Thallus: fissured to areolate, with thin to moderately thick verrucae; margins: entire, unzoned upper surface: yellow-green to sulfur-yellow, smooth or tuberculate, shiny or dull, epruinose; usually lacking soredia or isidia but some specimens with dispersed soredia fertile verrucae: concolorous with thallus, pertusariate or erect, flat-topped, numerous, c. 0.5-1.7 mm in diam.; ostioles: 1-8 per verruca, level to sunken, blackish brown Apothecia: 1-6 per verruca; epithecium: dark brown to black, K-; hypothecium: hyaline to yellowish asci: clavate or cylindrical, 260-400 x 55-84 µm, mostly 4-spored. Ascospores: hyaline, oval to ellipsoid, 65-100 x 35-55 µm; spore wall: 2-layered; outer spore wall: c. 2-6 µm thick; inner spore wall: 5-15 µm thick, smooth, laminated; apices: up to 25 µm thick Pycnidia: not seen Spot tests: K- or + yellow, C+ yellow, KC+ orange, P-, UV+ orange-red Secondary metabolites: confluentic, planaic, and thiophaninic acids (all major), hyperconfluentic and 2'-O-methylmicrophyllinic acids (both minor). Substrate and ecology: on siliceous rocks, seldom on soil, and up to 3000 m throughout western North America World distribution: endemic to North America from central Mexico to the Southwest Sonoran distribution: widely distributed from coastal California, but primarily in mountainous areas of Arizona, Chihuahua, Sonora, Sinaloa and Baja California Sur at 700 to 2000 m. Notes: Pertusaria tejocotensis is a characteristic yellowish species with poriform apothecia, white pruinose ostioles that may or not dilate to form a pseudolecanorate disc 4-spored asci and thiophaninic acid and long side chain depsides. It is similar to P. wulfenoides which, however, can be distinguished by having larger verrucae and a different chemistry. It usually grows on bark, while P. tejocotensis grows seldomly on siliceous rocks. Another similar species is P. flavicunda which is easily distinguished by its disciform ascomata and the presence of stictic acid. Pertusaria tejocotensis is a uniform species. Some specimens differ in producing soralia instead or in addition to apothecia.