Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Thallus: fissured to fissured-areolate, with thin to moderately thick verrucae; margins: entire, unzoned upper surface: yellow-green to sulfur-yellow, smooth to rugose-plicate, dull, slightly pruinose; lacking soredia or isidia fertile verrucae: concolorous with thallus, pertusariate to erect, flat-topped, few or numerous, grouped in a central depression, c. 0.6-2.8 mm in diam.; ostioles: 1-7 (-12) per verruca, dark, level to sunken, sometimes dilating and fusing to form a pseudolecanorate disc Apothecia: 1-5 per verruca; epithecium: brown to black, K-; hypothecium: hyaline asci: cylindrical, 280-460 x 50-78 µm, mostly 4-spored ascospores: hyaline, ellipsoid to oval, 68-110 x 38-58 µm; spore wall: 2-layered; outer spore wall: c. 2-6 µm thick; inner spore: wall 6-18 µm thick, smooth; apices: up to 32 µm thick Pycnidia: not seen Spot tests: K+ yellow to red, C+ orange, KC-, P+ yellow to orange, UV+ orange-red Secondary metabolites: norstictic and thiophaninic acids (both major), connorstictic acid, 2-chloro-6-O-methylnorlichexanthone, and 4-chloro-6-O-methylnorlichexanthone (all minor). Substrate and ecology: on bark, including Alnus, Juniperus, Pinus, Populus, Pseudotsuga, or Quercus, and was also collected on siliceous rocks World distribution: endemic to SW North America Sonoran distribution: widely distributed in mountainous areas at 2000-3100 m. Notes: This taxon is characterized by its yellowish thallus, large verrucae with poriform ascomata with ostioles that dilate and fuse to form pseudolecanorate discs, 4-spored asci, and the presence of the norstictic and thiophaninic acids chemosyndromes. Similar species include P. azulensis and P. tejocotensis and the differences to these species are discussed above.