Distribution: N - Frl, TAA (Nascimbene & al. 2021), Lomb, Piem (Isocrono & al. 2004), VA (Valcuvia 2000), Emil (Fariselli & al. 2020), Lig. C - Tosc (Nascimbene & al. 2021), Sar. S - Cal (Puntillo 1996).
Description: Thallus small-foliose to squamulose, heteromerous, c. 130 μm thick, red brown to blackish brown and often somehow glossy when dry, dark green to almost black when wet. Lobes crowded, initially rounded, then often elongate and c. twice as long as wide, flattened, 0.5-1.5(-2) mm broad, 0.5-3(-10) mm long, irregularly branched and overlapping, often forming rosettes 1-3 cm in diam., the margins dissected by numerous, flattened, usually paler, isidia-like lobules or warts; lower surface whitish to pale brown, with sparse brown rhizines. Upper cortex paraplectenchymatous, 25-30 μm thick; lower surface ecorticate, but with densely interwoven, longitudinally arranged hyphae. Apothecia rare, rounded, without a thalline margin, sessile to substipitate, up to 2 mm across, with a red-brown to flesh-coloured disc and a thin, pale brown, sometimes short-hairy proper margin. Proper exciple 100-150 μm wide, paraplectenchymatous, of isodiametric cells; epithecium brownish, K-; hymenium colourless, 70-130 μm high, I+ deep blue; paraphyses coherent, simple, straight, 2-6 μm thick, the upper cells slightly thicker; hypothecium colourless, penetrated by photobiont cells. Asci 8-spored, cylindrical, fissitunicate, the thickened apex with a K/I+ blue ring, Fuscidea-type. Ascospores 1(-3)-septate, hyaline, fusiform to narrowly ellipsoid, 11-25(-35) x 4.5-7(-8) μm, thin-walled, without epispore. Pycnidia rare, dark, the wall paler below, semi-immersed or projecting, to 0.6 mm in diam. Conidia bacilliform or slightly bifusiform, hyaline, 4-6 x 1 μm. Photobiont cyanobacterial (Nostoc, the cells in short chains). Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a circumpolar arctic-alpine to boreal-montane lichen found on bryophytes and soil rich in humus, on steeply inclined or underhanging faces near the ground level, with optimum above or near treeline in areas with siliceous substrata; the species is certainly most frequent in the Alps, but it also occurs in the mountains of Calabria and Sardinia.
Growth form: Squamulose
Substrata: soil, terricolous mosses, and plant debris