Description: Thallus crustose, endosubstratic, not apparent. Apothecia lecanorine, immersed in pits in the rock at least when young, later subsessile, 0.2-0.6 mm across, with a flat, dark brown to black, pruinose disc, and a thin, smooth, entire thalline margin. Thalline exciple corticate, usually more or less obscured by crystals which are insoluble in K, but soluble in N; epithecium greenish brown to patchily green and brownish, not granular, K-, N+ purple; hymenium colourless, 35-45 μm high; paraphyses slender, simple, free in K; hypothecium colourless, without granules. Asci 8-spored, elongate-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 K/I+ blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, 9-11 x 5.5-6.5 μm. Photobiont chlorococcoid. Spot tests: thallus (apothecial margin) K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a taxon worthy of further study, found on inclined surfaces of hard, compact calciferous rocks, mostly at low elevations.