Adult: Species description based on Savage and Myers (2002). Medium to large frog with a large head and prominent crests on the head. Males and females are dimorphic in size, with males probably reaching lengths of 40 mm, and females to 69 mm. Dorsal: The color of the dorsal surface varies from light gray to very dark brown. Some specimens may have orange or reddish tones . The dorsal surface is mostly smooth but has some distict tubercules. The upper surfaces of the limbs are barred in some specimens, but not others. Ventral: The ventral surface is typically darker on the throat, the color fading to solid white on the belly. Throat coloration varies from barely darker than the belly to mottled with brown to almost all dark brown with many small white spots. The ventral surface is smooth . Concealed surfaces: Rear surfaces of the thighs dark. Distinguishing characteristics: The lip line is light,interrupted only by a few dark bars that radiate from the eye to the lip. Additional alternating light and dark spots are often present under the eye. A small black spot is often present at the top of the tympanum. Eye: Iris dark bronze-brown, or black with bronze flecks.
Habitat: Lowland and premontane forest to 1040 m. Ecology: May be found in forest leaf litter (Savage and Myers 2002). Karyotype: 2N = 20 (Chen 2001) Type locality: Quebrada Docordó, about 10 km above junction with Río San Juan, about 100 m elv., Dept. Chocó, Colombia (approx. 4° 34′ N, 77° 03′ W) Diet: Craugastor opimus consumes rather large arthropods (as Eleutherodactylus biporcatus, Toft 1981). It most likely sits and waits to ambush large prey as they pass by (Toft 1981, Savage and Myers 2002).