Distribution: N - Frl (TSB 15363), Lomb, Piem (TSB 25801). C - Tosc.
Description: Thallus crustose, episubstratic, brownish to yellowish grey, areolate. Medulla white, amyloid I+ blue. Apothecia lecideine, black, 0.3-0.6 mm across, subsessile, with a soon convex, heavily white-pruinose disc, and a soon excluded proper margin. Epithecium brown; hymenium colourless; paraphyses simple, slightly capitate. Asci 8-spored, clavate, with a thick apex, amyloid, with a distinct axial mass, Lecanora-type. Ascospores 3-septate, brown, ellipsoid, 10-15 x 3-5 μm. Photobiont chlorococcoid. Spot tests: thallus and medulla K-, C-, KC-, P-, UV-. Chemistry: no lichen substances.
Note: an apparently widespread but rare, or at least rarely distinguished, mostly silicicolous species, characterised by four-celled spores with transversal septa only, and by the J+blue reaction of the medulla.