Thallus orbicular to spreading, loosely attached, to 12 cm diam., corticolous or saxicolous. Lobes rounded to sublinear, dissected, to 8 mm wide, crowded, margins sorediate, often revolute, ciliate. Upper surface dull, greenish-blue to pale greenish-grey, maculate at lobe tips (×10 lens), with patterned cracking continuing throughout thallus, sorediate. Soralia mainly marginal, causing lobe tips to become recurved and often capitate-hooded. Medulla white, often rusty-red when wet (decomposition products of salazinic acid). Lower surface dark brown to black, with a variable, shining naked marginal zone. Rhizines central, simple or squarrosely branched, black. Apothecia rare, pedicellate, to 8 mm wide, disc deeply concave when young, becoming ± plane with age, red-brown, perforate, thalline exciple sorediate, inflexed. Ascospores 13-16 × 9-11 µm. Pycnidia minute, black, punctiform, marginal. Chemistry: Cortex K+ yellow; medulla K+ yellow → red, C-, KC+ red, Pd+ orange. Salazinic acid and atranorin.