Global occurrence: Eurasia – Europe | Americas – North America (incl Mexico) | Arctic.  Substrate:  rock – calcareous, calciferous, basic.  Life habit: lichenized (mutualistic with algal photobionts).  Thallus: crustose (crustaceous) – episubstratal – unspecified | squamulose (squamulous); [th] upper surface: grey(ish) | brown(ish) (if pale: fawn, tan; if mid: cinnamon) | brown(ish) green (olivaceous, olive green); [th upper surface]: pruinose; [th marginal and upper surface] specific structures: present; [th margin] cilia, cilioid structures: absent; [th upper surface] isidia, isidioid structures: absent; [th upper surface] soredia, soralia, soralioid structures: absent | present.  Ascomata: absent | present; ascoma: apothecial, apothecioid – hymenial; ascoma: immersed, innate; [ascm, if apoth] disc, mazaedium: concave; [ascm, if apoth] disc, mazaedium: brown(ish) (if pale: fawn, tan; if mid: cinnamon); [ascm, if apoth] disc, mazaedium:  pruinose; [ascm, if apoth] subhymenial layers, hypothecium; [if perith] basal excipulum: hyaline, colourless; [ascm] paraphyses/-oids: present; [ascm] paraphyses/-oid cells width [µm]: (low) 2.0 (high) 3.0; [ascm] paraphyses/-oid apical cells width [µm]: (low) 2.0 (high) 4.0; [ascm] epihymenium, epithecium: brown(ish) (if pale: fawn, tan; if mid: cinnamon).  Asci: lecanoralean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): absent.  Ascospores: (median) 0.0; [asp] septa: absent – spore lumen unilocular, monolocular;[asp] pigmentation: hyaline, colourless.  Secondary metabolites: absent.  Primary photobiont: present, chlorophytaceous – trebouxiaceous, chlorococcoid.  Secondary photobionts (eg in cephalodia): absent.