Thallus crustose, yellow-grey to greenish-grey, thin, often cracked and fissured, especially about the lirellae, outer border of thallus marked by a black prothallus. Lirellae immersed, pale, flexuous and branched, seen from the surface as a pale slit, thalline exciple wide, variable, sometimes raised around the lirellae, sometimes in the same plane and distinguished only by cracking parallel to the lirellae, proper exciple pale, uncarbonised, often turning brown. Ascospores 8 per ascus, uniseriate, 4-locular, 8-9 × 18-21 µm. Chemistry: Negative.