Phytotaxa 480 (2): 201–209 https://www.mapress.com/j/pt/ Copyright © 2021 Magnolia Press ISSN 1179-3155 (print edition) Article PHYTOTAXA ISSN 1179-3163 (online edition) https://doi.org/10.11646/phytotaxa.480.2.9 Begonia nangunheensis, a new species of Begoniaceae from Yunnan province, China SHI-WEI GUO1,2,3,6, WEN-HONG CHEN1,2,7, AUNG AUNG1,3,8, SIRILAK RADBOUCHOOM1,3,9, JIN-CHAO ZHAO4,10, ZHI-HONG LI5 & YU-MIN SHUI1,2,11* 1 Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China 2 Karst Conservation Initiative of Yunnan, Kunming 650201, China 3 University of Chinese Academy of Sciences, Beijing 100049, China 4 Management Bureau of Nangunhe National Nature Reserve, Cangyuan Va Autonomous County, 677400, Yunnan, China 5 Management Bureau of Caiyanghe Provincal Nature Reserve, Pu’er City, 665000, Yunnan, China 6 � guoshiwei@mail.kib.ac.cn; https://orcid.org/0000-0001-6987-1240 7 � whchen@mail.kib.ac.cn; https://orcid.org/0000-0002-2033-9648 8 � aungaung.uof@gmail.com; https://orcid.org/0000-0003-3770-731X 9 � sirilak.rad@yahoo.com; https://orcid.org/0000-0002-6027-7832 10 � 320824995@qq.com; https://orcid.org/0000-0002-7928-4645 11 � ymshui@mail.kib.ac.cn; https://orcid.org/0000-0003-2975-7851 * Corresponding author Abstract Begonia nangunheensis belonging to Begonia sect. Platycentrum is described and illustrated as a new species in Caryota obtusa forests in Yunnan province of China. It is similar to Begonia siamensis in 3-winged fruits, 2-loculed ovary and axile placentation with 2 segments per locule, but differs in its glabrous petiole and abaxial leaf-blade, ovate outer tepals and oblanceolate to narrowly obovate inner tepals of staminate flower, and the unequal pistillate tepals. The new species is assigned to Critically Endangered according to the guidelines of IUCN Red List Categories and Criteria (version 13). Keywords: Begonia sect. Platycentrum, Begonia siamensis, Southwestern China, Thailand Introduction Begonia Linnaeus (1753: 1056) grows mainly in the shady and humid habitats of tropical Africa, America and Asia (Doorenbos et al. 1998, Shui et al. 2002, de Wilde 2011, Moonlight et al. 2018). There were 1,925 species of 48 sections and 14 subgenera in this mega-diverse genus recorded by the end of 2018 (Shui et al. 2019) and 1,995 accepted species till 3 December, 2020 (Hughes et al. 2015 onward). Begonia was also divided into 70 sections under different taxonomic treatments (Moonlight et al. 2018). In Asia, Begonia sect. Platycentrum (Klotzsch 1855: 243) de Candolle (1859: 134) is one of two mega-diverse sections with more than 200 species and diverse morphology, such as 2- or 3loculed ovaries, baccate and capsule fruits (Moonlight et al. 2018, Shui et al. 2019). The other is B. sect. Petermannia with 617 species and mainly distributed in S. China to S.E. Asia, extending to the Oceanian islands (Shui et al. 2019). In general, B. sect. Platycentrum is characterized by absence of tubers among the begonias from the Himalaya regions and adaptive to the humid and subtropical montane habitats (Shui & Chen 2017; Hughes et al. 2018). Yunnan province is located in the Southwest of China and adjacent to Vietnam, Laos and Myanmar and becomes one of the hotspots of biodiversity worldwide (Myers et al. 2000). Also, it is the center of the richest species of Begonia of Begoniaceae Agardh (1824: 200) in China and its adjacent countries. Up to 3 December 2020, Yunnan has 97 species of Begonia among the 218 species from China (Huang & Shui 2006, Hughes et al. 2015 onward). In the adjacent countries, there are 81 species in Vietnam, 28 species in Laos, 74 species in Myanmar, 62 species in India, 23 species in Nepal (Hughes et al. 2015 onward). So, the species diversity of Begonia in Yunnan is very high and the further field exploration should be conducted in the future. Accepted by Daike Tian: 18 Dec. 2020; published: 20 Jan. 2021 201 During the surveys of the Caryota obtusa forests in South Yunnan in 2017, two of the authors (SWG and JCZ) have accidentally found an unknown species growing in the Caryota obtusa forests at Nangunhe National Nature Reserve of Cangyuan Va autonomous country, which is bordering with Myanmar (Fig. 1). The robust rhizome, 5 tepals of pistillate flower, 2-loculed ovary with 2 stigmas and capsules revealed that the unknown species is a member of B. sect. Platycentrum. As to the stemless habit, glabrous adaxial surface of leaves, 2 stigmas and 5 petals of pistillate flowers, it is similar to Begonia siamensis Gagnepain (1919b: 278), B. manhaoensis Shui & Huang (1999: 21) and B. subhowii Shui & Huang (1999: 20) in China and its adjacent countries (Gu et al. 2007, Phutthai 2011, Aung et al. 2020). Sharing with the lanceolate-elliptic leaves, the species is similar to B. coptidimontana Wu & Ku (1995: 251), B. medogensis Li et al. ( 2018: 14) and B. taiwaniana Hayata (1911, 125) with the erect stems in B. sect. Platycentrum, and B. acetocella Craib (1912:153), B. balansana Gagnepain (1919a: 194), B. ceratocarpa Shui & Huang (1999: 13), B. longifolia Blume (1823: 102), B. hayamiana Tanaka (2007: 83) in B. sect. Sphenanthera [Hasskarl (1855: 139)] Warburg (1894: 141) with the berry-like fruits, which is combined into B. sect. Platycentrum (Moonlight et al. 2018, Shui et al. 2019). After further comparison of specimens and literatures related to the unknown species and its similar species of China and the adjacent countries (Gu et al. 2007, Phutthai 2011, Shui & Chen 2017, Camfield & Hughes 2018, Hughes et al. 2018), we confirmed that this species is new in B. sect. Platycentrum. FIGURE 1. The Geographical Distribution of Begonia nangunheensis and B. siamensis. Taxonomic Treatment Begonia nangunheensis Y.M.Shui & W.H.Chen, sp. nov. Figs. 2–4 Type: CHINA. Yunnan: Cangyuan Va autonomous county, on the surface of rocks along the valley in the Caryota obtusa forest, 23°16’27” N, 99°10’19” E, elev. 1752 m, 18 January 2017, with flowers, S.W. Guo & H.H. Xi B2017–121 (holotype, KUN!; isotype, PE!) The new species is most similar to Begonia siamensis Gagnepain in 3-winged fruits, 2-loculed ovary and axile placentation with 2 segments per locule, but differs in its petiole glabrous (vs. dense brown pubescent in B. siamensis) and leaf blade abaxially glabrous (vs. dense brown pubescent), ovate and 2.0–2.3 × 1.3–1.6 cm (vs. broadly-ovate to orbicular and 1–1.5 × 1–1.2 cm) outer tepals and oblanceolate to narrowly obovate (vs. oblong) inner tepals of staminate flower, and the unequal (vs. nearly equal size) pistillate tepals. 202 • Phytotaxa 480 (2) © 2021 Magnolia Press GUO ET AL. FIGURE 2. Habitat and morphology of Begonia nangunheensis Y.M. Shui & W.H. Chen, sp. nov. A. Habitat: Caryota obtusa forest; B. Habitat: cliff; C. Whole plant and inflorescence; D. Leaf and young inflorescence; E. Whole plant and rhizome; F. Leaf: adaxial surface; G. Leaf: abaxial surface. Scale bar: C–D = 5 cm, E = 8 cm, F–G = 4 cm. A–E. Photographed by Jin-Chao Zhao, F and G by Yu-Min Shui. BEGoNIA NANGUNHEENSIS Phytotaxa 480 (2) © 2021 Magnolia Press • 203 FIGURE 3. Flowers and fruits of Begonia nangunheensis Y.M. Shui & W.H. Chen, sp. nov. A. Inflorescence with flowers and fruits; B. Pistillate flowers: different view; C. Inflorescence: staminate and pistillate flowers and fruit: lateral view; D. Staminate and pistillate flowers; E. Staminate flower and fruit; F. Pistillate flower, lateral view; G. Staminate flower, back view; H. Face view of staminate flower; I. Front view of androecium; J. Face view of pistillate flower; K. Style; L. Pistillate flower, styles and fruit; M. Middle cross section of ovary. Scale bar: A–G, J, L = 2 cm, H & M= 1 cm, I & K = 2 mm. A–L. Photographed by Jin-Chao Zhao, M by Luo-Yan Li. 204 • Phytotaxa 480 (2) © 2021 Magnolia Press GUO ET AL. FIGURE 4. Begonia nangunheensis Y.M. Shui & W.H. Chen, sp. nov. (Drawn by Ling Wang) A. Habit; B. Male flower; C. Female Flower; D. The middle section of ovary; E. Fruit. Scale bar: A=4 cm, B–E=1 cm. All based on the holotype. BEGoNIA NANGUNHEENSIS Phytotaxa 480 (2) © 2021 Magnolia Press • 205 Herb perennial, rhizomatous. Rhizome 5–10 cm long, 0.4–0.7 cm in diam, with short erect stems 2–12 cm tall. Stipules glabrous, lanceolate, 6–15 × 3–5 mm, margin entire, apex acuminate. Leaves on rhizomes or at the base of short stem, asymmetric, lanceolate-elliptic , 7–16 × 3–8.5 cm, length-to-width ≥ 2; base auriculate, 1.5–3 ×1.5–5 cm; margin with 3–5 shallow lobes, irregularly serrate; apex acuminate to caudate; adaxially green to dark green, glabrous, glossy, abaxially light green, glabrous along nerves; venation greenish, palmate, 6–7 primary veins, 2–4 secondary veins; petiole glabrous, 6–22 cm long, 2–4 mm thick. Inflorescence axillary, usually rising from the short stem with 1–2 smaller leaves than those on rhizomes or at the base of short stem; peduncle glabrous, 8–19 cm long, 1–2 mm thick. Bracts caducous, greenish-brownish, ovate, margin entire, apex acute. Staminate flowers: tepals 4, white (occasionally abaxially red along the main nerves), abaxially glabrous, adaxially glabrous or slightly ramentaceous; outer tepals 2, ovate to broadly ovate, 2.0–2.3 × 1.3–1.6 cm, base rounded, margin entire, curved, apex extended; inner tepals 2, oblanceolate to narrowly obovate, 1.1–1.6 × 0.5–0.7 cm, margin entire, curved, apex obtuse or rounded, base cuneate; stamens numerous, anther broadly obovate with round apex, filament fused at base. Pistillate flowers: pedicel 1.5–2.5 cm long; tepals 5 (or 6), white, abaxially glabrous, adaxially glabrous or slightly ramentaceous; outer tepals, 4 broadly elliptic, 1.5–1.7 × 1–1.5 cm, margin entire, apex obtuse or rounded, base cuneate to rounded; inner tepals 1 (or 2), ovate, 1–1.3 × 0.5–0.7 cm, margin entire, apex acute apex, base cuneate; ovary pinkish to greenish, slightly ramentaceous, 3-winged, locules 2, placentae axile, bifid per locule; styles 2, stigmas bifid with spiral surface. Capsules nodding, unequally 3-winged, slightly ramentaceous, abaxial wing oblong-ovate or triangularly oblong, 1.2–2 × 1.2–1.7 cm, apex obtuse; lateral wing crescent, 1.2–1.7 × 0.4–0.8 cm. Seeds not observed. Phenology: Flowering from December to April in the next year, fruiting from January to May. Etymology: The epithet ‘nangunheensis’ refers to the type locality: Nangunhe National Natural Reserve. Habitat and Distribution: This species is only distributed at Cangyuan Va autonomous county, Yunnan province, Southwestern China. It grows along the cliffs or on the rocks on the forest floor of Caryota obtusa forest in Nangunhe National Nature Reserve. The main accompanying plants are Caryota obtusa Griff. (1845: 480), Dysoxylum sp., Caryodaphnopsis tonkinensis (Lec.) Airy Shaw (1940: 74) in the tree layer, Ardisia sp. and Sarcandra glabra (Thunb.) Nakai (1930: 17) in the shrub layer, and Elatostema platyphyllum Wedd. (1956: 301), E. sinense H. Schroter (1936: 152) and Asplenium sp. in the herb layer. Conservation Status: Begonia nangunheensis is only known from Cangyuan Va autonomous county, Southwestern China. As the local staff of the Management Bureau of Nangunhe National Nature Reserve, the author (JCZ) searched all the potential distributions in the field in the past two years, but so far, only found ca. 25 mature individuals of one population with 400 m2 area (10 m × 40 m). Therefore, we provisionally assessed this new species as Critically Endangered [CR: (B1ab(iii)+C2a(ii)] according to IUCN Standards and Petitions Subcommittee (2017) based on the Chinese data. Additional Examined Specimens: CHINA (Yunnan): Yunnan Province, Lincang city, Cangyuan Va autonomous county, Nangunhe National Nature Reserve, alt. 1752 m, in flowers, 29 April 2018, Zhao Jin-Chao B2017-121A (KUN!); the same locality, 5 December 2020, in flowers and fruits, Zhao Jin-Chao CYNGH286 (KUN). Examined Specimens of Begonia siamensis: LAOS. Attopeu Plateau, Mar 8177, F.F. Harmand 1387 (P!). MYANMAR: Shan state, Ywangan township, 96°32’ 1’’E, 21°6’ 15’’N, elev. 1346 m, 5 Oct 2017, Y.D. Kim et al., MM6355 (HHU!). THAILAND. Chantaburi province, Kao Soi Dao, A.F.G. Kerr s.n. (ABD). Chiang Mai, Doi Suthep, C. Chernsiriwathana 543 (BM); Chiengmai province, Doi Sootep, Payap, Doi Sutep, 98º 54’E, 18º 50’N, 31 Oct 1909, A.F.G Kerr 888 (Syntype, ABD, K). The same locality, A.F.G. Kerr 2606 (ABD). Phitsanulok, Phu Rom Rot, T.Shimizu et al. 11487 (BKF!). Puh Mieng Mountain, K. Larsen et al. 944 (AUU). Loei province, Loei, Phu Luang, alt. 1100–1500 m, 4 Dec 1965, M. Tagawa et al. T 1177 (L!). The same locality, Phu Luang district, Ban Na Noi, Phu Luang wildlife sanctuary, Trai to Knok Huai Tae, alt. 900–1100 m, herb, 20 cm high on rock, in dry evergreen forest, flowers in pinkish, stamens yellow, 19 December 2001, Voradol Chamchumroon V.C. 1211 (BKF132578!). The same locality, Non Yai, alt. 1100 m, on stone by stream, 20 January, 1970, C.F. van Beusekom & C. Phengklai 4114 (L!). Notes: The new species is mostly similar to B. siamensis in auriculate leaf base, ungrooved petioles and obtuse connectives (Figs. 2–5). According to the examination on the specimens of B. siamensis and the book titled as “Asian Begonia: 300 species portraits” edited by Hughes et al. (2018), its leaf blade is variable from ovate to lanceolate with auriculate leaf base. However, the new species we proposed is obviously different from B. siamensis in the morphology of petals and indumenti (Phutthai 2011; Hughes et al. 2018). The detailed differences between them are shown in Table 1. Besides, the new species is also similar to B. manhaoensis in leaf morphology, but considerably differs in the latter’s acute connectives and grooved petioles (Aung et al. 2020). 206 • Phytotaxa 480 (2) © 2021 Magnolia Press GUO ET AL. FIGURE 5. The type specimen of Begonia siamensis Gagnepain (K000035486, K). TABLE 1. The comparison of the new species Begonia nangunheensis and B. siamensis. Characters Leaf blade Leaf abaxial surface Petiole Flowers Outer petals of staminate flower B. nangunheensis lanceolate-elliptic glabrous glabrous white, abaxially rarely pinkish ovate, 2.0– 2.3 × 1.3–1.6 cm, apex obtuse Inner petals of staminate flower oblanceolate to narrowly obovate, 1.1–1.6 × oblong, 0.7–1.2 × 0.5–1.0 cm 0.5–0.7 cm obviously unequal, outer 4, broadly elliptic, nearly equal, all broadly elliptic with obtuse inner 1 ovate or obovate with acute apex apex Petals of pistillate flower BEGoNIA NANGUNHEENSIS B. siamensis ovate, rarely lanceolate-elliptic densely brown pubescent densely brown pubescent pink, rarely white broadly-ovate to orbicular, 1–1.5 × 1–1.2 cm, apex rounded Phytotaxa 480 (2) © 2021 Magnolia Press • 207 A key to the species with lanceolate leaf blades and capsules in Begonia sect. Platycentrum (Begoniaceae) in China and Indo-China region 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 Plants with erect stems .......................................................................................................................................................................2 Plants with short erect stems or no erect stems ..................................................................................................................................5 Plants not lobed ..................................................................................................................................................................................3 Plants shallowly lobed (China).................................................................................................................................B. gungshanensis Leaf base slightly oblique (China and Myanmar) .........................................................................................................B. medogensis Leaf base strongly oblique..................................................................................................................................................................4 Leaves lanceolate, major fruit wing triangular (China)................................................................................................. B. taiwaniana Leave ovate-lanceolate, major fruit wing falcate (China) ...................................................................................... B. coptidimontana Leaf base cuneate or shallowly cordate, slightly oblique ...................................................................................................................6 Leaf base auriculate, strongly oblique ................................................................................................................................................7 Petioles grooved and connectives acute (China, Myanmar) ...................................................................................... B. manhaoensis Petioles not grooved and connectives obtuse .....................................................................................................................................7 Petiole and abaxial leaf-blade glabrous, pistillate tepals unequal (Laos, Myanmar, Thailand) .......................................B. siamensis Petiole and abaxial leaf-blade densely brown pubescent, pistillate tepals nearly equal (China) .............. B. nangunheensis, sp. nov. Leaf base cuneate .............................................................................................................................................................................12 Leaf base truncate or slightly cordate .................................................................................................................................................9 Petiole pubescent ..............................................................................................................................................................................10 Petiole glabrous ................................................................................................................................................................................11 Leaf blade truncate (Myanmar and India) .......................................................................................................................... B. hatacoa Leaf blade shallowly cordate (Myanmar and India)....................................................................................................... B. perakensis Plants without erect stems, leaf margin remotely serrulate, not lobed (China: Guangxi) .................................................. B. tsoongii Plants with short erect stems, leaf margin irregularly and remotely serrate, very shallowly lobed (China: Hongkong) ..................... ................................................................................................................................................................................. B. hongkongensis Peduncle with 1–2 small leaves (Vietnam) ............................................................................................................... B. caobangensis Peduncle without small leaves..........................................................................................................................................................13 Leaf blade 5–7.5 cm wide (China: Yunnan) ............................................................................................................. B. yingjiangensis Leaf blade 2–2.5 cm wide (Myanmar: Kachin)............................................................................................................ B. rheophytica Acknowledgements We thank Ms. Luo-Yan Li, Ms. Chang-Li Fan, Mr. Hui-Hui Xi and Mr. Li Chen from Kunming Institute of Botany, CAS, and Mr. Hong-Qiang Yang, Mr. Qiang Wang from Management Bureau of Nangunhe National Nature Reserve for preparing the figures and joining field work. We also thank Ms. Ling Wang for drawing the illustration. This study was supported by National Natural Science Foundation of China (31770251, 31370228, 31070174, 30270109); Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences (2015CASEABRI001); Committee of Research and Exploration of the National Geographic Society (NGS 8288-07). References Agardh, C.A. (1824) Aphorismi Botanici. Quos, Venia Ampliss. ord. Philos. Lund. Literis Berlingianis, Lundae, 200 pp. Aung, A., Chen, W.H. & Shui, Y.M. (2020) Begonia naga, a synonym of B. manhaoensis (Begoniaceae). Phytotaxa 429: 297–300. https://doi.org/10.11646/phytotaxa.429.4.6 Blume, C.L. (1823) Catalogus van eenige der Merkwaardigste Zoo in-als Uit-heemse Gewassen te Vinden in ‘s Lands Plantentuin te Buitenzorg opgemaakt Door. Directeur van Voorz. Tuin, Batavia, 102 pp. Camfield, R. & Hughes, M. (2018) A revision and one new species of Begonia (Begoniaceae, Cucurbitales) in Northeast India. European Journal of Taxonomy 396: 1–116. https://doi.org/10.5852/ejt.2018.396 Candolle, A. de (1859) Mémoire sur la famille des Bégoniacées. [ser. 4.] Annales des Sciences Naturelles; Botanique 11: 93–149. Craib, W.G. (1912) Contributions to the Flora of Siam. Bulletin of Miscellaneous Information, Kew (3): 144–154. https://doi.org/10.2307/4104569. Doorenbos, J., Sosef, M.S.M. & Wilde, J.J.F.E. (1998) The sections of Begonia including descriptions, keys, and species lists (Studies in BegoniaceaeVI). Wageningen Agricultural University Papers 98 (2): 1–266. Gagnepain, M.F. (1919a) Nouveaux Begonia D’Asie; quelques synonymes. Bulletin du Muséum National d’Histoire Naturelle 25 (3): 208 • Phytotaxa 480 (2) © 2021 Magnolia Press GUO ET AL. 194–201. Gagnepain, M.F. (1919b) Nouveaux Begonia D’Asie; quelques synonymes (Suite). Bulletin du Muséum National d’Histoire Naturelle 25 (4): 276–283. Gu, C.Z., Peng, C.I & Turland, N.J. (2007) Begoniaceae. In: Wu, C.Y., Raven, P.H. & Hong, D.Y. (Eds.) Flora of China. Vol. 13. Science Press & Missouri Botanical Garden Press, Beijing & St. Louis, pp. 153–207. Hasskarl, J.K. (1855) Brief van den Pleer. Verslagen en mededeelingen der Koninklijke Akademie van Wetenschappen 4: 135–141. Hayata, B. (1911) Materials for a flora of Formosa. The Journal of the College of Science, Imperial University of Tokyo, Japan 30 (Art. 1): 125. Huang, S.H. & Shui, Y.M. (2006) Begoniaceae. In: Wu, C.Y. (Ed.) Flora Yunnanica, Vol. 12. Science Press, Beijing, pp. 18–227. Hughes, M., Peng, C.I, Liu, Y., Thomas, D.C., Phutthai, T., Rubite, R.R., Girmansyah, D., Ardi, W.H., Tanaka, N., Mui, C.Y. & Tan, J. (2018) Species Portraits. In: Hughes, M. & Peng, C.I (Eds.) Asian Begonia: 300 species portraits. KBCC Press & RBGE, Taipei & Edinburgh, pp. 1–353. Hughes, M., Moonlight, P., Jara, A., Tebbitt, M. & Pullan, M. (2015–Present) Begonia Resource Centre. The Royal Botanic Gardens, Kew. Available from: http://elmer.rbge.org.uk/begonia/ (accessed 3 December 2020) IUCN Standards and Petitions Subcommittee (2017) Guidelines for Using the IUCN Red List Categories and Criteria, version 13. Prepared by Standards and Petitions Subcommittee. Available from: http://www.iucnredlist.org/documents/RedListGuidelines.pdf (accessed 19 February 2020) Klotzsch, J.F. (1855) Begoniaceen-Gattungen und Arten. Abhandlungen der Königlischen Akadamie der Wissenschaften, Berlin, 1854, 123 pp. Li, J.W., Tan, Y.H., Wang, X.L., Wang, C.W. & Jin, X.H. (2018) Begonia medogensis, a new species of Begoniaceae from Western China and Northern Myanmar. PhytoKeys 103: 13–18. https://doi.org/10.3897/phytokeys.103.25392 Linneaus, C. (1753) Species plantarum, exhibentes plantas rite cognitas ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. Imprensis Laurentii Salvii, Homiae, 1056 pp. Moonlight, P., Ardi, W.H., Padilla, L.A., Chung, K.F., Fuller, D., Girmansyah, D., Hollands, R., Jara-Muñoz, A., Kiew, R., Leong, W.C., Liu, Y., Mahardika, A., Marasinghe, L.D.K., Connor, M.O., Peng, C.I., Pérez, Á.J., Phutthai, T., Pullan, M., Rajbhandary, S., Reynel, C., Rubite, R.R., Sang, J., Scherberich, D., Shui, Y.M., Tebbitt, M.C., Thomas, D.C., Wilson, H.P., Zaini, N.H. & Hughes, M. (2018) Dividing and conquering the fastest-growing genus: Towards a natural sectional classification of the mega-diverse genus Begonia (Begoniaceae). Taxon 67 (2): 267–323. Myers, N., Mittermeier, R.A., Mittermeier, C.G., Fonseca, G.A.B.D. & Kent, J. (2000) Biodiversity hotspots for conservation priorities. Nature 403 (6772): 853–858. Phutthai, T. (2011) The genus Begonia L. (Begoniaceae) in Thailand. Prince of Songkla University, pp. 251–254. Shui, Y.M. & Huang, S.H. (1999) Note on the genus Begonia from Yunnan. Acta Botanica Yunanica 21 (1): 11–23. Shui, Y.M., Peng, C.I & Wu, C.Y. (2002) Synopsis of the Chinese species of Begonia (Begoniaceae), with a reappraisal of sectional delimitation. Botanical Bulletin of Academia Sinica 43: 313–327. Shui, Y.M. & Chen, W.H. (2017) Begonia of China. Yunnan Publishing Group Corporation Yunnan Science & Technology Press, Kunming, pp. 1–285. Shui, Y.M., Chen, W.H., Peng, H., Huang, S.H. & Liu, Z.W. (2019) Taxonomy of Begonias. Yunnan Science and Technology Press, Kunming, 468 pp. Tanaka, N. & Hughes, M. (2007) Begonia (sect. Sphenanthera) hayamiana (Begoniaceae), a new species from Northern Myanmar. Acta Phytotaxonomica et Geobotanica 58 (2/3): 83–86. Warburg, O. (1894) Begoniaceae. In: Engler, A. & Prantl, K. (Eds.) Die Natürlichen Pflanzenfamilien, III (6a). Verlag von Wilhelm Engelmann, Leipzig, pp. 121–150. de Wilde, J.J.F.E. (2011) Begoniaceae. In: Kubitzki, K. (Ed.) The Families and Genera of Vascular Plants, Vol. 10. Springer Press, Berlin, pp. 56–71. Wu, C.Y. & Ku, T.C. (1995) New taxa of the Begonia L. (Begoniaceae) from China. Acta Phytotaxonomica Sinica 33 (3): 251–280. BEGoNIA NANGUNHEENSIS Phytotaxa 480 (2) © 2021 Magnolia Press • 209