Description: Thallus crustose, continuous to rimose- cracked, grey, brownish green to olive-brown, often delimited by a dark brown to black prothallus and forming mosaics. 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. Epithecium brown; hymenium pale or faintly brownish; paraphyses 1.5-2 μm thick, 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, (7-)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 lichen found on bark (mainly of Fagus); perhaps declining, especially in northern Italy. According to Roux & coll. (2014) it should be better treated as a variety of F. cyathoides; molecular data as well (Zahradnikova et al. 2017) do not justify a separation at species level from F. cyathoides.
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)