Global occurrence: Eurasia – Europe | Americas – North America (incl Mexico) | Arctic.  Substrate: rock – siliceous, siliciferous, acidic | rock, stones, pebbles – unspecified. Life habit: lichenized (mutualistic with algal photobionts).  Thallus: crustose (crustaceous) – episubstratal – unspecified; compartimentized – areolate, squamulate; [th] upper surface: white(ish) | white(ish) grey | green(ish) white; [th upper surface]: epruinose; [th marginal and upper surface] specific structures: absent; [th] morphol substructures (eg areoles, lobes, branches) upper surface: smooth, plane; [th] medulla amyloidity: absent.  Ascomata: absent | present; ascoma: apothecial, apothecioid – hymenial; ascoma [mm]: (low) 0.2 (high) 0.5 (max) 0.6; ascoma: immersed, innate; [ascm, if apoth] disc, mazaedium: concave | plane, flat, flattened, expanded; [ascm, if apoth] disc, mazaedium: black(ish); [ascm, if apoth] margin surface; [if perith] periostiolar area, ostiole, involucrellum: red(dish) brown (if pale: orange brown); [ascm, if apoth] margin excipular photobionts: present; [ascm, if apoth] subhymenial layers, hypothecium; [if perith] basal excipulum: red(dish) brown (if pale: orange brown); [ascm] paraphyses/-oids: present; [ascm] paraphyses/-oid cells width [µm]: (min) 3.0; [ascm] epihymenium, epithecium: red(dish) brown (pale: orange brown).  Asci: lecanoralean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): present.  Ascospores: (median) 8.0; [asp] shape: ellipsoidal; [asp] length [µm]: (low) 12.0 (high) 18.0 (max) 23.0; [asp] width [µm]: (low) 5.0 (high) 6.0 (max) 7.0; [asp] septa: absent – spore lumen unilocular, monolocular; [asp] perispore, epispore: not apparent.  Secondary metabolites: present, atranorin | psoromic acid.  Primary photobiont: present, chlorophytaceous – trebouxiaceous, chlorococcoid.  Secondary photobionts (eg in cephalodia): absent.