Thallus thin, smooth or finely rimose-cracked, sometimes delimited by a dark prothallus and mosaic-forming, dull olive to red-brown, rarely grey, often with a white-dotted appearance due to accumulations of crystals.
Anamorph: conidia pycnidia, immersed in the thallus, visible as black dots. Conidia 4-8 × 0.8-2 μm, variable, straight or curved.
Teleomorph: ascomata lirellate apothecia, (0.25-) 0.32-0.5 (-1) × 0.09-0.15 (-0.3) mm, immersed, sometimes elevated on a thalline cushion, curved or substellate, usually numerous and often contiguous. Disc ± fully exposed, surrounded by a very thin exciple (K–) and sometimes a thin, persistent, whitish, raised, pseudothalline exciple. Epithecium brown. Hymenium 50-60 μm tall, K–. Ascospores (15-) 17-27 × 3-5 μm, fusiform, often curved, 3-septate, quite thick-walled, smooth, becoming brown when over-mature.
Chemistry: thallus C–, K–, KC–, Pd–, UV– (no lichen products detected by TLC).
Assessed by Woods & Coppins (2012) as of Least Concern.
Characterized by the small, immersed, often slightly raised apothecia with a ± fully exposed disc, thin true exciple, a surrounding, thin, whitish pseudothalline margin and curved, fusiform ascospores. Pseudoschismatomma rufescens resembles the rare Schismatomma graphidioides, but the true exciple of the former species is always clearly apparent in sections.
Locally distributed, throughout the British Isles. BLS map here.
On smooth, shaded, nutrient-rich bark of broad-leaved trees, particularly Acer, Corylus, Fraxinus and Ulmus, in wayside and woodland sites.