Thallus: foliose, ± orbicular, 2-8 (-15) cm wide, adnate to loosely adnate, with or without concentric rings, lobate, lobes: flabellate or cuneate, 1-3 (-7) mm wide, contiguous to imbricate or well separated, lobulate (especially older parts) and weakly branched; apices: rounded and deflexed, broader than interior parts of the lobes, usually incised upper surface: light gray to dark bluish gray when dry, darker when wet, smooth, usually glossy, rarely scabrid, epruinose, sometimes with concentric, curved ridges; lacking isidia, but often with small rounded, laminal or marginal accessory lobules in central parts of the thallus upper cortex: white or pale yellow, 12-20 µm thick, with an epicortex cortex: hyaline to black, 12-20 µm thick medulla: white or pale yellow, loose, 30-60 µm thick lower surface: usually pale brown but sometimes deeper brown to black, glabrous, rhizinate; rhizines: white, light to dark brown or black (black in Sonoran material), scarce to numerous, sometimes forming a dense hypothallus Apothecia: usually present, laminal, irregularly orbicular, 1-4 (-9) mm wide, adnate or sessile, orbicular; margin: thin, only visible in young apothecia, sometimes with white hairs (especially towards base of apothecia and hidden when viewed from above); disc: reddish brown to black (black in Sonoran material), flat to strongly convex; exciple: hyaline or light brown, up to 200 µm thick but covered by disc, epihymenium: pale brown or brownish or black, 4-8 µm thick; hymenium: colorless, 40-60 µm high; paraphyses: ± branched, septate, apically capitate; subhymenium: pale brown to almost black, up to 100 µm thick asci: narrowly clavate, 8-spored ascospores: narrowly to broadly fusiform to ellipsoid, hyaline, simple, often with two oil droplets, 7-14 x 3-5 µm Pycnidia: laminal or marginal, immersed or sessile, ostiole dark conidia: bacilliform, 2-4 x 1 µm Spot tests: all negative Secondary metabolites: none detected (reports of atranorin may be in error). Habitat and ecology: on rocks and soil among mosses in moist habitats, but also on tree trunks (Quercus etc.) World distribution: pantropical and subtropical with a few outlying temperate to arctic localities Sonoran distribution: scattered locations in SE Arizona and south along the Sierra Madre Occidental in Chihuahua, Sonora and Sinaloa.