Oklahoma designated the bullfrog, Lithobates catesbeianus (formerly Rana catesbeiana), as the official state amphibian in 1997. The bullfrog is the largest frog in North America and can be found throughout the state of Oklahoma (although it prefers larger, deeper bodies of water, it can be found in almost every lake, pond, bog, sluggish stream, and even cattle tanks).

The voice of the male bullfrog, used to attract females, is a vibrant series of bass notes with a distinctive sound best described as "jog-o-rum." The loud, guttural bellow carries a long distance, giving the impression of a much larger creature, which is an advantage in keeping predators away. The bull frog has large talons and is an opportunistic predator eating anything it can swallow including beetles and other insects, small turtles, snakes, birds, worms, crustaceans, tadpoles, and frogs (including other bullfrogs).

Bullfrog coloring varies - they are generally varying shades of green or brown, with dark brown, dark green, or black blotching and a yellow or white underside. Females are usually larger than males.

Bull frogs are present year-round (burrowing into the mud beneath the water to hibernate in winter). The versatile and prolific bullfrog is an integral part of the ecology of Oklahoma and represents the importance of all species of amphibians to the environment and the state.

Source:

Bullfrog: Wikipedia
OKLAHOMA STATE ICONS: OK.gov

Links:

List of state Reptiles & Amphibians