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Phrynosoma coronatum

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA REPTILIA SQUAMATA PHRYNOSOMATIDAE

Scientific Name: Phrynosoma coronatum
Species Authority: (Blainville, 1835)
Common Name/s:
English Blainville Horned Lizard, San Diego Horned Lizard
French Phrynosome Couronné De San Diego
Spanish Lagarto Cornudo De San Diego
Taxonomic Notes: Some literature of the mid-1900s regarded the coronatum-blainvillii complex as comprising two species. Stebbins (1985, 2003) did not recognize any subspecies of P. coronatum. Grismer and Mellink (1994) concluded that P. cerroense lacks discrete diagnostic characteristics and should not be recognized as a species. Brattstrom (1997) examined morphological variation and also determined that P. cerroense should be included in P. coronatum; furthermore, he concluded that there are no valid subspecies of P. coronatum. Grismer (2002) treated the named subspecies of P. coronatum as pattern classes rather than as valid taxa. In a morphological study, Montanucci (2004) concluded that P. coronatum should be split into four species (P. blainvillii, P. cerroense, P. coronatum, and P. wigginsi), with P. blainvillii in the United States and the northern half of Baja California, and the three other species in Baja California. Given the disparity among the conclusions from morphological studies, genetic data are needed in order to determine whether or not P. coronatum (sensu Stebbins 2003) represents multiple species.

Reeder and Montanucci (2001) examined phylogenetic relationships of horned lizards (Phrynosoma) based on mtDNA and morphology. They did not consider phylogenetic patterns within P. coronatum.

Leaché and McGuire (2006) report that "a thorough analysis of the P. coronatum group based on mtDNA and nuclear data is currently underway".

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2007
Date Assessed: 2007-03-01
Assessor/s: Hollingsworth, B. & Hammerson, G.A.
Reviewer/s: Cox, N., Chanson, J.S. & Stuart, S.N. (Global Reptile Assessment Coordinating Team)
Justification:
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: This lizard ranges throughout most of west-central and southwestern California (United States) as well as most of Baja California (Mexico) (except the northeastern portion). In California, it ranges north to Shasta County, though a disjunct population occurs farther north at Grasshopper Flat, Siskiyou County, California (Jennings 1988, Grismer 2002, Stebbins 2003). The elevational range extends from near sea level to around 2,438 m (8,000 feet) (Stebbins 2003). Attempted introductions at Yosemite Valley and San Clemente Island (California), and in Hawaii, Colombia, and Guatemala have failed (Jennings 1988).
Countries:
Native:
Mexico; United States
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is known from hundreds of collection sites in California and well over 100 in Baja California (Jennings 1988), but many of these sites no longer support substantial populations. The total adult population size is unknown but surely exceeds 10,000 and may exceed 100,000. The species is common in parts of Baja California (Grismer 2002). The area of occupancy and population size appear to have declined significantly in California but much less so in Baja California. Its area of occupancy and population size are probably still declining, but the rate of decline is unknown (probably it is substantially less than 30% over the past three generations).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This lizard occurs in a variety of habitats, including scrubland, grassland, coniferous woods, and broadleaf woodlands. Typically it is found in areas with sandy soil, scattered shrubs, and ant colonies, such as along the edges of arroyo bottoms or dirt roads (Grismer 2002, Stebbins 2003). In southern California, P. coronatum was most common in areas with native ants and few or no Argentine ants, in areas with native chaparral vegetation, and in sites with porous soils relatively free of organic debris (Fisher et al. 2002). Individuals bury themselves in loose soil. Eggs are laid in a nest dug in the soil or in a burrow.
Systems: Terrestrial

Threats [top]

Major Threat(s): The Coast Horned Lizard is now absent from much of its former southern Californian range due to urbanization, agricultural development, and over-collecting (Jennings 1987, 1988). In some areas, the non-native Argentine ant is displacing native ant species upon which this lizard feeds (Stebbins 2003). In Baja California, the expansion of intensive agriculture is also a threat, in particular in the Vizcaíno Desert, the Magdalena Plain, and the Isthmus of La Paz.

Conservation Actions [top]

Conservation Actions: It is presumably present in a number of protected areas. It is listed on CITES Appendix II. Further research employing genetic methods is needed to determine the taxonomic status of the named subspecies. Then further consideration should be given to the conservation status of the identified valid taxa. The impact of collecting for the pet trade needs to be assessed.
Citation: Hollingsworth, B. & Hammerson, G.A. 2007. Phrynosoma coronatum. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 20 April 2014.
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