Description: Thallus crustose, episubstratic, pale to dark grey, turning greenish when wet, thick and verrucose, continuous or cracked, sometimes delimited by a pale to dark grey prothallus. Soralia rarely present, rounded, convex, discrete, widely dispersed in scattered groups, often few in number, usually occurring together with apothecia. Apothecia common, biatorine, 0.5-2(-3) mm across, black, with a flat to strongly convex disc and a thin, soon excluded proper margin, developing on a bright carmine-red thalline cushion that may be exposed when the thallus is abraded. Proper exciple reduced, the hyphae vertically arranged and resembling paraphyses; epithecium blue-black; hymenium greenish (‘cinereorufa-green’), without crystals visible under polarized light; paraphyses branched and anastomosing; hypothecium red-brown in upper part, carmine-red in lower part. Asci 1(-3)-spored, cylindrical-clavate, thick-walled, the apical dome K/I+ blue, with a distinct ocular chamber, the outer layer thickenend and forming a K/I+ dark blue apical cap, intermediate between the Biatora and the Bacidia-type. Ascospores 1-celled, hyaline, oblong to ellipsoid with rounded ends, 65-100 x (28-)32-50 μm, the wall 5-7 μm thick. Pycnidia common, with a dark green wall. Conidia bacilliform, 6-9 x c. 1 μm. Photobiont chlorococcoid. Spot tests: thallus K+ dirty yellow, C-, KC-, P+ yellowish or P-, UV-; hypothecium and the underlying red tissue K+ red, P-, UV-. Chemistry: atranorin, chloratranorin, rhodocladonic acid, caperatic acid.
Note: a circumboreal-montane species found on lignum and bark of conifers (especially Larix), mostly in the subalpine belt; perhaps restricted to the Alps in Italy.