Begonia chenii Y.H.Tan, M.B.Maw & H.B.Ding, 2020

Maw, Mya Bhone, Ding, Hong-Bo, Yang, Bin, Win, Pyae Pyae & Tan, Yun-Hong, 2020, Taxonomic studies on Begonia (Begoniaceae) in Myanmar I: three new species and supplementary description of Begonia rheophytica from Northern Myanmar, PhytoKeys 138, pp. 203-217 : 203

Begonia chenii Y.H.Tan, M.B.Maw & H.B.Ding sp. nov. Figure 1

Diagnosis.

Begonia chenii Y.H. Tan, M.B. Maw & H.B. Ding is mostly similar to B. mariachristinae Wahlsteen (2018: 1) in lanceolate-ovate leaves with silver patches or dots on the upper surface, but significantly differs by stipules slightly pilose (vs. glabrous), petiole densely reddish pilose (vs. sparsely puberulous), 6 (rarely 4 or 7) tepals of female flower (vs. 4 tepals) and red, 3 or 4 locular ovary (vs. green, 2 locular).

Type.

Myanmar. Kachin State: Putao District, on the way from Putao to Upper Shankhaung, in tropical rain forest, 27°25'36.87"N, 97°16'13.56"E, 512 m, 4 May 2017, Y.H. Tan, B. Yang, H.B. Ding, X.D. Zeng, M.B. Maw & T.S. Tin M1378 (holotype: HITBC!; isotypes: RAF!).

Description.

Perennial herb, dioecious or rarely monoecious, lacking rhizome or tuber. Stem erect, 40-60 cm tall, reddish brown, densely white pilose, internode 2-11 cm long, branching. Stipule persistent, ovate, 1-15 × 3-5 mm, papery, keeled, apex cuspidate (1-4 mm), margin entire, slightly pilose. Leaf alternate, petiole 1.5-3 cm long, reddish-brown, densely reddish pilose; blade asymmetric, lanceolate-ovate, 8-11 × 2.5-4 cm, apex attenuate, base oblique, margin serrate and with reddish hispid, venation palmate-pinnate, 5-6 pairs of veins; upper surface green or dark green with white patches and dots between the veins, bright green shot with metallic blue depending on the angle of the light, especially on young leaves, sparsely reddish hispid, especially along the midrib and lateral veins; lower surface deep red or deep red with light green areas both margin linings, scattered reddish hispid and densely along the midrib and lateral veins. Inflorescence axillary, flower solitary or in a simple cyme, pendulous; bract persistent, ovate to narrow lanceolate, 4-8 × 2-3 mm. Staminate flower: pedicel 0.8-1.1 cm, reddish, glabrous or sparsely pilose; tepals 4 (rarely 5 or 6), reddish with white margins, unequal, inner 2 (rarely 3), ovate, 7-1 × 6-1 mm, glabrous, outer 2 (rarely 3), ovate, 7-9 × 7-1 mm, reddish or whitish pilose on the outer surface, margin entire; androecium actinomorphic, stamens numerous, filament free, anther oblong, golden yellow. Pistillate flower: pedicel 0.6-0.8 cm, tepals 6 (rarely 4 or 7), unequal, inner 3, elliptic, 8-10 × 3-4 mm, pink to white, glabrous, outer 3, ovate or elliptic, 7-11 × 5-7 mm, reddish or whitish pilose on outer surface; ovary red, slightly or densely pilose on the surface, triangular or rhomboid winged, 3-5 × 2-5 mm, placentation axillary, locules 3 or 4, placentae 2 per locule; styles 3, fused at base, stigma bifid with twisted bands, highly convolute, yellow or golden yellow. Fruit berry-like, red, reddish or whitish pilose, triangular, rhomboid (8-15 × 6-9 mm) or suboblate (8-15 mm in diam.), 3 or 4 horned, rarely wingless.

Phenology.

Flowering from April to May; fruiting from May to June.

Distribution.

The species is only known from the type locality, Putao District, Kachin State, Northern Myanmar.

Ecology.

The species grows in the moist shaded environment of tropical rain forest, elevation about 512 m.

Etymology.

The species epithet " chenii " is named after Professor Chen Jin, the director of Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, who gave us the opportunity to study the Myanmar flora, which led to the discovery of this new species.

Conservation status.

Data Deficient (DD). Begonia chenii was collected along the path on the way from Putao to Upper Shankhaung where any signs of major anthropogenic disturbance were noticed in the type locality. However, further explorations are needed for a proper assessment of conservation due to insufficient information on its distribution and population status. Therefore, the species has been preliminarily assigned to Data Deficient (DD) category according to The Guidelines for Using The IUCN Red List Categories and Criteria ( IUCN 2017).

Additional specimens examined

(paratypes). Myanmar. Kachin State: Putao District, Upper Shankhaung, in tropical montane forest, 27°25'36.87"N, 97°16'13.56"E, 512 m, 4 May 2017, Y.H. Tan, B. Yang, H.B. Ding, X.D. Zeng, M.B. Maw & T.S. Tin M1379 (HITBC!); Kachin State: Putao District, Upper Shankhaung, 27°25'35"N, 97°16'14"E, 500 m, 29 April 2016, Y.H. Tan & S.S. Zhou M201627 (HITBC!); Kachin State: Putao District, Upper Shankhaung, 27°25'34"N, 97°16'13"E, 520 m, 7 May 2017, S.S. Zhou & X.D. Zeng M2030 (HITBC!; RAF!)

Affinities. Begonia chenii is morphologically similar to B. mariachristinae . But it can be easily distinguished in having 3 or 4 locules (vs. 2 locules). See Table 1 for detailed comparison of B. chenii with morphologically allied species.

Figures

Figure 1. Begonia chenii Y. H. Tan, M. B. Maw & H. B. Ding, sp. nov. (photographed by H. B. Ding and Y. H. Tan) A habitat B leaves (back view) C inflorescence D staminate flower showing 6 tepals E pistillate flower F infructescence showing monoecious G infructescence showing stigmas H staminate flower showing variation of 4, 5, 6 tepals I tepals of staminate flower J androecium K tepals of pistillate flower L ovary and stigma M ovary (3 - winged) N ovary (4 - winged) O-P serial cross section of ovary (locules 4) Q serial cross section of ovary (locules 4 and wingless) R serial cross section of ovary (locules 3).