Description: L. onca has a snout-vent length between 44 and 87 mm, and is distinquished from similar species of the Rana pipiens complex by its short, indistinct, dorsolaterl folds that extend 1/2 to 3/4 down the dorsum, generally shortened legs, an incomplete supralabial stripe, upper surfaces of the thighs usually spotted and not barred, and males having enlarged tympana, paired vocal sacs, and no vestigial oviducts. It has a dorsum which is brown, gray, or greenish above, with discrete greenish-brown spots that are usually reduced or faded on the front of the body. These dorsal spots are indefinitely bordered and are usually present on the upper surfaces of the thighs. Usually, the venter is whitish, and the throat has dark mottling. The groin and the undersides of the hind limbs are yellow to yellow-orange.

Habitat: Historically, this frog probably occupied a variety of habitats including springs, streams, and wetlands characterized by clean, clear water, in both deep and shallow water, and cover such as submerged, emergent, and perimeter vegetation. Leopard frogs generally require shallow water with emergent and perimeter vegetation for foraging and basking, and deeper water, root masses, undercut banks, and debris piles for cover and hibernacula. Emergent or submergent vegetation provides cover and egg-deposition substrate. Adults appear to prefer relatively open shorelines where dense vegetation does not dominate. The recently extant populations inhabit spring systems with largely unaltered hydrology and no introduced American bullfrogs or game fishes

Range: It is found along the Colorado river in extreme northwestern Arizona, and adjacent Nevada and southwestern Utah, although its present range seems to be restricted to the Lake Mead National Recreation Area.

Found in these States: AZ | NV | UT

Diet: Adults probably are mainly invertivorous. Larvae probably eat algae, organic debris, plant tissue, and minute organisms in water.

Reproduction: Information is incomplete due to inadequate study; eggs have been found in November and February; calling has been heard in February, June, November. Individuals reach sexual maturity in 1-2 years, and some likely live 4-5 years or more.

Status: It is threatened by habitat loss to agriculture and water development as well as invasive species.

Subspecies: None

Taxonomy: This species was placed in the genus Lithobates by Frost et al. (2006). However, Yuan et al. (2016, Systematic Biology, doi: 10.1093/sysbio/syw055) showed that this action created problems of paraphyly in other genera. Yuan et al. (2016) recognized subgenera within Rana for the major traditional species groups, with Lithobates used as the subgenus for the Rana palmipes group. AmphibiaWeb recommends the optional use of these subgenera to refer to these major species groups, with names written as Rana (Aquarana) catesbeiana, for example.