occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Big Bend region (Brewster and Presidio counties), Texas, and adjacent Mexico (southern Coahuila and northeastern Durango) (Dixon 2000). Curious gaps exist in the known distribution (Dixon 2000).
Distribution: USA (Texas), Mexico (Coahuila)
Type locality: Black Gap (elevation: 2500 feet), 50 mi. SSE of Marathon, Brewster County, Texas.
Length: 17 cm
Chihuahuan Desert Habitat
This taxon is found in the Chihuahuan Desert, which is one of the most biologically diverse arid regions on Earth. This ecoregion extends from within the United States south into Mexico. This desert is sheltered from the influence of other arid regions such as the Sonoran Desert by the large mountain ranges of the Sierra Madres. This isolation has allowed the evolution of many endemic species; most notable is the high number of endemic plants; in fact, there are a total of 653 vertebrate taxa recorded in the Chihuahuan Desert. Moreover, this ecoregion also sustains some of the last extant populations of Mexican Prairie Dog, wild American Bison and Pronghorn Antelope.
The dominant plant species throughout the Chihuahuan Desert is Creosote Bush (Larrea tridentata). Depending on diverse factors such as type of soil, altitude, and degree of slope, L. tridentata can occur in association with other species. More generally, an association between L. tridentata, American Tarbush (Flourensia cernua) and Viscid Acacia (Acacia neovernicosa) dominates the northernmost portion of the Chihuahuan Desert. The meridional portion is abundant in Yucca and Opuntia, and the southernmost portion is inhabited by Mexican Fire-barrel Cactus (Ferocactus pilosus) and Mojave Mound Cactus (Echinocereus polyacanthus). Herbaceous elements such as Gypsum Grama (Chondrosum ramosa), Blue Grama (Bouteloua gracilis) and Hairy Grama (Chondrosum hirsuta), among others, become dominant near the Sierra Madre Occidental. In western Coahuila State, Lecheguilla Agave (Agave lechuguilla), Honey Mesquite (Prosopis glandulosa), Purple Prickly-pear (Opuntia macrocentra) and Rainbow Cactus (Echinocereus pectinatus) are the dominant vascular plants.
Because of its recent origin, few warm-blooded vertebrates are restricted to the Chihuahuan Desert scrub. However, the Chihuahuan Desert supports a large number of wide-ranging mammals, such as the Pronghorn Antelope (Antilocapra americana), Robust Cottontail (Sylvilagus robustus EN); Mule Deer (Odocoileus hemionus), Grey Fox (Unocyon cineroargentinus), Jaguar (Panthera onca), Collared Peccary or Javelina (Pecari tajacu), Desert Cottontail (Sylvilagus auduboni), Black-tailed Jackrabbit (Lepus californicus), Kangaroo Rats (Dipodomys sp.), pocket mice (Perognathus spp.), Woodrats (Neotoma spp.) and Deer Mice (Peromyscus spp). With only 24 individuals recorded in the state of Chihuahua Antilocapra americana is one of the most highly endangered taxa that inhabits this desert. The ecoregion also contains a small wild population of the highly endangered American Bison (Bison bison) and scattered populations of the highly endangered Mexican Prairie Dog (Cynomys mexicanus), as well as the Black-tailed Prairie Dog (Cynomys ludovicianus).
The Chihuahuan Desert herpetofauna typifies this ecoregion.Several lizard species are centered in the Chihuahuan Desert, and include the Texas Horned Lizard (Phrynosoma cornutum); Texas Banded Gecko (Coleonyx brevis), often found under rocks in limestone foothills; Reticulate Gecko (C. reticulatus); Greater Earless Lizard (Cophosaurus texanus); several species of spiny lizards (Scelopoprus spp.); and the Western Marbled Whiptail (Cnemidophorus tigris marmoratus). Two other whiptails, the New Mexico Whiptail (C. neomexicanus) and the Common Checkered Whiptail (C. tesselatus) occur as all-female parthenogenic clone populations in select disturbed habitats.
Representative snakes include the Trans-Pecos Rat Snake (Bogertophis subocularis), Texas Blackhead Snake (Tantilla atriceps), and Sr (Masticophis taeniatus) and Neotropical Whipsnake (M. flagellum lineatus). Endemic turtles include the Bolsón Tortoise (Gopherus flavomarginatus), Coahuilan Box Turtle (Terrapene coahuila) and several species of softshell turtles. Some reptiles and amphibians restricted to the Madrean sky island habitats include the Ridgenose Rattlesnake (Crotalus willardi), Twin-spotted Rattlesnake (C. pricei), Northern Cat-eyed Snake (Leptodeira septentrionalis), Yarrow’s Spiny Lizard (Sceloporus jarrovii), and Canyon Spotted Whiptail (Cnemidophorus burti).
There are thirty anuran species occurring in the Chihuahuan Desert: Chiricahua Leopard Frog (Rana chircahuaensis); Red Spotted Toad (Anaxyrus punctatus); American Bullfrog (Lithobates catesbeianus); Canyon Treefrog (Hyla arenicolor); Northern Cricket Frog (Acris crepitans); Rio Grande Chirping Frog (Eleutherodactylus cystignathoides); Cliff Chirping Frog (Eleutherodactylus marnockii); Spotted Chirping Frog (Eleutherodactylus guttilatus); Tarahumara Barking Frog (Craugastor tarahumaraensis); Mexican Treefrog (Smilisca baudinii); Madrean Treefrog (Hyla eximia); Montezuma Leopard Frog (Lithobates montezumae); Brown's Leopard Frog (Lithobates brownorum); Yavapai Leopard Frog (Lithobates yavapaiensis); Western Barking Frog (Craugastor augusti); Mexican Cascade Frog (Lithobates pustulosus); Lowland Burrowing Frog (Smilisca fodiens); New Mexico Spadefoot (Spea multiplicata); Plains Spadefoot (Spea bombifrons); Pine Toad (Incilius occidentalis); Woodhouse's Toad (Anaxyrus woodhousii); Couch's Spadefoot Toad (Scaphiopus couchii); Plateau Toad (Anaxyrus compactilis); Texas Toad (Anaxyrus speciosus); Dwarf Toad (Incilius canaliferus); Great Plains Narrowmouth Toad (Gastrophryne olivacea); Great Plains Toad (Anaxyrus cognatus); Eastern Green Toad (Anaxyrus debilis); Gulf Coast Toad (Incilius valliceps); and Longfoot Chirping Toad (Eleutherodactylus longipes VU). The sole salamander occurring in the Chihuahuan Desert is the Tiger Salamander (Ambystoma tigrinum).
Common bird species include the Greater Roadrunner (Geococcyx californianus), Burrowing Owl (Athene cunicularia), Merlin (Falco columbarius), Red-tailed Hawk (Buteo jamaicensis), and the rare Zone-tailed Hawk (Buteo albonotatus). Geococcyx californianus), Curve-billed Thrasher (Toxostoma curvirostra), Scaled Quail (Callipepla squamata), Scott’s Oriole (Icterus parisorum), Black-throated Sparrow (Amphispiza bilineata), Phainopepla (Phainopepla nitens), Worthen’s Sparrow (Spizella wortheni), and Cactus Wren (Campylorhynchus brunneicapillus). In addition, numerous raptors inhabit the Chihuahuan Desert and include the Great Horned Owl (Bubo virginianus) and the Elf Owl (Micrathene whitneyi).
- C. Michael Hogan & World Wildlife Fund. 2013."Chihuahuan Desert". Encyclopedia of Earth, National Council for Science and the Environment, Washington DC ed.Mark McGinley.
- Clovis A. Stacey & Diane M. Post. 2009. Effects of disturbance by humans on small mammals in a Chihuahuan Desert ecosystem. The Southwestern Naturalist. 54(3): 272-278
Habitat and Ecology
Comments: This lizard occurs in limestone canyons and other rocky areas in desert regions; most of those found thus far were on roads on summer evenings (Bartlett and Bartlett 1999). Individuals may climb on rocks or, when inactive, hide under them (Behler and King 1979, Dial 1978). Eggs are laid probably underground or under rocks.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Comments: Known prey includes beetles, grasshoppers, and spiders (Dial 1978).
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: Unknown
Comments: Population size is unknown. Bartlett and Bartlett (1999) reported that this species is infrequently seen; it may be rare, secretive, or both. Dixon (2000) stated that this species is more common in Texas than was previously believed.
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: G3 - Vulnerable
Reasons: Small range in the Big Bend region of Texas and adjacent Mexico; locally common; probably stable; not threatened.
Intrinsic Vulnerability: Moderately vulnerable
Global Short Term Trend: Relatively stable (=10% change)
Comments: This lizard is locally common but very secretive and difficult to survey; it is probably stable, but population information is inadequate for reliably assessing trends (A. Price, pers. comm., 1997). The species is found infrequently but not endangered (R. Axtell, pers. comm., 1997). It has a fairly restricted range and has not been well studied; nevertheless, it probably has a very stable population (R. Savage, pers. comm., 1997). Status in Mexico is unknown but is assumed to be stable (J. Karges, pers. comm., 1997).
Global Long Term Trend: Increase of 10-25% to decline of 30%
Degree of Threat: Low
Comments: Threats are insignificant; the habitat is not suitable for other uses (R. Savage, pers. comm., 1997).
Potential threats include commercial collecting for the pet trade, but the habitat is not easily accessible, so collecting is not a major threat (A. Price, pers. comm., 1997). Individuals occur under cap rocks; breaking rocks while surveying may be detrimental (R. Savage, pers. comm., 1997).
Global Protection: Few to several (1-12) occurrences appropriately protected and managed
Comments: The species occurs in Big Bend National Park and Big Bend State Natural Area (R. Savage, pers. comm., 1997).
Reticulated geckos can grow to 6.5 inches long, and are a pink or brown color with brown or black spots, sometimes with faint banding. They can easily be mistaken for Coleonyx brevis, as they share habitat, but Coleonyx reticulatus grows to a larger size.
C. reticulatus is nocturnal and carnivorous, consuming almost any small species of arthropod. They are found in semi-arid, rocky areas. They are capable of vocalizations, and sometimes will emit squeaking sounds if handled.
The reticulated gecko is listed as a threatened species in the state of Texas, as it only occurs in two counties, but its habitat is fairly remote and not easily accessible and is not under immediate threat. Also, part of its habitat is found within the protected confines of Big Bend National Park.
- Davis, W. B., and J. R. Dixon. 1958. A new Coleonyx from Texas. Proc. Biol. Soc. Washington 71:149-152
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Names and Taxonomy
Comments: For many years Coleonyx geckos were placed in the family Gekkonidae. In a cladistic analysis of the Gekkonoidea, Kluge (1987) placed the genus Coleonyx in the family Eublepharidae (subfamily Eublepharinae), recognized as distinct from the Gekkonidae. Bartlett and Bartlett (1999), Grismer (2002), and Stebbins (2003) likewise placed Coleonyx in the Eublepharidae, whereas Dixon (2000) retained Coleonyx in the Gekkonidae.