Thallus crustose, 0.5-4 cm diam., sometimes coalescing to cover large areas, areolate. Prothallus distinct, black. Areoles arising discretely on the prothallus, 1-2 mm diam., bright yellow to green-yellow, matt, smooth, contiguous to somewhat dispersed on the prothallus, initially round and convex, soon curving around adjacent apothecia and becoming crescent-shaped, eventually entirely surrounding the apothecia and forming a pseudo-lecanorine margin. Medulla I+ blue. Soredia and isidia absent. Photobiont chlorococcoid. Anamorph: no information available. Teleomorph: ascomata apothecia, to 1 mm diam., black, not pruinose, ± round, flat to concave. Thalline exciple absent. True exciple persistent but often thin and indistinct, brown-black at the rim, the inner part hyaline, K–. Epithecium pale olive-brown, K– or intensifying green. Hymenium colourless to faintly blue-green. Hypothecium thin, brown-black, K–; no crystals or granules in the apothecium. Interascal tissue of cellular pseudoparaphyses, conglutinate, richly branched and anastomosed, the apical cell only slightly thickened. Asci clavate, fissitunicate, with a well-developed tholus that is K/I– in the lower part and K/I+ blue near the apex, lacking an ocular chamber, Rhizocarpon-type, 4- to 8-spored. Ascospores 34-57 × 15-24 μm, ellipsoidal to ovoid-ellipsoidal, muriform, with 15-38 cells in optical section, dark brown when mature, without an epispore, gelatinous sheath or appendages. Chemistry: medulla K+ yellow, Pd+ orange (stictic acid, often in low concentration, and rhizocarpic acid). According to Roca-Valiente et al. (2016), Pd reactions are variable in this species, and unhelpful for species recognition.