Crotalus totonacus
Common name: Totonacan rattlesnake

Crotalus totonacus is a venomous pit viper species found in northeastern Mexico. No subspecies are currently recognized. Description
 
Adults frequently grow to more than  in length. The largest recorded specimen was  in length. Geographic range
It is found in northeastern Mexico from central Nuevo León through southern Tamaulipas, northern Veracruz, eastern San Luis Potosí and northern Querétaro. The type locality given is "Panaco Island, about  south of Tampico, Veracruz, Mexico,  inland from Cabo Rojo". Diet 
Crotalus totonacus is known to prey on small mammals and birds. In addition to mammal hair and bird feathers found in stomachs, specific prey items include cave rats (Neotoma sp. ), Allen’s tree squirrels (Sciurus alleni), and rock squirrels (Spermophilus [Otospermophilus] variegatus). Taxonomy
This species was previously considered a subspecies of C. durissus. References

Further reading
 Gloyd, H.K. and C.F. Kauffeld. 1940. A new rattlesnake from Mexico. Bull. Chicago Acad. Sci. 6 (2): 11-14 + one plate. totonacus
Reptiles described in 1940