Distribution: C - Laz. S - Cal (Puntillo 1996), Si (Grillo 1998, Grillo & Caniglia 2004, Ottonello & al. 2011).
Description: Thallus foliose, subgelatinous when wet, lead-grey, 100-150 µm thick, forming extensive patches up to 10 cm in diam. Lobes finely striate, rounded, flat, (3-)5-8(-10) mm wide, with wavy, often ascending margins. Lower surface usually paler than upper surface, not tomentose. Upper and lower cortex paraplectenchymatous, composed of a single layer of angular cells. Apothecia frequent, lecanorine, (0.5-)1-3(-4) mm across, sessile and constricted at base, sometimes slightly stipitate, with a flat to slightly convex, reddish brown disc, and a finely striate, thin but persistent thalline margin. Amphithecium 70-115 µm wide laterally; proper exciple c. 25 µm wide, paraplectenchymatous; epithecium orange-brown to yellowish brown; hymenium colourless, 125-140 µm high, I+ blue; hypothecium colourless, prosoplectenchymatous. Asci 8-spored, cylindrical-clavate, the apex thick, with a I+ blue apical dome and a I+ blue annulus projecting downwardly. Ascospores muriform, hyaline, ellipsoid with pointed ends, (20-)25-32(-37) x (10-)13-15(-17) µm. Photobiont cyanobacterial (Nostoc), in long chains. Spot tests: all negative. Chemistry: without lichen substances.
Note: a mild-temperate to Mediterranean species found on mossy trees and rocks in ancient, humid woodlands of Tyrrhenian Italy. It is included in the Italian red list of epiphytic lichens as “Vulnerable” (Nascimbene & al. 2013c).