Thallus: crustose, granular to minutely bullate, thin to moderately thickened, closely aggregated or dispersed; prothallus: absent surface: usually pale yellow to greenish yellow, rarely becoming brownish (older herbarium specimens), shiny or rarely dull, smooth, epruinose, phenocorticate, esorediate medulla: white, lacking calcium oxalate (H2SO4-) Apothecia: lecideine, soon sessile, (0.2-)0.3-0.6(-0.8) mm in diam. margin: black, prominent, usually persistent, rarely excluded with age disc: black, epruinose or rarely with faint yellow pruina, plane, rarely becoming slightly convex with age proper exciple: distinct, leptocline-type, exciple thick and not distinctly differentiated into an inner and outer part, hyphae thin-walled (mesodermatous), prosoplectenchymatous and usually ±densely interwoven (textura intricata), dull fuscous brown throughout, becoming ±carbonized by various amounts of a brown pigment (cf. elachista-brown, HNO3-), hypothecium deep reddish brown (leptoclinoides-brown, textura intricata) epihymenium: brown, pigmentation continuous with the outer exciple (HNO3-) hymenium: hyaline, not inspersed with oil droplets; paraphyses: simple to moderately branched, apically swollen, with a brown pigment cap (cf. elachista-brown) asci: clavate, Bacidiatype, 8-spored ascospores: soon brown, 1-septate (rarely with additional transversal septa forming at both ends), ellipsoid to ±citriform, rarely constricted, with tapered ends, often distinctly curved, (13-)15.6-[18.5]-21.3(-24) x (6-)7.9-[8.9]-9.9(-11) µm (n=60); proper septum: becoming thickened early but only briefly during spore ontogeny (±Physconia-type); ornamentation: microrugulate becoming rugulate with age (best seen in DIC) Pycnidia: rare, urceolate to globose, unilocular; ontogeny similar to the Umbilicaria-type conidiogenous cells: mostly terminal, rarely also intercalary (cf. conidiophore-type V) conidia: bacilliform to ellipsoid, 2-4 x 1.5-2 µm (n=20) Spot tests: usually C+ orange or sometimes pinkish, K+ yellow, KC- orange, P+ orange, CK+ orange fluorescence: UV+ pale or bright yellow to orange iodine reaction: medulla ±amyloid Secondary metabolites: arthothelin, isoarthothelin, 6-O-methylarthothelin, 4, 5-dichloronorlichexanthone, 4, 5-dichloro-6-O-methylnorlichexanthone, asemone and thiophanic acid, gyrophoric, lecanoric, and orsellinic acid (J. A. Elix, HPLC). Substrate and ecology: epilithic, on a variety of hard, siliceous (HCl-) rock substrates, often on vertical cliffs World distribution: temperate to subarctic, subalpine and alpine climates throughout the Northern Hemisphere Sonoran distribution: moderately common at higher elevations of Arizona, southern California, and Sonora. Notes: In the Sonoran Region, granular to minutely bullate thalli may superficially be mistaken for B. subaethalea, a species that does not react with C, and has distinctly ornamented and "banded" spores.