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

Thallus: foliose, loosely appressed, up to 8 cm in diam. lobes: flat or slightly concave, 0.6-1.3 mm wide upper surface: beige gray, brownish gray, leaden or bluish gray; pseudocyphellae: very distinct along the lobe margins, sometimes gray pruinose and reticulately confluent; pruina: punctiform on the peripheral parts of the lobes soredia: always present, granular, rarely farinose, initially in marginal, fissural, then in laminal, in orbicular soralia, sometimes secondarily with a cortex and then simulating polysidiangia; isidia and true polysidiangia lacking medulla: upper part lemon yellow, ochraceous to orange yellow lower surface: black in center, paler towards lobe tips; rhizines: ± dense, blackish to blackish blue, furcately divided Apothecia: obscurascens-type, rare, laminal, 0.5-1.4 mm wide; disc: black, not pruinose internal stipe: distinct, upper part dark orange, lower part white ascospores: one-septate, brown, 14-19 x 6-8 µm Pycnidia: immersed conidia: bacilliform, 3-4 x 1 µm Spot tests: upper cortex K+ yellow or K-, C-, KC-, P- or P+ pale yellow; medulla upper and lower part K-, C-, KC-, P-; internal stipe upper part K+ red, C-, KC+ purple, P-; lower part K-, C-, KC-, P- Secondary metabolites: upper cortex atranorin (sometimes in very low concentration); medulla with terpenes of a characteristic pattern on TLC plates, and an unknown pigment. Substrate and ecology: on bark, acidic rocks and over mosses from sea level to subalpine areas World distribution: subtropical with collections from temperate regions (North America, Europe, Africa, Nepal, India, Japan, Australasia) and insular Laurimacaronesia Sonoran distribution: Arizona and Sierra Madre Occidental region of adjacent Chihuahua in regions with high summer precipitation.