Phrynosoma blainvillii

Leaché et al. (2018) noted that the populations within P. blainvillii corresponding to three mtDNA clades from their earlier study (Leaché et al. 2009) exhibit narrow geographic zones of admixture and were supported as species in some of their analyses (see also Yang and Rannala 2014). Köhler (2021) recognized the two sets of populations corresponding to the earliest mtDNA divergence as subspecies, although he treated them as subspecies of P. coronatum (a name restricted to the populations from southern Baja California by Leaché et al. (2018). Nicholson (2025) is following Leaché et al. (2009, 2018) in recognizing P. blainvillii and P. coronatum as separate species, and have treated the subspecies recognized and resurrected by Köhler (2021) as subspecies of this species: P b. blainsvillii and P. b. frontale. Nicholson (2025) has also returned the standard English name for this species from Blainville's Horned Lizard to Coast Horned Lizard.

This species still occupies a fairly large range from northern California to northwestern Baja California where several California populations benefit from land-based preservation and other conservation efforts. It is likely that a large number of populations still exist, but many historically occupied sites no longer support substantial populations due to historical and ongoing threats from urbanization, agriculture, over-collecting, and the effects of food competition with non-native ant species.

This species is found in California, United States, and northern Baja California Norte, México. The range includes the coastal plain and foothills from around Ensenada, Baja California Norte northward to the southern end of the Sacramento Valley, extending up the eastward side to the coast up to San Francisco Bay, and extending up the westward side of the Sacramento Valley to the vicinity of Chico. There is also an isolated range in Shasta County in the vicinity of Redding (Thompson et al. 2016, Leaché et al. 2018). Using Global Biodiversity Information Facility (GBIF) (2025) records, range extent is estimated to be 215,281 km² (RARECAT 2025).

Applying a 5 km separation distance to extant California Natural Diversity Database (CNDDB) (2025) records, approximately 154 occurrences are estimated (RARECAT 2025).

This species is now absent from much of its former southern California and Mexican range due to urbanization, conversion of native chaparral and scrub habitat to agricultural uses, historical over-collecting, and the effects of climate change on native vegetative communities. In some areas, the non-native Argentine ant (Linepithema humile) has displaced native ant species upon which this species relies in large part for food (Stebbins 2003). Invasive grasses are degrading habitat by reducing the amount of open ground (Gerson 2011, Hult and Germano 2015). Individuals often are collected for the pet trade or as curiosities. Most of these die in captivity or are released in sites other than the collection site.