About Sistrurus tergeminus (Say, 1823)
Description: Adult Sistrurus tergeminus have a total length (including the tail) that ranges from 35 to 91 cm (14 to 36 in). For a sample of 43 adult male and 63 adult female specimens, the "standard" total length was measured at 68 cm (27 in). Conant (1975) reports a different total length range of 46–66 cm (18–26 in), with a recorded maximum length of 88.3 cm (34+3⁄4 in). Its color pattern is similar to that of S. catenatus, but is paler overall: dark brown blotches show strong contrast against a tan-gray or light gray base body color. The venter (belly) is light in color, with only a small number of dark markings. Geographic distribution: In the United States, Sistrurus tergeminus occurs on the southwestern plains, ranging from southeastern Colorado to extreme southeastern Nebraska and northwestern Missouri. From this area, its range extends southwest through east-central Kansas and west-central Oklahoma into northern and central Texas, reaching as far southwest as the Colorado River. This species is also found in Mexico, where it occurs in the states of Tamaulipas, southern Nuevo León, north-central Coahuila, and Samalayuca, Chihuahua. The documented type locality for the species is "between the Mississippi River and the Rocky Mountains".
