Thallus white to grey, pale fawn-buff, rather smooth, areolate cracked, areolae minute, angular, ± convex, often intersected by dark lines of prothallus, forming mosaics on flat rocks 5-8(-10) cm diam. Apothecia sessile, often subinnate at first, 0.2-1.5 mm diam., disc pale brown, white or grey-pruinose, C+ orange, pruina thin to dense, concave to plane to subconvex, margins thin, entire or crenulate, concolorous with thallus. Ascospores ellipsoid, 10-14 × 6-7 µm. Chemistry: Atranorin, chloratranorin, thiophanic and roccellic acids.

Thallus in rounded or irregular patches 2-6(-8) cm diam., dingy yellow-white or glaucous or fawnish, slightly shining, smooth or roughened-verrucose, areolate, areolae ± angular, 1 mm diam., flat. Apothecia rather few, solitary, immersed, 1-3 per areole, rounded, 0.1-0.3 mm diam., black, matt, sometimes grey-pruinose, plane, often wrinkled, and obscuring areolae, margins black, entire, not obvious. Epithecium granular, greenish-black. Hymenium colourless or pale bluish, 80-95 µm tall. Hypothecium colourless. Ascospores ellipsoid, 11.9-13.6(-15) × 5.5-7 µm.