The false stag beetles (Diphyllostoma) are a group of three species of rare beetles known only from California. Almost nothing is known of their life history beyond that the adults are diurnal and females are flightless; larvae have not been observed.
Their length ranges from 5 to 9 mm; bodies are elongate, with a generally dull brown to reddish-brown color. Both body and legs are covered with longish hairs.
Originally classed with the Lucanidae, Diphyllostoma have a number of characteristics not shared with any other type of stag beetle, and so in 1972 Holloway proposed a separate family Diphyllostomatidae, which has since been accepted.