Plestiodon skiltonianus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Squamata Scincidae

Scientific Name: Plestiodon skiltonianus Baird & Girard, 1852
Common Name(s):
English Western Skink
Eumeces skiltonianus (Baird & Girard, 1852)
Taxonomic Notes: Recent phylogenetic analyses using DNA data indicate that the Plestiodon gilberti morphotype (generally large-bodied and uniformly colored, versus the small-bodied and striped P. skiltonianus morphotype) has arisen independently at least three times (three clades) and that two of the three clades are nested within the geographically more widespread P. skiltonianus (Richmond and Reeder 2002). Plestiodon lagunensis of southern Baja California is also nested phylogenetically within P. skiltonianus (Richmond and Reeder 2002). A taxonomic revision is therefore warranted, but further study is needed before the species limits within this group can be definitively determined (Richmond and Reeder 2002).

Stebbins (2003) treated P. lagunensis of southern Baja California as a subspecies of P. skiltonianus whereas Grismer (2002) recognized P. lagunensis as a distinct species (following Grismer 1994).

In a phylogenetic analysis of Eumeces based on morphology, Griffith et al. (2000) proposed splitting Eumeces into multiple genera, based on the apparent paraphyly of Eumeces. Smith (2005) and Brandley et al. (2005) formally proposed that all North American species (north of Mexico) be placed in the genus Plestiodon. This was accepted by Crother (2008) and Collins and Taggart (2009).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2007
Date Assessed: 2007-03-01
Needs updating
Assessor(s): Hammerson, G.A. & Hollingsworth, B.
Reviewer(s): Cox, N., Chanson, J.S. & Stuart, S.N. (Global Reptile Assessment Coordinating Team)
Listed as Least Concern in view of its wide distribution, tolerance of a broad range of habitats, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.

Geographic Range [top]

Range Description:The range of this species extends from south-central British Columbia in Canada, through the western United States to northwestern Baja California in Mexico. In the United States it ranges from the Pacific coast to western Montana, Idaho, eastern Utah, and north-central Arizona, including various islands off the west coast of California and Baja California (Grismer 2002, Stebbins 2003). In Mexico, its range extends possibly as far south as el Rosario. Its elevational range is from sea level (California) to about 2,530 m (8,300 feet) (southern Utah, southern Nevada, northern Arizona) (Tanner 1988, Stebbins 2003).
Countries occurrence:
Canada; Mexico; United States
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is represented by a large number of occurrences or subpopulations. For example, Tanner (1988) mapped nearly 200 collection sites rangewide. Nussbaum et al. (1983) mapped even more localities than did Tanner for the Pacific Northwest portion of the range. The secretive habits of this skink suggest that it occurs in many more localities than have been so far documented. The total adult population size is unknown but surely exceeds 100,000 and is probably in the millions. The species is locally common in many areas. Like most skinks, it is secretive and much more numerous than visual observations would suggest. Population trends are undocumented, but its extent of occurrence, area of occupancy, number of subpopulations, and population size are large and probably relatively stable.
Current Population Trend:Stable
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Habitats include grassland, chaparral, pinyon-juniper woodland, open pine or pine-oak woods, and rocky areas near streams (Stebbins 2003); the species is partial to open wooded foothills and is usually associated with rocks, under which it takes shelter. It also digs burrows in soil. Eggs are laid in burrows or areas excavated by the female under rocks and stones.

Threats [top]

Major Threat(s): No major threats have been identified. Reductions from habitat loss appear to be minimal.

Conservation Actions [top]

Conservation Actions: This lizard occurs in many national parks and other protected areas. No direct conservation measures are currently needed for this species as a whole.

Classifications [top]

1. Forest -> 1.4. Forest - Temperate
3. Shrubland -> 3.4. Shrubland - Temperate
3. Shrubland -> 3.8. Shrubland - Mediterranean-type Shrubby Vegetation
4. Grassland -> 4.4. Grassland - Temperate
0. Root -> 6. Rocky areas (eg. inland cliffs, mountain peaks)

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
  Occur in at least one PA:Yes
In-Place Species Management
In-Place Education

Bibliography [top]

Brandley, M.C., Schmitz, A. and Reeder, T. W. 2005. Partitioned Bayesian analyses, partition choice, and the phylogenetic relationships of scincid lizards. Systematic Biology 54: 373-390.

Collins, J.T. and Taggart, T.W. 2009. Standard Common and Current Scientific Names for North American Amphibians, Turtles, Reptiles, and Crocodilians. Sixth edition. The Center for North American Herpetology, Lawrance, Kansas.

Crother, B. I. (ed.). 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Sixth edition. Society for the Study of Amphibians and Reptiles Herpetological Circular 37: 1-84.

Grismer, L.L. 1994. The origin and evolution of the peninsular herpetofauna of Baja California, Mexico. Herpetological Natural History 2: 51-106.

Grismer, L.L. 1996. Geographic variation, taxonomy, and distribution of Eumeces skiltonianus and E. lagunensis (Squamata: Scincidae) in Baja California, Mexico. Amphibia-Reptilia 17(4): 361-375.

Grismer, L.L. 2002. Amphibians and Reptiles of Baja California, Including its Pacific Islands and the Islands in the Sea of Cort├ęs. University of California Press, Berkeley and Los Angeles, California.

IUCN. 2007. 2007 IUCN Red List of Threatened Species. Available at: (Accessed: 12th September 2007).

Jones, K.B. 1985. Eumeces gilberti. Catalogue of American Amphibians and Reptiles 372: 1-3.

Nussbaum, R.A., Brodie Jr., E.D. and Storm, R.M. 1983. Amphibians and Reptiles of the Pacific Northwest. University Press of Idaho. 332 pp.

Richmond J.Q. and Reeder, T.W. 2002. Evidence for parallel ecological speciation in scincid lizards of the Eumeces skiltonianus species group (Squamata: Scincidae). Evolution 56: 1498-1513.

Rodgers, T.L. and Fitch, H.S. 1947. Variation in the skinks (Reptilia: Lacertilia) of the skiltonianus group. University of California Publications in Zoology 48(4): 169-220.

Smith, H. 2005. Plestiodon: a replacement name for most members of the genus Eumeces in North America. Journal of Kansas Herpetology 14: 15-16.

Stebbins, R.C. 2003. A Field Guide to Western Reptiles and Amphibians. Third Edition. Houghton Mifflin Company, Boston, Massachusetts.

Tanner, W.W. 1988. Eumeces skiltonianus. Catalogue of American Amphibians and Reptiles 447: 1-4.

Welsh, H.H. 1988. An ecogeographic analysis of the herpetofauna of the Sierra San Pedro Martir region, Baja California with a contribution to the biogeography of the Baja California herpetofauna. Proceedings of the California Academy of Science, 4th series 46: 1-72.

Zweifel, R.G. 1952. Notes on the lizards of the Coronados Islands, Baja California, Mexico. Herpetologica 8: 9-11.

Citation: Hammerson, G.A. & Hollingsworth, B. 2007. Plestiodon skiltonianus. The IUCN Red List of Threatened Species 2007: e.T64240A12757706. . Downloaded on 24 September 2018.
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