Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Thallus: foliose, 3-10 (-15) cm diam., adnate to loosely adnate, subdichotomously lobate lobes: sublinear to irregular, elongate, plane, often imbricate, 2-6 mm wide; apices: subtruncate to subrotund upper surface: whitish to greenish gray (tan in herbarium with age), smooth, shiny, usually strongly white maculate isidia: laminal to submarginal, dense, cylindrical, simple to coralloid branched, slender, rarely becoming lobulate, concolorous with the thallus but tips sometimes blackened; soralia, pustulae and dactyls absent medulla: white with continuous algal layer lower surface: black, peripherally brownish black, shiny; rhizines: dense, often visible from above, black, dichotomous Apothecia: rare, laminal, sessile, 2-7 mm in diam.; disc: brown; margin: crenulate, without isidia asci: clavate, 8-spored ascospores: ellipsoid, spores 8-10 x 4-6 µm Pycnidia: not seen Spot tests: upper cortex K+ yellow, C-, KC-, P+ yellow, UV-; medulla K-, C-, KC-, P- Secondary metabolites: upper cortex with atranorin and chloroatranorin; medulla with protoconstipatic acid (major), constipatic, dehydroconstipatic, protopraesorediosic acids (all minor), and praesorediosic acid (trace). Substrate and ecology: usually on hardwood or pine bark and rarely on rock in montane to subalpine forests, World distribution: pantropical and subtropical Sonoran distribution: Chihuahua and Sinaloa in the Sierra Madre Occidental.