Lichenostigma saxicola, growing on silicate rocks and lichens, is described from southern California from both the Sonoran and Mojave deserts as well as from the Santa Monica Mountains on the coast. The species belongs to the subgenus Lichenostigma, has a non-amyloid centrum, and dark one-septate ascospores, 10–12 × 5–6 µm, cells equal or not, constricted at the septum, the walls of over-mature ascospores becoming granular-verrucose. The species is considered facultatively lichenicolous, not host specific, and is pathogenic.