Distribution: N - Ven (Thor & Nascimbene 2007), Lomb (UPS-L166832). S - Cal (Puntillo 1996, 2000).
Description: Thallus crustose, thin, ecorticate, continuous, rimose or warted, grey-green, smooth to granulose, usually not producing goniocysts. Apothecia biatorine, usually numerous, 0.15-0.25 mm across, whitish, pale yellow or pale grey, with a flat to slightly convex, epruinose disc, and a usually paler, white or very pale yellow, persistent proper margin. Proper exciple laterally 24-33 μm wide, without crystals, of very thin-walled (0.5-1 μm), not distinctly radiating hyphae, the outer rim colourless or very pale brown in uppermost part, the medullary part colourless. Epithecium colourless or rarely very pale brown and in this case K+ purple, indistinctly delimited from the hymenium; hyrnenium 30-40(-50) μm high, mostly colourless; paraphyses mostly simple, 1.5-2 μm thick at mid-level, the apical cells clavate or only slightly thickened, to 3-4(-6) μm wide; hypothecium poorly developed, colourless. Asci 8-spored, cylindrical-clavate, approaching the Bacidia-type, the ocular chamber lacking, the axial body never penetrating through the d-layer. Ascospores (0-)1-3-septate, hyaline, needle-like, straight to sigmoid, twisted in the asci, (17-)21-34(-39) x 0.9-1.8 μm. Pycnidia immersed, colourless. Conidia filiform, curved, 0-l-septate, 30-43 x 0.5-1 μm. Photobiont chlorococcoid, the cells 5-12(-14) μm in diam. Spot tests: thallus and apothecia K-, C-, KC-, P-, UV-. Chemistry: thallus without lichen substances.
Note: a mainly temperate to southern boreal species found on evergreen leaves and base-rich bark, sometimes on plant debris, calcareous stones, etc., mostly near the ground; certainly overlooked, and perhaps more widespread in Italy below the subalpine belt, including in the Alps.
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)