Thallus: crustose, placodioid, continuous, forming rosettes, usually 1-3 cm in diam., sometimes confluent and up to 6 cm wide, effigurate lobes: radiating, but sometimes irregular, discrete or confluent; lobe tips: usually rotund or ±truncate, eciliate upper surface: whitish gray to glaucous gray, leaden to bluish gray, ±plane to convex or concave towards the periphery, shiny or dull, usually epruinose, but often pruinose at the blackish lobe tips; with soralia that develop from small bulges on the thalline surface, finally bursting and forming a crateriform soralium with bluish gray soredia upper cortex: pseudoparenchymatous, formed by vertically arranged hyphae, filled with many minute crystals not dissolving in K, 15-30 µm thick medulla: usually white or faintly yellow to mustard colored, lax, formed from loosely interwoven 4-5 µm thick hyphae, 150-300 µm thick lower cortex: absent lower surface: usually pale tan to pink, attached by medullary hyphae, without rhizines, cyphellae, pseudocyphellae or tomentum Apothecia: orbicular, first covered by the thallus, later sessile, up to 1 mm in diam., lecideine (without a thalline margin), laminal on thallus disc: black or brown-black, epruinose epihymenium: granular, brown-black, K-; hypothecium: generally brown or brown-black asci: lecanoral, apex wall layers thickened, apex I+ blue, with distinct axial body, 8-spored ascospores: brown, one-septate, thick-walled, intermediate type between mischoblastiomorphic and Physcia-type, ellipsoid, 9-15 x 4-8 µm Pycnidia: laminal, when fully developed immersed in the thallus conidia: colorless, simple, ±bacilliform, formed acrogenously, conidiophore-type V (Vobis 1980), 4-5 µm long, 0.8-1 µm wide Spot tests: cortex K+ yellow, C-, KC-, P+ yellow; medulla: K-, C-, KC-, P- Secondary metabolites: upper cortex atranorin (often accompanied by chloroatranorin); medulla with diploicin (major), dechlorodiploicin (minor), isofulgidin (minor), dechloro-O-methyldiploicin (minor or trace), buellolide (minor), canesolide (minor or trace), and secalonic acids A, B and C (minor or trace). Substrate and ecology: mostly on bark and wood; also on rock walls, acidic and calcareous rocks in nutrient-enriched sheltered as well as open, coastal habitats in areas with frequent fogs World distribution: predominately Atlantic-subatlantic temperate Europe, Mediterranean region, Africa, Hawaii, Australasia, Japan, and western North America Sonoran distribution: coastal areas of southern California, Baja California, Baja California Sur and Sonora. Notes: While all specimens were tested by TLC and atranorin, diploicin and dechlorodiploicin were readily identified, a random selection of specimens growing on bark as well as on rocks from various parts of the Sonoran region were analysed by HPLC. In addition to the lichen products mentioned above, chloroatranorin, isofulgidin, dechloroO-methyldiploicin, buellolide, canesolide, secalonic acid A, B and C were detected. Specimens with this chemistry had been described as D. canescens ssp. australasica Elix & Lumbsch.