Thallus indeterminate, squamulose-areolate, dark reddish or black as pitch, squamules subcontiguous or subdispersed, unequal or irregular, sublobate, appressed, margin free, dark below. Apothecia numerous, immersed, a few in each squamule, disc dilated, subconcolourous with thallus, concave, unequal, surrounded by indistinct, prominent margin. Upper cortex somewhat thick, CaCl-. Hymenium somewhat tall. Spores very thin, ellipsoid.
Squamules 1-3 mm large, 0.4-0.7 mm thick, grouped or separated by cracks, often +/- confluent and very irregular, surface somewhat shiny, on the whole plane but minutely uneven.—Upper cortex indistinctly limited in water, 35-40 µ thick, colourless, exterior 6-10 µ dark red-brown, amorphous stratum 10-18 µ, even. Cortical cells +/- indistinct, 1.7-2.5 µ, globular, thick-walled, hyphae in the cortex and the gonidial stratum distinct in KOH, 3-3.5 µ thick, thick-walled, in the cortex +/- perpendicular with distinct apices at the surface, 4-5 µ thick. Gonidia up to 20 µ large, stratum not dense, partly interrupted, surface not distinct. Medulla below the apothecia colourless or obscured by air, hyphae very densely intricate, rather thick-walled, indistinct, 2-3.5 µ thick. Lower side, 10-15 µ, blackish brown, also laterally up to the apothecial margin.
Apothecia (1)2-5 in the squamules, disc 0.6-1 mm large, in thallus level, brownish black, somewhat darker than the surface, irregular in shape, its surface somewhat rough or rugose. –Exciple distinct, colourless, 20-40 µ thick below, the same at the surface or narrower, indistinct, I-. Hypothecium 50-70 µ, cloudy or not, I+ blue. Hymenium varying in height, 70-100 µ high, lower limit indistinct, I- or yellowish. Paraphyses indistinct in water, apparently short-celled, in KOH distinct, 1.7-2 µ thick, straight, short-celled, apices dark brown, 4-5.5 µ thick, coherent, clavate-capitate. Asci 70-80 X 18-24 µ. Spores at least 200, in KOH 3.5 (4.5) X 1.7 µ, easily escaping, somewhat broadly ellipsoid.
Habitat. On non-calciferous mica-schist in a place rich in ammonium salts, associated with Lecanora conf. contractula, polytropa, Candelariella, Caloplaca etc.
Locality. West Greenland. Nugssuaq Peninsula north of Disko: Atanikerdluk, 1871, Th. Fries. Two specimens.
The new species is characterized by its very dark colour, its large, confluent squamules with large, little conspicuous apothecia and dark lower side.It may be rather near to A. Almquistii, but cannot be united with this species.