Psora sessitana (Bagl. & Carestia) Bagl. & Carestia

Syn.: Biatora sessitana (Bagl. & Carestia) Jatta, Lecidea sessitana Bagl. & Carestia
Lichenised. Poorly known taxon.
Substrate: siliceous rocks
Altitudinal range: from the subalpine belt (potential vegetation: open, taiga-like forests dominated by Larix decidua and/or Pinus cembra and Rhododendron) to the alpine belt (potential vegetation: treeless Alpine grasslands and tundras, to the lower limit of perennial snow and the equilibrium line of glaciers)
Note: a species with a distinctly squamulose thallus, the squamules thick, densely imbricate, brown above, white beneath, and large, rounded to lobed apothecia with a flat, black, white-pruinose disc, a dark greenish epithecium, a colourless hypothecium. rather thick, conglutinated paraphyses with a thicker apex, and small, elliptical-elongate, hyaline ascospores which are c. 2 times as long as wide; known only from the type collection, on granite. It is not certain that the species belongs to Psora s.str. (see Nimis 1993: 583).
Italy: Piemonte;