Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: 1-3 cm in diam., up to 0.3-0.5 mm thick, strongly adherent, rimose to areolate; prothallus: usually distinct, often rather thick, black to dark gray, visible often between or beyond the areoles areoles: scattered to contiguous or weakly imbricate, 0.1-1.5(-3) mm wide, rounded to irregular-angular, plane to slightly concave, often slightly rimose lobes: 1-2(-2.5) mm long, 0.5-1(-1.5) mm wide; edges: subentire to coarsely crenate, often raised or thickened, somewhat enlarged, isodiametric to moderately elongated surface: pale to grayish or greenish yellow, yellowish green, or yellow to grayish yellow, often becoming pale brown or olive in the herbarium, dull to slightly shiny, often somewhat pruinose near the edges, epruinose or occasionally slightly pruinose in places, without soredia; thallospores: often in clusters or chains of several cells, the cells 3-5 µm in diam., with blue-black (K+ blue-green) walls, esorediate internal structure: rather poorly differentiated, often composed of anticlinal hyphae throughout upper cortex: often with empty algal cells, indistinct, mostly 50-75 µm thick, inspersed with yellowish granules (soluble in K); hyphae: randomly oriented, the cells roundish, 3-5 µm in diam., with lumina 2-3 µm thick medulla: solid, filled with medium-fine granules (insoluble in K); algal layer: irregular but continuous, or interrupted by narrow, somewhat cone-like hyphal bundles lower cortex: absent or very thin, except near edges, black Apothecia: very common laminally, usually several per areole and long remaining immersed to adnate, finally broadly sessile, 0.3-0.7 mm in diam., often irregular in outline disc: +plane, epruinose, medium or deep yellow-brown, brownish orange, medium to dark brown, or dark red-brown margin: concolorous with or slightly paler than the thallus, little differentiated, level with the disc or slightly raised, persistent or finally crowded, either without or with parathecial ring paler and yellower than disc amphithecium: present, with an intermittant algal layer (c. 50 µm thick) medulla extending below the hypothecium, sometimes with the medulla vertically streaked with granules (soluble in K), corticate; cortex: similar to that of the thallus parathecium: hyaline, with conglutinate parallel to randomly oriented hyphae, c. 30 µm thick epihymenium: orangish brown, inspersed with fine granules (soluble in K) hymenium: hyaline, 60-80 µm tall; paraphyses: with somewhat enlarged, olivaceous tips 2.5-3 µm wide; subhymenium: often appearing somewhat gray or brown, with oil drops; hypothecium: 150-300 µm thick in center asci: clavate, 8-spored ascospores: often not developed, hyaline, simple, +ellipsoid when mature 11-13 x 4.5-5.5 µm Pycnidia: apparently rare; conidophores: type III of Vobis (1980) conidia: filiform, 25-30 µm long Spot tests: thallus K-, C-, KC-, P-; cortex KC+ yellow; medulla KC- Secondary metabolites: cortex with usnic acid; medulla with zeorin, usually unknown triterpenes (not leucotylin), and sometimes traces of fatty acids or unknowns. Substrate and ecology: on hard, acidic rock in spruce-fir forest, often among and perhaps parasitic on other crustose lichens World distribution: western North America, Europe, western Asia, and northern Africa Sonoran distribution: eastern Arizona at 2900-2960 m. Notes: Lecanora laatokkaenis differs from L. muralis in chemistry (lack of leucotylin), morphology (shorter lobes, on a black hypothallus; apothecia +immersed several per areole), and anatomy (poorly developed cortex without distinct conical hyphal bundles); L. laatokkaensis can be distinguished from L. semitensis by the epruinose apothecia immersed several per areole, and the tendency towards formation of conical hyphal bundles in the cortex. This species and L. mazatzalensis are distinguished from the rest of the section especially by having an areolate to weakly lobate thallus, semi-immersed epruinose apothecia, and a poorly developed upper cortex.