Begonia petrensis C.Y.Ling & S.Julia, 2022

Julia, S., Kiew, R. & Ling, C. Y., 2022, ADDITIONS TO THE BEGONIA FLORA OF SARAWAK, BORNEO, I: TWELVE NEW SPECIES AND A NEW RECORD, Edinburgh Journal of Botany 79 (410), pp. 1-46 : 25-27

10. Begonia petrensis C.Y.Ling & S.Julia , sp. nov.

Similar to Begonia xiphophylloides Kiew in its narrow, almost non-oblique leaves, and 2-tepaled male flowers, but B. petrensis differs in being little branched, to 50 cm tall (versus bushy and much branched, to 30 cm tall); and having leaf width:length ratio of 1:3–4.8 (versus 1:5.5–7); male flowers with larger tepals, 4–5.5 × 3.5–4 mm (versus 2.2–3.5 × 1.5–2.5 mm); fewer stamens, 20–22 (versus 30–35); female flower with longer pedicel, c. 7 mm (versus 2 mm long); ovary including the wings c.13 × 20.5 mm (versus c.10 × 8 mm); and larger tepals, 14–15 × 5–7 mm (versus c.5 × 2.5 mm).

– Type: Malaysia, Borneo , Sarawak, Belaga District , Linau Forest Management Unit , Gua Layanglayang , Tributary of Sungai Bahau, 2°18′42′′N, 114°40′56′′E, 27 ix 2016, Ling et al. SFC 7042 (holotype SAR!, isotype KEP!). Figure 11 .

Slender herb to 50 cm long, little branched; whole plant glabrous. Stems greenish or reddish, erect when young, becoming pendent, internodes (1–) 2.5–7 cm long, 2–4 mm thick. Stipules pale green or reddish, narrowly ovate, 4–7 × 2–4 mm, margin entire, apex acute, caducous. Leaves alternate, distant, slightly asymmetrical, held more or less horizontally; petioles reddish or greenish, 0.3–1 cm long, slightly grooved above or terete; lamina glabrous, plain dark green above, reddish beneath, slightly falcate, in life succulent, glossy, narrowly lanceolate, 6–13.5 × 1.5–2.8 cm, broad side 0.7–1.4 cm wide, base slightly cordate, slightly unequal, basal lobes not well developed, margin broadly dentate, more prominent towards the apex, vein endings sometimes toothed, apex acuminate, acumen 1–2.5 cm long; venation pinnate, veins concolorous above, pale green beneath, slightly impressed above, prominent beneath, 4 or 5 on either side of the midrib. Inflorescences protogynous, terminal, opposite the uppermost leaf, a single female flower at the base of the inflorescence, above with male flower, sparsely branched; bracts pale green, ovate, c.6 × 2 mm, margin entire, apex acute, caducous; bracteoles, similar to bracts but smaller, c.3 × 1.5 mm, caducous. Male flowers: pedicel pale green or whitish, 3–6 mm long, tepals 2, white or white tinged pink at base, ovate, 4–5.5 × 3.5–4 mm; stamens 20–22, cluster globose, subsessile; filament pale yellow green, 0.2–0.5 mm long; anther pale yellow, obovate, 0.8–1 × 0.5–1 mm, apex emarginate. Female flowers: pedicel pale green, c. 7 mm long; ovary pale green sometimes tinged pink, ovate, ovary including the wings c.13 × 20.5 mm, wings 3, equal, locules 3, placentas 2 per locule; tepals 5, white, sometimes tinged pink outside, white inside, outer two tepals narrowly elliptic, c.14 × 5 mm, inner three tepals elliptic, c.15 × 7; styles 3, pale yellow green, 2–3 mm long, divided to base, anchor-shaped; stigma pale yellow, papillose with continuous twisted band. Capsules pale green, sometimes tinged pink at wings, ovate, 12–14 × 14–20 mm, locules 3, wings 3, equal, acute proximally rounded to truncate distally, 5–9 mm wide, thinly fibrous, dehiscing between locule and wing, pedicels pendent, pale green, sometimes tinged pink, 4–9 mm long.

Distribution. Malaysia ( Sarawak). To date, known only from Belaga District (see Figure 1 ).

Habitat. On mossy sandstone boulders in mixed dipterocarp forest at elevations to 825 m.

Etymology. Latin, petrensis (‘growing among rocks’).

This species resembles Begonia amidalae C.W.Lin & C.I Peng and B. bayae S.Julia & Kiew in having lanceolate leaves with petiole in line with the midrib, but it has much narrower and more elongate leaves.

Begonia petrensis is also similar to B. chaiana Kiew & S.Julia in its erect, slender, glabrous stems with narrow, almost non-oblique leaves, and 2-tepaled male flowers, but it differs in its scarcely developed basal lobe (versus rounded basal lobe 5–10 mm long); female flowers with 5 large tepals, 14–15 × 5–7 mm (versus 3 tepals c.9 × 6 mm); and fruits with a rounded wing tip (versus a truncate or pointed wing tip). Begonia chaiana is restricted to limestone rocks, whereas this new species grows among sandstone boulders.

Figures

Figure 1. Distribution of Begonia papyraptera and the 12 new species of Begonia recorded from Sarawak and described in this article.

Figure 11. Begonia petrensis C.Y.Ling & S.Julia, sp. nov. A, Habit; B, stipule, stem and lower surface of lamina; C, male inflorescence and capsule; D and E, male flower; F and G, female flower; H, capsule; I, cross-section of capsule. All photographs of the type specimen, Ling et al. SFC 7042, taken by C. Y. Ling.