We describe Tephromela eviolacea as a new species from California, Idaho and Washington, U.S.A. Externally we cannot distinguish it from T. atra and T. pacifica, but it differs from both in ITS sequences, secondary metabolites and in lacking all violet coloration in the hymenium. In the Pacific Northwest, T. atra is found on rock and T. eviolacea and T. pacifica are found on bark and wood on the east and west sides of the Cascade Range, respectively. We provide a key to the genus in the region.