Sedum formosanum subsp. miyakojimense (Crassulaceae) 51 Sedum formosanum subsp. miyakojimense (Crassulaceae), a new subspecies from Miyako-jima Island of the Ryukyu Islands, Japan Takuro Ito 1,2 , Chih-Chieh Yu 3 , Masatsugu Yokota 4 , Goro Kokubugata 2 1 Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan 2 Department of Botany, National Museum of Nature and Science, Amakubo 4-1-1, Tsukuba, Ibaraki 305-0005, Japan 3 CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China 4 Laboratory of Ecology and Systematics, Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan Corresponding author: Takuro Ito (896wfbt5@gmail.com) Academic editor: Y. Mutafchiev  |  Received 16 January 2020  |  Accepted 24 March 2020  |  Published 26 May 2020 Citation: Ito T, Yu C-C, Yokota M, Kokubugata G (2020) Sedum formosanum subsp. miyakojimense (Crassulaceae), a new subspecies from Miyako-jima Island of the Ryukyu Islands, Japan. PhytoKeys 148: 51–70. https://doi.org/10.3897/ phytokeys.148.48957 Abstract We re-examined the taxonomic status of plants treated as Sedum formosanum (Crassulaceae) from Miyako- jima Island of the Ryukyu Islands, Japan, using morphological comparison and molecular phylogenetic analyses with related species. In morphology, plants from Miyako-jima Island bore a close resemblance to the other plants of S. formosanum, but difered in being perennial, polycarpic, and having lateral axillary branches. Molecular analyses based on ITS of nrDNA and six regions of cpDNA sequencing indicated that the Miyako-jima plants formed a distinct subclade. Tis subclade was part of a polytomy with three other subclades comprising nine taxa endemic to Taiwan and S. formosanum from other areas, including the type locality. Terefore, we propose and describe the Miyako-jima plants as a new subspecies, Sedum formosanum subsp. miyakojimense. Keywords Miyako Islands, phylogeny, stone crop, succulent plants, taxonomy Copyright Takuro Ito et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. RESEARCH ARTICLE Launched to accelerate biodiversity research A peer-reviewed open-access journal PhytoKeys 148: 51–70 (2020) doi: 10.3897/phytokeys.148.48957 http://phytokeys.pensoft.net