The bolsón night lizard (''Xantusia bolsonae'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

night lizard Night lizards (family Xantusiidae) are a group of small scincomorph lizards, averaging from less than to over snout–vent length. Most species are viviparous (live-bearing), with the exception of those in the genus '' Cricosaura''. The family ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Xantusiidae. The species, which was originally described by

Robert G. Webb Robert Gravem Webb (18 February 1927 – 18 September 2018) was an American herpetologist, expert in the systematics and biogeography of reptiles and amphibians, and professor emeritus of biological science at the University of Texas, El Paso. ...

in 1970, is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the state of

Durango Durango (), officially named Estado Libre y Soberano de Durango ( en, Free and Sovereign State of Durango; Tepehuán: ''Korian''; Nahuatl: ''Tepēhuahcān''), is one of the 31 states which make up the 32 Federal Entities of Mexico, situated in ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. Not much is known about the lizard at present, as it appears to be simultaneously rare and rather secretive in nature.

Description

The bolsón night lizard is predictably small, due to its behavior and habitat. It tends to be around 6 centimeters (2.4 inches) in snout-to-vent length (SVL) length, with a similar tail length proportionate to body size. The body is covered by scales, totaling 50 in the dorsal region, featuring

leopard The leopard (''Panthera pardus'') is one of the five extant species in the genus '' Panthera'', a member of the cat family, Felidae. It occurs in a wide range in sub-Saharan Africa, in some parts of Western and Central Asia, Southern Russia, a ...

print markings of a dark brown pigment across the back. The species can be distinguished from close relatives through fewer rows of

dorsal scales In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales. Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publis ...

, a decreased number of

upper labials In reptiles, the supralabial scales, also called upper-labials, are those scales that border the mouth opening along the upper jaw. They do not include the median scaleWright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates ( ...

, a lack of dark peppering on the stomach, fewer femoral pores, a narrower head to body ratio, and an attainment of reduced eventual size at the end of maturation.

Distribution and habitat

The species is prevalent in the state of

, in particular the area around the township of Pedriceña. It has also been reported in the nearby Cañon San Fernandes protected reserve, and has been observed crossing State Highway 40. The lizard inhabits fissures in andesitic rock outcrops, predominantly within areas dominated by yucca vegetation. Physiographically, the area falls within the boundaries of the

Bolsón de Mapimí The Bolsón de Mapimí is an endorheic, or internal drainage, basin in which no rivers or streams drain to the sea, but rather toward the center of the basin, often terminating in Swamp, swamps and Ephemeral lake, ephemeral lakes. It is located in ...

and the

Chihuahuan Desert The Chihuahuan Desert ( es, Desierto de Chihuahua, ) is a desert ecoregion designation covering parts of northern Mexico and the southwestern United States. It occupies much of far West Texas, the middle to lower Rio Grande Valley and the lower P ...

Reproduction

''X. bolsonae'' is

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...

Population

The population size of the species ''X. bolsonae'' is currently unknown, but the lizard seems to be quite rare. The lack of accurate population data can generally be attributed to the secretive nature of the species, creating issues in regards to collecting and examining specimens. During the initial survey of 1969, researchers located ten male and female individuals including the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, and recent colored photographic evidence from 2007 proves that the species is still extant in the original location of surveyal. Images.

Threats

The only apparent threat to the ''X. bolsonae'' is the disturbance of the

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

in which it resides. The habitat is not particularly wide-ranging in size, and is concentrated to only a fairly localised area. However, due to a lack of knowledge regarding the species, it is impossible to determine the impacts of habitat encroachment until a later interval.

Description

Distribution and habitat

Reproduction

Population

Threats

References

Further reading