Mexican small head rattlesnake
Central and southern Mexico: southeastern Hidalgo, southern Tlaxcala, northeastern and south-central Puebla, and west-central Veracruz, Cerro San Felipe and surrounding mountains, Sierra de Cuatro Venados, Sierra Madre del Sur, and Sierra de Milhuatlán (McDiarmid et al., 1999).
Pine-oak forest, cloud forest, and high desert between 2000 and 32000 m elevation (McDiarmid et al., 1999).
Holotype: Originally in Müller collection, later in Bonn (ZFMK); destroyed in World War II
Type-locality: Not given in the original description, but "Mexico" is inferred from paper title.