Thallus prostrate, decumbent, in extreme forms becoming subfoliose or even crustose or pulverulent, generally forming ± circular, closely attached thalli, to 7 cm diam. Branches always flattened especially in older parts, to 1 mm broad, tapering irregularly, to 0.2-0.5 mm on main stems and 0.1 mm at tips, where branches are very uneven but ± terete, branching irregularly isotomicdichotomous with numerous, short, lateral branches often present giving a "ciliate" appearance, internodal distance short, usually 0.2-0.5(-1.0) mm, dark brown to black, shiny or dull, occasionally pale brown at base. Apothecia fre quent, disc dark red-brown to black, flat, to 3 mm diam., margins persistent, smooth to verrucose. Ascospores 7.7-8.0 × 6.7-9.0 µm. Pycnidia abundant, embedded in thallus and opening to surface through broad ostioles. Conidia 6-8 × 1 µm.