Distribution: N - Frl, Ven, TAA, Lomb, Piem (Isocrono & al. 2004), Emil (Fariselli & al. 2020), Lig. C - Tosc (Tretiach & al. 2008), Laz (TO 1729). S - Camp (Ricciardi & al. 2000, Ravera & Brunialti 2013), Si (Jatta 1909-1911).
Description: Thallus crustose, continuous to rimose- cracked, pale to dark grey, brownish grey or brown, often delimited by a dark brown to black prothallus and forming mosaics. Soralia very rarely present, yellowish, sometimes tinged brown, bursting from
the apices of the areoles. Medulla I-. Apothecia lecideine, constricted at base, round to irregular, to 1.8 mm across, with a brown to black, flat disc, and a prominent, smooth to strongly flexuose proper margin which is often slightly paler than disc. Proper exciple brown in outer part, paler within, P+ rust red; epithecium brown; hymenium colourless or faintly brownish; paraphyses 1.5-2 μm thick at mid-level, simple or sparingly branched, weakly conglutinated in water, becoming free in K, the apical cells to 4-5 μm wide; hypothecium colourless. Asci 8-spored, clavate, with a thin external and internal K/I+ dark blue cap surrounded by a thick K/I+ pale blue apical cap, and with a K/I- apical tube in tholus, Fuscidea-type. Ascospores 1-celled, hyaline to finally pale brown, broadly ellipsoid when young, bean-shaped when mature, (8-)10-11(-14.5) x 4-6 μm. Pycnidia abundant, brown, immersed to emergent, with a thin thalline rim. Conidia bacilliform 3-4.5 x 1-2 μm. Photobiont chlorococcoid. Spot tests: thallus K+ brownish yellow, C-, KC-, P+ rust red, UV-. Chemistry: fumarprotocetraric acid (major), protocetraric acid (trace).
Note: a cool-temperate to southern boreal-montane, perhaps circumpolar lichen found on siliceous rocks, mostly in humid upland areas. See also note on F. stiriaca.
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)