Begonia villosula T. S. Hoang & C. W. Lin 2021, sp. nov.
Creators: name: Hoang, Thanh Son
name: Lin, Che-Wei
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Cucurbitales
Begoniaceae
Begonia
Begonia villosula

description: 1. Begonia villosula T.S.Hoang & C.W.Lin, sp. nov. —
TYPE: VIETNAM. Quang Nam Province, Bac Tra My District, Tra Giap Commune, 15°14’26.46”N, 108°16’31.21”E, 702 m elev., growth on the moist rocky in broad-leaved evergreen forests, 18 August 2018, Hoang Son 3617 (Holotype: VAFS).
Figs. 2, 3
Monoecious rhizomatous herb. Rhizome stout, to 13 cm or more long, 10–15 mm thick, internodes congested, velutinous; erect stems seen only at anthesis, ca. 3 nodes, internodes 1.5–4 cm long, 3–5 mm thick, densely velutinous. Stipules persistent, yellowish green to reddish, ovate to narrowly triangular-ovate, strongly reflexed, 1.4–2 cm long, 5–8 mm wide, herbaceous, strongly keeled, abaxially densely hirsute at midrib, margin entire, apex aristate, arista 4–8 mm long. stipules of erect stem similar but smaller. Leaves alternate, petiole terete, pale green to reddish, 10–28 cm long, 4–6 mm thick, densely white velutinous; leaf blade asymmetric, oblique, widely ovate to orbicular, 14–18 cm long, 10–15 cm wide, broad side 7–9.5 cm wide, basal lobes cordate, 5–7 mm long, margin crenate to crenulate and densely white hirsute, apex acuminate; leaf thickly chartaceous, succulent, adaxially lime green, densely minutely raised cones topped, a white hirsute on a top; abaxially pale green, densely velutinous; venation basally ca. 9 palmate, midrib distinct, ca. 3 secondary veins on each side, other primary veins branching dichotomously or nearly so, tertiary veins reticulate; smaller leaves of erect stem similar to terrestrial ones. Inflorescences axillary, monoecious, cymose panicle arising directly from rhizome or on a short stem, dichasial cymes branched ca. 3 times; peduncle reddish, 4–10 cm long, velutinous; bracts persistent, pale yellow-green to reddish, those at basal node of inflorescence elliptic to oblanceolate, 7–15 mm long, 3–6 mm wide, abaxially hirsute at midrib, margin entire or sparsely denticulate and velutinous; bracts of upper inflorescence similar but smaller. Staminate flower: pedicel 10–17 mm long, sparsely red hirsute, tepals 4, white, outer 2 very widely ovate to orbicular, 10–15 mm long, 8–12 mm wide, abaxially red hisute, inner 2 elliptic to oblanceolate, 10–13 mm long, 4–6 mm wide; androecium actinomorphic, ca. 5 mm across; stamens 80–120, golden yellow; filaments fused at base; anthers obovate, ca. 1 mm long, 2-locular, apex obtuse, subequal at filaments. Pistillate flower: pedicel ca. 7 mm long, red hirsute, tepals 4, white, orbicular to depressed obovate, 8–10 mm long, 9–11 mm wide, abaxally red hirsute; ovary trigonous-ellipsoid, ca. 4 mm long, 2 mm thick (wings excluded), pinkish, sparsely red hirsute; 3-winged, wings unequal, pinkish, triangular, sparsely red hirsute, lateral wings narrower, ca. 2 mm wid e, abaxial wing ca. 4 mm wide, margin entire; ovary 2-locular, placenta bilamellate; styles 2, fused at base, yellowish green, ca. 4 mm long, stigma spirally twisted. Capsule tepals caducous; capsule trigonous-ellipsoid, 10–12 mm long, 4–5 mm thick (wings excluded); wings unequal, trapezium, lateral wings 2–4 mm wide, abaxial wing ca. 10 mm wide.
Distribution and ecology:
The new species is currently known only in Tra Giap Commune, Bac Tra My District, Quang Nam Province, the Central Highlands of Vietnam, and probably also occurs in its adjacent areas. The new species grows on the humid, moist rocky in broad-leaved evergreen forests, at ca. 702 m elevation, together with the dominant plants of Orchidaceae (Habenaria rhodocheila Hance), Rubiaceae (Argostemma sp., Lasianthus sp.), Urticaceae (Elatostema sp., Pilea sp.), Polypodiaceae (Microsorum sp., Polypodium sp.), and Melastomaceae (Sonerila sp., Medinilla sp.)
Etymology: The specific epithet ‘ villosula ’ referring to the hairy leaves of this species.
Conservation: Begonia villosula has been collected in only one location from the type locality. However, the type locality is located in the protection forest in Tra Giap Commune and any strong pressure has not been observed on the species. Thus, the species should be considered Vulnerable (VUD2) category is appropriate according to the guidelines for using the IUCN Red List Categories and Criteria (IUCN 2019).
Notes: Begonia villosula resembles B. thomsonii A.DC. (1859: 134), which belongs to the same section and also occurs in Indochine. The two species are similar in their ovate, hairy leaves and hairy inflorescence arising directly from a short aerial stem, yet B. villosula differs from B. thomsonii (Fig. 4) in its leaves’ upper surface with minutely raised cones topped (vs. relatively flat), a white hirsute (vs. villous) top, leaf margins crenate to crenulate (vs. entire with teeth at end of veins to denticulate), stamens 80–120 (vs. 35–70), pistillate flower 4-tepaled (vs. 5-tepaled) and ovary hirsute (vs. villous). In its hairy foliage, 4-tepaled staminate flower and 5-tepaled flower, ovary 2-loculate with three unequal wings. Begonia villosula also resembles B. villifolia Irmsch. (1951: 43). However, the new species is clearly distinct from B. villifolia in its aerial stems being seen only at anthesis (vs. persistent), stem shorter (up to ca. 10 cm vs. to 80 cm), leaf margins crenate to crenulate (vs. irregularly serrate) and unlobed (vs. shallowly lobed), stamens 80–120 (vs. ca. 400). A comparison of the salient characters of the three species is presented in Table 1.
description: Published as part of Hoang, Thanh Son & Lin, Che-Wei, 2021, Two new species of Begonia (sect. Platycentrum, Begoniaceae) from the Central Highlands of Vietnam: B. villosula and B. lophura, pp. 263-274 in Phytotaxa 510 (3) on pages 263-268, DOI: 10.11646/phytotaxa.510.3.6, http://zenodo.org/record/5426458