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DescriptionThallus: crustose to subfruticose, thick, pulvinate-verruculose or glebulose-areolate; prothallus: seldom visible, radiate, the outer most edges gray to blackish blue, the inner edges soon covered by white or yellowish white radiate hyphal layers; areoles: at first adnate and semi-globular (0.2-0.3 mm in diam.), later becoming globose to irregular, 0.8-1.5(-2.3) mm high, 1(-1.5) mm in diam., dispersed or tightly aggregated, sometimes becoming narrow, +cylindrical (c. 0.5 mm in diam.) and finally +coralloid branched, 1-5(-6) mm high; surface: yellowish white, pale to grayish or greenish yellow, towards thallus margin sometimes weakly lobed (rosulate), esorediate; Apothecia: very frequent, dispersed or aggregated, broadly then narrowly sessile, (0.5-)1.2(-3) mm in diam.; disc: mostly dark red-brown to black, mostly shiny, plane then +convex, epruinose; margin: persistent, usually thin, +repand, subcrenulate, mostly 120-140 µm wide, concolorous with thallus, somewhat prominent when young, without a parathecial ring; amphithecium: present, with an algal layer, filled with small crystals that do not dissolve in K, corticate; cortex: gelatinous, distinct, 10-30 µm laterally, 30-70 µm basally; parathecium: indistinct, lacking crystals, 15-30 µm thick; epihymenium: light to dark brown, with crystals dissolving in K; hymenium: hyaline, mostly 70-75 µm tall; paraphyses: 2 µm thick, short and slightly expanded apically; asci: clavate, 8-spored; ascospores: hyaline, simple, broadly ellipsoid to ellipsoid, 9.5-16.2 x 5.7-9.5 µm; Pycnidia: rather rare, immersed; ostioles: black; conidia: filiform, straight or slightly curved, 21-39 µm long; Spot tests: cortex K+ yellow, C-, KC+ yellow, P- or P+ pale yellow; medulla usually K- (or pale yellow), C-, KC-, P-; Secondary metabolites: atranorin, usually with epanorin, zeorin, and fatty acids, less often with other combinations of substances in addition to atranorin.; Substrate and ecology: on siliceous or calcareous rocks, sometimes spreading to detritus, moss, or other lichens; World distribution: circumpolar with center of distribution in +continental areas, known from Europe, northern Africa, western and central Asia, Greenland, and North America; Sonoran distribution: Arizona, southern California, Baja California, Baja California Sur and Sonora.; Notes: The thallus color of L. argopholis varies from pale gray to pale yellow. Yellowish forms are easily recognized, but grayish morphs may resemble members of the L. subfusca-group. They differ, however, in amphithecial anatomy. The thallus not infrequently develops small marginal lobes, causing it to resemble rosulate species of Lecanora subg. Placodium, from which it is easily separated by containing atranorin (K+ yellow) and lacking usnic acids (KC-).