Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.

Thallus: continuous to weakly fissured, with thin to very thin verrucae; margins: entire, unzoned upper surface: ash gray to greenish gray, smooth, shiny, epruinose; lacking soredia or isidia fertile verrucae: darker than thallus, lecanorate, numerous, c. 0.2-1.2 mm in diam. Apothecia: 1 (-2) per verruca; disc: black, sunken, grayish pruinose; epithecium: yellowish brown to dark brown, K+ strongly violet; hypothecium: yellowish asci: clavate, 120-250 x 40-70 µm, (-1) 2 (-3)-spored ascospores: hyaline, ellipsoid to fusiform, 60-120 x 30-65 µm, K-; spore wall: c. 2-16 µm thick, smooth, apices up to 30 µm thick, 1-layered Pycnidia: not seen Spot tests: K-, C-, KC-, P-, UV- Secondary metabolites: no phenolic substances detectable by HPLC. Substrate and ecology: Pertusaria stenhammarii grows on bark of high elevation conifers World distribution: circumboreal in the Northern Hemisphere Sonoran distribution: mountainous areas of Arizona. Notes: This 2-spored species is characterized by a hypophloedal, grayish thallus, disciform apothecia, a K+ violet epithecium, and the lack of lichen substances. It might be confused with P. sommerfeltii but this species differs in having poriform ascomata and the presence of stictic acid and 4,5-dichlorolichexanthone.