Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Thallus: foliose, 2-8 cm in diam., tightly adnate to adnate, subdichotomously lobate lobes: sublinear to subirregular, somewhat elongate, plane, (0.5-) 1-3.5 mm wide; margin: entire; apices: subtruncate, plane upper surface: gray to dark gray, smooth to rugose, becoming cracked with age, dull to shiny, epruinose, white maculate; isidia, soredia, pustulae and dactyls all absent medulla: white with continuous algal layer lower surface: black, somewhat shiny; rhizines: sparse, black, dichotomous Apothecia: abundant, laminal, sessile to substipitate, 1.5-5 mm in diam.; disc: brown; margin: crenulate asci: clavate, 8-spored ascospores: broadly ellipsoid, 11-15 x 7-9 µm Pycnidia: marginal, immersed conidia: not seen Spot tests: upper cortex K+ yellow, C-, KC-, P+ yellow, UV-; medulla K+ yellow to red, C-, KC-, P+ red Secondary metabolites: upper cortex with atranorin and chloroatranorin; medulla with salazinic acids (major), consalazinic acid (minor) and norstictic acid (trace). Substrate and ecology: on acidic rocks or on soil over rocks, frequently in canyons on relatively open boulders and cliff faces in montane and upper montane forests World distribution: Central America north to southern Arizona Sonoran distribution: SE Arizona and S along the Sierra Madre Occidental in Chihuahua and Sinaloa. Notes: In the northern part of its range the species is somewhat more narrow lobed.