Crotalus polystictus

The  Mexican lance-headed rattlesnake or lance-headed rattlesnake (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 60 to 70 cm, although exceptionally large specimens may be as much as 100 cm 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 1450 and 2600 m. 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.