Thallus: continuous to irregularly fissured, with thin to moderately thick verrucae; margins: entire, zoned or unzoned upper surface: gray to yellow-gray or greenish gray, smooth or rugose-plicate, shiny or dull, epruinose; lacking soredia or isidia fertile verrucae: concolorous with thallus, pertusariate to falsely lecanorate, numerous, crowded and locally fused (2-4) in mutually deformed groups, c. 0.4-3.0 mm in diam.; ostioles: 1-8 per verruca, well sunken, soon dilating to form a pseudolecanorate disc, blackish brown, grayish pruinose Apothecia: 1-4 per verruca; epithecium: dark brown to black; hypothecium: hyaline or yellowish asci: clavate, 270-450 x 40-100 µm, (6-) 8-spored ascospores: hyaline, ellipsoid or fusiform, 60-130 x 25-50 µm.; spore wall: 2-layered; outer spore wall: c. 1-4 µm thick; inner spore wall: 2-10 µm thick; apices: up to 28 µm thick Pycnidia: immersed conidia: bacilliform, 7-15 x 0.5-1.0 µm Spot tests: K- or + yellow, C- or + yellow, KC+ orange, P-, UV+ orange-red Secondary metabolites: thiophaninic acid (major), gyrophoric acid (minor). Substrate and ecology: on Quercus or Pinus bark World distribution: temperate Europe and western North America Sonoran distribution: widely scattered, SE Arizona and coastal Sinaloa, at c. 500 - 2300 m. Notes: Pertusaria hymenea is characterized by a moderately thick yellowish thallus, poriform ascomata with sunken ostiola which soon dilate and fuse to form a blackish pseudolecanorate disc, a K+ violet epithecium, 8-spored asci and the presence of thiophaninic and gyrophoric acids. A very similar species is P. rubefacta which is best separated by the presence of the norstictic acid chemosyndrome.