Distribution: C - Tosc (Tretiach 2004, Puntillo & Puntillo 2009), Sar (Puntillo & Puntillo 2009).
Description: Thallus crustose, episubstratic, rimose to usually verrucose, grey, the surface and the medulla inspersed with coarse granular crystals. Apothecia sessile, 0.3-0.8 mm across, 0.1-0.3 mm tall, at first subcylindrical, then lenticular, the disc covered with a black mazaedium, the margin white-pruinose. Exciple 28-60 μm wide laterally, at the base up to 100 μm tall, of densely interwoven, sclerotized, dark-coloured hyphae; hypothecium dark brown to black, 100-130 μm high, the upper part convex. Asci cylindrical, dissolving early, with uniseriately arranged spores. Ascospores 1-septate, clearly constricted at septum, brown, ellipsoid with pointed ends, 7-14 x 4-7 μm, with an ornamentation of spirally arranged ridges. Photobiont chlorococcoid. Spot tests: thallus K+ yellow, C-, KC-, P+ yellow turning red. Chemistry: thallus either with norstictic acid, atranorin and chloroatranorin, or, rarely, with norstictic acid only.
Note: a mild-temperate lichen found beneath overhanging surfaces of siliceous rocks in humid situations; certainly very rare and probably confined to Tyrrhenian Italy.
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)