Begonia kimlongii V.C.Nguyen, T.S.Hoang & C.W.Lin, 2022

Nguyen, Van Canh, Hoang, Thanh Son, Lin, Che-Wei & Nguyen, Van Khuong, 2022, Begonia kimlongii (B sect. Petermannia, Begoniaceae), a new species from Dak Lak, Central Highlands, Vietnam, Phytotaxa 547 (2), pp. 193-200 : 193-198

Begonia kimlongii V.C.Nguyen, T.S.Hoang & C.W.Lin , sp. nov. § Petermannia ( Figs. 1 & 2 )

Type: — VIETNAM. Dak Lak Province, M’Đr ắk District, Cý Króa Commune , 12.701979 N, 108.798395 E, 480 m alt., on moist land and rocks in broad-leaved evergreen forests, 22 August 2021, flowers and fruits, Nguyen Van Canh, Nguyen Van Khuong, Hoang Thanh Son 9022 (holotype VAFS; isotype VNMN) .

Plant perennial, monoecious, terrestrial. Stem erect or ascending, unbranched or little branched, olive green to brownishred, ca. 30 cm tall, 3–7 mm across, sparsely appressed villous, glabrescent; internodes 1–3 cm long, nodes swollen. Stipules deciduous, narrowly ovate-triangular, 5–7 × 2.5–4 mm, pinkish-green to brownish-pink, hyaline, slightly keeled, glabrous or glabrescent, margin entire, apex cuspidate, cusp ca. 1 mm long. Petioles terete, reddish-brown to pinkish-olive green, grooved above, 2.5–5 × 2–3.8 mm, appressed villous, glabrescent. Leaves 3–5, oblique, slightly pointing upward; lamina oblanceolate to obovate, basifixed, asymmetric, 10–14 cm long (basal lobes included), 3.5–5.5 cm wide, broadside 2–3.3 cm wide, base unequal, basal lobes cordate on broadside, 1–1.8 mm long, thinly succulent, adaxially emerald green to dusky green, glabrous or subglabrous, sometimes with silvery white irregular dots between veins each with a puberulous hair in center, glabrescent; abaxially pale green to pinkish; venation pinnate, midrib distinguishable, 8.5–12 cm long, ca. 3 major lateral veins on either side of midrib, other primary veins branching dichotomously; margin sparsely denticulate; apex attenuate. Bracts deciduous, yellowish-pink, pale green tinged red at base, hyaline, those at basal nodes of the inflorescence in one or two pairs, ovate-triangular to ovate, ca. 5 × 2.8 mm, aristate, arista ca. 1 mm long, margin entire; bracts at the summit of the inflorescence obovate to oblanceolate, 3–9 × 1.5–5 mm, apex obtuse to truncate, margin denticulate, sometimes with a puberulous hair at the tip of each tooth. Inflorescence a terminal, bisexual, cymosely branching panicle 3.5–6.5 cm long, peduncle crimson to reddish-green, 1.5–3.5 cm long, up to 4 orders of branching, erect or ascending, glabrous, protogynous. Staminate flower: pedicel reddish, 1–2 cm long, glabrous, tepals 4, white to pinkish-white tinged rosy pink, glabrous; outer 2 orbicular to widely ovate, margin entire, 8–11 × 9–13 mm, inner 2 narrowly lanceolate to narrowly elliptic, 5–8 × ca. 2 mm; androecium actinomorphic, stamens 32–40, filaments fused at base; anthers ca. 0.7 mm long, obovate, apex retuse, filaments ca. 1 mm long. Pistillate flower: pedicel white to pink, 3–6 mm long, glabrous; ovary whitish-green to creamy white, body trigonous-ellipsoid, 8–12 × 4–5 mm, 3-winged; wings equal, rounded trapezium, 12–16 × 3–5 mm, margin entire; ovary 3-locular, placenta bilamellate; tepals 5, pinkish-white, sometimes creamy white tinged red at base, glabrous, outer 4 tepals widely ovate to widely obovate, 5–10 × 3–7 mm, inner 1 tepal oblanceolate to obovate, 4–7 × 1.7–3.8 mm; styles 3, yellow, bifid, deeply divided to base, Y-shaped, ca. 2 mm long; stigmas in a spiral band and papillose all around. Fruit pendent on a stalk ca. 6 mm long, capsule ca. 20 × 17 mm (wings included), glabrous; tepals persistent.

Distribution and ecology: —The new species is currently known from Cý Króa Commune, M’Ðrắk District, Dak Lak Province, Central Highlands Vietnam and probably also occurs in adjacent areas. The new species grows on humid, moist, or rocky areas in broad-leaved evergreen forests, at elevations of ca. 480 m, associated with Poaceae ( Arundinaria sp. ), Gesneriaceae (Chrita sp.), Urticaceae ( Elatostema sp. ), Pentaphragmataceae ( Pentaphragma sp. ), and Melastomaceae ( Sonerila sp. ).

Etymology: —The specific epithet is named in honor of Mr. Nguyen Kim Long, who first discovered this new species.

Conservation status: —A small population of the new species is distributed in an area of about 1 km 2 that is not included in any protected forest, therefore its survival is potentially threatened by Begonia collectors and habitat degradation. However further botanical surveys are needed in this realtively unexplored area for a complete conservation assessment of this species, until then we assess Begonia kimlongii to be Data Deficient (DD) according to IUCN (2019).

Notes: — Begonia kimlongii is distinctive for its dimorphic bracts that are relatively unusual in B. sect. Petermannia. However, it is a typical member of the section in having a cane-like habit, 3-locular ovary with bifid placentae, and protogynous inflorescences. This new species is related to Begonia cucphuongensis Nguyen & Tebbitt (2005: 248) in its cane-like habit, sparsely hairy stem, adaxially glabrous leaves and the number of staminate tepals. It is readily distinguished from B. cucphuongensis by its oblanceolate to obovate (vs. lanceolate to narrowly ovate) leaves, terminal inflorescences (vs. axillary, rarely terminal) and pistillate flowers with 5 tepals (vs. 3). Moreover, it resembles B. lamxayiana Souvannakhoummane et al. (2016: 2) and B. hainanensis Chun & Chun (1939: 20) which also share oblanceolate leaves, lax inflorescences and 3-locular ovaries. A comparison of the salient characters of the four species is presented in Table 1 .

Figures

FIGURE 1. Begonia kimlongii T.S.Hoang, V.C.Nguyen & C.W.Lin.A. Habit; B, B’. Portion of leaf, upper and lower surfaces; C. Stipule; D-D’’’’. Bracts; E, E’. Staminate flower, face and side views; F, F’. Stamens, ventral and dorsal views; G, G’. Pistillate flower, face and side views; H, H’. Style and stigmatic band, dorsal and ventral views; I. Capsule; J. Cross section of an immature capsule.

FIGURE 2. Begonia kimlongiiT.S.Hoang,V.C.Nguyen & C.W.Lin.A. Habit and habitat; B. Leaf, upper and lower views; C. Inflorescence, D. same, staminate flowers, E. pistillate flowers; F. Pistillate flower, face and side views; G. Staminate flower, face and side views; H. Capsule.