Thallus 20-30 mm diam., irregular in form, carpet-forming, attached by a holdfast, consisting of soft, coarse, cylindrical, much-branched, decumbent, sometimes matted filaments, >50 μm diam., with only occasional short spine-like branches, dark-green to brown, black when dry, somewhat shiny. Filaments without a cellular cortex, hyphae external to the photobiont when young or irregularly reticulate, later forming a central strand with elongate to rounded cells. Photobiont Stigonema, not staining in iodine. Anamorph: Conidiomata pycnidia, developing laterally from the thallus filaments. Conidiophores branched, long-celled. Conidiogenous cells elongate-ampulliform, proliferating percurrently. Conidia 3-4.5 × 1.2-1.7 μm, ellipsoidal to bacilliform, aseptate, hyaline. Teleomorph: ascomata apothecial in structure, developing from pycnidia, to 250 µm diam., rare, occurring as minute, concolorous structures in swellings on the branches; with a proper margin, discs punctiform. Hymenium gelatinous, the upper part brown, I+ blue-green, K/I+ blue. Hypothecium dense. Interascal tissue of septate paraphyses, sparsely branched, the apices thickened. cylindrical to obclavate, thin-walled, the wall with a K/I+ blue outer layer, apical dome absent, 8-spored. Ascospores 11-18 × 3.5-6 μm, ellipsoidal, aseptate or occasionally with 1 or 2 plasma bridges, hyaline.