K. Svenska Vetensk.-Akad. Handl., ser. 3, 7, 4: 175, 1929.
Distribution: N - Ven (Nascimbene & al. 2021), TAA (B-8504 Leg. H. Sipman).
Description: Thallus crustose, episubstratic, areolate-subsquamulose, without a distinct prothallus, forming c. 1 cm wide patches. Areoles 0.2-1.4 mm wide, contiguous, irregular in shape, sometimes sublobulate, slightly concave to flat, dark chestnut brown, epruinose. Apothecia lecanorine, 0.1-0.6 mm across, rounded or sometimes irregular by mutual compression, at first immersed then slightly protruding, with a slightly concave to flat, rugose, sometimes umbonate, dark brown disc (darker than thallus), and a usually paler brown, raised, smooth thalline margin. Epithecium yellowish brown; hymenium colourless, 50-90 µm high, paraphyses c. 1.5 µm thick, the apical cells capitate, 3-4 µm wide; hypothecium colourless, 15-35 µm high. Asci 100(-200)-spored, clavate, the apical dome K/I-. Ascospores 1-celled, hyaline, narrowly ellipsoid to cylindrical, 3-6.5 x 1-2 μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a lignicolous species, often found on woody roofing tiles, from the dry submediterranean to the subalpine belt.