Begonia lophura T.S.Hoang & C.W.Lin, 2021

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, Phytotaxa 510 (3), pp. 263-274 : 268-273

2. Begonia lophura T.S.Hoang & C.W.Lin , sp. nov. —

TYPE: VIETNAM. Quang Ngai Province, Tra Bong District, Tra Bui Commune , 15°7'38.65" N, 108°18'45.45" E, 565 m elev., growth on hill slopes composed of sandstone, under the canopy of lower primary evergreen broad-leaved forest, 12 August 2017, Hoang Son 784 (Holotype: VAFS) .

Figs. 5 , 6

Monoecious rhizomatous herb. Rhizome stout, to 10 cm or more long, 6–13 mm thick, internodes congested, hispid. Stipules persistent, reddish-green, narrowly triangular, 8–15 mm long, 5–11 mm wide, herbaceous, strongly keeled, abaxially hispid, margin entire, apex aristate, arista extended to ca. 8 mm long. Leaves alternate, petiole terete, olive green to brownish-red, 9–22 cm long, 3.5–5 mm thick, densely white to pink hispid; leaf blade asymmetric, oblique, widely ovate, 10–19 cm long, 7–13.5 cm wide, broad side 4.5–9 cm wide, basal lobes cordate, 2.5–5.5 cm long, apex acuminate, margin denticulate and shortly hirsute; leaf thick chartaceous, succulent, adaxially olive green, sometimes embellish with dusky malachite green between veins, surface glabrous or very sparsely red hirsute; velvety, with ultramarine blue to aquamarine iridescence giving a amazing appearance; abaxially pale green to purplish red, sparsely red hispid; 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. Inflorescences axillary, bisexual, cymose panicle arising directly from rhizome, dichasial cymes branched ca. 3 times; peduncle dusky vermilion to crimson, 8–14 cm long, white hirsute; bracts persistent, reddish, lanceolate, 4–10 mm long, 1–4 mm wide, abaxially hirsute, margin sparsely denticulate and hirsute. Staminate flower: pedicel 1.5–3.5 cm long, sparsely hirsute, tepals 4, white or rosy pink, outer 2 widely ovate to widely obovate, 1.6–2 cm long, 1.5–1.9 cm wide, abaxially red hirsute, inner 2 narrowly obovate, 1.7–2 cm long, 7–9 mm wide, glabrous; androecium actinomorphic, ca. 6 mm across; stamens golden yellow, up to 200; filaments fused at base into a short column ca. 1.5 mm long; anthers narrowly obovate, ca. 1 mm long, 2-locular, apex obtuse to truncate, longer than filaments. Pistillate flower: pedicel ca. 1.5 cm long, sparsely hirsute, tepals 5, white to rosy pink, outer 3 widely obovate to very widely obovate, 1.1–1.5 cm long, 1–1.3 cm wide, abaxially red hirsute, inner 2 obovate to widely obovate, 1–1.4 cm long, 0.7–1 cm wide; ovary trigonous-ellipsoid, ca. 5 mm long, 2.5 mm thick (wings excluded), rosy pink, hirsute; 3-winged, wings unequal, pink, ca. 8 mm long, lateral wings narrower, narrowly triangular, 1.5–2 mm wide, abaxial wing crescent-shaped, 4–5 mm wide, sparsely hirsute, margin entire; ovary 2-locular, placenta bilamellate; styles 2, fused at base, golden yellow, ca. 5 mm long, stigma spirally twisted. Capsule trigonous-ellipsoid, 1.2–1.4 cm long, ca. 8 mm thick (wings excluded), reddish to olive fresh, scabrous; wings unequal, 1.5–1.8 cm long, lateral wings ca. 5 mm wide, abaxial wing slightly falcate and strongly swollen, 1.5–1.8 cm wide.

Distribution and ecology: The new species is currently known to be available in Tra Bui Commune, Tra Bong District, Quang Ngai Province, the Central Highlands of Vietnam and probably also occurs in adjacent areas. It grows on hill slopes composed of sandstone at 565 m elevation, under the canopy of lower primary evergreen broad-leaved forests.

Etymology: The epithet ‘ lophura ’ refers to the resemblance of the blue iridescent sheen leaves, which resemble the metallica blue feather of Lophura edwardsi.

Conservation: Begonia lophura was collected along the roadside from protection forest in Tra Bui Commune where no signs of major anthropogenic disturbance have been noticed. Therefore, the species is preliminarily assigned to Vulnerable (VUD2) category according to The Guidelines for Using The IUCN Red List Categories and Criteria ( IUCN 2019).

Notes: Begonia lophura resembles B. pavonina Ridley (1909: 22) , while the latter is a handsome species from Cameron Highlands in Peninsular Malaysia and also belongs to sect. Platycentrum. The two species bear superficial similarities by having ovate leaves that have upper surfaces which produce an indigo blue iridescence when the light is reflected at certain angles, 4-tepaled staminate flower and 5-tepaled pistillate flower. However, B. lophura is distinct from B. pavonina ( Fig. 7 ) in its leaves that are widely ovate (vs. ovate) and red hirsute on abaxial surface (vs. glabrous), bracts persistent (vs. caducous), tepals hirsute in both of staminate and pistillate flowers (vs. glabrous), capsule scabrous (vs. glabrous) and abaxial wing strongly swollen (vs. thin, not swollen). The new species is also closely similar to B. menglianensis Y.Y. Qian (2001:461) in widely ovate, velvety foliage and inflorescence structure, but differs in its adaxial lamina surface with blue iridescence (vs. absence of blue iridescence), ovary hirsute (vs. fusco-villose) and abaxial wing strongly swollen (vs. thin, not swollen). A comparison of the three phonetically similar species is presented in Table 2 .

Figures

FIGURE 5. Begonia lophura T.S.Hoang & C.W.Lin. A. Habit; B, B’. Upper and lower surface of leaf sections; C. Stipules; D, D’, D’’. Bracts; E, E’. Face and side views of staminate flower; F, F’. Ventral and dorsal views of stamen; G, G’. Face and side views of pistillate flower; H, H’. Style and stigmatic band, ventral and dorsal views; I. Cross section of an immature capsule; J. Capsule.

FIGURE 6. Begonia lophura T.S.Hoang & C.W.Lin. A, B, C. Habit and habitats, showing indigo blue iridescence leaves; D, E. Upper and lower surface of leaf sections; F. Young inflorescence and petioles, showing densely hispid; G. Habit; H. Staminate flowers, face and side views; I. Pistillate flower, face view; J. Capsules; K. Cross section of an immature capsule.All photos from Hoang Son 784 by Thanh Son Hoang.

FIGURE 7. Begonia pavonina Ridley. A, B. Habit and habitats; C. Staminate flowers, face and side views; D. Pistillate flowers, face, back and side views; E. Immature capsule. Photos A, B & E by Che-Wei Lin; Photos C (left) from Peng 20239 and C (right) & D from Peng 22710 by Ching-I Peng.