Synonyms: Biatora polytropa var. intricata (Ach.) Th. Fr.; Lecanora intricata f. coerulea Lamy; Lecanora polytropa var. intricata (Ach.) Rabenh.
Distribution: N - Frl (Tretiach & Hafellner 2000), Ven (Caniglia & al. 1999), TAA (Caniglia & al. 2002, Nascimbene 2003, Lang 2009), Lomb, Piem (Isocrono & al. 2004, Isocrono & Piervittori 2008, Favero-Longo & al. 2015), VA (Piervittori & Isocrono 1999), Emil (Dalle Vedove & al. 2002, Tretiach & al. 2008), Emil (Fariselli & al. 2020), Lig. C - Tosc (Tretiach & al. 2008), Sar (Nöske 2000).
Description: Thallus crustose, episubstratic, rimose-areolate, rather thick, yellowish green yo grey green, sometimes delimited by a dark prothallus. Areoles 0.2-0.6 mm wide, flattened, contiguous or scattered, with a crenulate margin, smooth or finely wrinkled, epruinose. Cortex with abundant dead algal cells, the upper part with coarse hyaline granules which are insoluble in K; medulla white, dense. Apothecia lecanorine, crowded, (0.4-)0.8-1(-1.5) mm across, at first immersed, then subsessile, not constricted at base, 1-2(-3) per areole, with a slightly concave to convex, greenish brown to blackish green, epruinose disc, and a prominent to finally excluded thalline margin. Thalline exciple corticate, the cortex with dark brown granules soluble in K; algal layer dense, extending below the hypothecium; medulla white, lacking crystals; proper exciple colourless, without crystals; epithecium green-brown or brown, c. 10 µm high, with numerous small crystals visible under polarized light, which are soluble in K; hymenium colourless, 60-70 µm high; paraphyses simple or sparingly branched in upper part, the apical cells slightly swollen, up to 2.5 µm wide; hypothecium colourless. Asci 8-spored, clavate, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, oblong or oblong ellipsoid, (8-)9-13(-15) x 4.5-7 µm. Pycnidia dark, immersed. Conidia curved, 23-25 x 0.5-1 µm. Photobiont chlorococcoid. Spot tests: thallus K- or K+ pale yellow, C-, KC+ yellow, P-; medulla KC-. Chemistry: usnic acid and zeorin.
Note: a circumpolar, arctic-alpine, ecologically wide-ranging silicicolous species, common in the Alps, much rarer in the mountains of southern Italy, with optimum above treeline, reaching the nival belt in the Alps.