Begonia compacta 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 : 23-25

5. Begonia compacta S.Julia & Kiew , spec. nov. ( Figure 4 )

Section Petermannia

Diagnosis: —Similar to Begonia vulgare S. Julia & Kiew (2013: 26) in habit, leaf shape and inflorescence that has a basal pair of female flowers and male flowers in a dense cluster above but it is different in its shorter stem to 60 cm tall (vs. to 2 m tall in B. vulgare ), longer petioles 4–13 cm long (vs. 0.5–3.5 cm), shorter inflorescences, 1.5–5 cm (vs. 9–19 cm) and the shorter fruit, 15–25 × 12–24 mm (vs. the more oblong fruit, 35–45 × 17–27 mm in B. vulgare ).

Type: — MALAYSIA. Borneo. Sarawak. Lubok Antu District: Batang Ai, Sungai Jengin , 1°15’00”N and 112°06’00”E, 127 m, 1 August 2015, Julia et al. SFC 2751 (holotype SAR!; isotypes KEP!, SNP!) .

Cane-like begonia 15–60 cm tall. Stems erect, reddish, 12–14 mm thick, little-branched, succulent, minutely pubescent; internodes 3–8(–16) cm long, thicker at nodes. Stipules brownish, lanceolate, 11–19(–28) × 5–8(–12) mm, margin entire, keeled, apex acuminate, caducous. Leaves alternate, distant, oblique, held horizontally; petioles reddish, (4–) 8– 13 cm long, grooved, minutely pubescent; lamina plain green on both surfaces, in life succulent, drying papery, matt, ovate to obovate, 15–22 × 8–17 cm, broad side 5.5–15 cm wide, often markedly concave on the narrower side, base slightly cordate, sometimes slightly overlapping, basal lobes 0.75–1.1 cm, margin shallowly dentate, apex sharply acuminate, 1.5–2 cm long; venation palmate-pinnate, veins pale green on both surfaces, minutely pubescent, 3–5 veins on either side of the midrib, 3–5 veins in the basal lobe, prominent on both surfaces. Inflorescences protogynous, axillary in the upper leaf axils, rachis 1.5–5 cm long, with a pair of female flowers below and a dense cluster of male flowers above, each cymule enveloped in upto 2 pairs of bracteoles. Bracts reddish, lanceolate, 12–20 × 8–12 mm, margin entire, caducous; bracteoles broadly lanceolate, setose at apex, increasing in size to 11–13 × 8–10 mm, then abruptly diminishing in size towards the developing apex. Male flowers with pale pink pedicels, 4–8 mm long; tepals 2, pale yellowish green, oval, 5–6 × 3–5 mm, margin entire, apex rounded; stamens 29–32, cluster globose, subsessile; filaments pale yellow, 0.8–1 mm long; anthers pale yellow, obovate, ca. 1.5 × 0.8 mm, apex emarginate. Female flowers with greenish pedicels, 2–4 mm long; ovary pale green, wings tips pale green, obovoid, 9–10 × 8–12 mm, wings 3, equal, locules 3, placentas 2 per locule; tepals 5, pale green, outer 4 tepals ovate, 7–8 × 5–6 mm, margin entire, apex broadly acute, inner tepals ovate, ca. 6 × 5 mm, margin entire, apex rounded; styles 3, pale yellow, 3–4 mm long, divided to base, deeply Y-shaped; stigma pale yellow with reddish stripe, papillose forming a continuous twisted band. Capsules single or a pair, pale green, triangular or sometimes to slightly oblong-triangular in outline, 15–25 × 12–24 mm, glabrous, locules 3, wings 3, equal, rounded proximally and expanded and pointed distally, wings 6–7 mm wide, thinly fibrous, dehiscing between locule and wing; pedicel pendent, 7–11 mm long, reddish towards the base.

Etymology: —Latin, compacta = close-packed, referring to the compact male inflorescence subtended by many pairs of bracteoles.

Distribution: — MALAYSIA. Borneo. Sarawak. Endemic in Sarawak, known only from the Batang Ai. Habitat: —Riparian forest to 127 m elevation on steep earth or rocky slopes above the river bank in light shade. Additional specimen examined: — MALAYSIA. Borneo. Sarawak. Lubok Antu District: Batang Ai National Park, Sungai Bebiyong Besai, 2 August 2015, Julia et al. SFC 2760 (KEP, SAR, SNP). Proposed conservation status: —Least Concern as the species occurs within a Totally Protected Area and their habitat is not threatened by any local disturbance.

6. Begonia darthvaderiana C.W.Lin & C.-I Peng (2014: 132). Type:— MALAYSIA. Borneo , Sarawak. Lubok Antu District : Batang Ai , 5 July 2013, C.W. Lin 549 (holotype SAR n.v.; isotypes E, HAST, KEP, TAIF).

Distribution: —Endemic in Sarawak; known only from Batang Ai in Lubok Antu District.

Habitat: —In lowland mixed dipterocarp forest at 130–200 m elevation in valleys, on lower to upper soil slopes or soil at the cliff base in deep shade.

Notes: —The species was collected from forest areas outside the Batang Ai National Park boundary (Lin, C.W. pers.comm.). So far no record of this species has been recorded within the Park boundary.

Proposed conservation status: —Data Deficient. The species was previously recorded from forest area outside the park boundary and the species occurrence within the park boundary is yet to be ascertained. It may also be under pressure from commercial collecting because it is currently the most sought after begonia from Sarawak.

Figures

FIGURE 4. Begonia compacta. A. Habit; B. Stipule; C. Male inflorescence surrounded by persistent bracteoles; D. Female inflorescence surrounded by persistent bracteole; E. Female flower showing tepals and pistil; F. Fruits surrounded by persistent bracteole; G. Cross section of ovary. All photos from SFC 2751 by Julia Sang (A–F) and Ling Chea Yiing (G).