Begonia dakrongensis (Begoniaceae), a new species from Dakrong Nature Reserve, Quang Tri province in Central Vietnam Author Nguyen, Cuong Huu 0000-0003-2281-741X Vietnam National University of Forestry, 21 A Street, Xuan Mai, Chuong My, Hanoi, Vietnam nguyenhuucuong.tvr@gmail.com Author Le, Anh Tuan 0000-0002-5917-3243 Mien Trung Institute for Scientific Research, Vietnam National Museum of Nature, Vietnam Academy of Science and Technology, 321 Huynh Thuc Khang street, Thua Thien Hue, Vietnam tasa207@gmail.com Author Ha, Van Bac 0009-0003-0024-2608 Dakrong Natural Reserve, Ta Long, Dakrong, Quang Tri, Vietnam havanbacklqt@gmail.com Author Lin, Che Wei 0000-0002-8564-5793 Herbarium of Taiwan Forestry Research Institute, Taiwan Forestry Research Institute, No. 53, Nan-Hai Road, Taipei 100, Taiwan varalba@gmail.com text Phytotaxa 2024 2024-04-18 645 1 85 90 http://dx.doi.org/10.11646/phytotaxa.645.1.8 journal article 10.11646/phytotaxa.645.1.8 1179-3163 13214900 Begonia dakrongensis C.H.Nguyen, T.A.Le & C.W.Lin , sp. nov. ( Figs. 1 & 2 ) Type:— VIETNAM . Quang Tri province , Dakrong district , Huc Nghi commune, Dakrong Nature Reserve , around point 16°27’46.9”N , 107°05’32.4”E , common in the moist shady areas under evergreen primary evergreen forest on the rocky crevices in association with of waterfall Do Quyen at elevations of about 800 m a.s.l. , 26 May 2023 , Tuan Anh Le , Ha Van Bac , LTA.DKR.09 ( holotype VNMN B0000608 !; isotype VNF 20230526010 !) Rosette, rhizomatous perennial herbs, monoecious. Rhizomes dusky magenta to reddish-brown or brownish-green, terete, to 6 cm or longer, 4–7 mm across, creeping, sparsely villous-hirsute, internodes 1.5–9 mm long. Stipules ovate-triangular, slightly oblique, 5–8 × 3.5–4.5 mm , glabrous or very sparsely hirsute, apex attenuate and aristate, arista 0.8–3 mm long, margin entire or very sparsely denticulate. Leaves alternate, nearly pressed to substrate; petiole dusky red, 1.3–3.5 cm long, 2.5–4 mm across, grooved above, sparsely to densely villous-hirsute, leaf blade asymmetric, not oblique or nearly so, obtriangular-spathulate to oblong-obovate or widely obovate, 4.7–17 × 3–12 cm , base obliquely cordate, lobes 6–12 mm long, broad side 2–7.3 cm wide, margin denticulate on the upper two-thirds and subentire to repand on the lower one-third, slightly revolute and undulate with rows of sparsely white villous and red scabrous, sometimes with coarsely dentate and irregularly angular, apex acuminate to acute; leaf subcoriaceous, succulent, adaxially emerald green, glabrous, waxy, abaxially pale green, veins pink to red, sparsely pinkish-white villous-hirsute and red scabrous; venation palmate-pinnate, midrib distinct, 2 or 3 secondary veins on broad side and 0 or 1 on narrow side, lateral through connection between with other basal veins, minor veins inconspicuous. Inflorescence axillary and terminal, unisexual or bisexual, cymose-paniculate or racemose, 1.5–3 cm long, rose pink to red, erect, glabrous or subglabrous; Bracts creamy pink to creamy white or greenish-white, hyaline, persistent, ovate-triangular to widely triangular or narrowly triangular, the first pair up to 7 × 4.5 mm , decreasing in size towards the more distal inflorescence nodes, attenuate and aristate at apex, arista 0.5–2.5 mm long, margin denticulate; Pistillate flower produced from a very short peduncle at the basal node of the inflorescence, usually solitary; staminate flowers produced in distal inflorescence part, in several 1–3-flowered compressed monochasial partial inflorescences borne on lateral branches ( 2–12 mm ). Staminate flower: pedicel 10–14 mm long, tepals 4, outer 2 white to pinkish-white, sometimes with pale greyishpink veins, orbicular to obovate, 7–12 × 8.5–10 mm , margin entire, abaxially red scabrous; Inner 2 white or pinkish-white, oblanceolate, apex round, base cuneate, 7.5–9 × 2–3 mm , glabrous; Androecium actinomorphic, stamens ca . 25, yellow, filaments free, ca. 0.4 mm long, anthers widely obovate, ca . 0.7 mm long, 2-locular, apex retuse. Pistillate flower (immature): subsessile, tepals 5, white or pinkish-white, outer 4 tepals widely ovate to oblong, margin entire, apex rounded to obtuse, abaxially red scabrous; inner 1 obovate to oblanceolate, glabrous; Ovary trigonous-globose, densely red scabrous, 3-locular, 3-winged, wings subequal, trapeziform, truncate to broadly acute proximally, pointed distally, placentation axle, bilamellate; styles 3, Y-shaped, divided to base, stigmatic band spiralled. Capsule pedicel ca . 1 mm long, body trigonous-globose, 10–11 × 12–14 mm long (wings included). Distribution and ecology: —The new species is only known from Dakrong Nature Reserve, in Quang Tri province , Central Vietnam . Begonia dakrongensis usually grows in moist shady places near waterfalls, along streams and occasionally on the rocky crevices covered by evergreen broad-leaved forests at elevations of about 800 m a.s.l. Etymology: —The specific epithet refers to the type locality (Dakrong Nature Reserve, Central Vietnam .). Conservation status: —The new species is known from a single collection, and we do not have information about its abundance at type locality its conservation status is assessed as Data Deficient ( DD ; IUCN 2022 ). Notes: —Among the rhizomatous begonias in Vietnam , Begonia dakrongensis closely resembles B. abbrevata and B. eberhardtii Gagnepain (1919: 198) in their axillary and terminal inflorescence with densely bracts and flower structure, but these three species differ in many morphological characteristics. A detailed comparison is provided in Table 1 .