AbstractThree new species ofAtlaare described from calcareous rocks in northern Finland based on morphology and ITS sequences. All new species have dark brown spores but have smaller perithecia and spores than previously known brown-spored species ofAtla.Atla tibelliorumsp. nov. resemblesSporodictyon arcticum, but has a dark brown exciple and larger spores.Atla oulankaensissp. nov. andA. vitikaineniisp. nov. differ fromA. alpinain the smaller perithecia and spores. Atla vitikaineniihas an involucrellum often slightly diverging from the exciple.Atla oulankaensisis similar toA. vitikainenii, differing in slightly narrower spores and in having some involucrella incurving under the exciple or even enveloping the exciple. An unidentified ITS sequence from Canada obtained from GenBank most probably belongs toA. oulankaensisand another unidentified sequence from the USA toA. tibelliorum. The new results strengthen the conclusion that the genera ofAtlaandSporodictyoncannot be separated by morphology alone. A key to all known species ofAtlaandSporodictyonis provided.