Geographic range: Neotropical: Endemic to Mexico. The southern portion of the Mexican Plateau from northwestern Veracruz, and southern San Luis Potosí, southward and westward through northern Hidalgo, Querétaro, Guanajuato and northwestern Michoacan to the Chapala region of Jalisco.

Physical characteristics: This heavy-bodied snake reaches a maximum length of 67.8 cm. There is a great amount of color variation within the species, the ground color of many populations is sexually dimorphic. Adult males frequently have a greenish or yellowish cast, whereas females are brownish or grayish, a pair of dark brown nape blotches is followed by 21-41 middorsal blotches and 3-8 bands on the tail. The dorsal blotches are usually 5-7 scales wide and frequently are roughly quadrangular, although they may be subcircular or may even form bands.

Food habits: Feeds on small mammals and lizards.

Reproduction: Some captive snakes have been observed in copulation in the months of April and October, and the births were on June and July. The litter size is of 3 to 7.

Behavior: This snake is active in the morning and afternoon, and it may be found foraging at night where the temperatures are occasionally favorable for activity, some ritualized combats between males have been observed in captivity.

Habitat: Open grassy and usually rocky habitats, pine-oak forest, open karstic areas, grassy montane meadows and stone mesquite grassland. It was abundant en La Estanzuela, Hidalgo, beneath cultivaded agaves. It can be found at a heights of 1600-3110 m at El Chico, Hidalgo.

text: © Alfonso Delgadillo