Distribution: N - Piem (Isocrono & al. 2004, Isocrono & Piervittori 2008). C - Tosc (Loppi & Baragatti 2011), Abr (Herb. Nascimbene 2537). S - Bas (Nimis & Tretiach 1999), Cal (Puntillo 1996).
Description: Thallus crustose, episubstratic, smooth to granulose, grey-green. Apothecia micareoid, 0.2-0.6 mm across, yellowish brown to pale reddish brown, at first flat and with a whitish marginal rim, then slightly convex and often confluent, forming up to 2 mm wide clusters, without a distinct proper margin. Proper exciple usually indistinct, evident only in very young apothecia, colourless; epithecium colourless; hymenium colourless, 35-45 μm high; paraphyses branched, 1-1.5 μm thick, the apical cells not swollen; hypothecium colourless. Asci 8-spored, clavate to cylindrical-clavate, with an unstained wall and a K/I+ blue outer layer and apical dome, the latter with a non-amyloid, cylindrical axial mass. Ascospores 1-celled to 1-septate, hyaline, ovoid to elongate-ellipsoid, 9-16 x 3-5 μm. Macroconidia ellipsoid to oblong, 6-10 x 2-3 μm, produced in white, cream-coloured to pale ochraceous, convex, up to 0.25 mm wide sporodochia resembling small apothecia; mesoconidia cylindrical, 4-5.5 x 1-1.5 μm. Photobiont micareoid, the cells 4-7 μm wide. Spot tests: thallus and apothecia K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on rather decomposed lignum, such as on old oak stumps and associated decaying bryophte mats, more rarely on loose bark of deciduous trees in areas with high rainfall and mostly in woodlands; certainly more widespread in the Alps. The species is included in the Italian red list of epiphytic lichens as “Data Deficient” (Nascimbene & al. 2013c).
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)