Thallus forming orbicular patches or irregularly spreading, to 20 cm diam., loosely attached, corticolous, saxicolous or terricolous. Lobes 1.5-2.5 mm wide, hollow, occasionally 3-4 mm wide, branching dichotomous to ± irregular. Upper surface grey to white, copiously sprinkled with pycnidia and often with black lines, bands and patches, margins often blackened as they are not always sharply delimited from lower surface. Medulla of loosely interwoven hyphae forming an arachnoid layer ± parallel to cylindrical wall, darkened or not. Lower surface black, shining, deeply and persistently wrinkled, with occasional apical perforations. Apothecia sparse to moderate, 2-10(-20) mm diam., disc dark brown, concave, becoming ± flat to subconvex, margin entire to crenate. Ascospores ellipsoid 4-6 × 5-8 µm. Chemistry: Cortex K+ yellow, KC+ red, Pd+ red. Atranorin, chloroatranorin, physodic, physodalic, protocetraric ±, 2' -O-methylphysodic ±, alectoronic ±, 3-hydroxy-physodic ± and vittatolic ± acids. Austral