Thallus in irregular, conspicuous patches, spreading over bryophytes on bark or rock, 5-10(-15) cm diam. Surface arachnoid-byssoid, white below and at margins, overlain with coarse to fine, aeruginose-green to green-white contiguous granules, not areolate-cracked. Photobiont green, unicellular cells 2-5 µm diam. Apothecia numerous, inapparent, solitary or rarely 2-confluent, rounded or irregular, 0.5-1.2 mm diam., in subglobose to ± flattened pustules, margins irregular, granular, uneven, concolorous or paler than disc, disc plane or ± convex, grey, white-pulverulent, granular and pruinose. Epithecium minutely granular, ± grey-opaque. Hymenium to 400 µm tall. Paraphyses very numerous, c. 1 µm thick, forming a densely anastomosing network. Asci thin-walled, 400 × 100 µm. Ascospores 1 per ascus, large, oblong-ellipsoid with rounded apices, 17-21(-23)-septate, cells thin-walled, lenticular, 285-390 × 79-95 µm. Chemistry: Atranorin, psoromic, neopsoromic and protocetraric ± acids.