Thallus crustose, ± minutely squamulose becoming areolate-cracked with age, very closely attached, orbicular to spreading, to 10 cm diam., bounded by a blue-black prothallus extending 0.5-2.0 mm beyond squamules, saxicolous. Squamules at first distinctly lobate-radiating, rosette-forming, ± stellate with deeply incised margins, to 2 mm diam., older squamules crowded, strongly imbricate, becoming densely lobulate, lobules minute, ± dorsiventral (not to be confused with isidia), and often forming a diffract-areolate crust. Upper surface yellow-brown, dark olive greenish or greyish, smooth, matt, without isidia, or soredia, brownish at lobe margins. Lower surface dark, with a felt of blue-black tangled rhizines. Apothecia frequent, sessile, to 1 mm diam., disc pale yellowish to red-brown with a paler, thin proper margin, plane at first, becoming convex, thalline margin entire, thin, concolorous with thallus, ± crenulate, often occluded. Ascospores ellipsoid, with one or both ends acute, wall smooth to crenulate, 14-20(-22) × 6-9(-11) µm.