Distribution: N - Emil (Fariselli & al. 2020), Lig (Tretiach 1993). C - Tosc (Tretiach 1993, Pišút 1997, Lastrucci & al. 2009, Helms & al. 2003), Laz (TSB 17739), Sar (Monte 1993, Tretiach 1993, Nöske 2000). S - Camp (Aprile & al. 2002), Bas (CLU 18075), Cal (Tretiach 1993, Puntillo 1996), Si (Ottonello & Romano 1997, Merlo 2004, Ottonello & al. 2011).
Description: Thallus foliose, rather tightly attached, forming regular to irregular, often confluent rosettes to over 10 cm in diam. Lobes epruinose, brown to brown-black in exposed situations, dark olive-green when wet, often whitish but not pruinose at tips, 0.3-3(-5) mm wide, contiguous or often densely overlapping, especially in the central parts, without marginal cilia; lower surface corticate, prosoplectenchymatous, pale to dark brown, with simple, dark rhizines. Upper cortex prosoplectenchymatous, the hyphae running parallel to the surface; medulla white. Apothecia lecanorine, strongly constricted at base, often almost substipitate, 1-3(-5) mm across, with a dark brown to brown-black, epruinose disc, and a smooth to crenulate thalline margin. Epithecium brown; hymenium and hypothecium colourless. Asci 8-spored, clavate, the K/I+ blue tholus penetrated by a faintly amyloid apical cushion with parallel or diverging flanks, the wall K/I-, surrounded by a K/I+ blue outer layer, Lecanora-type. Ascospores 1-septate, brown, ellipsoid, (31-)34-45 x 17-23(-27) µm, Physconia-type. Pycnidia black, immersed in thalline warts. Conidia bacilliform. Photobiont chlorococcoid. Spot tests: thallus and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a Mediterranean-Atlantic, European species found in rather shaded situations with frequent humid winds on hard siliceous boulders, sometimes overgrowing epilithic mosses; most common along the Tyrrhenian coast, but also found in the montane belt of the Tyrrhenian mountains (e.g. M. Amiata in Toscana).
Growth form: Foliose, narrow lobed
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)