A new auger beetle, Cretolgus minimus gen. et sp. nov., of the subfamily Polycaoninae (Bostrichidae) is described from mid-Cretaceous Burmese amber. The new genus differs from the genera Melalgus Dejean, 1833 and Polycaon Castelnau, 1836 in the subcylindrical body, striate elytra, contiguous procoxal cavities, four-segmented tarsi, and small body size. This is the first fossil record of the subfamily Polycaoninae and the second record of Bostrichidae in Burmese amber.