Thallus corticolous, firmly attached to substrate. Primary branches conspicuous, sparingly branched in upper parts, terete to compressed, 1 mm wide, lateral branches terete or slightly compressed, at right angles to primary branches, repeatedly dividing into small isidioid branchlets, ± terete and c. 0.2 mm wide. Cortex smooth, faintly cracked in places, green on dorsal surface, white on ventral surface. Apothecia terminal or subterminal, wider than supporting fertile branch, margins without isidioid branchlets, 1-2(-3) mm diam., ± globose, mazaedium exposed at an early stage through rupture of surrounding receptacle, black, globose at maturity. Ascospores brown, 14-16 µm diam. Chemistry: K+ yellow, KC-, C-, Pd-. Isousnic acid.