Crotalus willardi obscurus

Description

The color pattern consists of a gray or brownish gray ground color with scattered dark punctations. The facial stripes that are characteristic of this species may be completely absent. In the Sierra San Luis population, traces of the pale upper facial stripe may be visible on the posterior upper labials, but there is no pale stripe on the lower labials.

Geographic range

Found in the Animas and adjacent Peloncillo Mountains (Hidalgo County) in extreme southeastern Arizona and extreme southwestern New Mexico in the United States, and in the Sierra San Luis of extreme northwestern Chihuahua and extreme northeastern Sonora in Mexico. The type locality given is "one canyon in the Animas Mountains" (New Mexico, USA).

Conservation status

This species is listed as Threatened by the U.S. Fish and Wildlife Service, and is therefore afforded protection by the Endangered Species Act. It is listed because of its limited geographic range and the supposed threat to it of overcollection for the reptile trade.

References

References

1. McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. {{ISBN. 1-893777-00-6 (series). {{ISBN. 1-893777-01-4 (volume).
2. [http://ecos.fws.gov/speciesProfile/SpeciesReport.do?spcode=C01S ''Crotalus willardi obscurus''] at [[U.S. Fish and Wildlife Service]]. Accessed 13 August 2007.
3. Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. {{ISBN. 0-8069-6460-X.
4. {{ITIS
5. Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. 2 volumes. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. {{ISBN. 0-8014-4141-2.