The flat bark beetle (Coleoptera: Cucujidae) fauna of the Philippines consists of two species of Pediacus Shuckard, 1839: Pediacus ater Grouvelle, 1897 and Pediacus australis Marris and Ślipiński, 2004. Very few literature data records exist, showing P. ater recorded from two specimens from one locality on Mindanao Island, and P. australis known from a single specimen on Luzon Island. New distributional data for P. ater in the Philippines are provided, including the first records from the Bangsamoro Autonomous Region in Muslim Mindanao (Lanao del Sur Province), Soccsksargen Region (South Cotabato Province), and Central Visayas Region (Negros Oriental Province). These records show a much wider distribution for P. ater than was previously known and indicate that the species is widely distributed, at least in central and southern regions of the Philippines. Phenological activity of the species is discussed for the first time. A map with locality records for both cucujid species from the Philippines is given as well as morphological diagnostic information to discriminate the species.