Begonia nangunheensis Y.M.Shui & W.H.Chen, 2021

Guo, Shi-Wei, Chen, Wen-Hong, Aung, Aung, Radbouchoom, Sirilak, Zhao, Jin-Chao, Li, Zhi-Hong & Shui, Yu-Min, 2021, Begonia nangunheensis, a new species of Begoniaceae from Yunnan province, China, Phytotaxa 480 (2), pp. 201-209 : 202-206

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.

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 m 2 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 B2017-121 A ( 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).

Figures

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.

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.

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.