Global occurrence: Eurasia – Europe | Americas – North America (incl Mexico) | Arctic. Substrate: rock – siliceous, siliciferous, acidic | rock – calcareous, calciferous, basic. Life habit: lichenized (mutualistic with algal photobionts). Thallus: crustose (crustaceous) – episubstratal – unspecified; compartimentized – areolate, squamulate; [th] upper surface: yellow(ish) (if dull: buff); [th marginal and upper surface] specific structures: present; [th upper surface] isidia, isidioid structures: absent; [th upper surface] soredia, soralia, soralioid structures: present. Ascomata: absent | present; ascoma: apothecial, apothecioid – hymenial; [ascm] paraphyses/-oids: present. Asci: lecanoralean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): present; [asc] tholus amyloidity pattern: amyloid with widening axial body towards the apex (= Lecanora-, Parmelia-, Rinodina-types etc). Ascospores: (median) 8.0; [asp] septa: absent – spore lumen unilocular, monolocular; [asp] pigmentation: hyaline, colourless; [asp] perispore, epispore: not apparent. Primary photobiont: present, chlorophytaceous – trebouxiaceous, chlorococcoid. Secondary photobionts (eg in cephalodia): absent.