Toninia sedifolia (Scop.) Timdal

    Thallus squamulose, squamules thick, to 3 mm wide, convex, tips rounded, smooth, whitish, pale grey to dull dark grey, pale greenish when moist, more or less visible due to a conspicuous white pruine. Apothecia usually numerous, sessile, to 3 mm diam., flat to slightly convex, pruinose when young, disc and exciple black, exciple excluded when mature. Ascospores fusiform, 1-septate, 15-28 x 3-5 µm. Photobiont: Trebouxia. On dry calcareous dunes where this species grows in association with the Toninion caeruleonigricantis other species. N.B. See the Fulgensia fulgens file to consider  the question of the common photobiont between these two species. N.B. This species, like Toninia aromatica, can appear on black cyanolichens (or free cyanobacteria), see the photographs, it will then be distinguished from Toninia verrucarioides which seems specific to Placynthium nigrum..