Thallus: crustose, continuous to rimose, 0.3-0.6 mm thick; prothallus: absent or rarely present, black, visible at the thallus margin, up to 0.1 mm wide surface: yellowish white, rough, without soredia or isidia Apothecia: sparse or moderately abundant, orbicular, semi-immersed to sessile, slightly constricted at base, 0.45-0.8 mm in diam. disc: black, plane, epruinose margin: distinct from the beginning, c. 0.6 mm wide exciple: bluish to greenish black, without algal cells parathecium: hyaline, without crystals epihymenium: pale to strongly green to bluish green hymenium: hyaline, 50-85 µm tall, not inspersed; paraphyses: not to rarely distinctly branched, not to rarely anastomosing, not to slightly thickened apically hypothecium: hyaline asci: clavate, lecanoral, 8-spored ascospores: hyaline, simple, ellipsoid to ovoid, 7.5-14 x 4.5-10 µm Pycnidia: not seen Spot tests: thallus surface K+ yellow, C+ orange, KC+ yellow, P+ yellow Secondary metabolites: 3-O-methylthiophanic acid (= 2,4,5,7-tetrachloro-3-O-methylnorlichexanthone), arthothelin (2,4,5-trichloronorlichexanthone), atranorin, diploicin, and thurin-gione (=2,4,5-trichloro-3-O-methylnorlichexanthone). Substrate and ecology: on wood, bark, or non-calciferous rocks World distribution: Europe, North and South America Sonoran distribution: central and eastern Arizona.