Thallus in rounded to irregular patches 1-3(-5) cm diam., 0.2-0.3 mm thick, whitish or pale grey-white or finely spotted with minute black dots, ± finely granular or powdery. Apothecia appearing superficially lecanorine, sessile to subinnate, scattered or crowded, mainly central, rounded, 0.4-1.2 mm diam., disc flat, black, matt, at first grey-pruinose, margins entire to subcrenulate, black or grey-pruinose, surrounded by a thin, white collar of thalline tissue. Epithecium green-black, granular, 9-22 µm thick. Hymenium colourless, 65-85 µm tall. Hypothecium massive, brown-black. Ascospores ellipsoid, 12-15.3 × 7-8.3 µm.