Thallus: fissured, with thin to moderately thick verrucae; margins: entire, unzoned upper surface: yellowish gray to ash gray or green-gray, smooth to tuberculate, dull, slightly pruinose; lacking soredia or isidia fertile verrucae: concolorous with thallus, lecanorate, numerous, c. 0.7-1.2 mm in diam. Apothecia: 1 (-2) per verruca; disc: brown to blackish brown, level to sunken, whitish pruinose; epithecium: yellow-brown to blackish brown, K-; hypothecium: hyaline to yellowish asci: clavate, 170-350 x 45-85 µm, (1-) 2-spored ascospores: hyaline, ellipsoid to cylindrical, 75-150 x 35-75 µm; spore wall: c. 5-20 µm thick, smooth, 1-layered Pycnidia: not seen Spot tests: K+ yellow to red, C- or red, KC- or red, P+ yellow, UV+ orange-red Secondary metabolites: norstictic and thiophaninic acids (both major), connorstictic acid, 2-chloro-6-O-methylnorlichexanthone, 4-chloro-6-O-methylnorlichexanthone, and ± gyrophoric acid (all minors). Substrate and ecology: bark of different phorophytes, most commonly collected on Quercus in mountainous regions World distribution: endemic to North America Sonoran distribution: along the west coast from central California to Baja California and Baja California Sur at 200-600 m. Notes: Pertusaria lecanina has a yellowish gray thallus with lecanorate verrucae with dark, but heavily whitish gray pruinose, discs. It is further characterized by 2-spored asci and the presence of norstictic and thiophaninic acids. It may superficially resemble P. xanthodes when poorly developed, but this species is readily distinguished by the poriform ascomata and the presence of stictic acid. Another somewhat similar species is P. neolecanina, the differences of these two species are discussed under the latter.