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; thallus: compartimentized – areolate, squamulate;[th] upper surface: grey(ish) | blue(ish) grey | yellow(ish) grey; [th marginal and upper surface] specific structures: absent; ascomata: absent | present; ascoma: apothecial, apothecioid – hymenial; ascoma [mm]: (median) 0.8; [ascm, if apoth] disc, mazaedium: black(ish).  Asci: lecanoralean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): absent; [asp] length [µm]: (low) 20.0 (high) 26.0; [asp] width [µm]: (low) 12.0 (high) 14.0 (max) 18.0; [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.