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.

[2] It is named after Dr. Ernst Williams, a friend and colleague of the scientist that described the species.

Dorsal skin is glandular with prominent dorsolateral ridges.

[4] Nevertheless, being restricted to a single location, the population is vulnerable stochastic processes.