Thallus corticolous, with numerous, small, crowded, sterile branches and occasional longer fertile branches occurring together. Branches irregularly flattened to subterete, erect, to 1.5 cm long and 1-2.2 mm wide. Upper surface smooth, brownish to greyish-brownish-yellow with parasitic algae often covering the region around apothecia, lower surface pale grey to white, upper cortex 80-120 µm thick, lower cortex 60-80 µm thick. Algal layer 20-30 µm thick, continuous between upper cortex and medulla, in subterete branches almost encircling central medulla. Apothecia common, subterminal, 1.5-4 mm diam., mazaedium subterminal to ventral, becoming exposed at an early stage of development by irregular rupture of surrounding receptacle, prominent, black, globose at maturity. Asci cylindrical 35-55 × 5-7 µm. Ascospores spherical, brownish-grey to brown, 6.5-9.5 µm diam., surrounded by black, carbonaceous material at maturity. Chemistry: K-, Pd+ red. Sphaerophorin and protocetraric acid.