Thallus light orange-brown to grey-brown or dark grey (orange tints disappearing on storage), thin, 20–70 μm thick, continuous or with scattered cracks. Prothallus brown, very thin and inconspicuous. Isidia and soralia absent. Photobiont trentepohlioid. Anamorph: Conidiomata to 80 μm diam., occurring near junctions of conspecific thalli. Conidia 4–4·5 × ca 1·2 μm, rod-shaped, aseptate. Teleomorph: ascomata perithecia, 160–400 μm diam., prominent, dark brown or black, sometimes orange-brown or brown at the extreme base. Involucrellum of isodiametric thick-walled cells, enclosing numerous photobiont cells, without crystals; inner part yellow to orange, K+ orange-red (Porina-yellow), near upper surface dark grey to purplish red, K+ dark grey or bluish grey (Sagedia-red at least in part), a small area adjacent to ostiole often dark dull violet. Centrum 185–295 μm diam.; peridium colourless or yellow (Porina-yellow). Asci ± cylindrical, thin-walled, I−, with truncate apex, with a ring structure, 8-spored. Ascospores 13–17·5 (–18·5) × 4–5·5 μm, narrowly ellipsoid, 2·3–4·1 (–4·3) times as long as wide, 3-septate, hyaline, thin- and smooth-walled, without an epispore, gelatinous sheath or appendages.