K. svenska Vetensk-Akad. Handl., n.f. 7, 4: 174, 1929
Distribution: N - VG, Lig (Knudsen & Kocourková 2020). C- Laz, Sar.
Description: Thallus crustose, episubstratic, areolate, pale to dark brown, epruinose. Areoles 0.5-1 mm in diam., 0.2-0.4 mm thick, round to irregular in shape, some of them slightly lobed and with a brown underside. Epicortex lacking; cortex 15-20(-30) μm thick, the upper layer dark brown, 5-10 μm thick, the lower layer brown or colourless, the cells mostly round, 2-4 μm across; algal layer continuous, not interrupted by hyphal bundles, 35-90 μm thick; medulla 75-90 μm thick, mixed with substrate crystals, white and opaque, the medullary hyphae thin-walled, 3-4 μm wide. Apothecia lecanorine, at first immersed, then becoming elevated above the areoles, the thalline margin sometimes darker or paler then the areoles, usually 1-4 per areole, less than 1 mm across, with a brown, round to irregular, often distinctly rugulose, epruinose disc, and a margin that sometimes is darker or paler then the areoles. Proper exciple thin, 5-15 μm wide or indistinct; epithecium dark brown, c. 10 μm high; hymenium colourless, 60-110(-120) μm high, K/I+ reddish or blue (hemiamyloid); paraphyses coherent, 1–2 μm thick at mid-level, the apical cells 2-4 μm wide; subhymenium 20-30 μm thick, hypothecium 5–10 μm thick or indistinct. Asci c. 100-spored, clavate, the apical dome K/I-. Ascospores 1-celled, hyaline, narrowly ellipsoid, 4-5 x c. 1.5 μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a lowland species of siliceous rocks in sunny situations; poorly developed samples with immersed apothecia are practically undistinguishable from A. veronensis.