Thallus thick, whitish-chalky, in circular patches or spreading on pebbles and stones, 2-5(-8) cm diam., minutely verrucose-uneven, areolate-cracked centrally, ± placodioid at margins. Apothecia frequent, immersed to sessile, scattered 0.5-3.5 mm diam., disc concave to plane to sub-convex, blue-black to black, finely white-pruinose, margins thin or thick, black or blue-black, persistent, crenulate. Epithecium olive-brown or brown-black to 15 µm thick. Hymenium colourless, 80-120 µm. Hypothecium very well developed, dark brown to black. Paraphyses delicate, 1.5 µm thick, capitate at apices, to 3 µm thick. Excipulum with relatively narrow brown-black marginal zone. Ascospores ellipsoid, 13-18(-22) × 6-8.5 µm. Chemistry: Stictic, ± norstictic acids.