Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Thallus: foliose, 2-5 cm in diam., tightly adnate, subdichotomously to irregularly lobate lobes: sublinear, elongate, plane to subconvex, separate, 0.4-2 mm wide; margin: entire but sometimes incised; apices: subtruncate, plane to convex upper surface: light gray, smooth to somewhat rugulose, plane, dull, faintly maculate or emaculate, epruinose soredia: farinose to slightly granular, in laminal, capitate soralia that sometimes become confluent; isidia and dactyls absent medulla: white with continuous algal layer lower surface: black centrally, brown peripherally; rhizines: dense, black, dichotomous Apothecia: rare, laminal, substipitate, 1-2.5 mm diam.; disc: brown; margin: smooth, esorediate asci: clavate, 8-spored ascospores: broadly ellipsoid, 8-11 x 5-7 µm Pycnidia: not seen Spot tests: upper cortex K-, C-, KC-, P+ pale orange, UV+ yellow; medulla K-, C-, KC-, P+ red Secondary metabolites: upper cortex with lichexanthone; medulla with echinocarpic acid (major). World distribution: throughout the neotropics, including the Carribean Sonoran distribution: Sinaloa in the Sierra Madre Occidental. Notes: Initially Hale (1975, p. 66) inadvertently created confusion about this species by listing the cortex as having usnic acid in the description of the species. However, in the introductory pages Hale (1975, p. 10) listed the species as having lichexanthone, a fact that we confirm for several specimens in addition to the Sonoran material.