Thallus crustose, inconspicuous, immersed or sometimes forming a thin ± scurfy mid to dark grey film, often limited by a black prothallus. Isidia and soralia absent. Photobiont trebouxioid. Anamorph: no information available. Teleomorph: ascomata apothecia, to 0.5 mm diam., numerous, closely scattered, sunk in depressions, the top of disc level with the surface or slightly emergent, flat to slightly convex, black, sometimes thinly white-grey pruinose, leaving pale, shallow pits when shed; at first with a grey thalline margin, becoming excluded. Epithecium grey, with colourless or pale brown crystals. Interascal tissue of thin-walled paraphyses, branched towards the apex, with apical cells slightly swollen, 2-5 μm diam. Asci clavate, 8-spored (frequently with some aborting). Ascospores 15-18 × 7-8 μm, ellipsoidal, 1-septate, the septum 1-3 μm wide, about 1/6-1/9 of the length of ascospore, hyaline, smooth, without an epispore, gelatinous sheath or appendages. Chemistry: thallus K–, the epithecium and upper part of hymenium K+ mauve-lilac.