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; compartimentized – areolate, squamulate; [th] upper surface: brown(ish) (if pale: fawn, tan; if mid: cinnamon); [th upper surface]: epruinose; [th marginal and upper surface] specific structures: absent; [th] morphol substructures (eg areoles, lobes, branches) width [mm]: (low) 0.15 (high) 0.3 (max) 0.6; [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) 0.3 (high) 0.4 (max) 0.55; ascoma: sessile, superficial; [ascm, if apoth] disc, mazaedium: plane, flat, flattened, expanded; [ascm, if apoth] disc, mazaedium: black(ish); [ascm, if apoth] disc, mazaedium: epruinose; [ascm, if apoth] margin surface; [if perith] periostiolar area, ostiole, involucrellum: black(ish); [ascm, if apoth] subhymenial layers, hypothecium; [if perith] basal excipulum: brown(ish) (if pale: fawn, tan; if mid: cinnamon); [ascm] paraphyses/-oids: present; [ascm] epihymenium, epithecium: brown(ish) (if pale: fawn, tan; if mid: cinnamon).  Asci: lecanoralean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): present; [asc] tholus amyloidity pattern: with amyloid tube and flanks (= Rimularia-, Trapelia-types etc).  Ascospores: (median) 8.0; [asp] shape: broadly ellipsoidal | ellipsoidal; [asp] length [µm]: (low) 5.5 (high) 10.0; [asp] width [µm]: (low) 6.0 (high) 8.0; [asp] septa: absent – spore lumen unilocular, monolocular; [asp] pigmentation: hyaline, colourless; [asp] perispore, epispore: not apparent.  Secondary metabolites: present, gyrophoric acid | norstictic acid | stictic acid. Primary photobiont: present, chlorophytaceous – trebouxiaceous, chlorococcoid.  Secondary photobionts (eg in cephalodia): absent.

Thallus crustose, thin, verrucose-areo-late, verrucules to 0.3 mm, shining, dark brown to black; black hypothallus present. Apothecia small, to 0.7 mm broad; margin and disk black, flat, margin shining, disk dull; exciple black-brown and grading into black-brown hypothecium; epithecium brown; hymenium 50-60 μm, hyaline; paraphyses intricately branched, with constricted septation; asci davate; spores 7-12 x 5-6 μm. Conidia straight, 8-10 x 1 μm.

Reactions: K—, C —, P —, I —.

This species grows on acid rocks in the open. It is rather rare, known from Europe (Scandinavia), Greenland, and northern Canada.