Thallus large, orbicular to spreading, loosely attached, to 20 cm diam., corticolous and saxicolous. Lobes broad (6-12 mm wide), rounded to subirregular, often laciniate or dissected, margins entire, sinuous, ciliate: Upper surface pale greyish-white (greenish when wet), finely maculate-cracked, in older specimens cracked to margins, soredia and isidia absent. Lower surface black, with a broad, brown, naked marginal zone. Rhizines central, black, dense, simple or squarrosely branched. Apothecia rare, pedicellate, disc brown, to 8 mm diam., consistently perforate in older fruits, margins entire at first becoming deeply lacerate with age, thalline exciple smooth or wrinkled, maculate near margin. Ascospores 13-16 × 6-7 µm. Pycnidia common at lobe margins, punctiform, black. Chemistry: Cortex K+ yellow; medulla K+ yellow → red; C-, KC+ red, Pd+ orange. Salazinic acid and atranorin.