A minute (1-4 mm diam.) yellow-brown to brown discomycete growing from a lumpy black crust (Xenotypa aterrima) on Betula (birch) spp., often where the bark appears to have been stripped away.
Anamorph: not known.
Teleomorph: stromata absent. Ascomata apothecia, superficial, scattered, developing from a black crust of Xenotypa aterrima; 1-2 (-4) mm diam., cupulate, externally yellow-brown when very young and maturing to dark brown, with a paler irregular fringe-like margin; striate and finely scurfy, with a short stout stalk. Disc yellowish-brown, drying blackish brown. Outer excipulum to ca 60 µm thick, composed of globose cells 4-5 µm diam., covered with short undulating thin-walled septate hairs 3-4 µm diam. Internal tissues of loosely interwoven hyaline hyphae to ca 4 µm diam. Interascal tissue of simple cylindrical paraphyses ca 2 µm diam., slightly enlarged and pale yllowish brown at the apices. Asci 110-110 x 10-12 µm, clavate, short-stalked, with croziers, the apex rounded with a broad shallow ring staining blue in iodine, 8-spored. Ascospores (18-) 25-33 x 6-8 µm, fusiform, straight or slightly curved, hyaline, aseptate, 1-septate or infrequently 2- to 4-septate, often with several large lipid globules when living.