Thallus crustose, variable, thick or thin, whitish, pale grey to ochraceous, rimose and flat or of discrete warts, often with slightly indented edges, effuse. Prothallus inconspicuous. Soralia and isidia absent. Photobiont trebouxioid. Anamorph: not known for British material. Matzer & Mayrhofer (1996) found conidiomata in South African collections containing bacillar conidia 4-5.5 x 1-1.5 µm in size. Teleomorph: ascomata apothecia, 0.6-1.5 mm diam., sessile, sometimes contiguous. Thalline exciple 50-100 µm broad, concolorous with the thallus, entire to slightly crenulate and persistent at maturity. True exciple hyaline. Disc black, flat, becoming slightly convex, not pruinose. Epithecium dark brown due to pigmented tips of paraphyses. Hymenium 80-100 μm high. Hypothecium 60-135 μm high, hypothecium and hymenium I+ blue. Interascal tissue of paraphyses, mostly unbranched except near the apices, apices swollen, brown-capped. Asci 75-80 × 16-19 μm, Lecanora-type, clavate, inner walls uniform, 8-spored. Ascospores arranged biseriately, 17-27 × 8-13 μm, 1-celled, the locules persistently angular with thick apical walls (Physcia-type), dark chocolate brown at maturity with the lumina sometimes difficult to see, smooth, without a gelatinous sheath or epispore. Chemistry: thallus K+ yellow, Pd+ yellow (atranorin, chloratranorin, zeorin).