著者

Kenji Suetsugu Shun K. Hirota Koji Yonekura Atsushi Abe Yoshihisa Suyama Tian-Chuan Hsu

出版者

The Japanese Society for Plant Systematics

雑誌

Acta Phytotaxonomica et Geobotanica (ISSN:13467565)

巻号頁・発行日

vol.74, no.2, pp.121-129, 2023-07-31 (Released:2023-09-08)

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The present study documents the first record of Thrixspermum annamense (Orchidaceae) from Iriomote Island, Ryukyu Islands, Japan, expanding its known distribution beyond Vietnam, Thailand, Taiwan, China, and Malaysia. While the morphologically similar taxon T. fantasticum is present on the island, it can be distinguished from T. fantasticum by its somewhat narrower and more rigid leaves, slightly narrower sepals, densely hairy midlobe of the lip, and the absence of two horn-like appendages at the base of the midlobe. A detailed morphological analysis also revealed that the plants discovered on Iriomote Island closely resemble T. annamense from Taiwan but show consistent morphological and molecular distinctions from T. annamense from Vietnam, the type locality. Despite those differences, the high similarity in gross morphology and most lip structures of the plants from Japan, Taiwan, and Vietnam indicates that they all belong to T. annamense at the species level. Consequently, considering the genetic and morphological differences, we propose resurrecting the name T. devolianum, originally described from Taiwan, and reclassifying it as a variety of T. annamense (T. annamense var. devolianum). A neotype for T. devolianum is also designated.