Begonia zonata 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 : 86-89

2. Begonia zonata C.W.Lin & C.H.Nguyen , sp. nov. § Platycentrum ( Figs. 3 & 4 )

Type:— VIETNAM. Northern Vietnam, Thai Nguyen province, type herbarium specimens were prepared from cultivated plants on 20 October 2024 by Che Wei Lin, C. W.Lin 728 (holotype: TAIF).

Rosette, monoecious rhizomatous herb. Rhizome stout, dusky orangish-red to brownish-red, 6–10 mm thick, internodes 3–30 mm or longer, densely white villous-hirsute. Stipules persistent, orangish-red to pale reddish-brown, triangular-ovate, 10–16 × 6–10 mm, herbaceous, more or less cucullate, strongly keeled, abaxially densely red to white villous-hirsute, margin fimbriate, apex aristate, arista ca. 2 mm long. Leaves alternate, oblique, held horizontally; petiole terete, creamy green to brownish-pink, 8–22 cm long, 3.5–6 mm diameter, densely white villous-hirsute; leaf blade asymmetric, oblique, widely ovate to widely oblong-ovate, 13–20 × 9.5–15 cm, broad side 5.3–9.5 cm wide, basal lobes cordate, 3–7 cm long, apex acuminate to attenuate, margin denticulate with a line of pinkish-white hirsute, sometimes serrate and irregularly shallowly triangular lobes; leaf chartaceous, succulent, adaxially dark olive green to bronzy purplish-green, embellished with a wide emerald green to silvery green band running parallel to the margin; upper surface densely covered by small raised cones each topped by a pinkish-white hirsute, giving a wrinkled texture; abaxially pale green, with a patch of purplish-red corresponding to the pattern on adaxial surface; venation basally ca. 8 palmate, midrib distinct, ca. 2 secondary veins on each side, other primary veins branching dichotomously or nearly so, tertiary veins reticulate; densely white to magenta villous-hirsute on all veins abaxially. Inflorescence protandrous, terminal or axillary on upper leaf axils, bisexual, cymose arising directly from the rhizome, up to 7 orders of branching; peduncle 2.3–7 cm long, orangish-red to brownish-red, erect, densely white to pink villous-hirsute; bracts orangish-red to pale reddish-brown, hyaline, semi-persistent, ovate to triangular-ovate, more or less cucullate, abaxially densely red to white villous-hirsute, margin entire or nearly so, acute and mucronate at apex; first pair 8–11 × 5–6.5 mm, decreasing in size towards the more distal inflorescence nodes. Staminate flower: pedicel creamy pink, 14–25 mm long, red hispid-hirsute; tepals 4, pink, outer 2 orbicular to widely ovate, sometimes widely oblong-obovate, 10–13.5 × 10–12 mm, margin entire, abaxially red hispid-hirsute; inner 2 lanceolate to lanceolate-elliptic, apex obtuse, 7–11 × 3.5–4.5 mm, glabrous; androecium zygomorphic, ca. 3.5 mm diameter; stamens 22–50, lemon yellow, filaments free, 1–1.5 mm long, anthers obovate, ca. 1 mm long, 2-locular, apex obtuse to rounded-truncate. Pistillate flower: pedicel creamy pink to pinkish-white, 11–17 mm long, red hispid-hirsute; tepals 5, pale pink, outer 4 oblong-elliptic to widely elliptic-lanceolate, 10–15 × 5–8.5 mm, red hispid-hirsute abaxially; inner 1 elliptic to oblong, 7–12 × 2–4 mm, glabrous; ovary creamy white to pale pink, trigonous-globose, 3–5 mm long, 4–6 mm thick (wings excluded), red hispid-hirsute; 3-winged, wings unequal, 4–7 mm long, pale creamy pink to pale yellowish-green, triangular, sometimes hooklike towed at the tip, rounded proximally, truncate distally, red hispid-hirsute, margin entire; larger 2, 3–7 mm wide, smaller 1, 2–3 mm wide; ovary 3-locular, placenta bilamellate; styles 3, ca. 3.5 mm long, yellow, shortly fused at base, stigmatic band U-shaped and spirally twisted. Capsule not seen.

Distribution and ecology:— Begonia zonata is currently only found exclusively in Thai Nguyen province, northern Vietnam ( Fig. 11 ). It thrives on slopes with stony soils or rocky cliff faces within shaded areas of mixed broad-leaved and bamboo forests, at elevations reaching up to 800 m.

Etymology:— The specific epithet ‘ zonata ’ refers to the plant's distinctive maroon foliage, marked by a green ring pattern.

Conservation status:— A comprehensive botanical survey of the area has yet to be conducted, leaving us with limited knowledge about the species’ distribution. As such, we currently classify it as Data Deficient ( IUCN 2024).

Notes:— Begonia zonata is an attractive new species known for its bicolored, rugose foliage and multi-flowered inflorescences with delicately rosy pink flowers, making it popular among plant enthusiasts and widely cultivated in greenhouses. Superficially, it resembles B. versicolor Irmscher (1939: 546) and B. aurora Liu et al. (2020: 3) in having rugose leaves, 4-tepaled staminate flowers, and 5-tepaled pistillate flowers. However, B. zonata differs from B. versicolor by having a multi-branched inflorescence with up to 7 (vs. 2 or 3) branches, a zygomorphic (vs. actinomorphic) androecium, and a 3-loculed (vs. 2-loculed) ovary. It is further distinguished from B. aurora by its densely villous-hirsute (vs. velutinous along the midrib) stipules, fimbriate (vs. entire) margins, pink (vs. white) tepals in both staminate and pistillate flowers, a zygomorphic (vs. actinomorphic) androecium, and having 22–50 (vs. approximately 90) stamens.

Figures

FIGURE 3. Begonia zonata C.W.Lin & C.H.Nguyen. A. Habit; B, B'. Portion of leaf, upper and lower surfaces; C. Stipule; D. Bract; E–E''. Staminate flower, face, back and side views; F–F''. Stamens, dorsal and ventral views; G, G'. Pistillate flower, face and side views; H, H'. Style and stigmatic band, dorsal and ventral views; I. Cross section of an immature capsule. Drawn from the holotype, C.W.Lin 728 by Che-Wei Lin.

FIGURE 4. Begonia zonata C.W.Lin & C.H.Nguyen.A. Habit; B. Rhizome, also showing stipules, petioles and peduncle; C. Stipule; D, E. Portion of leaf, upper and lower surfaces; F. Bract; G. Inflorescences; H. Staminate flowers; I. Pistillate flowers; J. Cross section of an ovary. All photos by Wei-Feng Li of plants used for the preparation of type herbarium specimen C.W.Lin 728.

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).