Description: Thallus crustose, endosubstratic or very thinly episubstratic, continuous or minutely granulose, white ot whitish grey. Apothecia lecanorine, sessile, 0.2-0.6(-0.8) mm across, with a grey-brown to reddish brown, flat to slightly convex, sometimes slightly pruinose disc, and a white-pruinose, prominent, usually smooth or irregularly crenulate thalline margin. Thalline exciple with an indistinctly delimited cortex, filled with small crystals insoluble in K, but soluble in N; epithecium yellowish brown, rarely with a few superficial granules; hymenium colourless, 40-70 µm high; paraphyses simple, thick, capitate, brown-pigmented at tips, usually free in K; hypothecium colourless. Asci (8-)16-32-spored, clavate, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, (6-)8-10(-12) x (3-)4-6(-7.5) µm. Pycnidia frequent, black, erumpent. Conidia 10-12 x c. 1 µm, straight or curved. Photobiont chlorococcoid. Spot tests: thallus and apothecial margin K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a mainly mild-temperate species found on base-rich bark, especially on Sambucus and Populus.