Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: crustose, bullate to subsquamulose, areolate; prothallus: indistinguishable to conspicuous, black, black-green, sometimes dendroidic; areoles: contiguous to dispersed, flat to highly convex, squamiform, subbullate to bullate, up to 2 mm in diam., regular to irregular, angular to round in outline; surface: usually pale yellowish brown to more rarely dark brown in the center of areoles and with a small, whitish, grayish or blackish margin, esorediate; cortex: consisting of 3 layers: (a) a 5-30 µm thick, indistinctly to distinctly lammelated, unpigmented, translucent epinecrotic layer, (b) a thin (c. 5 µm) brown pigmented layer, and (c) a (sic) unpigmented cortical zone; medulla: white, I+ intensely violet; algal layer: 60-90 µm thick; Apothecia: black, or (more rarely) with bluish prunia, with a slightly to moderately constricted base, up to 1.6 mm in diam.; disc: black, flat to convex; margin: black, usually persistent, dull to shiny; exciple: with a greenish black, epihymenium-like rim, unpigmented inside; epihymenium: bright green, olive-green to green-brown, 8-15 µm thick; hymenium: hyaline, 40-65 µm tall, I+ blue; paraphyses: simple, occasionally scarcely branched and anastomosing; subhymenium: hyaline, 15-45 µm tall; hypothecium: hyaline to medium brown (rarely dark brown); asci: clavate, 40-65 X 13-16 µm, 8-spored; ascospores: hyaline, simple, ellipsoid-oblong, mean values: 7.5-11.6 X 3.4-4.8 µm; Pycnidia: immersed, graphidoid; conidia: bacilliform to cylindrical, straight, (7.5-)10-14.5(-16.5) X 1.2 µm [studied in 15 specimens]; Spot tests: medulla K+ yellow turning into red, C-, KC-, P- or P+ yellow; Secondary metabolites: norstictic acid (major), connorstictic acid (minor or trace).
Substrate and ecology: in open habitats on acidic rocks in the high montane to predominately in the alpine belt (in USA often collected in altitudes above 4000 m); World distribution: Arctic regions and high mountains of North America, Europe and Asia; Sonoran distribution: alpine belt of mountains in Arizona and southern California.