Synonyms: Biatora instrata (Nyl.) Arnold; Lecidea subobscura H. Magn.
Distribution: N - TAA, Lomb (Nascimbene & al. 2021). C - Sar (Nascimbene & al. 2021).
Description: Thallus crustose, episubstratic, minutely areolate, often starting the life-cycle on the thalli of other crustose lichens, the areoles irregularly rounded to angular, concave to flat, 0.3-0.5(-1) mm wide, brown to brown-black, waxy-dull, often with a paler, greyish margin, developing on a dark hypothallus. Medulla white, I-. Apothecia rare, at first immersed in the areoles and almost aspicilioid (surrounded by a kind of 'thalline margin'), then slightly prominent, rounded to irregular in outline, 0.3-0.5(-0.7) mm across, with a black to brown-black disc and an indistinct proper margin. Proper exciple thin, poorly developed, greenish brown to olive brown in outer part, colourless to yellow-brown within; epithecium brown to olive-brown; hymenium colourless, (35-)34-65(-70) µm high, I+ blue; paraphyses coherent, 1.5-1.7(-2.5) μm thick at mid-level, the apical cells 2-4.5(-6) μm wide; hypothecium colourless or yellowish. Asci 8-spored, broadly cylindrical to subclavate, more or less of the Lecanora-type, but with a weakly defined apical cushion and ocular chamber. Ascospores 1-celled, hyaline, broadly ellipsoid, (7-)9-12(-16) x 4-6(-7) µm. Pycnidia black, immersed. Conidia thread-like, curved, 20-22 x c. 0.5 µm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-. Chemistry: miriquidic acid.
Note: on siliceous rocks, with optimum above treeline, sometimes starting the life-cycle on other crustose lichens; probably more widespread in the Alps.