Thallus: rimose- to verrucose-areolate, with thin to moderately thick verrucae; margins: indefinite, unzoned upper surface: whitish gray to reddish gray, smooth, dull, epruinose; lacking soredia or isidia fertile verrucae: concolorous with thallus, lecanorate, numerous, c. 0.5-1.7 mm in diam Apothecia: 1-2 per fertile verruca; discs: gray-brown to blackish brown, grayish pruinose; epithecium: dark brown to red-brown; hypothecium: hyaline asci: cylindrical, 215-400 x 45-74 µm, 2-4-spored ascospores: hyaline, ellipsoid, 75-110 x 33-45 µm; spore walls c. 8-13 µm thick, apices up to 18 µm thick, 2-layered; outer spore wall: c. 1-3 µm thick; inner spore wall: 7-11 µm thick Pycnidia: not seen Spot tests: medulla K+ yellow to red, C-, KC-, P+ orange, UV- Secondary metabolites: norstictic acid (major), connorstictic and subnorstictic acids and unknowns (minors). Substrate and ecology: occurring on coastal, siliceous rocks at 0-300 m World distribution: endemic to the western coast of North America Sonoran distribution: coastal, southern California and the adjacent NW Baja California. Notes: Pertusaria brattiae is characterized by the apothecioid ascomata, 2-4-spored asci and the presence of norstictic acid and related substances. The species is similar to P. chiodectonoides which, however, is readily distinguished by 8-spored asci and the presence of stictic acid. Pertusaria flavicunda is another species, which might be confused with P. brattiae. This taxon differs in containing thiophaninic and stictic acids.