The leafy liverwort Mesoptychia (Lindb.) A. Evans was treated as being monotypic since its inception in 1889. Hattoriella and Leiocolea were recently synonymised with it, increasing its species to 17 and expanding its range to encompass the whole of the Holarctic zone, with an outlier in Sumatra. To define Mesoptychia, test its monophyly and establish its phylogenetic position within the Jungermanniales, the first systematic revision of this genus was conducted using an integrative taxonomic approach: a detailed taxonomic revision combined with multivariate statistical analyses of character traits and two phylogenetic studies using molecular markers (rbcL, rps4, psbA-trnH, trnL-F, ITS2). Mesoptychia was shown to be monophyletic and nested within the Jungermanniaceae. Eleven species and two varieties are now recognized in Mesoptychia and one potential cryptic entity was revealed. The most discriminating characters were found to be the presence or absence of underleaves, the shape of the underleaves and sexuality.