Thallus: areolate, sometimes rimose at the edge, 1.5-8(-15) cm in diam., (0.1-)0.2-0.6(-1.2) mm thick areoles: angular or sometimes irregular, flat to slightly convex or somewhat uneven, (0.2-)0.4-1.1(-2) mm in diam., contiguous, separated by distinct cracks prothallus: often absent, when present found in parts along the thallus edge as a narrow dark zone, rarely fimbriate, black to blue-black or brown-black, 0.1-0.5(-1) mm wide surface: gray to white-gray or almost white, sometimes with a yellowish tinge, dull or slightly shiny upper cortex: (15-)20-40 µm thick, with crystals, uppermost part usually ±brown, 5-12(-15) µm thick, with cells (4-)5-7(-9) µm in diam.; cortex covered with an epinecral layer 2-12(-20) µm thick photobiont: chlorococcoid, cells ±round, 5-16(-20) µm in diam. Apothecia: aspicilioid, usually numerous, (0.1-)0.3-1(-1.6) mm in diam., 1-3(-10) per areole, when several then ±confluent, round to angular or irregular disc: black, rarely brown-black, usually concave, sometimes plane, rarely convex, without pruina or sometimes with a thin, white pruina thalline margin: flat to ±elevated, in larger apothecia often prominent, usually concolorous with thallus, but sometimes darker, rarely lighter exciple: (20-)40-90(-100) µm wide, usually I- but sometimes partly I+ blue medially; uppermost cells brown to olive-brown, ±globose, 4-6(-7) µm in diam. epihymenium: brown to olive-brown, sometimes olive to green, usually without or with a few crystals, rarely with numerous crystals, N+ green or sometimes blue-green, K+ brown hymenium: hyaline, I+ persistently blue, 90-120(-150) µm tall paraphyses: moniliform, with (3-)4-7(-9) upper cells ±globose (2.5-)3-4(-5) µm wide, in lower part 1.5-2 µm wide, not or slightly branched and anastomosing subhymenium and hypothecium: pale, I+ persistently blue (hypothecium usually darker I+ blue than subhymenium), together (20-)40-60(-80) µm thick asci: clavate, (45-)60-90(-100) x (13-)17-26(-30) µm, 8-spored ascospores: hyaline, simple, ellipsoid, (10-)12-18(-22) x 7-11(-14) µm Pycnidia: rare to rather common, 1(-4) per areole, rarely aggregated, immersed, (100-)120-220(-350) µm in diam., with a black, punctiform ostiole, 50-100(-170) µm in diam. conidia: filiform, straight or slightly curved, (10-)12-19(-22) x (0.6-)0.8-1(-1.3) µm Spot tests: cortex and medulla I-, K+ red, P+ orange, C- Secondary metabolites: norstictic acid, usually with trace of connorstictic acid, rarely also with hyposalazinic acid (2 specimens). Substrate and ecology: on ±exposed siliceous rock, schist or volcanic rock, rarely also on calciferous rock; temperate, boreal and arctic-alpine World distribution: circumpolar; Eurasia, and North America Sonoran distribution: common in Arizona; seems to be more rare in California and Baja California, at 1700-3300 m. Notes: Aspicilia cinerea is characterized by a gray to almost white thallus with quite large, sometimes confluent apothecia, a brown to olive-brown epihymenium, a short hymenium, moniliform paraphyses, medium sized spores (usually less than 20 µm long), conidia of medium length and the presence of norstictic acid. Several other norstictic containing species occur in the Sonoran area. Aspicilia brucei resembles A. cinerea but has smaller apothecia, non-moniliform to submoniliform paraphyses, smaller spores and shorter conidia. Aspicilia pacifica, another similar species, has smaller apothecia, larger spores, taller hymenium and shorter conidia. Aspicilia cuprea and Aspicilia olivaceobrunnea differ in thallus color, and both have taller hymenium and larger spores. In addition, A. cuprea has much longer conidia than A. cinerea.