Thallus endophloeodal indicated by discolouration of the substrate, usually whitish or greyish, rarely darker, in a few species consisting of an epiphloeodal, dark brown subicular layer of hyphae, or epilithic in a single species. Photobiont when present green, or blue-green. Perithecia with a brown to blackish wall, usually lacking below. Ostiole erect or rarely eccentric. Paraphyses thick and irregular with short cells, often appearing almost parenchyma-like to slender and regular with relatively long cells, sometimes partially gelatinised, rarely completely so. Asci various, ovate to narrowly ovate, narrowly elliptical, obovate or cylindrical, tip often thickened, with or without an obvious ocular chamber. Ascospores typically 8 per ascus, often fewer, rarely 2-4 per ascus, colourless, oval-ellipsoid, mostly 1-3-septate (to 7-septate), constricted at septa, spore wall ornamented in some species at maturity, perispore usually evident, often well developed.