Begonia lii C.W.Lin & C.H.Nguyen, 2025

Nguyen, Cuong Huu, Bui, Huong Van, Le, Anh Tuan, Pham, Dien Van & Lin, Che Wei, 2025, Five new species of Begonia (Begoniaceae) from Vietnam, Phytotaxa 698 (2), pp. 82-100 : 92

4. Begonia lii C.W.Lin & C.H.Nguyen , sp. nov. § Coelocentrum ( Figs. 7 & 8 )

Type:— VIETNAM. Northern Vietnam, Phu Tho province, type herbarium specimens were prepared from cultivated plants on 5 October 2024 by Che Wei Lin, C. W.Lin 727 (holotype: TAIF).

Rosette, monoecious rhizomatous herb. Rhizome stout, reddish-brown, ca. 10 mm thick, internodes congested, subglabrous. Stipules persistent, whitish-green to pinkish-yellow, triangular, 5–8 × 4–7 mm, herbaceous, keeled, glabrous or very sparsely hirsute on base of midrib abaxially, margin entire or very sparsely minute denticulate, apex aristate, arista ca. 3 mm long. Leaves alternate, oblique, held horizontally; petiole terete, brownish-red, 4.5–11.5 cm long, 2.5–3 mm diameter, white to pinkish-white villous; leaf blade asymmetric, widely ovate to suborbicular, 7.5–15.5 × 6–11.5 cm, broad side 3.3–8 cm wide, basal lobes cordate, 2.4–6 cm long, apex acute to obtuse, margin crenulate with a line of white or rosy pink hispid-hirsute; leaf thick chartaceous, succulent, adaxially pale greyishgreen to silvery grey, with maroon to dark brownish-green zones extending along the primary veins, covering up to half to three-quarters of their length, and emicontinuous maroon stripes along the tertiary veins near the margins; adaxially slightly bullate, subvelutinous, sparsely white to pink hispid-hirsute; abaxially pale pinkish-green to greyish-pink, with magenta stripes aligned to the adaxial surface pattern, veins brownish-pink to magenta; venation basally ca. 7 palmate, midrib distinct, ca. 2 secondary veins on each side, other primary veins branching dichotomously or nearly so, tertiary veins reticulate; densely rosy pink villous and hispid-hirsute on all veins abaxially. Inflorescence protandrous, axillary, bisexual, cymose arising directly from the rhizome, up to 5 orders of branching; peduncle 5–11 cm long, pale green to rosy red, erect, glabrous; bracts creamy greenish-white to pale greenish-pink, hyaline, deciduous, suborbicular to elliptic-oblong, first pair up to 6.5 × 5 mm, decreasing in size towards the more distal inflorescence nodes, margin entire, apex obtuse to acute. Staminate flower: pedicel pale greenish-white to pink, 20–25 mm long, glabrous; tepals 4, white or pinkish-white, glabrous; outer 2 suborbicular to ovate, 9–12 × 8–10 mm, margin entire, apex rounded; inner 2 oblanceolate, apex rounded to truncate, 7.5–10 × 2.5–4 mm; androecium zygomorphic, ca. 4 mm diameter; stamens 16–30, yellow, filaments free, 1–1.5 mm long, anthers obovate-oblong, ca. 1 mm long, 2-locular, apex truncate to rounded. Pistillate flower: pedicel pale greenish-white to pink, ca. 15 mm long, glabrous; tepals 3, white or pinkish-white, glabrous; outer 2 suborbicular to obovate, 8.5–11 × 8–9 mm, margin entire, apex rounded, inner 1 oblanceolate, ca. 8 × 3.5 mm, apex obtuse to rounded; ovary trigonous-ellipsoid, ca. 10 mm long, 3.5 mm thick (wings excluded), pale green to rosy pink, glabrous; 3-winged, wings unequal, pale green to rosy pink, glabrous, margin entire; wings narrowly triangular to trapezoid, acute proximally, rounded to obtuse distally, ca. 10 mm long; lateral wings narrower, ca. 3 mm wide, abaxial wing ca. 5 mm wide, sometimes with 1 very reduced wings running parallel along the one side of the ovary; ovary 1-locular with intruded parietal placentation, placentae 3, bilamellate; styles 3, fused at base, golden yellow, ca. 3.5 mm long, stigmatic band U-shaped and spirally twisted. Capsule body trigonous-ellipsoid, ca. 12 × 15 mm (wings included).

Distribution and ecology:— Begonia lii is endemic to Phu Tho province in northern Vietnam ( Fig. 11 ), where it grows on limestone cliffs and boulders in semi-shaded areas at elevations up to 500 m.

Etymology:— The specific epithet honors Mr. Weng-Feng Li, an plant enthusiast who cultivated and provided material of this new species.

Conservation status:— Begonia sect. Coelocentrum is adapted to limestone environments and has a highly restricted distribution, we consider it a rare endemic species, likely confined to only a few limestone hills in Phu Tho province. However, detailed information on its habitat and population status remains lacking. In light of the limited data, we classify B. lii as Data Deficient ( IUCN 2024).

Notes:— Begonia lii resembles B. lui Liu et al. (2020: 15) from China, which is also a member of sect. Coelocentrum. Both species share several morphological characteristics, including widely ovate to suborbicular foliage, villous petioles, glabrous tepals in both staminate and pistillate flowers, and a zygomorphic androecium. However, B. lii is sharply distinct due to its sparsely hispid-hirsute (vs. moderately densely setulose) upper surface of the lamina, entire (vs. fimbriate) bract margins, obtuse to rounded anther apices (vs. retuse), narrowly triangular (vs. crescent-shaped) ovary wings, and a U-shaped, spirally twisted (vs. C-shaped, less pronounced helicoid) stigmatic band. Among Vietnamese species, it also shares similarities with B. babeana Averyanov & Nguyen (2012: 7) , but can be distinguished by its larger (7.5–15.5 × 6–11.5 cm vs. 4–6 × 3–4.5 cm) leaves, slightly bullate (vs. strongly rugose-bullate) upper surface, zygomorphic (vs. actinomorphic) androecium, and narrowly triangular (vs. crescent-shaped) ovary wings.

Figures

FIGURE 7. Begonia lii C.W.Lin & C.H.Nguyen.A. Habit; B, B'. Portion of leaf, upper and lower surfaces; C. Stipule; D, D'. Bract; E, E'. Staminate flower, face and side views; F, F'. Stamens, dorsal and ventral views; G, G'. Pistillate flower, face and side views; H, H'. Style and stigmatic band, ventral and dorsal views; I. Cross section of an ovary. Drawn from the holotype, C.W.Lin 727 by Che-Wei Lin.

FIGURE 8. Begonia lii C.W.Lin & C.H.Nguyen A. Habit; B. Stipules; C. Petioles; D, E. Portion of leaf, upper surface; F, G. Portion of leaf, lower surface; H. Inflorescence, showing staminate flowers; I. Pistillate flower; J. Cross section of an ovary.All Photos from C.W.Lin 727, the plants used for the preparation of type herbarium specimen, photos A, D–F & H by Che-Wei Lin, photos B, C, G, I &J by Wen- Feng Li.

FIGURE 11. Distribution map of Begonia quangnamensis (yellow star), B. zonata (pink circle), B. thuanchauensis (orange square), B. lii (blue triangular) and B. ducii (green hexagon) in Indochina (The map is modified from https://geocat.iucnredlist.org/editor).