Begonia tandangii, C.I Peng & Rubite, 2013

Nakamura, Koh, Rubite, Rosario Rivera, Kono, Yoshiko, Callado, John Rey & Peng, Ching-I, 2013, Begonia tandangii (Begoniaceae, section Baryandra), a new species from Luzon Island, the Philippines, Phytotaxa 145 (1), pp. 27-37 : 34

Begonia tandangii C.-I Peng & R.Rubite, sp. nov. ( Fig. 2 & 3 )

Begonia tandangii resembles B. fenicis in gross morphology, differing from the latter in having leaf margin sparsely fringed with minute hairs (vs. glabrous or with minute hairs only on teeth) and capsules with broadly-ovate outline, acuminate apex, and rounded base (vs. capsules with broadly-obovate outline, rounded to truncate apex, and rounded base).

Type: –– PHILIPPINES. Luzon Island, Aurora Province, Baler, Barangay Zabali , elev. ca. 10 m, E121° 33' 1", N15° 45' 16", 27 October 2011, Ching-I Peng 23400 (holotype HAST) .

Monoecious perennial herbs, rhizomatous. Stems pink when young, green when mature, prostrate, to 1 cm in diameter, internodes 5–13 mm. Stipules pink to green, caducous, ovate to triangular, 1.2–2.5 × 0.8–1.2 cm, adaxially glabrous, abaxially sparsely puberulous with minute hairs, with a prominent keel, apex cuspidate. Leaves basal, alternate; petiole pink, 8.5–20 cm × 5 mm, erect, terete, succulent, glabrous to remotely puberulous; blade green, obliquely ovate to orbicular, 8.4–12.5 × 6.8–10.5 cm, adaxially glabrous, abaxially glabrous or sparsely puberulous with fine hairs, venation palmate, 8–10-veined, base oblique, cordate, basal lobes rounded, sinus narrow, apex mucronate to acuminate, margin with sparse minute hairs less than 1 mm long and irregularly denticulate, teeth small, apiculate. Inflorescences axillary, arising directly from rhizome, dichasial cymes; peduncle green, basally pink, 18–24 cm long, glabrous; bracts caducous, orbicular to oblate, 4–6 × 6–10 mm, glabrous, margin entire and often reflexed, apex obtuse to apiculate. Staminate flowers: pedicel ca. 1.5 cm, glabrous or sparsely puberulous with fine hairs; tepals 4, pinkish white, outer 2 obovate to orbicular, 10–13 × 8–12 mm, inner 2 oblanceolate to narrowly obovate, 7–10 × 3–5 mm; stamens ca. 30; filaments ca. 1.5 mm long, united at base; anthers broadly obovate, ca. 1.0 mm long, apex obtuse. Pistillate flowers: pedicel 1.5–2 cm, glabrous or sparsely puberulous with fine hairs; tepals 5, pinkish white, sometimes persistent when fruiting, oblanceolate to broadly obovate, outer pair orbicular 10–11 × 8 mm, inner three 10– 11 × 5–8 mm; ovary green, glabrous, 3-loculed; placentae axile, bilamellate; styles 3, fused at base, ca. 3 mm long; stigmas 2-cleft, spiraled. Capsules nodding, brown, glabrous, 4–5 × 10–11 mm (excluding wings), broadly ovate in outline, apex acuminate, base rounded; unequally 3-winged; abaxial wing lunate, 3–5 × 10– 11 mm; lateral wings lunate, 1–2 × 10–11 mm. Somatic chromosome number, 2 n = 28 ( Fig. 6 ).

Distribution, habitat and ecology: — Begonia tandangii is currently known only from the type locality. The species grows on limestone rocks in semi-shaded hill of broadleaf forest at seashore and only a patch of a few square meters was observed. The species was flowering and fruiting when collected in late October. In cultivation in the greenhouse of Academia Sinica in Taipei, Taiwan, it flowered and fruited from July to December.

Etymology: —The species epithet is named after Mr. Danilo N. Tandang, Philippine National Herbarium, who guided us to the type locality.

Note: — Begonia tandangii resembles B. fenicis in gross morphology but they are distinguished basing on hairs on leaf margin and capsule shape, as described above. The ITS phylogeny clearly separated the two species. The two species are allopatric.

IUCN Red list category: —Vulnerable ( VU D2 ) . Begonia tandangii is known only from the type locality in Baler, Aurora Province. Although it is in the neighborhood of Aurora Memorial National Park, the type locality is not under any protection. Habitat disturbance brought about by timber harvesting and rapid development of Aurora Province may have a negative impact on the survival of the species .

Figures

FIGURE 2. Begonia tandangii. A. Habitat. B. Habit. C. Rhizome. D. Stipule. E. Leaf, adaxial view. F. Leaf margin sparsely fringed with minute hairs. G. Bracts. H. Staminate flower. I. Pistillate flower, ventral view. J. Pistillate flower, lateral view. K. Transverse section of developing capsule. L. Capsule with persistent tepals. Scale bars are 5 cm for B, 5 mm for C–D and F–L, 10 mm for E. [All photos from Ching-I Peng 23400 (HAST)]

FIGURE 3. Begonia tandangii. A. Habit. B. Stipule. C. Leaf margin sparsely fringed with minute hairs. D. Bracts. E. Staminate flower. F. Stamens. G. Pistillate flower, ventral view. H. Pistillate flower, lateral view. I. Styles and stigmas. J. Transverse section of developing capsule. K. Capsule with persistent tepals. All drawn from Ching-I Peng 23400 (HAST) by Chien-Yu Ke.

FIGURE 6. Somatic chromosomes at metaphase of Begonia tandangii (A, 2n = 28: Ching-I Peng 23400) and B. fenicis (B, 2n = 28: Koh Nakamura 20100209).