Thallus: chasmolithic (mostly immersed in its substrate); apothecia: black, lecideine, 0.4-0.6(-1.3) mm wide, ca. 0.3 mm thick, stipitate, under side black; disc: black, epruinose, usually black when wet, smooth, melanized accretions forming on surface when beginning to divide, replicating by division; margin: black, prominent above the disc, curling inward, smooth without incisions when small, larger apothecia with some shallow incisions, in largest apothecia some segmentation of the margin; true exciple: formed of thin radiating hyphae 100-120 μm wide, outer layer up to 100 μm melanized wide, hyphae not visible, inner layer lacking or narrow to 20 μm wide and reddish-orange; hymenium: 60-120 μm high, reddish to hyaline, epihymenium reddish brown10 μm high, paraphyses 1-1.7 um wide, apices unexpanded, hymenial gel IKI+ dark blue (euamyloid); asci: 40-90× 10-17 μm wide, cylindrical to clavate; ascospores 3-5 x 1-1.5 μm; subhymenium: reddish, indistinct,ca. 20 μm tall, IKI+ dark blue; hypothecium: black, up to 200 μm tall. Pycnidia: not seen.
Spot tests: negative.
Secondary metabolites: not producing any.
Substrate and ecology: on primarily acid rock.
Distribution: Europe, eastern North America at least from Ontario, Canada to Smokey Mountains National Park, west to Wisconsin.
Discussion: This species is usually misidentified as Sarcogyne clavus which has apothecia up to 4 mm wide, a thicker, crenulate margin, sometimes in two layers, sometimes warty, a hypothecium paler in thin section, and when sterile produces multiple pycnidia inside an apothecial margin instead of a hymenium. See picture of typical S. clavus on the CNALH taxon profile page. The color picture of S. clavus in Vol. 3 of Sonoran flora is S. hypophaeoides. It was only recently reported from North America (2020) and in herbaria specimens identified as S. clavus need to be checked.