Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: foliose, loosely adnate, bluish-gray, turning buff in the herbarium with age, lobate lobes: subirregular, contiguous, plane, 2-4 mm wide, apices truncate upper surface: gray to yellowish gray, only lobe tips sometimes tinged brown, smooth, dull, sometimes white pruinose, especially towards the lobe tips pseudocyphellae: numerous, conspicuous, white, circular to rounded, laminal, reaching 0.3 mm soredia: granular, capitate to irregular, grayish-white, originating from pseudocyphellae, mostly laminal, occasionally also marginal, up to 0.5 mm in diam. lower surface: usually black centrally, brown marginally, rhizinate Apothecia: unknown from the area Pycnidia: absent Spot tests: upper cortex K+ yellow, C-, medulla K-, C+ rose , KC+ rose Secondary metabolites: upper cortex with atranorin (minor or trace); medulla with gyrophoric acid (major) and orcinyl lecanorate (=decarboxygyrophoric acid) (minor). Substrate and ecology: rare on bark of Quercus from 300 to 410 m World distribution: probably cosmopolitan, known from North and South America, Europe, Africa, Asia and Australia Sonoran distribution: rare in southern California and the Channel Islands.