Thallus foliose, peltate, monophyllous, attached to substrate by a central umbilicus, often in ± crowded, congested clumps, saxicolous or terricolous. Lobes undulate, shell-like, 7-15 mm wide, margins entire or slightly notched, sinuous, slightly thickened, downrolled, sorediate. Upper surface greyish olive-green or olive-brownish, smooth or scabrid, rather coriaceous, sorediate. Soralia mainly marginal but also laminal, circular, blue-grey, soredia granular, rather coarse. Lower surface smooth, pale buff to brownish-red. Umbilicus ± central, rigid, to 0.4 mm diam. Apothecia many per squamule, immersed, discs punctiform or expanded, to 0.7 mm wide, without a thalline margin. Asci with a gelatinous sheath, 100-120 × 21-27 µm containing 100 or more spores. Ascospores ellipsoid to fusiform 6-7.6 × 3-4.5 µm. Pycnidia immersed, minute, black. Conidia fusiform 3.4 × 1.5 µm.