Distribution: N - Frl (TSB 20586), TAA (Nascimbene 2003, Lang 2009, Hertel & Schuhwerk 2010), Piem (Isocrono & al. 2004, 2006, Giordani & al. 2014), VA (Piervittori & Isocrono 1999, Matteucci & al. 2015c). C - Tosc.
Description: Thallus crustose, endosubstratic or thinly episubstratic and then reduced to sparse, white granules/areoles around the apothecia, without a distinct prothallus. Medulla I+ intensely blue-violet. Apothecia lecideine, black, usually numerous and often arranged in lines along cracks in the rock, sessile and strongly constricted at base, rounded to angular by mutual compression, 0.5-2(-4) mm across, with a flat to convex, epruinose or slighly pruinose disc, and a thin, weakly raised, persistent proper margin. Proper exciple greenish black along a thin, peripheral rim partly extending below the hypothecium, pale grey or colourless within, C-; epithecium dark green to greenish black, 12-18 μm high, N+ purple; hymenium colourless of pale green in upper part, 40-80 μm high, I+ blue; paraphyses coherent, the apical cells swollen and to 7 μm wide; hypothecium medium to dark brown. Asci 8-spored, clavate, Lecidea-type. Ascospores 1-celled, hyaline, oblong or oblong-ellipsoid, (7-)8-12 x (2.5-)3.5-4.2(-5) μm, 2.1-3.7 times as long as wide µm. Pycnidia black, semi-immersed. Conidia bacilliform to filiform, 9-15 μm long. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: thallus with the confluentic acid syndrome, sometimes with 2’-0-methylperlatolic acid.
Note: a circum- and bipolar, arctic-alpine to boreal-montane lichen (Hertel 2006) found on boulders close to the ground and on siliceous pebbles in Alpine heaths; certainly more widespread in the Alps, where it reaches the nival belt, and also reported from the northern Apennines. See also note on L. auriculata.