Thallus determinate, radiate, pitch black or dark brown/grayish-brown-black, outline indistinct, lobate, for the most part in discrete semiglobose, verrucae, dissolute, tightly adnate, pale below.
Apothecia solitary in each central areole or sometimes a few, immersed, disc punctiform, impressed, concolourous with thallus, ornate. Upper cortex somewhat thick, CaCl-, medulla crystals dark. Hymenium somewhat thick. Paraphyses thick. Spores broadly ellipsoid.
The single thalli dispersed upon the stone, about 1 cm in diam., +/- circular, only few, very convex marginal lobes developed, 1-1.5 mm long and about 0.5 mm broad, partly sinuate at the apices, firmly affixed. Central verrucae somewhat regularly half globose and 0.5-0.7(1) mm in diam., 0.3-0.4 mm thick, their cortex, especially round the base, destroyed so that the white medulla is visible, often as a narrow ring at the base. (Fig. 7).
Upper cortex 35-45(50) µ thick, transparent, exterior 8-12 µ very dark brown, amorphous stratum 5-7 µ thick, regularly developed, even. Cortical cells indistinct, also in KOH or HCl, 1.5-3 µ in diam., irregular, hyphae apparently intricate. Gonidia 7-13 µ in diam., stratum 50-75 µ thick, continuous, with even surface. Medulla 100-400 µ thick, gray from granules on the hyphae. These 3-4 µ thick, in KOH or HCl indistinctly thick-walled, very long-celled and very loosely intricate. Marginal cortex dark brown, areolae largely attached to the stone with the medulla.
Apothecia at first in the shape of a slight depression at the top of the verruca, solitary, finally somewhat prominent and simple with rough disc, 0.3-0.4 mm large, or consisting of 2-5 very minute, punctiform apothecia.—Exciple 10-15 µ thick at the bottom, widened towards the surface, sometimes the exciples of approaching apothecia touching one another. Hypothecium 20-30 µ thick, I+ dark blue, little developed. Hymenium 85-110 µ high, upper 20-30 µ blackish brown; I+ greenish or pale blue. Paraphyses 2-3 µ thick, apices KOH+ dark brown, 3-4 µ thick. Asci 65-70 X 25 µ, easily bersting (sic). Spores about 100, 3-4.5 X 1.7 (2) µ, somewhat broadly ellipsoid, especially as young.
Habitat. On non-calciferous mica-schist with a specimen of Sporastatia testudinea and traces of Caloplaca and Gyrophora, but most part of the stone devoid of lichens.
Locality. East Greenland. Franz Josef Fjord: Reinbukta, 1929, Lynge.
One of the most curious species I have met with in this genus, through colour and marginal lobes reminding of a meagre species of A. molybdina, but quite different from that species in structure.