Global occurrence: Eurasia – Europe | Americas – North America (incl Mexico) | Arctic.  Substrate: rock – siliceous, siliciferous, acidic.  Life habit: lichenized (mutualistic with algal photobionts). Thallus: crustose (crustaceous) – episubstratal – unspecified, cracked, fissured, fractured, rimose | compartimentized – areolate, squamulate; [th] upper surface: grey(ish) | green(ish) grey; [th marginal and upper surface] specific structures: absent.  Ascomata: absent | present; ascoma: apothecial, apothecioid – hymenial; ascoma [mm]: (median) 0.4; [ascm, if apoth] disc, mazaedium: concave | plane, flat, flattened, expanded.  Asci: lecanoralean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): absent.  Ascospores: [asp] length [µm]: (low) 13.0 (high) 17.0 (max) 23.0; [asp] width [µm]: (low) 9.0 (high) 13.0; [asp] septa: absent – spore lumen unilocular, monolocular; [asp] pigmentation: hyaline, colourless.  Secondary metabolites: present, norstictic acid | stictic acid.  Primary photobiont: present, chlorophytaceous – trebouxiaceous, chlorococcoid.  Secondary photobionts (eg in cephalodia): absent.