Phytotaxa 302 (1): 097–100 ISSN 1179-3155 (print edition) http://www.mapress.com/j/pt/ PHYTOTAXA Copyright © 2017 Magnolia Press Correspondence ISSN 1179-3163 (online edition) https://doi.org/10.11646/phytotaxa.302.1.11 Chimonocalamus elegans, a new temperate woody bamboo species (Poaceae: Bambusoideae) from Doi Phu Kha National Park, Thailand ATCHARA TEERAWATANANON1, 2, 4, DOKRAK MAROD3, 4, TREVOR R. HODKINSON5 & SARAWOOD SUNGKAEW2, 3, 4* 1Natural History Museum, National Science Museum, Technopolis, Pathum Thani 12120, Thailand. 2Center of Excellence for Bamboos, Kasetsart University, Bangkok 10900, Thailand. 3Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand. 4Center for Advanced Studies in Tropical Natural Resources, Kasetsart University, Bangkok 10900, Thailand. 5Botany Building, School of Natural Sciences, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland. *Corresponding author, e-mail: [email protected]. Chimonocalamus elegans, a tentatively endemic new species of temperate woody bamboos from Northern Thailand is de- scribed and illustrated. The new species differs from other members of Chimonocalamus by its glabrous nodes, culm leaf sheaths with narrow apex (3−4 mm) and 4−7 mm long ligules. Key words: Arundinarieae, endemic, IUCN Introduction Doi Phu Kha National Park is considered to be one of the key biodiversity areas in the Indo-Burma Hotspot (Mittermeier et al. 1998, Myers et al. 2000, Tordoff et al. 2012). The national park mainly consists of mountainous ranges and valleys, lying in a north to south direction and ranging in elevation from about 500 m to 1980 m a.s.l. Its vegetation types vary with elevation, so that as one moves from low to high elevation there is a transition from deciduous dipterocarp forest, to dry evergreen forest, to lower montane forest and to lower montane scrub (ICEM 2003, Srisanga 2005). There is no unique floristic element for Thailand, which transcends a north-to-south change in natural biomes. It can be divided into three major floristic groups, namely: 1) an Indo-Burmese element (East Himalayan element) from Northeast India, Nepal, Bhutan, Sikkim, Bangladesh and Myanmar, 2) an Indo-Chinese element from South China, Lao PDR, Vietnam and Cambodia and 3) a Malesian element from Malaysia and Indonesia (Srisanga 2005, Van Welzen et al. 2011). The flora of the Doi Phu Kha has characteristics of both the Indo-Burmese and Indo-Chinese elements, providing the southernmost distributional limit for many genera, especially in the lower montane forest, such as Bretschneidera Hemsley (1901: pl. 2708) (Akaniaceae), Helwingia Willdenow (1806: 716) (Helwingiaceae) and Dactylicapnos Wallich (1826: t. 39) (Papaveraceae) (Srisanga 2005). The Indo-Burmese element is also a key area for temperate woody bamboo genera including Chimonocalamus Hsueh & Yi (1979: 75) which belongs to the tribe Arundinarieae (Sungkaew et al. 2009, Hodkinson et al. 2010). This genus comprises about 17 species which have limited distribution and are narrowly endemic (Li & Stapleton 2006, Le et al. 2009, Triplett & Clark 2010, Yang et al. 2013). Members of Chimonocalamus are recorded from elsewhere including southwest China, northeast and north India and north Vietnam but have never been reported from Thailand (Ohrnberger 1999, Li & Stapleton 2006). We found a new species to show that Doi Phu Kha National Park is the southernmost known limit for the distribution of this temperate bamboo genus. During research on the biodiversity of temperate woody bamboos in Thailand, voucher specimens with flowers were found of an unnamed Chimonocalamus species. Previously, this bamboo was placed in the genus Chimonocalamus in a phylogenetically study by Sungkaew et al. (2009). It grouped with C. pallens Hsueh & Yi (1979: 78) with high support but was also distinct in its sequences of the trnL-F atpB-rbcL, rps16 and matK regions of plastid DNA (GenBank numbers EU434045, EU434109, EU434173, EU434237, respectively). However, no flowering specimens of this species were observed at that time. Based on the distinctiveness of the newly discovered flowering material, we recognize and describe this as a new species to science. Accepted by Yunfei Deng: 20 Jan. 2017; published: 28 Mar. 2017 97 FIGURE 1. Chimonocalamus elegans. A. Flowering branchlet; B. Portion of culm showing node; C. Culm leaves on the new shoot (flying shoot); D. Culm leaf sheaths; E. Spikelet without glumes; F. Glumes; G. Lemmas; H. Paleas; I. Lodicules. Drawn by A. Teerawatananon from P. Pinyo s.n. (BKF). 98 • Phytotaxa 302 (1) © 2017 Magnolia Press TEERAWATANANON ET AL. Taxonomic treatment Chimonocalamus elegans Sungkaew & Teerawat., sp. nov. (Fig. 1) Diagnosis: The new species differs from other members of Chimonocalamus in having glabrous nodes, culm leaf sheaths with narrow apex (3−4 mm) and 4−7 mm long ligules. Type:—THAILAND. Nan Province: Doi Phu Kha National Park, 18°53’33.4”N, 101°12’59.7”E, ca. 1,700 m a.s.l., 24 August 2004, P. Pinyo s.n. (holotype BKF!, isotypes BK!, Natural History Museum, Thailand!). Description:—Arborescent, unarmed bamboo. Rhizomes pachymorph with short necks, forming a dense clump of culms. Culms erect, 2−3 m tall, 0.8−1.2 cm in diameter, glabrous; nodes prominent, glabrous, the basal nodes with a ring of root- thorns that are 2−4 mm long; internodes terete, 10−20 cm long, walls thin, 1−1.5(−2) mm thick (mid-culm portion). Branches developing from the lower quarter or from around the mid-culm upwards. Mid-culm branch complement with 3 sub-equal branches at each node. Culm leaf sheaths 10−17 × 2−3 cm, top shallowly convex to truncate, back covered with sparsely appressed golden-brown hairs, especially at the upper half, margins scarious, apex 3−4 mm wide; culm leaf blades erect to patent, narrowly triangular, 4−6 × 0.15−0.3 cm; auricles absent, oral setae few, 1−1.5 cm long; ligule 4−7 mm long, margin fimbriate. Leaves 3−7 per branchlet; blade with inconspicuous transverse veins, 6−13 × 0.4−0.7 cm, glabrous, occasionally sparsely hairy on nerves, base rounded to acute or attenuate, apex acuminate, pseudo-petiole 0.2−0.5 cm long; leaf sheaths 1.5−3 cm long, glabrous, margins scarious; oral setae 3−7, 3−7 mm long; ligules membraneous, 0.5−1 mm long, margin irregularly toothed. Inflorescence semelauctant, a panicle (with a raceme-like arrangement of stalked spikelets), terminal to a leafy branch, 3−6 cm long; rachis filiform, 3−8 mm long. Spikelets 1.5−3 cm long; empty glumes 2, perfect florets 2−3 and vestigial terminal florets 1–2, disarticulating below each floret; glumes similar, coriaceous, 4−7 mm long, mucronate to acute, margins ciliate at upper half, 3−7-nerved; rachilla internodes between the florets compressed, 1−5 mm long, upper half pubescent; lemmas coriaceous, lanceolate, 7−9 mm long, mucronate to acute, margins ciliate at upper half, 7−9-nerved; paleas chartaceous, 3−8.5 mm long, 2-keeled, keels ciliate, 3-nerved between keels, 1-nerved on each wing; lodicules 3, membraneous, 0.8−1.5 mm long, margins ciliate; anthers 3, ca. 5 mm long, filaments free. Ecology and distribution—It is only found at Doi Phu Kha National Park, Nan Province, Thailand. It grows in the understory of montane forest around the summit, at ca. 1,600−1,700 m a.s.l. Conservation status—According to the IUCN Red List criteria (IUCN 2011), Chimonocalamus elegans could be considered as Endangered (EN) or possibly Extinct (EX). The taxon is known only from a single collection made in the Nan Province of northern Thailand in 2004 by Mr. Piya Pinyo, despite subsequent attempts by the authors to re-collect it. However, insufficient data exist regarding its distribution, so we provisionally assign the species conservation status as Data Deficient (DD). Acknowledgements The authors are grateful to Miss Wiraporn Baiya and other staff of Doi Phu Kha National Park for their help and support. Special thanks to Mr. Piya Pinyo and Dr. Supagit Vinitpornsawan for providing us with more information about the taxon. This paper was supported by the Higher Education Research Promotion, and National Research University Project of Thailand, Office of the Higher Education Commission and the Thailand Research Fund (TRF), Research Grant for New Scholar (MRG5480265). References Hemsley, W.B. (1901) Bretschneidera sinensis Hemsl. Hooker’s Icones Plantarum Ser. 4 8: pl. 2708. 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