Thallus: areolate, with moderately thick verrucae; margins: entire, zoned upper surface: ash gray to dark gray, smooth, shiny, epruinose, lacking soredia or isidia fertile verrucae: concolorous with thallus, pertusariate, hemispherical to flat-topped, numerous, rarely fused, c. 0.8-2.0 mm in diam.; ostioles: 1 or 2-10 per verruca Apothecia: 1-10 per verruca, 0.4-0.8 mm in diam.; epithecium: dark brown to black, K-; hypothecium: hyaline to yellowish asci: cylindrical, 300-500 x 60-90 µm, (1-) 2-spored ascospores: hyaline, ellipsoid, 145-270 x 50-80 µm, 2-layered; outer spore wall: c. 4-10 µm thick, inner spore wall: 10-20 µm thick Pycnidia: immersed conidia: bacilliform, 5-8 x 0.5-1.0 µm Spot tests: K+ yellow to red, C-, KC-, P+ yellow to orange, UV- Secondary metabolites: norstictic (major) and connorstictic (minor) acids. Substrate and ecology: The species grows on siliceous rocks at the coast and in coastal mountains World distribution: endemic to the west coast of North America Sonoran distribution: restricted to coastal California and Baja California. Notes: Pertusaria californica is characterized by the gray thallus with large pertusariate verrucae that have several dark ostioles, two- to single-spored asci, and the presence of norstictic acid. The relationships of P. californica were discussed in detail by Dibben (1980). Pertusaria californica may be confused with poorly developed specimens of P. brattiae which, however, differs in having disciform apothecia and can further be distinguished by smaller ascospores and the presence of stictic acid.