Synonyms: Biatorella fossarum f. hemisphaerica (Anzi) Vain.; Biatorella fossarum var. rubicunda Th. Fr.
Distribution: N - Frl, Ven (Nascimbene 2002, 2003b), TAA, Lomb, Lig. C - Tosc, Abr (Gheza & al. 2021).
Description: Thallus crustose, pale grey to greenish grey, thin and often inconspicuous, granulose to arachnoid. Apothecia biatorine, (0.8-)1-1.5(-2) mm across, orange-red to reddish brown, semi-immersed to adnate, not constricted at base, with a weakly to strongly convex disc, without an evident margin. Proper exciple poorly developed, of more or less parallel hyphae, I+ blue; epithecium pale to orange-yellow, K-, often with a layer of crystals which appear as a dark yellowish-brown pruina; hymenium colourless or yellowish in upper part, 150-300 µm high, I+ blue; paraphyses richly branched and anastomosing, 1-1.5 µm thick in lower part, the apical cells distinctly swollen, 2.5-3.5 µm wide; hypothecium yellowish grey, sometimes inspersed with oil droplets, 150-400 µm high, composed of interwoven hyphae, I+ blue. Asci 200-400-spored, broadly cylindrical, apparently fissitunicate, but without a tholus, with a gelatinous, K/I+ intensely blue outer layer extending about one third the length of the ascus, and a simple, K/I+ blue apical dome. Ascospores 1-celled, hyaline, elongate-ellipsoid, 5-8 x 2-3.5 μm. Photobiont chlorococcoid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on calciferous soil and amongst bryophytes, most often in rock fissures, mostly in upland areas; see also note on B. fossarum.
Growth form: Crustose
Substrata: soil, terricolous mosses, and plant debris