Thallus lobate-foliose, of elongated laciniae, stellate-radiating, 3-7(-12) cm diam., margins ± free, attached by a thick, black prothallus of entangled, black, simple to squarrose rhizines. Lobes ± flat, 2-4 mm wide, ± dichotomously branched at apices, margins slightly thickened, entire to ± lobulate, white-pubescent to blackened, with rhizines often projecting beyond margins. Upper surface greenish, mustard-yellow, pale whitish at margins, occasionally blue-black in places, smooth, glossy, waxy, finely white-pubescent at margins. Cephalodia infrequent, placodioid-lobed, bright blue when wet, yellowish to bluish when dry, often white-pruinose at margins, smooth, wrinkled-plicate, 1-3 mm wide, rather large, developed at margins and spreading over lamina. Apothecia common, laminal and marginal, subpedicellate, round to irregular, often clustered in conglomerate, contorted groups, 1-3 mm wide, disc ± consistently centrally perforate, often also with secondary, partial or complete concentric ridges or lobules of thalline tissue, disc pale red-brown to dark brown or blackened, with well-developed, uneven concentric ridges, ± faint pruinose, margins thick, crenate-striate, concolorous with thallus or blackened. Ascospores subglobose 11-16 µm diam.