Distribution: N - TAA, Lomb, Piem (TSB s.n.), VA (Piervittori & Isocrono 1999).
Description: Thallus squamulose or subsquamulose, consisting of scattered, to 1 cm wide clusters of squamules. Squamules up to 2(-3) mm in diam., rounded to irregularly lobed, convex, pale grey to white, sometimes with a brownish hue, weakly to moderately white-pruinose, smooth or shallowly fissured; lower surface pale brown. Upper cortex 25-60 mm thick, including a thick epinecral layer lacking crystals; algal layer continuous; medulla white, lacking crystals; lower cortex thin, partially absent. Apothecia lecideine, black, epruinose or sometimes faintly pruinose, up to 1(-1.5) mm across, soon becoming convex and immarginate. Proper exciple grey in outer part, colourless within, the pigmented parts K+ and N+ violet, lacking crystals; epithecium grey, K+ and N+ violet; hymenium colourless, 40-60 µm high; paraphyses easily made free, 1.8-2.5 µm thick, the apical cells clavate, up to 8 µm wide, surrounded by a pigmented gel; hypothecium colourless. Asci 8-spored, clavate, surrounded by a gelatinous I+ blue coat, with a well-developed I+ blue tholus with a I+ darker blue tube and a well-developed ocular chamber, Bacidia-type. Ascospores 1-septate, hyaline, ellipsoid, 8.5-13 x 4-5 µm. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: thallus without lichen substances; Sedifolia-grey pigment in apothecia.
Note: an arctic-alpine species found on steeply inclined to slightly underhanging seepage tracks of calciferous or basic siliceous rocks, almost always on cyanobacterial colonies, or on thalli of Placynthium, at least when young, mostly in upland areas.
Growth form: Squamulose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
On otherwise dry surfaces with short periods of water seepage after rain