Thallus dingy greyish or glaucous-grey, in patches 5-10 cm diam., matt, smooth to uneven and minutely roughened, 0.1 mm thick, diffract-areolate, areolae flat, ± angular 2-4 mm diam., slightly uneven, undulate or wrinkled, rarely granular-uneven, with a well defined, black, marginal prothallus, often in small, intersecting mosaics. Apothecia scattered, 1-4 per areole, subinnate, disc 0.1-1.5 mm diam., black, matt, epruinose or faintly white-pruinose in parts, subconcave to plane, 1-4 confluent, rounded to irregularly deformed through mutual pressure, margins black, thin, entire or flexuose, slightly raised above surface of thallus. Epithecium green-black, colour in clavate apices (4-6 µm thick) of paraphyses. Hymenium colourless, 110-130 µm tall. Hypothecium dense brown-black. Asci clavate, close to surface of disc. Ascospores oval-ellipsoid, 10-12 × 7-8.3 µm.