Research Article |
Corresponding author: Wen-Guang Wang ( wangwenguang@xtbg.ac.cn ) Corresponding author: Xin-Xin Feng ( xinxin8715@163.com ) Academic editor: Hanno Schaefer
© 2024 Ping-Ting Hu, Yu-Ni Huang, Meng-Ni Zhang, Bi-Xuan Chen, Shu-Shu Huang, Ren-Kun Li, Wen-Guang Wang, Xin-Xin Feng.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Hu P-T, Huang Y-N, Zhang M-N, Chen B-X, Huang S-S, Li R-K, Wang W-G, Feng X-X (2024) A new species in Begonia sect. Diploclinium (Begoniaceae) from Guangxi, South China. PhytoKeys 249: 277-285. https://doi.org/10.3897/phytokeys.249.133724
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Although Guangxi represents one of the distribution centres of begonias in China, the sect. Diploclinium (Wright) A. DC is not well documented herein. In this article, we illustrate a new species belonging to this section, Begonia fangchengensis Y.N.Huang, X.X. Feng & R.K.Li, which has been discovered in southern Guangxi. Begonia fangchengensis mostly resembles B. rotundilimba in elliptic leaf blade, palmate veins, dichasial cyme, three styles, axile placentation, and unequally 3-winged capsule. On the other hand, B. fangchengensis is characterized by creeping rhizome, pilose stipule, red and densely pilose petiole, pubescent leaf blade and pilose inflorescence bract, sparsely pilose ovary and the zygomorphic androecium, differing from the erect stem at anthesis, the green and densely villous petiole, the glabrous stipule, leaf blade, inflorescence bract, ovary and actinomorphic androecium in B. rotundilimba. Considering its small population size and narrow distribution, its conservation status is categorized as ‘Endangered (D)’ according to the IUCN Red List Categories and Criteria.
Limestone karst, morphology, new taxon, south China, taxonomy
As one of the fastest-evolving genera in vascular plants around the world, Begonia L. species are now 2,151 in number (
Approximately 90 species of Begonia have been documented in Guangxi and new species have been reported frequently in recent years (
In October 2021, an unknown begonia was discovered growing on the slope by a stream during fieldwork in the Shiwanshan Mountain, southern Guangxi. This taxon is distinct from the commonly karst distributed sect. Coelocentrum begonias in consideration of its ovary locule and placentae type in the field. Some individuals have been well cultivated in the nursery of Dongguan Botanical Garden and flower characters were observed in January 2022. Based on detailed morphological comparisons with similar species, this Begonia species is identified as a new species of the section Diploclinium.
Morphological characters were observed and measured from fresh samples in the field. Morphological comparisons with similar taxa were undertaken by consulting the literature, examining herbarium (IBK and
China • Guangxi Zhuang Autonomous Region (广西壮族自治区), Fangchenggang City (防城港市), Fangcheng District (防城区), Shiwanshan Yao Autonomous Town (十万山瑶族乡), Bajiao Mountain, 21°56'54"N, 108°14'20"E, (Fig.
Habitat and morphology of Begonia fangchengensis A habitat B flowering plant C creeping rhizome D stipules E leaf blade (adaxial) F, G leaf blade (abaxial) H juvenile leaf I inflorescence J bracts K, L front and side views of staminate flower M, N front and side views of androecium O stamens P pistillate flower with 3 tepals Q, R, S pistillate flower with 5 tepals T stigmas and ovary U ovary sections from upper to lower positions V capsule (Photos by Z.X. Liu).
Begonia fangchengensis mostly resembles B. rotundilimba in its elliptic leaf blade, palmate veins, dichasial cyme, three styles, axile placentation, and unequally 3-winged capsule. However, there are creeping rhizome, pilose stipule, red and densely pilose petiole, pubescent leaf blade and pilose inflorescence bract, sparsely pilose ovary and the zygomorphic androecium in B. fangchengensis. These characters differ from the erect stem at anthesis, the green and densely villous petiole, the glabrous stipule, leaf blade, inflorescence bract, ovary and actinomorphic androecium in B. rotundilimba.
Perennial evergreen herb, monoecious, 15–30 cm height.
Rhizome creeping, ca. 6–8 cm long and 8–10 mm in diameter, internode short. Stipules membranous, reddish-green, translucent, triangular, 4.5–8 × 4–5 mm, pilose. Leaves all basal, petiole 10–15 cm long, red and densely white pilose; leave blade asymmetric, widely ovate to elliptic, 12–17 × 8–10 cm; fleshy; adaxially bright green and smooth; abaxially pale-green, densely covered with white pilose along the veins; base oblique-cordate; margin irregularly denticulate; apex caudate acuminate; venation palmate, primary veins 8, adaxially slightly concave, abaxially convex. Inflorescences arising directly from rhizome, dichasial cymes, peduncle 6.5–8 cm long, pilose; flowers unisexual, 2–5 flowers per inflorescence; bracts membranous, pale green, triangular to subcircular, 2–3 lobed apically, margin serrate with cilia, 7–8 × 4–6 mm. Staminate flower tepals 4, white; outer 2 larger, widely ovate, 17–21 × 15–20 mm, abaxially sparsely pubescent; inner 2, lanceolate, margin entire, 10–12 × 4–6 mm, glabrous; androecium zygomorphic, sub-globose, ca. 6 mm in diameter; stamens numerous, 3–3.5 mm long, filaments fused at base; anthers yellow, ca. 1.5 mm long, cuneiform, apex slightly bent and retuse. Pistillate flower tepals 3–5, white, glabrous; outer 2, widely ovate to subcircular, margin entire, 11–12 × 9–10 mm; inner 1–3, widely ovate, 8–11 × 4–7 mm; ovary yellowish-green, trigonous-ellipsoid, 8.0–8.5 × 5.2–5.5 mm (wings excluded), sparsely pilose, 3-locular, upper 1 (abaxial wing side) degenerated occasionally; placentation axile, bilamellate. Styles 3, fused at base, yellow, ca. 3 mm in diameter, stigma spirally U-shaped twisted. Capsules nodding, trigonous-ellipsoid, 9–10 × 6.0–6.5 mm (wings excluded), yellowish-green, sparsely pilose, wings 3, unequal, 2-lateral wings smaller, crescent-shaped, abaxial wing semilune-shaped.
November-December (Flowering), January- February (Fruiting).
The specific epithet “fangchengensis” refers to the Fangcheng District, Guangxi where the species is distributed.
Only two populations with approximately 200 individuals have been found in the type locality. According to the IUCN Red List Categories and Criteria (
The putative new Begonia species is morphologically characterized by having three styles, 3-locular ovary with axile and bifid placentation, representing the typical circumstance of the Begonia section Diploclinium (Lindl. 1846: 319)
The putative new Begonia species mostly resembles B. rotundilimba from Pingbian, Yunnan in its elliptic leaf blade, palmate veins, dichasial cyme, three styles, unequally 3-winged capsule (Table
Character | B. rotundilimba | B. sinovietnamica | B. fangchengensis |
---|---|---|---|
Rhizome | creeping, erect stem at anthesis; internode 2-3 cm long | elongate; internode 0.3-0.5 cm long | creeping; internode 0.3-1 cm long |
Stipule | ovato-triangular, glabrous | oblong, pilose | triangular, pilose |
Petiole | green, densely villous | reddish brown, densely villous | red, densely pilose |
Leaves | blade adaxially green, glabrous | blade adaxially green, hirsute | blade adaxially bright green, smooth |
Inflorescence bract | bracts glabrous, apex acuminate | bracts glabrous, apex acuminate | bracts apex 2-3 lobed, both pilose |
Staminate flower | androecium actinomorphic, anthers oblong | anthers oblong, apex obtuse | androecium zygomorphic, anthers cuneiform, apex slightly bent and retuse |
Pistillate flower | tepals 5, styles 3, ovary pilose, unequally 3-winged | tepals 4, styles 3, ovary sparsely pilose, subequally 3-winged | tepals 3-5, styles 3, ovary sparsely pilose, unequally 3-winged |
Phenology (flowering; fruiting) | Apr; Jul | Jul; Aug | Nov; Jan |
Habitat | alt. 1600-1800 m, Yunnan | alt. 230-400 m, Guangxi | alt. 198 m, Guangxi |
Habitat and morphology of Begonia rotundilimba A habitat B flowering plant with erect stem at anthesis C leaf blade (adaxial) D leaf blade (abaxial) E petiole F, G front and back views of staminate flower H androecium I, J front and lateral view of pistillate flower K ovary section (Photos by W. G. WANG).
Besides the similarity to B. rotundilimba in morphology, the putative new Begonia species is closest to B. sinovietnamica in geographic distribution and altitude (200–400 m) (Fig.
We thank Zhixian Liu for providing the photographs. We are also grateful to the editor and the reviewers for improving our manuscript.
The authors have declared that no competing interests exist.
No ethical statement was reported.
This study was supported by the Dongguan Municipal Project for Improvement of Social Science and Technology (20231800940632); Guangdong Provincial Education Department Young Innovative Talent Project for Colleges and Universities (2022WQNCX124); the Science and Technology Innovation Project in Department of Housing and Urban Rural Development of Guangdong Province (2023-K13-384726) and the Guangdong Rural Revitalization Strategic Foundation (20211800400042).
Conceptualization: XXF. Data curation: MNZ, BXC. Formal analysis: SSH. Investigation: PTH, YNH, WGW. Resources: XXF, RKL.
Ping-Ting Hu https://orcid.org/0009-0001-2656-167X
Yu-Ni Huang https://orcid.org/0000-0001-5421-4192
Bi-Xuan Chen https://orcid.org/0009-0006-5022-6229
Xin-Xin Feng https://orcid.org/0000-0002-7421-2773
All of the data that support the findings of this study are available in the main text.