Ciboria rufofusca is a small discomycete in the family Sclerotiniaceae, recorded from temperate Europe. The species is a saprotrophic cup fungus that fruits on fallen plant material, with records suggesting an association with catkins or mast of various deciduous trees, consistent with other members of the Ciboria genus. The fruiting bodies are stalked cups with a reddish-brown to ochre coloration, giving the species its name, which translates roughly as red-brown Ciboria. The species has not been formally assessed by the IUCN. As with many small discomycetes, Ciboria rufofusca is likely under-recorded due to its inconspicuous size, brief fruiting season, and the specialist knowledge required for identification. Microscopic features—spore morphology, paraphysis structure, and excipular anatomy—are essential for distinguishing this species from close relatives. The genus Ciboria belongs to Sclerotiniaceae, a family that also includes major plant pathogens, though Ciboria species themselves are saprotrophic decomposers rather than parasites. European temperate woodlands support a diverse community of substrate-specific discomycetes, many of which remain poorly documented. The conservation status and population trends of Ciboria rufofusca are unknown, as systematic surveys of small cup fungi across Europe are limited. It likely plays a role in decomposing woodland organic matter and cycling nutrients within forest floor ecosystems.