Crotalus triseriatus


 * Common names: Mexican dusky rattlesnake, dusky rattlesnake 

Crotalus triseriatus is a venomous pit viper species found in Mexico. Two subspecies are currently recognized, including the nominate subspecies described here.

Description
Adult male specimens of C. triseriatus commonly grow to a total length (including tail) greater than 60 cm, with females somewhat smaller. The maximum recorded total length is 68.3 cm.

Geographic range
The species C. triseriatus is found in Mexico, along the southern edge of the Mexican Plateau in the highlands of the Transverse Volcanic Cordillera, including the states of Jalisco, México, Michoacán, Morelos, Nayarit, Puebla, Tlaxcala, and Veracruz. The type locality given by Wagler in 1830 is "Mexico". A restriction to "Alvarez, San Luis Potosí, Mexico" was proposed by H.M. Smith and Taylor (1950).

Habitat
Crotalus triseriatus occurs in pine-oak forest, boreal forest, coniferous forest and, bunchgrass grasslands. On Volcán Orizaba, it is found at very high altitudes. There, the snow line comes down to about 4,572 m, while green plants can be found up to 4,573 m: the species has been found within this zone. However, it is most common at 2700 to 3350 m in elevation.

Conservation status
The species C. triseriatus 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 stable when assessed in 2007.

Feeding
Prey reportedly found in stomachs of C. triseriatus include a frog, a murid rodent (Neotomodon alstoni), lizards, other small mammals, crickets, and salamanders.

Venom
Bite symptoms from C. triseriatus are reported to include intense pain, swelling, faintness, and cold perspiration.

Etymology
The subspecific name, armstrongi, is in honor of American herpetologist Barry L. Armstrong.

Taxonomy
In the relatively recent past, two additional subspecies were described:


 * C. t. anahuacus Gloyd, 1940 - currently regarded as a junior synonym of C. t. triseriatus
 * C. t. quadrangularis Harris & Simmons, 1978 - currently regarded as a junior synonym of C. aquilus