Yellow-backed Spiny Lizard - Sceloporus uniformis

Sceloporus magister taxonomy has been very confusing recently (as of May, 2009). As things stand, Sceloporus magister in California represents either one species, possibly with two subspecies, or two full species, the distribution of which does not follow the distribution of the long-accepted subspecies.

In 1996, Grismer & McGuire (1996 Herpetologica 52(3): 416-427) recommended that no subspecies of S. magister should be recognized.

1   In 2006, Schulte, Macey, and Papenfuss split S. magister into three species - S. magister, S. uniformis, and S. bimaculosus, with two subspecies of S. magister - S. m. magister, and S. m. cephaloflavus.  However, their sample size was very small which makes it difficult to determine the ranges of these new species in California.

In 2008, the S.S.A.R., whose list this web site follows, adopted the 3 species taxonomy of Schulte et al in the sixth edition of their Scientific and Standard English Names of Amphibians and Reptiles of North America north of Mexico list.
The taxonomy used on this site now follows this re-organization:

S. m. uniformis - Yellow-backed Spiny Lizard and S. m. transversus - Barred Spiny Lizard, has been re-arranged into two species: S. magister - Desert Spiny Lizard, and S. uniformis - Yellow-backed Spiny Lizard.
(You can see a range map of the former species here.)

S. uniformis now contains the entire former S. m. transversus subspecies and part of the S. m. uniformis subspecies - those lizards from Coast Range and Central Valley regions and the Mojave Desert north into Nevada and the extreme southwest corner of Utah and the extreme northwestern corner of Arizona and two small areas near the Colorado River. The remaining former S. m. uniformis from the Sonoran desert in California east into Arizona and south into Baja California are now S. magister - Desert Spiny Lizard, the subspecies S. m. magister - Purple-backed Spiny Lizard. S. magister farther east in southern Utah, northern Arizona and the four corners area of Colorado and New Mexico are the subspecies S. m. cephaloflavus - Orange-headed Spiny Lizard. The subspecies S. m. bimaculosus - Twin-spotted Spiny Lizard has been elevated to full species - S. bimaculosus - Twin-spotted Spiny Lizard.

California Department of Fish and Wildlife

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.

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.

1 A genetic perspective on the geographic association of taxa among arid North American lizards of the Sceloporus magister complex (Squamata: Iguanidae: Phrynosomatinae)
James A. Schulte II, J. Robert Macey & Theodore J. Papenfuss 2006.
Molecular Phylogenetics and Evolution 39: 873-880

2 Phylogeny, divergence times and species limits of spiny lizards (Sceloporus magister species group) in western North American deserts and Baja California
ADAM D. LEACHE and DANIEL G. MULCAHY
Molecular Ecology (2007) doi: 10.1111/j.1365-294X.2007.03556.

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.