Begonia jenginensis 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 : 26-28

8. Begonia jenginensis S.Julia & Kiew , spec. nov. ( Figure 6 )

Section Petermannia

Diagnosis: —Similar to Begonia awongii Sands (1997: 432) in its habit, hispid inflorescence, leaf shape and racemose inflorescence but differs in the shallowly cordate base with a basal lobe 1–2 cm long (vs. deeply cordate with a basal lobe 5.5–8.5 cm long in B. awongii ), male flowers with pale pink male tepals and fewer (28–30) but larger stamens with filaments ca. 2 mm long and anthers ca. 1.5 mm long (vs. white tepals and ca. 46 subsessile stamens with filaments ca. 0.5 mm long and anthers ca. 0.25 mm long), smaller tepals in the female flower, 6–7 × 4–6 mm (vs. 12–14 × 7–9 mm) and larger glabrous capsules, 12–14 × 14–24 mm (vs. densely hispid and 7–12 × 16–18 mm).

Type: — MALAYSIA. Borneo. Sarawak. Lubok Antu District: Batang Ai, Sungai Jengin , 1°15’00”N and 112°06’00”E, 194 m, 1 August 2015, Julia et al. SFC 2750 (holotype SAR!; isotypes BRUN!, KEP!, SNP!) .

Cane-like begonia to 1.35 m tall. Stems reddish brown, pilose, hairs brownish, terete and finely ridged, 6–8 mm thick, internodes 4–6(–10) cm, swollen at the nodes. Stipules narrowly or broadly lanceolate, 12–18 × 4–11 mm, keeled terminating in a seta 1–2 mm long, hispid outside. Leaves alternate, very oblique, held horizontally or sometimes slightly vertical; petioles reddish brown, (3–)5–10(–13.5) cm long, grooved, hispid; lamina plain green above, paler beneath, above sparsely hispid between veins, veins densely hispid, glabrous beneath except on veins, in life succulent, membranous when dry, matt, broadly ovate, 13.5–25 × 11.5–20.5 cm, broad side 9–14.5 cm wide, base shallowly cordate, basal lobes 1–2 cm, margin minutely dentate, apex acuminate, 1.5–2 cm long; venation palmate, prominent on both surfaces, 4–6 veins radiating from the base, in life veins pale green on both surfaces, reddish brown towards the base, drying reddish, 3–4 veins along the midrib on the broad side, 1–2 veins in the basal lobe. Inflorescences protogynous, axillary in the upper leaf axils, racemose, rachis unbranched, (2.5–) 10–15 cm long. Bracts greenish, lanceolate, 12–17 × 4–5 mm, margin entire, apex setose to 4 mm long, caducous; bracteoles similar to bracts but smaller, 4–10 × 4 mm, caducous. Male flowers with pale pink pedicels, 5–10 mm long; tepals 4, pale pink, reddish towards base, oval, outer 2 tepals 8–10 × 5–8 mm, inner 2 tepals 5–8 × 2–4 mm, margin entire, apex rounded; stamens 28–30, cluster globose, subsessile; filaments pale yellow, ca. 2 mm long; anthers pale yellow, obovate, ca. 1.5 × 1 mm, apex emarginate. Female flowers with greenish pedicels, 4–8 mm long, glabrous; ovary pale green, wing tips pale green, ovate, 7–8 × 8–11 mm, wings 3, equal, locules 3, placentas 1 per locule; tepals 5, ovate, 6–7 × 4–6 mm, margin entire, apex rounded; styles 3, pale yellow, 2–3 mm long, divided to base, widely Y-shaped; stigma reddish, papillose cells large and pale yellow forming a continuous twisted band. Capsules 2–4 pairs along the rachis, greenish yellow, glabrous, 12–14 × 14–24 mm, glabrous, locules 3, wings 3, equal, rounded proximally and distally or truncate distally, 3–6 mm wide, thinly fibrous, dehiscing between locule and wing; pedicel pendent, 6–15 mm long, glabrous, reddish towards the base.

Etymology: —Named after the type locality, Jengin River (Sungai = River) where the species was discovered.

Distribution: — MALAYSIA. Borneo. Sarawak. Endemic in Sarawak where the species is known only from Sungai Bebiyong Besai in Batang Ai National Park and Sungai Jengin in Batang Ai.

Habitat: —Riparian forest at 194 m elevation, growing on steep earth slopes above the river bank or on boulders with thin layer of soil in light shade.

Additional specimen examined: — MALAYSIA. Borneo. Sarawak. Lubok Antu District: Batang Ai National Park, Sungai Bebiyong Besai, Julia et al. SFC 2755 (SAR).

Notes: —The species is more common along the bank of Sungai Jengin than along Sungai Bebiyong Besai.

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 6. Begonia jenginensis. A. Habit; B. Stipule; C. Fruits and male inflorescence; D. Male inflorescence; E. Male flower with one inner tepal missing; F. Female flower; G. Female flower showing pistil; H. Fruit; I. Cross section of ovary.All photos from SFC 2750 by Julia Sang.