Thallus 2-6 cm diam., foliose, membranous, thin, ± rounded, ± loosely adnate to substrate, often partly ascending, ± deeply or rather shallowly and broadly lobate, dark olive-green to blackish, lower surface usually paler often greyish or bluish, paler and semi-transparent when moist, matt, epruinose, isidiate, smooth to uneven to pustulate centrally. Lobes few, sometimes single, 0.5-1.5 rarely to 3 cm wide, sparsely and shallowly lobulate, ± flattened or coarsely and irregularly folded and undulate, margins ± entire and sometimes bent downward or upwards, never swollen. Isidia usually numerous and often crowded, sometimes sparse, laminal (occasionally on the lower surface as well) and often marginal, globular at first, rarely squamiform at maturity, horizontal or mostly ± vertical, 0.05-0.1 mm diam., terete isidia to 0.3 mm long. Apothecia rare, scattered on upper surface, sessile, constricted at base, to 2.5 mm diam., but often less, disc plane, convex at maturity, pale to dark red, smooth, matt, epruinose or sometimes in young fruits white-pruinose, thalline margin thin, ± entire, smooth or subrugulose. Ascospores 8 per ascus, distichous and imbricate, narrowly fusiform or rather acicular, straight or slightly curved, 4-6(-8)-celled, 42-60(-65) × (3-)4-5-6.5 µm.