Flot. ex A. Massal., Ric. Auton. Lich. Crost.: 54, 1852.
Distribution: N - Ven (Grube & Giralt 1996, Lazzarin 2000b), Lomb (Valcuvia & Truzzi 2007, 2007b). C - Laz, Abr, Sar (Rizzi & al. 2011). S - Pugl, Si.
Description: Thallus crustose, mostly endosubstratic, effuse, greyish white to greenish grey, with or without a dark prothallus, the thalline hyphae I+ blue. Apothecia arthonioid, rounded to angular, up to 2 mm across, level with thallus, with a flat to slightly convex, black, epruinose, rough disc, without a distinct proper margin. Epithecium pale to dark reddish brown, often with bark fragments, K+ reddish; hymenium patchily brownish, up to 150 µm high, I+ red, K/I+ blue, K+ faintly green; paraphysoids branched and anastomosing, sinuous, c. 0.5-1.5 µm thick, the apices without a brown cap; hypothecium brownish, c. 50 µm high, with bark fragments, K+ faintly green. Asci 8-spored, subglobose, semi-fissitunicate, with a large apical dome and a distinct ocular chamber, lacking K/I+ blue structures. Ascospores muriform, with 5-7 transverse septa and 1-3 longitudinal septa in each transverse segment, hyaline, ellipsoid, 26-37 x 12-15 µm. Photobiont trentepohlioid. Spot tests: thallus K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: a temperate-suboceanic lichen found on the smooth bark of deciduous trees in ancient forests. It is included in the Italian red list of epiphytic lichens as “Vulnerable” (Nascimbene & al. 2013c).
Growth form: Crustose
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)