Description: Thallus crustose, episubstratic, rather thick, granular, greenish grey to dark grey, consisting of convex, rounded to vertically elongate, swollen, sometimes partly confluent, 0.6-0.8(-0.9) mm wide goniocysts. Cortical cells of goniocysts 5-10 μm thick, often with small papillae. Perithecia black, matt, ovoid or pyriform, with a short smooth neck and a pale top, sessile to 1/3 immersed, 0.17-0.22(-0.25) mm across (in section), smooth throughout. Exciple distinctly 2-layered, the outer layer dark brown, 11-30 μm thick, the inner layer pale brown to colourless, 12-60 μm thick; involucrellum absent; hymenial gel I+ blue; hamathecium of periphyses and periphysoids; interascal filaments absent. Asci 8-spored, clavate, thin-walled, fissitunicate, not or very weakly thickened above, I-, K/I-. Ascospores muriform, hyaline, ellipsoid, (33-)40-55(-75) x (15-)18-24 μm. Photobiont chlorococcoid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a species of the A. allobata-group, described from the Ukraine, with a record in the Alps (Southern Switzerland), found on mosses and mossy bark of old deciduous trees, especially Quercus and Fraxinus, in humid-shaded old-growth forest stands; to be looked for in the Italian Alps.