Thallus grey-white or dingy olivaceous-grey, thick, regularly areolate-cracked, areolae angular, plane, 0.2-1.5 mm diam., separated by deep cracks, smooth, matt, in spreading patches, 4-8(-12) cm diam., saxicolous. Fertile verrucae crowded, confluent, cerebriform, hemispherical to ± irregular lumpy, 2-6 mm diam., concolorous with thallus, often deeply fissured. Apothecia 1-4 per verruca, ostioles black, punctiform, innate to 0.2 mm diam., asci 8-spored. Ascospores biseriate, oval, often hard tofind, 100-122 × 43-61 µm, walls thin. Chemistry: K+ yellow → red, C-, KC+ red, Pd+ orange. Norstictic and connorstictic acids.