Begonia putaoensis 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 putaoensis Y.H.Tan, M.B.Maw & H.B.Ding sp. nov. Figures 2 , 3

Diagnosis.

Begonia putaoensis Y.H. Tan, M.B. Maw & H.B. Ding is morphologically similar to B. scintillans Dunn (1920: 111) in rhizomatous creeping habit and dark green ovate leaves with silver or white area on the upper surface, but it can be easily distinguished by the following characters: sparsely pubescent adaxially leaf (vs. densely strigose) and glabrous capsule (vs. red villose).

Type.

Myanmar. Kachin State: Putao District, on the way from Camp 2 to Camp 3 along Putao to Madwel, on moist rocky slope in tropical rain forest, 27°39'35"N, 97°22'30"E, 505 m, 29 November 2017, Y.H. Tan, B. Yang, H.B. Ding, X.D. Zeng, M.B. Maw & P.K. Linn M2923 (holotype: HITBC!; isotypes: RAF!).

Description.

Perennial herb, monoecious, 10-25 cm tall. Rhizome creeping with adventitious roots, sometimes branched, 3-30 cm long, 5-12 mm thick, reddish brown, densely pubescent or rusty villous, internode short, 3-8 mm long. Stipule triangular, 6-12 × 5-6 mm, apex cuspidate (3-5 mm), margin entire, rusty colored, densely rusty tomentose on both surfaces, persistent; petiole scarlet red to crimson, cylindrical, 3-15 cm long, densely rusty tomentose. Blade ovate to widely ovate, 6.5-15 cm long, 6-11cm wide, asymmetric, adaxially dark green with gray or light-green areas, slightly pubescent, abaxially light-green, deep red along veins, rarely entirely dark red or red with light-green areas, slightly pubescent, rusty villous on the veins; base cordate, apex acuminate to attenuate, margin sinuate, with sparse hairs; venation palmate, 7-9 veined, adaxial slightly impressed, abaxial distinctly prominent. Inflorescence axillary, sub-corymb, erect, branching 2-3 times, 7-19 cm long. Primary peduncle 5.5-14.5 cm long, densely rusty tomentose, dark red, secondary 0.6-1.5 cm long; bract ovate to lanceolate or obovate, 8-13 × 3-7 mm, glabrous, apex acute, margin entire, sometimes with ciliate, 2-10 flowers per inflorescence, male flowers open earlier at the same node. Staminate flower: pedicel white or pink, glabrous, 0.9-3.7 cm long, tepals 4, rarely 6, outer 2 (or 3) larger, pink, ovate to suborbicular, 1.3-1.8 × 1.1-2.1 cm, glabrous or abaxially strigose; inner 2 (rarely 3), smaller, white-pinkish, ovate or obovate, 9-17 × 7-11 mm., glabrous; androecium 4-6 mm long, 5-7 mm in diameter; stamens numerous, filaments ca. 1.7 mm long, anthers yellow, obovate, nearly 1.2 mm long, apex obtuse. Pistillate flower: pedicel dark red, glabrous, 2.6-3.3 cm long, tepals 5, rarely 6, outer 3, larger, pink, ovate, 14-16 × 1-13 mm, inner 2 (rarely 3), smaller, white-pinkish, ovate to suborbicular, 12-16 × 8-11 mm; ovary glabrous, 2-loculed, placentae axillary, placentae 2 per locule, styles 2 or 3, fused at base, stigma bifid with twisted bands, highly convolute, yellow or golden yellow. Capsule nodding, ovoid, glabrous, unequally 3-winged; abaxial wing nearly round-rectangular, 13-17 mm broad, lateral wings shorter, 2.5-3.0 mm broad.

Phenology.

Flowering from November to December; fruiting from December to February.

Distribution.

The species is known from the single locality in Putao District, Kachin State, Northern Myanmar.

Ecology.

The species grows on moist rocky slopes of tropical montane forest, elevation 500-900 m.

Etymology.

The species epithet refers to the type locality of the species, Putao District, Kachin State, Northern Myanmar.

Conservation status.

Data Deficient (DD). The species might not confront strong human pressures because of the remoteness of its type locality. But we cannot assess the species’ risk of extinction due to lack of data. Therefore, the species is temporarily assigned a status Data Deficient (DD) according to The Guidelines for Using The IUCN Red List Categories and Criteria ( IUCN 2017).

Affinities.

Begonia putaoensis is mostly similar in morphological characters to B. scintillans and B. annulata K. Koch (1857: 76) under the sect. Platycentrum . But it can be easily distinguished from B. scintillans in having shorter internode 0.3-0.8 cm long (vs. 3-5 cm long), sparsely pubescent leaf lamina (vs. densely hairy) and glabrous capsule (vs. red villose). It differs from B. annulata through having the following characteristics: rhizomatous creeping (vs. rhizomatous erect) and dark green with silver or light green area on upper surface of leaf (vs. dark green with silver or white bands). See Table 2 for detailed comparison of B. putaoensis with morphologically allied species.

Additional specimens examined

(paratypes). Myanmar. Kachin State: Putao District, near around Camp 5, along Putao to Madwel, on moist rocky slopes in tropical rain forest, 27°43'59.51"N, 97°22'52.27"E, 873 m, 3 December 2017, Y.H. Tan, B. Yang, H.B. Ding, X.D. Zeng, M.B. Maw & P.K. Linn M3168 (HITBC!; RAF!); MYANMAR. Kachin State: Putao District. Voucher from the cultivated plant in the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 12 November 2018, H.B. Ding XTBG-0050 (HITBC!).

Figures

Figure 2. Begonia putaoensis Y. H. Tan, M. B. Maw & H. B. Ding, sp. nov. (wild, photographed by H. B. Ding) A-B habitat C rhizome D inflorescence E stipule on stem F-H single leaf (front and back view) I flowers (front view) J flowers (back view) K outer tepals of male flower (back view) L inner tepals of male flower (back view) M androecium with pedicel.

Figure 3. Begonia putaoensis Y. H. Tan, M. B. Maw & H. B. Ding, sp. nov. (cultivated plants, photographed by H. B. Ding) A habit B staminate flower showing 4 tepals C staminate flower showing 6 tepals D pistillate flower showing 6 tepals and 3 styles E pistillate flower showing 5 tepals and 2 styles F rhizome G stipule (back view) H stipule (front view) I bract J uppermost bract K stigma (3, front view) L stigma (2, side view) M androecium (front view) N fruit with unequal wings O serial cross section of ovary.