Six new species of foliicolous lichenized fungi are described as new to science from lowland rainforest in the Congo Basin: Bapalmuia serusiauxiana Van den Broeck, Lücking & Ertz (Pilocarpaceae) characterized by (7–)15(–19)-septate ascospores of (40–)50–65(–72)×1·5–2·5 μm, Microtheliopsis ramazaniana Van den Broeck, Lücking & Ertz (Microtheliopsidaceae) characterized by 1-septate ascospores of 13–16×3–5 μm, Phylloblastiaverheyeniana Van den Broeck, Lücking & Ertz (Verrucariaceae) characterized by 3-septate ascospores of 13–15(–17)×3·0–4·5 μm, Porina duduana Van den Broeck, Lücking & Ertz (Porinaceae) characterized by 3-septate ascospores of 11·0–14·5×2·5–3·0 μm, perithecia 130–150(–170) μm diam. and a photobiont with angular-rounded and irregularly arranged cells, Porina gryseelsiana Van den Broeck, Lücking & Ertz (Porinaceae) characterized by orange-brown perithecia and 7–9(–12)-septate ascospores of 29–46×5·0–7·5 μm, Porina weghiana Van den Broeck, Lücking & Ertz (Porinaceae) characterized by the presence of disc-shaped isidia, yellow perithecia without apical appendages and (7–)9-septate ascospores of 33–50×5·0–6·5 μm. In addition, 53 species new for the Democratic Republic of the Congo are listed, including five species new for tropical Africa and six new for the Palaeotropics, thus raising the number of species known from the Democratic Republic of the Congo from 150 to 209. Keys are presented to all known species of Microtheliopsis and to species of Porina with disc-shaped isidia.