Oreocharis caobangensis (Gesneriaceae), a new species from Cao Bang Province, northern Vietnam

TRUONG VAN DO1 , YI-GANG WEI 2 & FANG WEN 2* 

1 Vietnam National Museum of Nature, Vietnam Academy of Science & Technology, 18 Hoang Quoc Viet, Hanoi, Vietnam; email: dovantruong_bttn@yahoo.com. 
2 Gesneriad Conservation Center of China, Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain, Guilin Botanical Garden, Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin 541006, China; email: weiyigang@aliyun.com. 
*author for correspondence: wenfang760608@139.com. 

Abstract A new species of Oreocharis (Gesneriaceae) from Cao Bang province, northern Vietnam is described and illustrated. The new species, Oreocharis caobangensis, is most similar to O. lungshengensis, but it can be easily distinguished from the latter by its petioles densely brownish villous, lateral veins 6–8 pair on each leaf blade, bracts smaller (1.5–2 mm long), corolla outside pubescent and pistil glabrous, 18–20 mm long. 

Keywords: flora of Vietnam, Gesneriaceae, new taxon, Oreocharis

Introduction
Oreocharis Bentham in Bentham & Hooker (1876: 1021) was once thought to be a small genus of Gesneriaceae Richad & Jussieu in Candolle (1816: 182) comprising ca. 29 species from China to Vietnam and Thailand, of which 28 species and five varieties are native to China (Li & Wang 2004). Based on molecular phylogenetic analysis (Möller et al. 2011, Middleton et al. 2013), Oreocharis has been expanded to include all species of the previously defined Ancylostemon Craib (1920: 233), Bournea Oliv. in Hooker (1893: tab. 2254), Dayaoshania Wang (1983: 319), Deinocheilos Wang (1986: 1), Isometrum Craib (1920: 250), Opithandra Burtt (1956: 162), Paraisometrum Wang in Weitzman et al. (1998: 431), Thamnocharis Wang (1981: 485), Tremacron Craib (1918: 217) and some species formely described in Briggsia Craib (1920: 238). Further molecular studies on the enlarged concept of Oreocharis and taxa in Briggsia lead to the transfering of rosette-forming plants in Briggsia to Oreocharis (Möller et al. 2014, 2016), which made the genus Oreocharis s. l. comprise at least 108 species (Tan et al. 2013, 2015, Rossini & Freitas 2014, Cai et al. 2015, Li & Li 2015, Yang et al. 2015, Chen et al. 2015, 2016, Möller 2015, Möller et al. 2016). For this broad sense of Oreocharis, ca. 104 species were documented native to China and with 100 endemic species, while only one species, O. aurea Dunn (1908: 19), was reported from Vietnam (Pham 1993, 2000, Nguyen 2003, Phuong 2005, Möller et al. 2011). In October 2013, during a field investigation in Phia Oac-Phia Den National Park in Cao Bang Province, Vietnam, we found some special flowering plants of Oreocharis that are endemic to the Phia Oac peak. After reviewing relevant literature (Wang et al. 1990, 1998, Pham 1993, 2000, Nguyen 2003, Li & Wang 2004, Phuong 2005, Wei et al. 2010, Möller et al. 2011, 2016), we suggest it to be a new species and here describ and illustrate it below.

Taxonomic treatment
Oreocharis caobangensis T.V.Do, Y.G.Wei & F.Wen, sp. nov. (Figs. 1 & 2) It is morphologically similar to Oreocharis lungshengensis (W.T.Wang 1975: 102) Mich.Möller & A.Weber (2011: 23), but it differs from the latter in having petioles densely brownish villous (vs. densely white pubescent), lateral veins of leaf blade 6–8 pair (vs. 4–6 pairs), bracts smaller and only 1.5–2 mm long (vs. 4–9 mm long), corolla outside pubescent (vs. sparsely glandular puberulent), and pistil 18–20 mm long and glabrous (vs. (12–)25–35 mm long and sparsely pubescent near apex). 
Type:—VIETNAM. Cao Bang Province: Nguyen Binh District, Phia Oac-Phia Den National Park, on the trail to Phia Oac peak, 22°36′25.27″ N, 105°52′10.12″ E, elev. ca. 1570 m, 26 October 2013, T.V. Do 57 (holotype: VNMN!; isotype: IBK!).

Oreocharis caobangensis
FIGURE 1. Oreocharis caobangensis. A. Habitat, B. Frontal view of corolla, C. Opened corolla showing stamens, D. Stamens (anthers and filaments) (D1 & D2: the filaments at the insertions of corolla inner), E. Pistil, F. Stigma (Drawn by Ms. Xuan Wen)

Oreocharis caobangensis
FIGURE 2. Oreocharis caobangensis. A Habit, B. Plant and cymes, C. Frontal and lateral view of corollas, D. Lateral view of cymes and corollas, E. Top view of corolla, F. Opened corolla showing stamens, G. Young fruits and fruit peduncle (Photographs by Fang Wen (A, C, D, E) and Do Van Truong (B)).
Phytotaxa 302 (1): 065–070

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