Thallus of slender filaments, sparsely to richly and divergently branched, brown-black, sometimes greyish in shade, with shining, often nodulose apices; forming small, loosely inter-woven, decumbent to cushion-like masses and strands. Filaments (50-) 60-120(-130) µm diam., slightly flattened, becoming progressively narrowed towards the apices. Cortex 1 to 3 cells thick; cells rounded or angular, 4-7 μm diam., the wall somewhat thickened, colourless or brown. Photobiont Nostoc, not in obvious chains. Anamorph: conidiomata pycnidia. Conidia 1.5-3.5 × 1 μm, bacilliform. Teleomorph: ascomata apothecia, occasional, lateral, to 2 mm diam., the disc red-brown, brighter when wet and the margin paler. Ascospores 22-29 × 5-7 μm, fusiform, 1-septate, sometimes becoming pale red-brown.