Begonia liangguangensis D.K.Tian & J.Y.Zhou, 2024

Tian, Dai-Ke, Zhou, Jin-Ye, Xiao, Yan, Wu, Yan-Nong, Hu, Ren-Chuan, Dong, Xun & Guan, Shi-Kai, 2024, Three new species of Begonia (sect. Platycentrum) from South China, Phytotaxa 675 (2), pp. 147-157 : 148-150

1. Begonia liangguangensis D.K.Tian & J.Y.Zhou , sp. nov. § Platycentrum (两ḞữåDz) ( Fig. 1 )

Type:— CHINA. Guangxi Zhuang Autonomous Region, Hechi city (ñàḿ), Wuxu town (五圩ḋ), back cave of Laohuyan ( AE Ẽä后 fi), 24°39'N, 107°55'E, alt. 300 m, with fruits, 16 November 2016, Daike Tian, Yi Tong, Yan Xiao, Lizhi Tian TDK3025 (holotype CSH [ CSH 0150087], isotypes CSH [2]).

Diagnosis:— Begonia liangguangensis is mostly similar to B. pedatifida Léveillé (1909) but differs in its taller (up to 80 cm vs. 40 cm) habit mostly having a 1–2 (–3)-internoded aerial stem at anthesis (vs. usually lacking an aerial stem or occasionally with 1-internoded aerial stem), mature petiole glabrous or nearly so (vs. densely or sparsely villous), leaf blade usually abaxially red-purple to only red-purple near the margin (vs. usually green and rarely red), later flowering (September–October vs. June–September), loosely arranged (vs. partially overlapped) narrower (8–17 mm vs. 10–20 mm wide) outer tepals of pistillate flower. In addition, the distributions of two species do not overlap.

Herb, evergreen perennial, rhizomatous, monoecious, 15–80 cm tall (including aerial stem at anthesis), aerial stem 1–2(–3)-internoded or absent at anthesis. Rhizome creeping, stout, 6–30 cm long, 0.5–3.6 cm thick, dark reddish-brown, nearly glabrous, unbranched to occasionally branched 1–2 times, internodes inconspicuous with pale spots. Stipules caducous, deep red, triangular, glabrous throughout, dorsal ridge and apex awn absent, entire, 8–20 × 8–16 mm. Petioles light green to reddish-brown, usually gradually deepening to reddish-brown downward to the base, cylindrical, 4–73 cm long and 1.5–12 mm thick, densely gray-white pubescent when young, nearly glabrous when mature. Leaves 3–8, mostly basal, slightly asymmetrical, broadly ovate to ovoid, 6.5–38 × 4–37 cm; cauline leaves subsymmetrical, broadly ovate to narrowly triangular, 10–18 × 5–15 cm; adaxially dark green to blackish green, paler along veins, darker between veins, covered with very short bristles, less than 0.5 mm long; venation palmate, veins distinct, 7–9, adaxially primary veins conspicuously convex, third and above veins gradually merged with leaf to slightly concave; abaxially deep purplish-red when young, fading to light red to green along the veins, and interveinal areas purplish-red when mature, rarely individuals with green leaves and a purplish-red margin; abaxially veins conspicuously convex, densely gray-white villous, shorter than 1 mm; leaves entire or shallowly lobed during seedling stage, deeply lobed up to 2/ 3 in adult plants, 7–9 lobed, middle lobes divided once to twice, lobes of leaf base slightly overlapped, rarely valvate to acute angled, margin with few serrate and short cilia, apex usually long caudate. Inflorescences: dichasial cyme, arising from rhizome, or from erect stem, 1–2 inflorescences per rhizome branch, 12–40 cm long, branched 1–2 times usually at lower position, peduncle sparsely pubescent or nearly glabrous, green to dark red, 10–30 cm long, 2–6 mm thick. Bracts caducous, green or deep red, ovate-triangular, 8–12 × 5–8 mm, glabrous, apex acute. Staminate flower: pedicel green or pink, 24–38 mm long, 1–1.3 mm thick, densely gray-white pubescent; flower 34–50 mm long, 29–47 mm wide, tepals 4, outer 2 slightly larger, short gray-white pubescent or nearly glabrous, pale pink to nearly white, broadly ovate, 15–25 × 11–20 mm, entire, middle part concave, much thicker than the edge; inner 2 smaller, glabrous, pale pink to white, long obovate to oblanceolate, 13–23 × 7–10 mm, entire; androecium short columnar or sub-globose, actinomorphic, 6.6–8.6 mm long, 5.5–8.5 mm wide, stamens 110– 150, filaments basally connate, connate part 3–5 mm long, 0.9–1.5 mm thick, free filaments 1.5–3.5 mm long, anthers yellow, cuneate, 0.8–2.5 mm long, 0.5–0.9 mm wide, apex rounded. Pistillate flower: pedicel green or pink, 23–26 mm long, 1.2–1.8 mm thick, very short pubescent; flower 33–45 mm long, 29–46 mm wide, tepals 5, rarely 4, pink to white, glabrous; outer 2 slightly larger, ovoid-cordate to elliptical, 17–21 × 8–17 mm; inner 3 gradually becoming smaller inward, oblong to oblanceolate, 6–25 × 6–13 mm; pistils 7–8 × 7–9 mm, styles 2, yellow, connate base 1–2 mm long, free part 4–6 mm, stigmatic band spiraled up to nearly 2 revolutions each side; ovary light green with reddish tint, nearly glabrous or sparsely very short pubescent, 2-locular, placentation axile, placentae 2 per locule. Fruits green, nearly glabrous; unequally 3-winged, abaxial wing larger, nearly rectangular or oblong, 12.5–14 × 16–20 mm; lateral wings smaller, nearly equal, narrowly falcate, 5–7.5 × 12–16 mm. Flowering Sept.–Oct., fruiting Oct.–Dec..

Distribution and Ecology: — The new species is currently known only from seven localities restricted to Guangxi and Guangdong ( Fig. 2 ). It grows on rock surface or rock-soil mixture usually along streams under forest canopy.

Etymology: — The species is named after the abbreviation of Guangxi and Guangdong, China, where this new species can be found. The Chinese name is given as “ 两ḞữåDz ”.

Additional specimens examined:— CHINA: Guangxi: Hechi city (ñàḿ), Wuxu town (五圩ḋ), back cave of Laohuyan ( AE Ẽä 后fi) , 24°39'N, 107°55'E, alt. 300 m, without flower, 27 June 2014, Daike Tian & Lizhi Tian TDK1910 ( CSH) ; ibid., in flowering, 20 September 2021, Jinye Zhou TDK4907 ( CSH) ; Huanjiang county (ṳȗ县), Xianan town (下南乡), Jingyang village (ạșť), 24°58'N, 107°55'E, alt. 425 m, 2 May 2013, Huanjiang Expedition Team 451226130502015 LY ( GXMG, IBK) ; Yizhou district (ûffl区), Longtou town (k头乡), Changdong village (Kfiť) , 24°27'N, 108°07'E, alt. 220 m, without flower, 25 June 2018, Daike Tian & Lizhi Tian TDK3055 ( CSH) . Guigang city (āăḿ), Gangbei district (ă北区), Pingtianshan National Forest Park ( Ṭ 天Ɯ国ẍŭūȓ园), on soil-rock mixture under Musa basjoo Siebold & Zucc. ex Iinuma , 23°11'N, 109°31'E, alt. 493–521 m, 25 April 2024, Daike Tian & Jinye Zhou TDK5634 ( CSH) . Guangdong: Yunfu city (云flḿ), Xinxing county ( NJ Ẋ县), Liuzu town (ẋffiḋ), Sitian village (ŵmť), Zangfokeng ( DZ 佛坑), 22°35'N, 112°14'E, alt. 230 m, 15 June 2019, Daike Tian, Gaodeng Xiang, Shiping Zhong TDK3762 ( CSH) ; ibid., 22°34'N, 112°14'E, alt. 160–220 m, near early flowering, 26 August 2022, Daike Tian, Songwei Wang, Xin Li, Yingwu Peng, TDK5123 ( CSH) ; Yangjiang city (șȗḿ), Yangchun county (șffḿ), Chunwan town (ffâḋ), Chetian village (ţmť), on rock surface of the shady places along a creek, 22°21'N, 111°58'E, alt. 70 m, 16 June 2019, Daike Tian, Gaodeng Xiang, Shiping Zhong TDK3767 ( CSH) ; Yangdong district (ș东区), Nalong town (Dk ḋ) , Dashuitian village (大AEmť), Baileng forest farm (ÞOiū场), on rock surface of the shady places along a creek, 22°7'N, 112°5'E, alt. 270 m, without flower, 19 June 2024, Daike Tian, Guodi Chen, Shiping Zhong TDK5647 ( CSH) ; ibid., 22°7'N, 112°5'E, alt. 357 m ; the same collectors TDK5648 (CSH); ibid., 22°8'N, 112°6'E, alt. 328 m ; the same collectors TDK5650 (CSH).

Conservation status: — The new species is uncommon in both Guangxi and Guangdong of China. It was only observed in seven locations or populations (four in Guangxi and three in Guangdong). The distribution is severally fragmented and each population has less than 50 mature individuals, although more populations are predicted to be found in the future. The extent of occurrence is about 4500 km 2 (<5000 km 2) and the area of occupancy is less than 24 km 2 (<500 km 2). The total number of mature individuals is less than 500 (<2500) and each subpopulation has less than 100 (<250) mature individuals. Its occupancy area and the total number of mature individuals are predicted to continuously decline in the future due to climate change and collection by human for horticultural and medicinal purposes. Based on the current data, this species should be considered as Endangered (EN) (B1B2ab(iii,iv,v), C2a(i)) following Guidelines for Using the IUCN Red List Categories and Criteria (IUCN Standards and Petitions Committee, 2024).

Figures

FIGURE 1. Habitat and morphology of B. liangguangensis D.K.Tian & J.Y.Zhou. A. Habitat inside a cave; B. Habit; C. Immature individuals inside a cave; D. Large mature individuals; E. Cultivated large plant in Dr. Cecilia Koo Botanic Conservation Center; F. Adaxial (upper leaf) and abaxial (lower two leaves) leaf surfaces; G. Inflorescence; H. Stem of mature plant, I. Hairs on petiole and white male (upper) and female (lower three) flowers; J. Front (upper) and back (lower) views of staminate flower; K. Oblique front (upper) and back (lower) views of pistillate flower; L. Pistillate flower showing four tepals (rare case) and color variation; M. Styles and stigmas; N. Top view of androecium; O. Side view of androecium showing fused filament column; P. Immature developing inflorescence with bracts; Q. Inflorescence at early growth stage; R. Stipule; S,T. Side views of young fruits.

FIGURE 2. Distribution map of the three new species: ■Begonia liangguangensis, ▲ B. shaoqingii, ★ B. qinzhouensis, ● B. qinzhouensis and B. shaoqingii.