Begonia edgariana S.Julia & Kiew, 2016

Sang, Julia & Kiew, Ruth, 2016, Begonia (Begoniaceae) from Batang Ai National Park and vicinity, Sarawak, Borneo, including six new species, Phytotaxa 252 (1), pp. 17-30 : 25-26

7. Begonia edgariana S.Julia & Kiew , spec. nov. ( Figure 5 )

Section Petermannia

Diagnosis: —It most resembles Begonia matangensis S.Julia & Kiew (2015: 95) in its habit, its dense hispid indumentums and its subopposite velvety leaves but it is different in its broader leaves about twice as long as wide (vs. leaves about three times longer than wide in B. matangensis ), its female flowers with dimorphic tepals with acute apex (vs. isomorphic tepals with pointed apex), style 3–4 mm long, more than half of the length of the tepals with only a shallow Y-shaped stigma (vs. style ca. 2 mm long, less than half of the tepal length and a with wide Y-shaped stigma) and a broader capsule, triangular in outline and 10–15 × 11–14 mm with wider wings, 4–6 mm wide (vs. an oblong capsule ca. 10 × 8 mm with narrower wings, 2–3 mm wide).

Type: — MALAYSIA. Borneo, Sarawak. Sarawak. Lubok Antu District: Batang Ai National Park , Sungai Bebiyong Besai , 1°19’00”N and 112°04’00”E, 222 m, 2 August 2015, Julia et al. SFC 2758 (holotype SAR!; isotypes BRUN!, KEP!, SNP!) .

Erect begonia 26–45 cm tall. Indumentum of stem, stipules and petioles densely hispid, hairs white, 5–6 mm long. Stem branched, dark brown, succulent, slender, 3–4 mm thick, internodes (0.7–) 3–8 cm long, thicker at nodes. Stipules reddish brown, 6–12 × 4–5 mm, margin entire, keeled, apex acuminate, seta to 6 mm long, caducous. Leaves alternate below, upper leaves sub-opposite, pairs distant, held horizontally, not oblique; petiole brownish, 0.3–0.5 cm long, slightly grooved above; lamina plain dark green above, paler beneath, velvety, densely covered in appressed hairs ca. 2 mm long, less dense beneath, in life papery and soft (not fleshy), matt, slightly asymmetric, obovate, slightly falcate, 6–14 × 2.5–6.5 cm, broad side 1.5–4 cm wide, base unequal, slightly lobed on narrow side, rounded on broad side, basal lobe rounded, 0.2–0.8 cm long, margin ciliate, minutely dentate in the lower half, becoming more deeply dentate towards the apex and appearing scalloped, apex acuminate, acumen 1–1.5 cm long; venation pinnate, 4–6 veins on either side of the midrib, concolorous on both surfaces, densely pilose, 1–2 veins in basal lobe, prominent on both surfaces, more so beneath. Inflorescences on short shoots below the subopposite leaf, protogynous, densely pilose, female flower single or occasionally in a pair, male flowers in umbellate clusters with individual flowers subtended by a bract. Bracts and bracteoles similar to stipules, persistent. Male flowers with white pedicels, sometimes dull red, 2–5 mm long; tepals 2, white or greenish white at the centre, sometimes dull red, densely pilose outside, hairs white, glabrous inside, oval, 4–5 × 3 mm, margin entire, apex acute; stamens 14–16, cluster conical, stalked to 0.5 mm long; filaments whitish, ca. 1 mm long; anthers pale yellow, obovate, 1–1.2 × 0.5 mm, apex emarginate. Female flowers with greenish white pedicels 2–6 mm long, sometimes reddish, sparsely hairy; ovary greenish yellow, sometimes reddish, sparsely hairy, oblong, 11–15 × 12–13 mm, wings 3, equal, locules 3, placentas 2 per locule; tepals 5, pale greenish yellow to white tinged pink or reddish, sparsely pilose outside, glabrous inside, lanceolate; outer 2 tepals 6–9 × 2–3 mm, margin entire, apex acute; inner 3 tepals 6–8 × 1.5–3 mm, styles 3, pale green, anchor-shaped, 3–4 mm long, divided to base, papillose forming a continuous twisted band. Capsules single, axillary, hispid, 10–15 × 11–14 mm, triangular in outline, narrowed proximally, expanded distally to a sharp point, locules 3, wings 3, equal, wings 4–6 mm wide, papery, dehiscing between the locule and wing; pedicel 2–5 mm long.

Etymology: —Named after Edgar Irmscher (1887–1968), a German botanist expert in Begonia , who in 1953 described 11 Begonia species collected by Odoardo Beccari from Sarawak ( Irmscher, 1953) and who explained the growth pattern of begonias with subopposite leaves.

Distribution: — MALAYSIA. Borneo. Sarawak. Endemic in Sarawak, known only from the Batang Ai National Park.

Habitat: —Lowland mixed dipterocarp forest, to 222 m elevation on steep or gentle slopes in deep shade.

Notes: —This species is common where it occurs. Two colour forms of leaves and flowers were observed in the field: (i) plants with green or bronzy-dark green leaves and (ii) male flowers usually white or occasionally dull red and the female flowers usually pale green or white tinged pink, occasionally dull red. However, the leaf colour is not associated with flower colour, thus plants with bronzy leaves may have white flowers and those with green leaves have red flowers. The species is monoecious but because the male phase does not overlap with the female, individual plants tend to have either female or male flowers.

Proposed conservation status: —Least Concern as the species occurs within a Totally Protected Area and their habitat is not threatened by any local disturbance.

Figures

FIGURE 5. Begonia edgariana. A. Habit (green form); B. Leaves of bronzy-dark green form; C. Stipule; D. Male flowers; E. Female flower; F. Female flower (dull red form); G. Female flower (white-tinged pink form) showing tepals and pistil; H. Mature fruit; I. Cross section of ovary. All photos from SFC 2758 by Julia Sang (A–H) and Ling Chea Yiing (I).