Description: Thallus crustose, thinly episubstratic, continuous to rimose, cream-coloured to grey-brown, paler when wet, sometimes with a greenish tinge. Apothecia biatorine, round to irregular in outline by mutual compression, black (the disc turning brown when wet), 0.1-0.3 mm across, with an initially concave, then flat, finally convex disc and a thin, raised, finally sometimes excluded proper margin. Proper exciple dark brown in outer part, more or less colourless within; epithecium dark brown, 9-17 µm high; hymenium colourless, 45-70 µm high, I+ blue then brownish; paraphyses simple, easily made free, the tips capitate with a dark brown pigment deposited within the walls; hypothecium colourless, 30-80 µm high. Asci 8-spored, subcylindrical, with a K/I+ blue outer coat and a K/I+ uniformly blue apical dome, Catillaria-type. Ascospores 1-septate, hyaline, narrowly ellipsoid, 10-16 x 4.5-6 µm. Photobiont chlorococcoid, the cells 8-12 µm wide. Spot tests: K-,C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a suboceanic species growing on nutrient-enriched siliceous rocks along the coasts, with a single Italian record from Sardinia.