Thallus of plane, sharp-angled, rather shiny, smooth, grey to copper-brown areolae, in a thick, black, dense prothallus, irregularly spreading, 2-5(-10) cm diam. Apothecia few to frequent, often ± pruinose, 0.2-1.5 mm diam., sunk in thallus, flush with areolae, disc black, matt or subpruinose, smooth, plane to convex, margins black or greyish, entire or ± crenulate, persistent, fruits sometimes forming a ± uniform, black, mosaic-pavement between areolae. Epithecium brown-black or red-brown, granular, 8-17 µm thick. Paraphyses dense, conglutinate, capitate at apices. Ascospores ellipsoid, small, 6-8.3 × 3-4 µm.