Thallus orbicular to spreading, in patches, 2-5(-10) cm diam. Upper surface minutely granular, appearing ± velvety, areolate-cracked, crazing of cracks very fine to ± gaping, whitish-grey to glaucous-green or dingy olivaceous, whitish-arachnoid at margins, surface regular and smooth on flat bark, closely following contours of substrate. Apothecia frequent, single or ± confluent in groups, sessile or ± innate, disc round to irregular, 0.1-1.1 mm diam., subconcave to plane, dark grey or black to occasionally red-brown, waxy, with a fine, white, delicate pruina, margins raised, ± inflexed, sinuous or irregular, cracked or split and ± fractured, white or creamy, often obscuring disc. Ascospores 3-8-septate (35-)40-60 × 4-5(-7) µm. Chemistry: Cortex K+ yellow. Stictic and hypostictic acids and unidentified compound A.