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

Thallus: foliose, 3-8 cm diam., adnate to loosely adnate, subdichotomously lobate lobes: linear to subirregular, short, plane, separate, becoming partially imbricate, 2-6 mm wide; apices: subtruncate to subrotund upper surface: whitish gray (tan in herbarium with age), smooth, shiny; usually white maculate isidia: laminal to marginal, 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: sparse to moderate, black, dichotomous Apothecia: rare, laminal, sessile, 1-2 mm in diam.; disc: brown; margin: crenulate, isidia absent asci: clavate, 8-spored ascospores: ellipsoid, spores 8-10 x 4-6 µm Pycnidia: marginal, immersed conidia: not seen Spot tests: upper cortex K+ yellow, C-, KC-, P+ yellow, UV-; medulla K+ yellow, C- or C+ pale yellow, KC + yellow, P+ orange Secondary metabolites: upper cortex with atranorin, chloroatranorin, and isousnic acid (Eliasaro et al. 1998); medulla with echinocarpic acid, 4-O-demethylbarbatic and barbatic acids (all major), norobtusatic, and obtusatic acids (minor to trace). Substrate and ecology: on rocks in open, but humid oak and pine forests World distribution: SE USA and throughout the neotropics Sonoran distribution: Sinaloa in the Sierra Madre Occidental.