Hedychium putaoense (Zingiberaceae), a new species from Putao, Kachin State, Northern Myanmar

Abstract Hedychium putaoense Y.H. Tan & H.B. Ding, a new species of Zingiberaceae from Putao, Kachin state, Northern Myanmar, is described and illustrated. It is similar to H. densiflorum Wall. and H. longipedunculatum A.R.K. Sastry & D.M. Verma, but differs by its very small bract (4–6 × 2.5–3 mm vs. 18–19 × 5–5.5 mm and ca. 11 × 7 mm, respectively), semicircle and dark red bracteole, orange flower and broadly falcate to lanceolate lateral staminodes.


Introduction
The pantropical Zingiberaceae is the largest family in the monophyletic order Zingiberales with 53 genera and more than 1377 species (Kress et al. 2002;Pederson 2004;Kong et al. 2010). Hedychium Koenig, commonly called the "ginger lily" or "butterfly lily", produces one of the most beautiful and fragrant flowers in the family Zingiberaceae (Sanoj et al. 2010). The genus was established by Koenig in 1783, based on the species H. coronarium Koenig. There is currently little consensus on the number of species, with recent estimates varying from about 50 (Wu and Larsen 2000) to 80 (Sirirugsa and Larsen 1995) and these are mainly distributed throughout most of tropical Asia (Sirirugsa and Larsen 1995;Wood et al. 2000). The genus has its highest species diversity in the tropical and subtropical Himalayan region (Sanoj et al. 2010). Hedychium is characterised by flowers with very long (rarely short) filaments, dorsifixed anther and usually fragrant flowers (Hu and Liu 2010a). Members of the genus can be easily recognised by their showy, many-flowered terminal spikes, some of which have been cultivated worldwide (Picheansoonthon and Wongsuwan 2011).
Several new species of Hedychium have been described in the last few decades (Williams et al. 2003;Wongsuwan 2008;Wongsuwan 2009, 2011;Sanoj et al. 2010;Liu 2010a, 2010b;Sanoj and Sabu 2011;Thomas et al. 2015;Odyuo and Roy 2017  . From April to May in 2017, a team from the Xishuangbanna Tropical Botanical Garden (XTBG) in collaboration with the Forest Research Institute of Myanmar, conducted field work in Northern Myanmar to survey plant diversity. During field work, some interesting specimens of Hedychium were found in Putao, Kachin state. Based on a detailed examination of the morphological characteristics of the collected material and those of the closely related similar species, the authors have arrived at the conclusion that the specimens of Hedychium collected in Myanmar belong to a species new to science, which are described and illustrated herein.

Material and methods
Measurements and morphological character assessments of the new species Hedychium putaoense have been examined based on fresh materials and dried specimens. It has been compared with the morphologically similar species H. densiflorum, H. longipedunculatum, with affinities inferred using descriptions, type specimens and other herbarium specimens (Wallich 1832; Sastry and Verma 1968;Wu and Larsen 2000;Moaakum and Dey 2013). Protologues and images of type specimens were gathered from JSTOR Global Plants (http://plants.jstor.org). it can be easily distinguished by its very small bract (4-6 × 2.5-3 mm vs. 18-19 × 5-5.5 mm and ca. 11 × 7 mm, respectively) and bracteole (2-2.5 × 3-3.5 mm vs. ca. 9 × 2 mm and ca. 6 × 4 mm, respectively), orange flower and broadly falcate to lanceolate lateral staminodes.
Phenology. Flowering from May to July. Distribution and habitat. This new species is known to grow at the top of the mountain from Masabu village to Namti village, Putao District, Kachin State, where it grows epiphytically on the trees of tropical montane forests at an elevation of ca. 1400-1800 m.
Etymology  1968), e.g. non-imbricating bracts, cincinnus 1-flowered, small and dense flower, oblong anther and sub-globose ovary. After comparison with specimens and descriptions in literature, it was found that H. putaoense can be clearly differentiated from the latter two species, even on the basis of their vegetative characters: e.g. the proportion of the bract to the calyx; H. putaoense has very small bracts that are shorter than the calyx (4-6 vs. 12-14 mm), whereas, the bracts of H. densiflorum are longer than the calyx (18-19 vs. 13-14 mm) and the bracts of H. longipedunculatum are equal in length with that of the calyx (ca. 11 vs. 11 mm). H. putaoense, furthermore, differs in having semicircular and dark red bracteole, corolla tube curved towards the tip by about 90° to 180°, orange lateral staminodes and labellum, filament intensely curved towards the tip by about 180°, densely villous ovary and dark red stigma. H. densiflorum has tubular and pale green bracteole, corolla tube slightly bent to one side towards the tip, orange-red lateral staminodes and labellum, straight filament, glabrous ovary and yellow stigma. H. longipedunculatum from India has notched ligule, hairy rachis, triangular bract, ovate bracteole, creamy yellow flower, erect corolla tube, straight filament and green stigma. A detailed comparison of the morphological differences amongst these taxa is given in Table 1 and the evidence from morphological analysis supports the recognition of H. putaoense as a distinct species.