Thallus to 5 cm diam., crustose, continuous to rimose, more rarely areolate in part. Prothallus poorly developed, black. Areoles to 0.5 mm diam., dull, chalk-white to medium-grey, matt, contiguous, mainly angular, flat. Upper cortex well-developed. Lower cortex absent. Photobiont chlorococcoid. Anamorph: no information available. Teleomorph: ascomata apothecia, to 1 mm diam., black, the disc not pruinose, usually orbicular, flat, sometimes forming in concentric rings. Thalline exciple absent. True exciple faintly to distinctly pruinose, persistent, brown-to dark blue-green at the rim, inner part hyaline to pale brown, K+ yellow, containing crystals partly dissolving in K. Epithecium olive-brown, crystals K+ yellow, dissolving in K. Hymenium hyaline, 150-200 μm high, K/I+ blue. Hypothecium dark brown, K–. Interascal tissue of cellular pseudoparaphyses, conglutinate, richly branched and anastomosed, the apical cell slightly thickened. Asci cylindrical, 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, 8-spored. Ascospores 20-50 × 13-25 μm, ovoid to clavate, rather variable in shape, muriform, hyaline, becoming dark when over-mature, smooth, with a perispore that degenerates at maturity. Chemistry: medulla K+ yellow, Pd+ orange (stictic acid).