190–192 (2019)

J. Jpn. Bot. 94(3): 190–192 (2019)

Kenji Sa,*, Hidekazu Mb, Seibun H and Masatsugu Yd: New Locality of the Mycoheterotrophic Orchid Didymoplexi ella siamensis (Orchidaceae) from Amami-Os hima Island, Kagoshima Prefecture, Japan aDepartment of Biology, Graduate School of Science, Kobe University, 1-1, Rokkodai, Nada-ku, Kobe, 657-8501 JAPAN; bAmami, Kagos hima, 894-0024 JAPAN; cUrasoe, Okinawa, 901-2112 JAPAN; dGraduate School of Engineering and Science, University of the Ryukyus, 1, Senbaru, Nishihara, Okinawa 903-0213, JAPAN *Corresponding author: [email protected]

(Accepted December 19, 2018)

Summary: We found a mycoheterotrophic third distributional record of D. siamensis from orchid Didymoplexiella siamensis (Rolfe ex Japan. Downie) Seidenf. (Orchidaceae) from Amami- Oshima Island, Kagoshima Pref., Japan. So far, Didymoplexiella siamensis (Rolfe ex in Japan, D. siamensis has been reported only Downie) Seidenf. in Bot. Tidsskr. 67: 99 (1972). from Yakushima Island and Tanegashima Island, Leucolena siamensis Rolfe ex Downie in Kagoshima Pref. Bull. Misc. Inform. 1925: 416 (1925). The genus Didymoplexiella Garay Didymoplexiella denticulata Aver. in ( Orchidaceae) consists of seven Taiwania 55: 92 (2010). mycoheterotrophic species (Averyanov 2011, Voucher specimen: JAPAN, Central Ryukyu Islands. Kagoshima Pref., Amami-Oshima Island, Amami City, 13 Hu et al. 2014, Tsukaya et al. 2014). This genus May 2018, H. Morita N15-C (TNS, spirit collection). is similar to Didymoplexis Griff. in both habit Additional specimens examined: JAPAN, Northern and floral appearance, even being considered Ryukyu Islands. Kagoshima Pref., Yakushima Island: congeneric by several authors (e.g., Holttum Nakasegawa-rindo, Yaku-cho, 9 June 1984, K. Miura s.n. (KYO); Yaku-cho, 16 June 1976, F. Maekawa s.n. 1953). However, Didymoplexiella can be (TNS01014021); loc. cit., 2 June 1982, T. Hashimoto s.n. distinguished from Didymoplexis by the presence (TNS8503788); Yaku-cho, 22 May 1993, J. Kanda & Y. of long recurved stelidia on the tip of the column Hanei s.n. (TNS8502375); Yaku-cho, 22 May 1993, J. and the absence of a distinct column foot (Hu et Kanda & Y. Hanei s.n. (TNS8504404); Yaku-cho, along al. 2014). Borneo is known to have the highest the Hanaage River, 22 May 1993, J. Kanda & Y. Hanei s.n. (TI); loc. cit., 22–23 May 1993, J. Kanda & Y. Hanei s.n. diversity of Didymoplexiella, harboring six (TI). Kagoshima Pref., Tanegashima Island: Nakatane-cho, species. Another species D. siamensis (Rolfe 28 May 2007, K. Maruno s.n. (KAG 086694). ex Downie) Seidenf. is known from Thailand, Note: About 20 flowering individuals Vietnam, China (Hainan, Hong Kong), Taiwan were found in a dense forest dominated by and Japan (Maekawa 1977, Hu et al. 2014, Shen Castanopsis sieboldii (Makino) Hatus. in et al. 2015). Amami-Oshima Island. So far, in Japan, D. siamensis has only been Averyanov (2010) recently described D. reported from the Ohsumi Islands (Yakushima denticulata using specimens collected from Island and Tanegashima Island), the Northern Vietnam. The taxon was distinguished from D. Ryukyus (Maekawa 1977, Inoue 2016). Here we siamensis by finely denticulate margins on the report D. siamensis from Amami-Oshima Island, lateral and midlobes of the lips. However, Hu the Central Ryukyus, Japan (Fig. 1). This is the et al. (2014) examined the morphology of D.

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末次健司a，森田秀一b，比嘉清文c，横田昌嗣d：コカゲラン（ラン科）を奄美大島から記録する奄美大島でラン科のコカゲランDidymoplexiella いる可能性があり，詳細な分布状況の検討が望まれる． siamensis (Rolfe ex Downie) Seidenf. の開花個体を発見（a神戸大学理学研究科，した．これは，タイ，ベトナム，香港，海南島，台湾と b鹿児島県奄美市，屋久島に次ぐ産地である．琉球列島で，菌従属栄養植物 c沖縄県浦添市，の新分類群や新産地の報告が相次いでいることを考え d琉球大学理学部海洋自然科学科）ると，他の琉球列島の島々においても，本種が分布して