Distribution: N - VG, Frl, Ven (Lazzarin 2000b), TAA (Nascimbene & al. 2022), Lomb (Lazzarin 2000b, Brackel 2013), Piem (Matteucci & al. 2013), VA (Gazzano & al. 2009, 2009b), Emil (Fariselli & al. 2020), Lig (Lazzarin 2000b, Watson 2014). C - Tosc, Marc (Nimis & Tretiach 1999), Abr (Nimis & Tretiach 1999), Mol (Nimis & Tretiach 1999, Caporale & al. 2008), Sar. S - Camp (Aprile & al. 2003b, Nimis & Tretiach 2004, Garofalo & al. 2010), Pugl, Bas (Bartoli & Puntillo 1998), Cal (Puntillo 1996), Si (Nimis & al. 1994, Ottonello & al. 1994, Ravera & al. 2023b).
Description: Thallus squamulose-umbilicate, homoiomerous, slightly gelatinous when wet, 0.3-0.45 mm thick, in section with a loosely reticulate network of thin hyphae enclosing groups of cyanobacterial cells. Squamules black, dispersed to crowded, 0.3-0.6(1.2) cm in diam., button-like, epruinose, not isidiate, attached by a central, compact bundle of rhizohyphae, with an often lobulate to incised margin, the lobules contiguous, radiating, smooth, slightly convex, rounded at apex. Apothecia pycnoascocarps, 2-10 or more per squamule, at first immersed and urceolate but soon expanded and clearly lecanorine, 0.3-0.9(-1.2) mm across, with a dark reddish brown, concave to flat disc, and a thick, usually smooth thalline margin. Proper exciple poorly developed; epithecium brownish orange, 5-15 µm high; hymenium colourless, 80-150 µm high, the hymenial gel I+ blue, paraphyses moniliform, 3-4.3 µm thick, the upper cell clearly swollen and to 7 µm wide; hypothecium yellowish, 70-130 µm high. Asci 8-spored, cylindrical-clavate, thin-walled, with an amyloid external apical cap. Ascospores 1-celled, hyaline broadly ellipsoid to ellipsoid, 7-15 x 4-10(-12) µm, the wall 1-2 µm thick. Pycnidia immersed, globose, unilocular. Conidia hyaline, ellipsoid, 2-4 x 0.5-1.5 µm. Photobiont cyanobacterial, chroococcoid, of a few 8-13 µm wide cells often penetrated by haustoria and surrounded by a gelatinous sheath which is colourless in inner parts, yellowish brown near the thallus surface. Spot tests: all negative. Chemistry: without lichen substances.
Note: on steeply inclined surfaces of limestone and dolomite with periodical water seepage after rain, below the subalpine belt. Some older records could refer to A. moedligense.