Thallus orbicular, to 10 cm diam., but generally smaller (5-7 cm), corticolous. Lobes short, moderately to densely crowded and contiguous, broad, 3-6(-10) mm wide, hollow, branching dichotomous to more complex and irregular, apices of marginal lobes rounded, expanded and flattened, central lobes rugose and puckered with marked indentations, younger lobes ± evenly inflated throughout. Upper surface ± convex, pale grey to grey, smooth, pycnidia abundant to sparse, numerous at apices of broader lobes. Medulla white, thin to relatively thick, of loosely woven hyphae forming an arachnoid layer ± parallel to the wall of the lobe. Lower surface black, fading to pale brown or grey near apices, strongly wrinkled, usually with apical perforations. Apothecia common, 2-8 mm (rarely to 10mm) diam., short to markedly pedicellate, pedicel hollow, to 5 mm long, commonly with a swollen, urceolate base when young, disc dull brown, concave, becoming ± flat, margins entire, often involute at first, then crenate. Ascospores ellipsoid, 7.5-8.5 × 4-6 µm.