The Western Australian endemic humicolous beetle genus Tympallopatrum Perkins is revised. A key to the four known species is given. Three new species are described: T. aureolum ( 12 km W. Walpole, Walpole National Park, Mt. Clare), T. callosum ( Beedelup National Park, 20 km W. Pemberton), and T. curvicostum ( Porongurup National Park, Bolganup Creek). These rare, markedly sculptured beetles were collected from litter and/ or fungi, or by pyrethrin fogging of bark, usually near streams or moist habitats. High resolution digital images of the holotypes are presented ( online version in color), male genitalia are illustrated, and geographic distributions are mapped.