Description: Thallus crustose, thinly episubstratic, continuous to rimose-areolate, dull grey, pale brown or ochraceous, the marginal parts of the 0.2-0.5 mm wide areoles sometimes paler, without a distinct prothallus. Apothecia usually numerous, scattered or clustered, 0.3-0.6 mm across, sessile, with a pinkish yellow to red-brown (translucent when wet), sometimes finally blackening, markedly convex disc, and a thin, soon excluded margin. Thalline exciple corticated only at the base, with a few algal cells in basal parts; proper exciple well-developed, colourless; epithecium colourless to pale yellowish brown; hymenium colourless, 40-60(-70) µm high; paraphyses simple or sparingly branched in upper part, the apical cells not distinctly swollen; hypothecium colourless. Asci 8-spored, narrowly clavate, with a K/I+ blue tholus and a central non-amyloid area, Bacidia-type. Ascospores 1-septate, hyaline, ellipsoid, 9-16 x 3-4.5 µm. Photobiont chlorococcoid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a Mediterranean-Atlantic lichen found on periodically wetted or immersed siliceous rocks, especially sandstone, in sheltered situations, mostly at low elevations; overlooked in Tyrrhenian Italy, but not common.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)