The greater earless lizard (Cophosaurus texanus) is the only species in the monotypic genus Cophosaurus. It is closely related to the smaller, lesser earless lizards and other species in the genus Holbrookia, and in fact was placed in that genus and referred to Holbrookia texana from 1852 into the 1970s. Earless lizards lack external ear openings, an adaptation to burrowing in the sand, as are the recessed lower jaw and flared upper labial scales. Greater earless lizards are sexually dimorphic, males grow larger and are more colorful than females, exhibiting pink and green colors that are particularly bright in the breeding season. Two bold black bars mark the lateral region of males but are greatly reduced and vague, or occasionally entirely absent in females.
The greater earless lizard is native to the Chihuahua Desert and other arid and semi-arid regions of Southwestern United States and northern Mexico, where they most often occupy moderately open areas of sparse vegetation with rocks, gravel, and sand. The overall color of individual lizards frequently match the colors of the rocks and soils of the local area they inhabit. They will often rely on camouflage and their speed to elude threats and predators before retreating into rock crevices. They are primarily insectivores, preying on wide variety of crickets, grasshoppers, caterpillars, ants, flies, beetles, and bugs. Spiders and small lizards are occasionally eaten as well. Cophosaurus are oviparous. Females lay 1 to 4 clutches of 2 – 9 eggs a year, with hatchlings emerging from June to October, and reaching adult size and sexual maturity in one year.
Etymology
The generic name Cophosaurus is derived from the Greek words copho (κουφός), meaning "deaf", and saurus, meaning "lizard", in reference to the animal's absent external ear openings. The trivial name, or specific epithet texanus, is a toponym in reference to the state of Texas, the original location where the specimens used in the lizard's description were collected. The subspecific names are both Latin, reticulatus, meaning "reticulated" or a "net-like" pattern, and scitulus, meaning "handsome" or "pretty". The genus Cophosaurus is monotypic, as Cophosaurus texanus is the only species within the genus. Franz Hermann Troschel described Cophosaurus (as well as the species C. texanus) in a paper dated to 1850 (but not published until 1852). Troschel's description was based on two specimens, cotypes or syntypes, both lost in the Second World War. In 1951, James A. Peters published a review of the species, recognizing three subspecies and designating a neotype for C. t. texanus, although still placing them in the genus Holbrookia. In a 1958 Ph.D. dissertation reviewing the genus Holbrookia, herpetologist Ralph W. Axtell omitted H. texana with little comment, something which was noted by Robert F. Clarke in his 1965 Ph.D. dissertation (subsequently placing the species back in the original genus, Cophosaurus). Both combinations, C. texanus and H. texana, were used by various authors during the 1970s, although, despite arguments for the placement of the species in Holbrookia, Cophosaurus was in predominant use by the 1980s; later allozymes analyses supported the recognition of the genus.
- Texas greater earless lizard, Cophosaurus texanus texanus, Troschel 1852 [1850]
- Sonoran greater earless lizard,
thumb|left|Chihuahuan greater earless lizard (C. t. scitulus), male, [[Doña Ana County, New Mexico (19 Sept 2015)]]
Greater earless lizards do not have external ear openings. The scales on the body are small and granular, with the dorsal scales slightly smaller than the ventral scales. Their legs, particularly the hind legs, are relatively long. The tail is slightly flattened and longer than head and body combined. The underside of the tail is white with 5 to 9 (usually 6 or 7) bold, contrasting black bands (excluding individuals with regenerated tails). The base color can be various shades of grays, browns, tans, or reddish brown and generally close to the prevailing colors of the local substrate. Cophosaurus texanus is a sexually dimorphic species, in addition to size differences, males and females differ in some aspects of colors and markings. Most noticeable in males are a pair of black bands located on the posterior third on the sides of the body, rising from two blue patches on the margins of the belly up sides and arching forward and ending before meeting on the back. The body anterior to the black bands is suffused with some shade of pink, orange, or red, and the body posterior to the black bands tented green, aqua-green, or lime-green. The colors are most prominent in the Chihuahuan greater earless lizard (C. t. scitulus) and are greatly enhanced and most noticeable in the breeding season in all subspecies. In parts of their range they are colloquially referred to as "the lizard with the pink shirt and green pants."
The subspecies were diagnosed in the original description with the following characters. Cophosaurus t. texana: typically, 80–86%, have 79 ventral scales or less from collar (last gular fold) to anus, 40 or more scales in head length, and 27 or less total femoral pores. Cophosaurus t. scitula: 80–84% have 80 or more ventral scales, 39 or less head scales, 28 or more femoral pores. Cophosaurus t. reticulata: 85–100% have 82 ventral scales, 36 or less head scales, less than 31 femoral pores, and the black lateral bars are faint and do not extend above the lateral fold in males.
The Texas greater earless lizard (C. t. texanus) occurs on the Edwards Plateau of Central Texas and northward to the state border with Oklahoma and southeastern areas of the Texas panhandle. It ranges southward into the Tamaulipan mezquital ecoregion, and along the Rio Grande into northeast Coahuila and north-central Nuevo León, Mexico. In south-central Tamaulipas, its occurrence becomes increasingly spotty and localized, with records just across the southern state line in eastern San Luis Potosí. Several accounts have commented on the problematic and poorly defined zone of integration between the subspecies C. t. texanus and C. t. scitulu.
The Chihuahuan greater earless lizard (C. t. scitulus) occurs throughout much of the Chihuahuan Desert, including much of the Trans-Pecos region of West Texas, In Mexico, it ranges into northeastern Chihuahua, much of Coahuila,
Ecology and natural history
Reproduction
thumb|Chihuahuan greater earless lizard (Cophosaurus t. scitulus), female, municipality of [[General Cepeda Municipality|General Cepeda, Coahuila, Mexico (27 March 2013)]]
The longevity of the greater earless lizard is typically 3 years, but records of individuals surviving five reproductive seasons in the wild have been documented. The incubation period is about 50 days. The hatchlings emerge from June to October, with reports of sizes varying from 20 to 25 mm. to 26–31 mm. snout–vent length.
Diet
The greater earless lizard is predominantly an insectivore and a generalist. A study in Mohave County, Arizona found insects comprised 85% of the diet, including 18.2% Orthoptera (crickets, grasshoppers, locusts), 15.8% Hymenoptera (ants, bees, sawflies, wasps), and 10.1% Lepidoptera (butterflies and moths), 9.2% Diptera (flies), 9.2% Coleoptera (beetles), and 8.4% Hemiptera (true bugs). Spiders made up 7.9% of the diet and Cophosaurus were found to occasionally feed on small lizards, particularly ornate tree lizards (Urosaurus ornatus), in the late summer and early spring when hatchling emerged and were abundant. Less frequent prey identified in these studies included Neuroptera (lacewings, mantidflies, antlions), mites, pseudoscorpions, termites, Homoptera, adult Lepidoptera, and Odonata (dragonflies, damselflies) The Arizona study found that plants made up 5.5% of the diet, while the Durango study found only two cases of plant ingestion and interpret them as accidental intake. The most common, or highest percentage of prey items (e.g. Hymenoptera, caterpillars, etc.) in the diet were found to change annually in the Durango study.
Habitat
thumb|[[Big Bend National Park in the Chihuahuan Desert, where greater earless lizards tend to occupy gulches, arroyos, and rocky areas of sparse vegetation.]]
The greater earless lizard native to the arid environment of the Chihuahua Desert, extending into western areas of the Tamaulipan mezquital, and the northeastern margins of the Meseta Central matorral, as well as the semi-arid Edwards Plateau and Central Great Plains in Texas, and the Arizona transition zone (between the Sonoran Desert and Arizona Mountains forests) in the west.
Within these ecoregions it typically occupies open scrubland and areas of sparse vegetation, with rocks and boulder. Gentle to moderate slopes of limestone and gravel and hills of granite and igneous rock are also habitat for the lizard. Plants identified in association with greater earless lizards include honey mesquite (Prosopis glandulosa), creosote bush (Larrea tridentata), ocotillo (Fouquieria splendens), sotol (Dasylirion), lechuguilla (Agave lecheguilla), prickly pear cactus (Opuntia), leatherstem (Jatropha dioica), and candelilla (Euphorbia antisyphilitica). At night, Cophosaurus will often burrow in loose sand as deep as 15.3 cm. (6 in.) or in areas without sand, they may partially bury in loose gravel or shale, or sleep on the surface. Females have been found communally buried under shale on cold winter days.
They are predominantly ground-dwelling lizards that often seek a high perch, such as a protruding rock, to survey their area for passing prey and approaching predators. They are reluctant to retreat into crevices or borrows to evade predators, but instead will run from one rock to another with great speed, or rapidly dash a few yards only to make an abrupt stop and then freeze, at which point their remarkable camouflage seems to make them disappear. Cophosaurus are known to engage in bipedal locomotion (running on two feet) during short burst of speed.
Gallery
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File:Earless lizard (cropped).jpg|Chihuahuan greater earless lizard (Cophosaurus t. scitulus), male, (20 May 2015)
File:1. Cophosaurus t. texanus, male, Llano Co. Texas (2022).jpg|Texas greater earless lizard (Cophosaurus t. texanus), male, Llano County, Texas (26 April 2022)
File:2. Cophosaurus t. texanus, female, Llano Co. Texas (2022).jpg|Texas greater earless lizard (Cophosaurus t. texanus), female, Llano County, Texas (26 April 2022)
File:Cophosaurus texanus - Flickr - aspidoscelis (3) (cropped).jpg|Chihuahuan greater earless lizard (Cophosaurus t. scitulus), male, Doña Ana County, New Mexico, (30 April 2015)
File:Cophosaurus texanus - Flickr - aspidoscelis (9) (cropped).jpg|Chihuahuan greater earless lizard (Cophosaurus t. scitulus), female, Doña Ana County, New Mexico, (14 September 2013)
</gallery>