Description: Thallus crustose-subsquamulose, olivaceous grey, ash-grey or grey-brown, usually epruinose, consisting of irregular, 0.3-0.5(-0.8) mm wide, convex, bullate to substipitate squamules with entire to crenate margins, coalescing into 1-2(-3) cm wide patches. Upper cortex up to 20 μm thick, lacking crystals; medulla white, sometimes becoming hollow in larger squamules, lacking crystals. Apothecia biatorine, 0.3-0.8(-1.5) mm across, black, shiny, sessile and more or less constricted at base, rounded, sometimes confluent, with a strongly convex, epruinose, disc, without an evident proper margin. Proper exciple not apparent; epithecium patchily blue-green, 8-13 μm high, K+ brighter green, N+ magenta; hymenium colourless, but often with pigmented vertical streaks originating from the epithecium, (40-)50-70(-75) μm high, I+ blue turning reddish; paraphyses 2-3(-4) μm thick, slightly branched in upper part, strongly conglutinated, the apical cells not swollen; hypothecium up to 350 μm high, densely opaque, the upper 50-75 μm dilute brown (K–, N+ dilute golden-brown) with darker spots, the lower part more or less colourless, K/I+ blue. Asci 8-spored, cylindrical-clavate, the tholus K/I+ blue with a narrow conical masse axiale, the border of the surrounding tholus K/I+ darker blue, Biatora-type. Ascospores (0-)1(-3)-septate, hyaline, ellipsoid dacryoid with one slightly pointed end, (5-)7-11(-14) x (2.5-)3.5-5(-5) μm. Photobiont chlorococcoid, the cells 6–12 μm wide. Spot tests: thallus K-, C-, KC-, P-, UV- or UV+ faintly grey or white. Chemistry: unknown, perhaps without lichen substances.
Note: on silicicolous mosses, mostly on Andreaea near or above treeline. For further details see Svensson & Fryday (2022).