Begonia tebiang 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 : 28-30

9. Begonia tebiang S.Julia & Kiew , spec. nov. ( Figure 7 )

Section Petermannia

Diagnosis: —Similar to Begonia johariana S.Julia & C.Y.Ling (2015: 110) in its slender creeping stem, small leaves, racemose inflorescence with large bracteoles and its small fruits wider than long but it is different in its succulent stem 3–4 mm thick (vs. wiry and 1–3 mm thick in B. johariana ), its larger stipules 10–15 mm long with an entire margin (vs. 5–8 mm long with a serrate margin), longer inflorescences 4–8.5 cm long with larger bracts 7–17 × 4–11 mm (vs. inflorescences to 5 cm long and bracts 5–7 × 2–4 mm) and outer tepals of female flower less than twice as long as wide (vs. 2–3 times as long as wide).

Type: — MALAYSIA. Borneo. Sarawak. Lubok Antu District: Batang Ai National Park, Lubang Baya , Bebiyong Mit trail, adjacent to the Ranger Post , 1°18’00”N and 112°04’10”E, 200 m, 2 August 2015, Julia et al. SFC 2763 (holotype SAR!; isotypes KEP!, SNP!) .

Creeping herb. Indumentum on stems and petioles pubescent. Stems dull brown, slender, 3–4 mm thick, branched, succulent, internodes 2.5–8.5 cm long, slightly thicker at nodes. Stipules pale green, broadly ovate, 10–15 × 7–10 mm, margin entire and ciliate, apex acuminate, acumen ca. 1 mm long, caducous. Leaves alternate, distant, slightly oblique, held more or less horizontally; petioles dull brown, 1–3.5(–5) cm long, slightly grooved; lamina plain green above, paler beneath, in life slightly fleshy, glossy, with scattered short hairs, asymmetric, ovate, 5.5–8(–10.5) × 4.5–6(–8.5) cm, broad side 2.5–4(–5.5) cm wide, base slightly cordate, sometimes overlapping, basal lobes 0.7–1.5 cm long, margin minutely serrate, teeth more prominent at the vein endings, apex acuminate, acumen to 1 cm long; venation palmate-pinnate, veins greenish above, dark brown towards the base above and beneath, minutely pubescent above and beneath, 2 pairs at the base and 3–4 veins on either side of the midrib, 2–3 veins in basal lobe, slightly impressed above, prominent beneath. Inflorescences protogynous, axillary in upper leaf axils, racemose, slender, 4–8.5 cm long, sometimes with a single lateral branch 1.5–2 cm long with a female flower. Bracts pale green, broadly lanceolate, (7–)10–12(–17) × (4–)6–7(–11) mm, margin ciliate, persistent; bracteoles 3–4 pairs, lower bracteoles subtending female flowers oval, pale green, ca. 8 × 4.5 mm, similar to bracts; upper bracteoles subtending male flowers broadly oval, 6–7 × 5–6 mm, sometimes tinged reddish at the tip, keeled, margin ciliate, persistent. Male flowers with pinkish or white pedicels, 2–5 mm long, pubescent; tepals 4, white sometimes tinged red or reddish, glabrous, margin entire, apex rounded, outer 2 tepals broadly elliptic, 6–8 × 4–6 mm, inner 2 tepals lanceolate, 4–5 × 2–3 mm; stamens 42–46, cluster globose, subsessile; filaments pale yellow, 0.8–1.1 mm long; anthers pale yellow, obovate, 0.6–1 × 0.2–0.4 mm, apex emarginate. Female flowers with pale green pedicels, ca. 1 mm long, glabrous; ovary pale green with reddish wings, broadly ovate, 5–6 × 14–15 mm, glabrous, wings 3, unequal, locules 3, placentas 2 per locule; tepals 5, reddish or greenish outside, white tinged reddish inside, glabrous, outer 3 tepals elliptic, 5–6 × 3–5 mm, margin entire, apex acute, inner 2 tepals slightly smaller, ca. 4 × 2 mm; styles 3, pale yellow, ca. 1 mm long, divided to base, shallow Yshaped; stigma pale yellow, papillose forming a continuous twisted band. Capsules broadly obovate, 6–7 × 9–14 mm, glabrous, locules 3, wings 3, equal, broadly rounded,acute proximally, rounded or truncate distally, 3–4 mm wide, thinly fibrous, dehiscing between locule and wing; pedicel slender, pendent, 5–8 mm long.

Etymology: —From local Iban word tebiang = slope, referring to the habitat where the species grows abundantly.

Distribution: —Endemic in Sarawak, as yet known only from Batang Ai National Park.

Habitat: —Lowland mixed dipterocarp forest at elevations below 200 m on steep or gentle earth slopes in deep to light shade areas.

Additional specimens examined: — MALAYSIA. Borneo. Sarawak. Lubok Antu District: Batang Ai National Park, Nanga Lubang Baya, Bebiyong Mit Trail, Julia et al. SFC 2764 (KEP, SAR), Rantai et al. S 88048 (SAR), Nanga Sungai Lelayang, Rantai et al. S 82793 (SAR).

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 7. Begonia tebiang. A & B. Habit; C. Male inflorescence with numerous pairs of bracteoles; D. Male flower; E & F. Female flowers; G. Old fruit; H. Cross section of ovary. All photos from SFC 2763 by Julia Sang (A–G) and Ling Chea Yiing (H).