, the Smoky Jungle Frog, is a large frog. Adult males can reach 177 mm while the larger females can measure up to 185 mm (Savage 2002). This frog can be distinguished from other frogs by the presence of paired dorsolateral folds, paired lumbar glands, and a spotted or barred upper lip, as well as its large size (Savage 2002). This species has a smooth dorsum, definite inguinal glands, and large eyes and tympana (Savage 2002). The snout is rounded, almost semicircular when viewed from above (Savage 2002). Adult males have paired elongated vocal slits and a single internal subgular vocal sac (Savage 2002). In addition, adult males have extremely muscular forelimbs and a pair of black spines on the chest, plus a black spine on each thumb (Guyer and Donnelly 2005). Dorsolateral folds extend from each eye to the groin (Hero and Galatti 1990). The adult coloration has been described as either uniform gray to reddish brown, or with darker spots or bars on the ground color (Savage 2002), It has also been described as a dark purple and light brown reticulum (Guyer and Donnelly 2005). The underside is dark gray with white to yellow mottling or tiny white speckles (Savage 2002). The posterior thigh has small white spots on a black background. A dark interorbital bar is present (Guyer and Donnelly 2005). Young frogs are more brightly colored than adults and have toe ridges (Savage 2002).
Tadpoles of this species are giant and elongate, growing up to 83 mm at stage 40 (Savage 2002; Hero and Galatti 1990). Dorsally, the tadpole is brown, with a lighter ventral surface (Savage 2002). The mouth is almost terminal, while the nostrils and eyes are on the dorsal side (Savage 2002). The spiracle is located laterally and sinistrally and the vent is medial (Savage 2002). This species has a long tail with low fins and a pointed tail tip (Savage 2002). The oral disk is complete and moderate, having two serrated beaks and 2/3 rows of denticles, with a broad gap in the row of denticles immediately above the mouth (Savage 2002). Labial papillae are lacking above the mouth, but are usually found in two rows lateral to the mouth and a single row ventral to the mouth (Savage 2002). The lateral line system is well-developed, particularly in comparison with larvae of other Leptodactylus species (Heyer et al. 1975).