Description: Thallus indistinct, doubtfully lichenized, immersed in the thalli of Rhizocarpon-species and other crustose lichens, which often appear darkened or bleached in the infected parts. Apothecia biatorine, black, 0.3-0.5 mm across, broadly attached, often clustered on the edge of the host’s areoles or on its hypothallus, with a soon convex, somewhat glossy disc, without a distinct proper margin. Proper exciple green-black in outer part, dark brown within, 30-50 μm wide, of radially arranged hyphae, K-, N+ orange-brown; epithecium blue green or emerald-green, c. 10 μm high, K+ emerald green, N+ blue; hymenium colourless or greenish in upper part, 40-55 μm high, I+ blue turning red-brown; paraphyses conglutinated, simple or sparingly branched and anastomosing, 2-2.5 mm thick, the apical cell only slightly enlarged and surrounded by blue-green pigment; hypothecium dark brown to brown, 50-120 μm high, K+ purple, N+ orange-brown. Asci 8-spored, clavate, the K/I+ blue tholus penetrated by a faintly amyloid apical cushion with parallel or diverging flanks, the outer wall very thin, K/I-, surrounded by a K/I+ blue outer layer, Lecanora-type. Ascospores 1-celled (rarely old spores 1-septate), hyaline, ellipsoid to oblong, 8-12(-16) x 3-5 μm. Photobiont absent (some authors report an epicapylic thallus with chlorococcoid photobiont). Spot tests: all negative. Chemistry: without lichen substances.
Note: perhaps circumpolar-alpine in distribution, this is a doubtfully lichenised, obligately lichenicolous fungus growing on Rhizocarpon-species near or above treeline. For further details see Hafellner (2006).