A small species of frog reaching up to nearly 2 cm in body length. It has a brown back, often with black patches. There is a dark horizontal stripe between the eyes, a dark marking on the upper back, and pale eye-spots on the lower back. There is a black stripe from the tip of the snout to behind the eye. The belly is brown, with white spots. Fingers and toes are unwebbed, both with small discs. The first finger is very short compared to the rest. It is only known from two individuals from one locality, so its status as a species is uncertain.
Eggs and development are unknown, but are likely to be similar to those of other Cophixalus species. Breeding season is unknown, but the species possibly breeds during summer.
Looks most similar to Cophixalus crepitans in its distribution, but is slightly larger. It is possible that Cophixalus peninsularis is not a species, but has just been confused with large Cophixalus crepitans individuals.
Found only in the McIlwraith Range in the Cape York region of QLD.