Until now, five species of mosses in the family Mniaceae are known from Myanmar. Herein, six species of this family are added to the bryoflora of the country, including Mnium lycopodioides Schwägr., Orthomnion dilatatum (Wilson ex Mitt.) P.C.Chen, O. yunnanense T.J.Kop., X.J.Li & M.Zang, Rhizomnium horikawae (Nog.) T.J.Kop., R. magnifolium (Horik.) T.J.Kop. and R. mieheanum Frank Müll. & T.J.Kop. The latter of these is described and figured as new to science from material collected in Kachin State, northern Myanmar. The taxonomy of Rhizomnium (Mitt. ex Broth.) T.J.Kop. is discussed.

  Schistochila yakushimensis N.Ohnishi & Deguchi is newly synonymized with S. sciurea (Nees) Schiffn. based on molecular phylogenetic analysis using the Thai plants of S. yakushimensis and on morphological observations for both species. A key to the species of Schistochila in Japan is provided.

  Bryoerythrophyllum inaequalifolium (Taylor) R.H.Zander (Pottiaceae) is reported here as a new genus and species record for Thailand, where it occurs on a degraded calcareous substrate in sub-alpine forest at the summit of Doi Chiang Dao Mt., Chiang Dao Wildlife Sanctuary, Northern Thailand. A description, line drawings, photographs, and SEM micrographs are also provided.

  We provide an updated taxonomic revision of the genus Marchantia L. in Japan. Seven taxa [Marchantia emarginata Reinw., Blume & Nees subsp. cuneiloba (Steph.) T.X.Zheng & M.Shimamura, M. paleacea Bertol. subsp. paleacea, M. paleacea subsp. diptera (Nees & Mont.) Inoue, M. papillata Raddi. subsp. grossibarba (Steph.) Bischl., M. pinnata Steph., M. polymorpha L. subsp. polymorpha and M. polymorpha subsp. ruderalis Bischl. & Boissel.-Dub.] were recognized based on the examination of types, newly collected specimens during intensive fieldwork and our recent molecular phylogenetic analyses. For each taxon, morphological descriptions, illustrations of important taxonomic features, distinguishing characters, distribution in Japan, habitat and detailed taxonomic notes were provided. Based on the remarkable morphological discontinuity, the elements of Marchantia subg. Preissia (Corda) D.G.Long, Crand.-Stotl., L.L.Forrest & J.C.Villarreal were reinstated as the genus Preissia Corda and the genus Bucegia Radian. We also discuss the redefinition of the genus Marchantia in anticipation of a comprehensive revision in the future.