Platymantis biak, also known as the Luzon limestone forest frog, is a species of frog in the family Ceratobatrachidae. It is endemic to the island of Luzon, the Philippines, where it is known from the Biak-na-Bato National Park, its type locality, and from the immediate vicinity of the park. The specific name biak is Tagalog meaning "crevice" or "crack" and refers to the preferred limestone karst habitat at the type locality.

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