River Frog

Average snout-vent length is 90-120 mm. Large males have snout-vent length between 110 and 120 mm, and females reach snout-vent lengths between 130 and 140 mm, and up to 155 mm. The dorsum is blackish green and unmarked or greyish olive with a pattern of small, well separated dark markings of irregular, angular, or linear shape. These markings may be larger, more rounded, and interconnected. Its venter is medium to dark grey or black with light spots or worm-like markings. A light girdle usually outlines the groin. Males have a throat which is dark grey or black washed with yellow and often bears prominent yellow spots. Both females and males have smooth to moderately rugose dorsal skin. Some individuals are very rugose and have skin which is heavily wrinkled by large warts and ridges. Rugose individuals have two parallel rows of elongate tubercles dorsolaterally, but these are poorly defined in smooth individuals. The calls of adult males are a rolling snore or an explosive grunt.

R. heckscheri inhabits Coastal Plain river swamps of the southeastern United States from the Cape Fear River drainage in North Carolina southward to northern Florida and westward along the Gulf Coast to the Biloxi River in Mississippi.

Up until they're 20 mm in length, larvae are black with a conspicuous gold band across the dorsum and no pigment in the tail. Between 21 and 40 mm, melanophores form along the crests of the tail and the gold band starts to fade. At 50-55 mm the dorsum is dark olive covered with tiny, greenish yellow flecks, the venter is purplish, and the tail is edged in black. Larvae transform at or before a size of 158 mm. There are two or three rows of labial teeth above and three below.