Distribution: N - TAA (Watson 2014), Lig (Giordani & al. 2002). C - Tosc (Brunialti & Frati 2010), Marc (Frati & al. 2004, Frati & Brunialti 2006), Umb (Ravera & al. 2006, 2006b), Laz (Stofer 2006), Sar. S - Camp (Nimis & Tretiach 2004, Garofalo & al. 2010), Pugl (Nimis & Tretiach 1999), Cal (Puntillo 1996, Incerti & Nimis 2006), Si.
Description: Thallus crustose, endosubstratic to thinly episubstratic, usually poorly visible, continuous or faintly cracked, yellowish grey to grey-green, smooth. Apothecia sessile to immersed, 0.2-0.4 mm across, with a concave, pale yellow-ochre to orange disc, and a smooth to crenulate proper margin. Proper exciple colourless, prosoplectenchymatous; epithecium pale orange-brown; hymenium colourless, 85-115 µm high; paraphyses simple or sparingly branched in upper part, slightly longer than the ature asci, coherent, the apical cells 3-4 µm wide; hypothecium colourless. Asci 8-spored, cylindrical to elongate-subclavate, thin-walled, without tholus, the wall and the contents I+ blue. Ascospores submuriform (with 3-4 tranverse septa and 1-3 longitudinal septa, up to 6 cells being visible in optical view), hyaline, ellipsoid, 9-18 x 6-8(-10) µm. Photobiont trentepohlioid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a mild-temperate lichen found on broad-leaved trees in clearings of ancient, undisturbed forests, especially in deep fissures of the bark, often on Acer and Fraxinus. The species, which however is easy to overlook, is included in the Italian red list of epiphytic lichens as “Near-threatened” (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)