Distribution: N - Ven, TAA, Lomb, Piem (Isocrono & al. 2004, Isocrono & Piervittori 2008), VA (Piervittori & Isocrono 1999, Piervittori & al. 2004, Blisa & al. 2011, Matteucci & al. 2015c), Lig (Petrak 1960). S - Bas (Ravera & al. 2019b), Cal (TSB 3223)
Description: Thallus foliose-umbilicate, dorsiventral, monophyllous, thick and rigid, 2-4(-5) cm diam., attached by a very thick, short and compact central holdfast. Upper surface ash-grey, scabrous, with a white, reticulately ridged pattern, raised towards the center. adpressed or undulating, with a strongly wavy margins, the edges often down-turned. Lower surface black or dark brown in places, paler at margins, even or shallowly pitted, sometimes radiately folded around umbilicus, erhizinate. Thalloconidia covering the whole lower surface, 1-celled, spherical, dark brown to black, 7.3-8.5 µm diam. Upper cortex dark brown, palisade-plectenchymatous; medulla white, very loose under ridges; lower cortex scleroplectenchymatous. Apothecia very rare, black, stipitate, omphalodisc. Asci 8-spored, clavate, thick-walled, with an amyloid apical dome, Umbilicaria-type. Ascospores 1-celled hyaline, ellipsoid, 6-14 x 4-8 µm. Photobiont chlorococcoid. Spot tests: K-, C+ red or rarely C-, KC+ red or rarely KC-, P-. Chemistry: gyrophoric acid and small amounts of lecanoric acidk, especially in the medulla.
Note: an arctic-alpine to boreal-montane, circumpolar lichen found on steeply inclined to slightly underhanging surfaces of wind-exposed siliceous rocks, reaching the nival belt in the Alps, and also reported from the mountains of Calabria.
Growth form: Foliose, umbilicate
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)