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The Columbia Spotted Frog may be brown, tan, or gray with irregular-shaped black spots with light-centers. The undersides are cream colored with an orange or salmon-colored pigment usually present on the hind legs and lower abdomen. In some Nevada populations the hind legs and abdomen of frogs are yellow. The hind legs are relatively short relative to body length and there is extensive webbing between the toes on the hind feet. The eyes are upturned. Females may grow to approximately 100 mm (4 inches) snout-to-vent length, while males may reach approximately 75 mm (3 inches) snout-vent length (Nussbaum et al. 1983; Stebbins 1985; Leonard et al. 1993).
Since nearly the time of its original description in 1853, the systematics of the "Western Spotted Frog" group has been a source of some confusion and debate. In 1996, however, a team led by David M. Green published the results of a study on the genetics of Spotted Frogs and concluded that the group actually contained two "sibling" species—the Oregon Spotted Frog and the Columbia Spotted Frog (Green et al. 1996, 1997). The decision to "split" the species was based upon the results of laboratory studies that indicated significant genetic differences, despite a lack of reliable morphological differences. Because the two species have allopatric ranges, they may be reliably identified based upon the location where a frog is encountered.