A new fossil species of auger beetle (Coleoptera: Bostrichidae), preserved in mid-Cretaceous (Albian-Cenomanian) amber from south-western France, is described as Stephanopachys vetus Peris, Delclòs et Perrichot sp. n. The species is the earliest fossil bostrichid discovered to date, but is remarkably similar to Recent species of the genus Stephanopachys, supporting long morphological conservation in wood boring beetles. The specimen is fossilized in fully opaque amber and was imaged in 3D using propagation phase-contrast X-ray synchrotron microtomography. Based on the ecology of extant related species habits, it is suggested that S. vetus sp. n. was a primary succession pioneer following wildfires in mid-Cretaceous forests. The fossil record of the family is reviewed.