Taxonomic revision of the genus Marchantia (Marchantiaceae) in Japan and the redefinition of the genus

Abstract

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.