The Mexican lance-headed rattlesnakeCampbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. . or lance-headed rattlesnakeMehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. . (Crotalus polystictus) is a venomous pit viper species found in central Mexico. No subspecies is currently recognized.
Description Adults usually grow to a total length of , although exceptionally large specimens may be as much as long.
Geographic range The species is found on the plateau of central Mexico from southern Zacatecas and northeastern Colima east to east-central Veracruz. It occurs at elevations between . The type locality given is "Table Land, Mexico", although a restriction to "Tupátaro, Guanajuanto, Mexico" was proposed by H.M. Smith and Taylor (1950).
Conservation status This species is classified as Least Concern on the IUCN Red List of Threatened Species (v3.1, 2001). Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was down when assessed in 2007.
References
Further reading Cope, E.D. 1865. Third contribution to the HERPETOLOGY of Tropical America. Proc. Acad. Nat. Sci. Philadelphia 17: 185-198. (Caudisona polysticta, pp. 191–192.) Smith, H.M. and E.H. Taylor. 1950. Type localities of Mexican reptiles and amphibians. Univ. Kansas Sci. Bull. 33: 313-380.
External links
Mexican Lance-headed Rattlesnake at the Saint Louis Zoo. Accessed 18 June 2008.