Pristimantis ernesti is a species of frog in the family Strabomantidae. It is endemic to the summit of Sumaco, a volcano in the Napo Province, Ecuador. Its common name is Ernest's robber frog. It is named after Dr. Ernst Williams, a friend and colleague of the scientist that described the species. It is a little studied species. Description Males measure about in snout–vent length. Female size is unknown. The dorsum is coffee-coloured with dark gray markings, including a "W" mark on its upper back. Dorsal skin is glandular with prominent dorsolateral ridges. Habitat and conservation Its natural habitat is grassland and bushland on the summit of Sumaco. Herpetological sources cite the altitude as being about , although other sources give maximum elevation of to this mountain. The volcano is in the Sumaco Napo-Galeras National Park. Nevertheless, being restricted to a single location, the population is vulnerable stochastic processes. References ernesti Endemic fauna of Ecuador Amphibians of Ecuador Amphibians described in 1987 Taxonomy articles created by Polbot