |
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P. o. orbiculare |
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Mexico (Mexico, Morelos) |
Max SVL approx 7.5 cm (m), 8 cm (f) |
Differs from orientale and cortezii in having fewer lateral spines, and in the narrower head of the male. P. o. orbiculare further differ from orientale in having more femoral pores. It differs from bradti and durangoensis in having fewer femoral pores and a proportionately shorter tail. It also differs from bradti in having proportionately longer occipital horns. [SOURCE: Horowitz] |
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P. o. bradti |
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Mexico (Chihuahua) |
Max SVL approx 7.5 cm (m), 8 cm (f) |
This subspecies differs from all of the other races of P. orbiculare in possessing a remarkably high number of femoral pores. The present subspecies differs from all other subspecies in having a proportionately longer tail. Furthermore, bradti differs from cortezii and orientale in having fewer spines in the lateral fringe. The males of bradti have proportionately narrower heads than the males of cortezii and orientale. The females of bradti are narrower headed than the females in orientale. P. o. bradti differs from orientale and orbiculare in its proportionately shorter occipital horn length. [SOURCE: Horowitz] |
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P. o. boucardii |
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Mexico (Hidalgo) |
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Closely allied to P. orbiculare. The occipital spines, which are nearly of the same size, and do not extend posteriorly quite as far as the longest temporals, are directed upwards and outwards. Head much broader than long. Gular scales feebly keeled. [SOURCE: Boulenger] |
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P. o. cortezii |
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Mexico (Puebla, Veracruz) |
Max SVL approx 8.5 cm (m), 9 cm (f) |
Horowitz discussed the possibility that this form might be divisible into two or more subspecies, and also discussed orientale-cortezii intergrades, although orientale is no longer recognised as valid. Spines subequal, the occipitals not extending posteriorly quite as far as the longest temporals. Head nearly as broad as long. Thiis, the closest related subspecies to orientale, differs from that form in possessing miore femoral pores. The present subspecies differs from orbiculare and bradti in possessing a greater number of spines in the lateral fringe. The males of cortezii differ from the males of orbiculare and bradti in having a comparatively wider head. P. o. cortezii may also be distinguished from bradti by its proportionately shorter tail. [SOURCES: Boulenger, Horowitz] |
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P. o. dugesii |
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Mexico (Colima, Jalisco) |
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Spines subequal, the occipitals not extending posteriorly quite as far as the longest temporals. Head nearly as broad as long. [SOURCE: Boulenger] |
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P. o. durangoensis |
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This subspecies was named by Horowitz in 1955 but is no longer considered a valid subspecies, being placed in P. o. bradti (see Reptile Database entry). |
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P. o. orientale |
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This subspecies was named by Horowitz in 1955 but is no longer considered a valid subspecies, being placed in P. o. dugesii (see Reptile Database entry). |
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Desert Horned Lizard [D: Wüstenkrötenechse] |
W USA, Mexico |
TL approx 12 cm, SVL 8 cm |
Description: very closely allied to P. mccalli, from which it is distinguished by the shorter head-spines. The occipital spines are only a little longer than the longest temporals and shorter than the horizontal diameter of the orbit. Nine or ten femoral pores on each side. Coloration: sandy-coloured above, with brown marblings or undulated cross bands on the back, interrupted on the vertebral line; a large brown spot on each side of the nape; lower surfaces white. [SOURCE: Boulenger] |
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Guerreran Horned Lizard |
Mexico (Guerrero) |
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Described in 2014: see Reptile Database entry. |
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Regal Horned Lizard [D: Vierhorn-Krötenechse] |
W USA, Mexico |
TL approx 14 cm, SVL approx 9.5 cm |
Description: head a little broader than long ; nostrils within the canthi rostrales; tympanum naked; postorbital spine small; head bordered posteriorly by a series of contiguous large spines obliquely directed upwards, viz. two smaller median and two larger outer occipitals and, on each side, four temporals. A series of very large projecting scales below the lower labials, almost continuous with the temporal spines; gular scales very feebly keeled, with a longitudinal series of enlarged ones on each side; two groups of spines on each side of the neck ; a double transverse gular fold. Back with very large trihedral tubercles, the largest broader than long; two lateral series of spines, lower very small; pectoral and ventral scales very feebly keeled. Fourteen or fifteen femoral pores on each side, extending only on the proximal third of the thigh, and the two series narrowly separated on the preanal region. Male with enlarged postanal scales. Tail a little over twice the length of the head. Coloration: Brownish above, with an ill-defined darker band on each side of the back ; belly whitish, with a few brownish spots. [SOURCE: Boulenger] |
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Mexican Horned Lizard |
Mexico |
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Description: head broader than long, with the temporal region much produced, the posterior outline of the head forming a strong concave curve; nostrils within the canthi rostrales; tympanum naked; the temporal processes covered with strongly enlarged scales, terminating in a long spine with a smaller detached one on the inner side; on each side a small occipital spine and a postorbital of equal size. A series of large scales below the lower labials ; gular scales subequal, keeled, with a more or less distinct longitudinal series of slightly enlarged pointed scales on each side; gular folds several, forming a pouch on each side of the neck ; a dermal appendage, bearing large spinose scales, on each side between the gular fold and the head. Back and limbs with scattered large spinose keeled scales; on the back they are as broad as long, or a little longer than broad; a lateral series of spines; pectoral and ventral scales keeled. Eight to eleven femoral pores on each side, not extending on the preanal region. Male with enlarged postanal scales. Tail as long as or shorter than the head. Coloration: greyish or yellowish above, with transverse series of large blackish spots; a large black patch on each side of the nape; lower surfaces more or less distinctly spotted with blackish. [SOURCE: Boulenger] |
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A Field Guide to Reptiles and Amphibians of Eastern and Central North America, R Conant and J T Collins, Peterson Field Guides, Houghton Mifflin, Boston/New York 1998.
A Field Guide to Western Reptiles and Amphibians, R Stebbins, Peterson Field Guides, Houghton Mifflin, Boston/New York 2003.
Green Iguanas and other Iguanids, Dr Hubert Bosch and Heiko Werning, TFH 1996 (originally published in German, 1991, as Leguane). See Iguanid page for recommendation of this book.
Lizard Care from A to Z, R D and Patricia Bartlett, Barron's, New York 1997.
Echsen [Lizards] 1, Manfred Rogner, Eugen Ulmer, Stuttgart 1992.
“Phrynosoma ditmarsi Stejneger, Rock Horned Lizard”, W L Hedges, Catalogue of American Amphibians and Reptiles, Society for the Study of Amphibians and Reptiles 1995.
Amphibians and Reptiles of Baja California, Lee Grismer, University of California Press, 2002. Impressive guide to the herpetofauna of the region.
“An Arrangement of the Subspecies of the Horned Toad, Phrynosoma Orbiculare (Iguanidae)”, Samel B Horowitz, The American Midland Naturalist, Vol 54 No 1, 1955.
I have not read the following, but as Wade Sherbrooke PhD has worked with horned lizards for over 30 years, it is probably informative:
Introduction to Horned Lizards of North America: Volume 64 (California Natural History Guides), Wade C Sherbrooke, California University Press 2003.
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