Desert Spiny Lizard (Sceloporus magister)

Desert Spiny Lizard, Pima Co., AZ. Photo by Jim Rorabaugh

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Description

This is one of the most conspicuous lizards in the desert around Tucson. It is frequently seen doing “push-ups” (a form of territorial display) on tree trunks, logs, rocks, and even roads, in areas where patches of prickly pear and other native plants remain. The species appears to have extraordinary vision as individuals often dart into a pack-rat nest when observed even from a considerable distance.

One of our largest lizards, it reaches a body length of 5.6 inches (142 mm). The species resembles its close relative, Sceloporus clarkii ( Clark ‘s Spiny Lizard; Bezy 2003), in size and in having large, overlapping, spine-tipped scales on the back and a conspicuous, wedge-shaped, black mark on each side of the neck. It differs in lacking the distinct cross-bands present on the lower forelimbs of S. clarkii. Adult males usually have a conspicuous purple patch on the anterior back, whereas females and juveniles often have large paired dark dorsal spots that may be united to form crossbands.

Vitt and Ohmart (1974) studied the ecology of Sceloporus magister along the lower Colorado River in Arizona and compared it with that of populations found elsewhere in the range (Parker and Pianka1972; Tanner and Krough 1973). They observed the lizards to be active on tree trunks, rocks, and high ground positions throughout the year, except for mid winter (December though January). Their analysis of stomach contents indicates that the species feeds on an unusually wide range of insects and other arthropods and occasionally on lizards. They deduced that copulation occurs in May and females lay 10-18 (average 12.3) eggs per clutch along the Colorado , considerably higher than that reported in other regions (Parker and Pianka 1973, Tanner and Krough 1973, Tinkle 1976). Females with enlarged follicles and oviducal eggs were found to be extremely wary and had distinctive rust-colored heads, a condition that was not seen at other times of the year. Hatchlings were abundant from August through October. Data on the frequency of tail-breaks and scars in this population support the view that fighting among males may be more important than predation as a source of tail loss (Vitt et al. 1974).

Niche overlap of Sceloporus magister with Urosaurus ornatus (Ornate Tree Lizard) and U. graciosus (Long-tailed Brush Lizard) was examined in a population near the confluence of the Verde and Salt Rivers in central Arizona (Vitt et al. 1981). In New Mexico , Gambelia wislizenii (Long-nosed Leopard Lizard) and Masticophis flagellum (Coachwhip) have been reported to feed on the species (Degenhardt et al.1996). Sceloporus magister has been found to harbor seven species of helminth
parasites, a more diverse fauna than that present in smaller members of the genus in Arizona (Goldberg et al. 1994).

The species occurs from northern Nevada , south to northern Baja California , Isla Tiburon, Sinaloa, and Durango (Grismer 2002, Parker 1982, Stebbins 2003). In Arizona it is found throughout the state except for higher elevations, particularly on the Colorado Plateau from the SanFrancisco Peaks to White Mountains (Lowe 1964). Four subspecies have been recognized in Arizona (Crother 2000, Parker 1982, Phelan and Brattstrom 1955, Tanner 1955), but these may represent “pattern classes” rather than lineages (Grismer 2002, Grismer and McGuire 1994). The species was described by Hallowell in 1854 on the basis of a specimen from “ Fort Yuma , California .” Degenhardt et al. (1996) speculated that the name magister (Latin, teacher) refers to the lesson taught to the original collectors by the strong bite of this lizard. The species appears to be important in ethnozoology of the native peoples of the Sonoran Desert . Malkin (1962) reported that Seri boys sometimes keep Sceloporus magister on strings for several days. The lizard is the subject of several Comáac (Seri) songs and lewd jokes, and some O’odam women are said to avoid urinating behind woodpiles out of fear that these spiny reptiles might lodge themselves in their private parts (Nabhan 2003).

Acknowledgments.

I thank George Bradley for information and access to specimens in the Herpetology Collection of the University of Arizona (UAZ); Erik Enderson, Kit Bezy, and Kathryn Bolles for participating in field work; Erik Enderson for producing the map; and Kathryn Bolles for photography and for review of the manuscript.

Literature Cited

Bezy, R. L. 2003. Clark Spiny Lizard ( Sceloporus clarkii ). Sonoran Herpetol. 16:18-19.

Crother, B. I. (ed.). ‘’1999″ [2000]. Scientific and standard English names of amphibians and reptiles of North America north of Mexico , with comments regarding confidence in our understanding. SSAR Herpetol. Circ. 29:iii+82.

Degenhardt, W. G., C. W. Painter, and A. H. Price. 1996. Amphibians and Reptiles of New Mexico . University of New Mexico , Albuquerque. Xix + 431 pp.

Goldberg, S. R., C. R. Bursey, and R. Tawil. 1994. Gastrointestinal helminthes of Sceloporus lizards (Phrynosomatidae) from Arizona . J. Helminthol. Soc. Washington 61:73-83

Grismer, L. L. 2002. Amphibians and Reptiles of Baja California . University of California , Berkeley. xiii + 399 pp.

Grismer, L. L., and J. A. McGuire. 1996. Taxonomy and biogeography of the Sceloporus magister complex (Squamata: Phrynosomatidae) in Baja California , Mexico . Herpetologica 52:416-427.

Hallowell, E. 1854. Descriptions of new reptiles from California . Proc. Acad. Natur. Sci. Philadelphia 7:91-92.

Lowe, C. H. 1964. The amphibians and reptiles of Arizona .. In C. H. Lowe (ed.), The Vertebrates of Arizona , pp. 153-174. University of Arizona , Tucson . 259 pp.

Malkin, B. 1962. Seri Ethnozoology. Occas. Paper 7 Idaho State College Museum , Pocatello .

Nabhan, G. P. 2003. Singing the turtles to sea. The Comáac (Seri) art and science of reptiles. University of California , Berkeley. xvii + 317 pp.

Parker, W. S. 1982. Sceloporus magister . Cat. American Amphibians and Reptiles 290:1-4.

Parker, W. S., and E. R. Pianka. 1972. Notes on the ecology of the iguanid lizard, Sceloporus magister . Herpetologica 29:143-152.

Phelan, R. L., and B. H. Brattstrom. 1955. Geographic variation in Sceloporus magister . Herpetologica 11:1-14.

Stebbins, R. C. 2003. A Field Guide to Western Reptiles and Amphibians. Third edition. Houghton Mifflin, Boston . xii + 533 pp.

Tanner, W. W. 1955. A new Sceloporus magister from eastern Utah . Great Basin Natur. 15:32-34.

Tanner, W. W., and J. E. Krough. 1973. Ecology of Sceloporus magister at the Nevada Test Site, Nye County , Nevada . Great Basin Natur. 33:133-146.

Tinkle, D. W. 1976. Comparative data on the population ecology of the Desert Spiny Lizard, Sceloporus magister . Herpetologica 32:1-6.

Vitt, L. J., and R. D. Ohmart. 1974. Reproduction and ecology of a Colorado River population of Sceloporus magister (Sauria: Iguanidae). Herpetologica 30: 410-417.

Vitt, L. J., R. van Loben Sels, and R. D. Ohmart. 1981. Ecological relationships among arboreal desert lizards. Ecology 62:398-410.

Vitt, L. J., J. D. Congdon, A. C. Hulse, and J. R. Platz. 1974. Territorial aggressive encounters and tail breaks in the lizard Sceloporus magister . Copeia 1974: 990-992.

Author: Robert L. Bezy
Originally published in the Sonoran Herpetologist “Herpetofauna of the 100-mile Circle” 16 (09) 2003

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