About Sistrurus miliarius Linnaeus, 1766
Sistrurus miliarius is a small but bulky species. Adults usually reach a total length including tail of 40–60 cm (16–24 in). The maximum total length ever officially reported is 78.8 cm (31.0 in), per Klauber 1972. Snellings and Collins (1997) documented a S. m. barbouri specimen measuring 80.3 cm (31.6 in) that had been kept in captivity for over 12 years. Gloyd (1940) recorded the largest wild S. m. barbouri he found was 63.8 cm (25.1 in), collected from St. Petersburg, Florida. Shine (1978) hypothesized that males may be larger than females in some populations of this species. However, a later 1996 study by Bishop et al. found no sexual dimorphism of any sort in a Sistrurus miliarius population from Volusia County, Florida. It is currently theorized that the general lack of sexual dimorphism in this species occurs because both males and females face the same selective pressures favoring larger body size. At midbody, this species usually has 23 rows of dorsal scales. Its dorsal color pattern is made up of a series of oval or nearly circular spots with relatively regular edges. Spots on the flanks are mostly round, and are not much taller than they are wide. On the rear part of the belly, pigment is restricted to faint, indistinct blotches that occur in pairs on adjacent scales. Juveniles have a color pattern similar to adults, though it may be paler or have more vivid markings, and the tip of the juvenile tail is yellow. Sistrurus miliarius is native to the Southeastern United States. Its geographic range extends from southern and eastern North Carolina, south through peninsular Florida, and west to eastern Texas and Oklahoma. The originally given type locality for this species is "Carolina". In 1953, Schmidt proposed restricting this type locality to "Charleston, South Carolina". Sistrurus miliarius has been reported to inhabit flatwoods, sandhills, mixed forests, and floodplains, and it can also be found near lakes and marshes. Because this species needs cover, pygmy rattlesnakes may tend to prefer more densely vegetated areas.
