We describe a new species of scandent/arboreal frog from Sudest Island, Louisiade Archipelago, off the southeastern tip of New Guinea that exhibits a remarkable ontogenetic change in color pattern. Juveniles are shiny black with lemon-yellow spots; adults are uniform peach with bright blue eyes. We detail the ontogenetic changes in color-pattern elements that comprise this transformation. This ontogenetic change, uniform peach adult coloration, and blue iris all appear to be unique features within the genus Oreophryne, most of whose members are tan, brown, or gray. We presume the striking juvenile color pattern to serve an aposematic function, but this conjecture requires testing. The new species is restricted to a relatively small patch of cloud forest perched on the highest peak of Sudest Island. Climate change may pose a threat to the new species if changing rainfall or temperature regimes result in the loss of this forest.