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.