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.

Thallus in irregular patches, 2-8 cm diam., 0.7-2.0 mm thick, dingy grey-white or pale yellowish- or brownish-white, often suffused rust-red, K+ yellow → red (norstictic acid), smooth to minutely wrinkled or papillate or ± coriaceous, areolate-cracked, areolae polygonal, plane, smooth, 0.2-2.0 mm diam., separated by gaping cracks. Apothecia frequent, irregular, often deeply cracked, 1-3 per areolae, often completely obscuring areolae, 0.5-2.0 mm diam., ± innate to plane, disc black, matt, epruinose or thinly white-pruinose, margins persistent, thin to indistinct, often with a thin collar of thalline tissue slightly raised around fruit, often confluent. Epithecium granular, greenish-brown, 8-10 µm thick. Hymenium colourless or pale straw-coloured, 65-90(-100) µm tall. Hypothecium dense brown-black. Ascospores oval, straight, 8.3-10.2(-13) × 5.1-6 µm.