Thallus attached in rosettes, peltate, white to brownish white; underside white, minute, 1-3 mm broad, the squamules verrucose above, crenate at margins. Apothecia covering much of thallus, to 1.5mm broad; disk flat, dark brown to brown-black, epruinose; thin thalloid margin commonly becoming excluded; margin I—; epihymenium dark brown to black, HN03—; hymenium hyaline, 85-100 μm, 1+ blue; paraphyses coherent, capitate 5-7 μm at tips; spores ellipsoid, 8-11 x 4-6 μm.

Reactions: K+ yellow, P—, I—; medulla C+ orange (xanthones).

Contents: not studied.

This species grows on rocks and old bones in nitrogen-rich habitats such as bird rocks. It is rare, known from Novaya Zemlya, Spitzbergen, Bear Island, Disko Island in Greenland, and near Churchill, Northwest Territories.