Begonia fangchengensis Y. N. Huang, X. X. Feng & R. K. Li, 2024

Hu, Ping-Ting, Huang, Yu-Ni, Zhang, Meng-Ni, Chen, Bi-Xuan, Huang, Shu-Shu, Li, Ren-Kun, Wang, Wen-Guang & Feng, Xin-Xin, 2024, A new species in Begonia sect. Diploclinium (Begoniaceae) from Guangxi, South China, PhytoKeys 249, pp. 277-285 : 277-285

Begonia fangchengensis Y. N. Huang, X. X. Feng & R. K. Li sp. nov.

Figs 1 , 2

Type.

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. 3 ), 198 m alt., on the rock or slope beside the stream, 18 October 2021, Yu Ni Huang, Xin Xin Feng & Ren Kun Li (holotype: 0925761 , IBSC!) .

Diagnosis.

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 .

Description.

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.

Distribution and habitat.

Currently only known from one locality in Fangcheng District, Fangchenggang City, Guangxi, China (Fig. 3 ). It grows in shaded environments along the stream or near a waterfall under the broad-leaved forest.

Phenology.

November-December (Flowering), January- February (Fruiting).

Etymology.

The specific epithet “ fangchengensis ” refers to the Fangcheng District, Guangxi where the species is distributed.

Conservation.

Only two populations with approximately 200 individuals have been found in the type locality. According to the IUCN Red List Categories and Criteria ( IUCN 2024), B. fangchengensis should be assessed as ‘ Endangered (D) ’ due to its small geographic distribution and low population size.

Figures

Figure 1. Begonia fangchengensis drawn by Yunxiao Liu A habitat B stipule C, D bracts of inflorescences E, F front and back view of staminate flower G androecium H stamens I, J pistillate flower with 3 or 5 tepals K styles L styles and ovary M – Q ovary section from upper to lower positions.

Figure 2. 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).

Figure 3. Distribution of B. fangchengensis, B. rotundilimba and B. sinovietnamica.