Gastrodia putaoensis sp. nov. (Orchidaceae, Epidendroideae) from North Myanmar

Gastrodia R.Br. (Gastrodieae, Epidendroideae, Orchidaceae) is a genus of mycoheterotrophic plants, comprising approximately 90 species, distributed from India and eastern Asia, through Malaysia to Australia, as well as in tropical Africa (Pearce and Cribb 2002, Pridgeon et al. 2005, Chen et al. 2009, Cribb et al. 2010, Govaerts et al. 2016, Suetsugu 2016, 2017, Tsukaya and Hidayat 2016). Gastrodia is characterized by a a tuberous rhizome, sepals united into tube throughout most of their length, a spurless lip, pollinia two and sectile, and a shield shaped stigma positioned at the base of the column (Pearce and Cribb 2002, Pridgeon et al. 2005, Chen et al. 2009). During our fieldwork in Hkakarborazi Natural Park, Putao, Kachin State, Myanmar, from 2010 to 2016, a new species of Gastrodia, described below, was discovered.

Gastrodia R.Br. (Gastrodieae, Epidendroideae, Orchidaceae) is a genus of mycoheterotrophic plants, comprising approximately 90 species, distributed from India and eastern Asia, through Malaysia to Australia, as well as in tropical Africa (Pearce and Cribb 2002, Pridgeon et al. 2005, Chen et al. 2009, Cribb et al. 2010, Govaerts et al. 2016, Suetsugu 2016, 2017, Tsukaya and Hidayat 2016. Gastrodia is characterized by a a tuberous rhizome, sepals united into tube throughout most of their length, a spurless lip, pollinia two and sectile, and a shield shaped stigma positioned at the base of the column (Pearce and Cribb 2002, Pridgeon et al. 2005, Chen et al. 2009).
During our fieldwork in Hkakarborazi Natural Park, Putao, Kachin State, Myanmar, from 2010 to 2016, a new species of Gastrodia, described below, was discovered.
Gastrodia putaoensis X.H. Jin sp. nov. (Fig. 1-3.) A species similar to G. dyeriana, but differing by having greyish white flowers with the lip narrowly triangular and subdivided into two parts with the apical part near tip densely covered with yellow hairs, and the lip apex obtuse and densely covered with red papillae.

Etymology
The epithet of the new species is derived from the name of Putao District, northern Myanmar, where the type was collected.

Description
Mycoheterotrophic leafless plant, 20-45 cm tall. Rhizome short, horizontal, greyish black with 3-5 spreading roots, 5-8 mm in diameter. Stem with 2-3, glabrous, 20-40 cm long. Inflorescence 10-15 cm long, laxly 3-to 6-flowered. Floral bracts short, ovate, membranous, 0.5 mm long. Pedicel 3 mm long. Flowers greyish white with sepal lobes slightly purple-tinged, pendent, more or less campanulate, 7-8-veined; tube 1.3 cm long, entire, 3-lobed at apex; sepal lobes triangular, their margins entire, 3 mm long, 3 mm wide; petals inserted at apex of sepal tube, ovate, 2 mm long, 2 mm wide; petal lip narrowly triangular, clawed, 5-6 mm long, 3-4 mm wide, strongly constricted at two thirds and subdivided into a basal part and an apical part, the basal part elliptic, with 3-5 parallel and thickened lines from the base to the base of the apical part, the apical part densely covered with yellow hairs, obtuse and densely covered with red papillae at apex; claw short, with two yellow, subglobose and raised calli. Column 5 mm long, with winged sides, with two long and erect teeth at apex; foot short, about 1 mm long; pollinia void. Ovary 4 mm long.

Ecology and distribution
Gastrodia putaoensis grows under montane broadleaf evergreen forest at 2000-2200 m a.s.l. During our fieldwork in Hkakaborazi in 2016, two populations with approximately 2000 plants were discovered. Both populations are far from any direct threats. Hence, this new species should be considered as 'Least Concern' (LC) according to IUCN Red List Categories and Criteria (IUCN 2001).

Similar species
Morphologically, G. putaoensis is closely related to G. dyeriana, G. gracilis, G. longibubularis, G. menghaiensis, and G. wuyishanensis. All these species have campanulate flowers and the disc of lip with a thickened line. However, G. putaoensis can readily be distinguished from them by  having a triangular lip subdivided into two part, of which the apical part is densely covered with yellow hairs and the apex is obtuse and densely covered with red papillae (Table 1).
Funding -This research was supported by grants from Southeast Asia Biodiversity Research Inst., Chinese Academy of Sciences (grant no. Y4ZK111B01), the National Natural Science Foundation of China (grant no. 31670194, 31110103911).