Begonia insolita 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 : 13-15

5. Begonia insolita C.Y.Ling & S.Julia , sp. nov.

Similar to Begonia tinjanii S.Julia in its erect habit and oblanceolate leaves with a cordate base, but differs in having smaller stipules, c.5 × 3 mm (versus 10–12 × 4 mm); terminal inflorescences (versus axillary); bracteoles with glandular knobs along the margin (versus bracteoles non-glandular); smaller male flowers, outer two tepals c.4 × 4 mm, inner two tepals c.4 × 1.5 mm (versus outer two tepals 8–12 × 5–10 mm, inner two tepals 6–8 × 1–4 mm); ovary narrower, 7–8 × 5–8 mm (versus 10–12 × 10–12 mm); placentas 2 per locule (versus placenta 1 per locule); and fruit broader than long, 3–8 × 6–12 mm (versus longer than wide, c.12 × 8 mm).

– Type: Malaysia, Borneo , Sarawak, Kapit District , Ulu Mengiong, 1°25′00′′N, 112°58′45′′E, 6 viii 2017, Ling et al. SFC 5584 (holotype SAR!, isotype KEP!). Figure 6 .

Erect herb to 15 cm tall, leaves crowded towards top of the stem. Stems brownish, unbranched, rarely branching at the base, pubescent, hairs brown, succulent, 2–4 mm thick, internodes 0.5–3 cm long, slightly thicker at nodes, sometimes rooting at nodes. Stipules pale green, narrowly ovate, c.5 × 3 mm, margin entire, apex acute, caducous.

Leaves alternate, distant, not oblique, held horizontally; petioles brownish, pubescent, hairs brown, 3–7 mm long, terete or slightly grooved above; lamina green above, pale green beneath, with green bristles between veins, in life succulent, glossy, asymmetrical, narrowly obovate, 5.5–9 × 2.3–3 cm, broad side 1.5–2.5 cm wide, base cordate, basal lobes c. 2 mm long, margin toothed at the vein ending, apex acuminate, acumen to 1 cm long; venation pinnate, concolorous, 2–4 veins on each side of the midrib, inconspicuous on both sides. Inflorescences protogynous, terminal or opposite upper leaf axil, racemose, 3–5 cm long, peduncle brownish, 5–6 mm long; bracts pale green or whitish, elliptic, 5–6 × 2–3 mm, margin entire, caducous; bracteoles white or pale green, elliptic, 1.5–4 × 1–2 mm, margin studded with glandular knobs, apex acute or rounded, persistent. Male flowers: pedicel white, c. 7 mm long, glabrescent; tepals 4, white, glabrous, margin entire, apex broadly acute to rounded, outer two tepals broadly ovate, c.4 × 4 mm; inner two tepals lanceolate, c.4 × 1.5 mm; stamens 13–17, cluster globose, subsessile; filaments pale yellow, c. 1 mm long; anthers yellow, obovate, c.0.8 × 0.5 mm, apex emarginate. Female flowers: pedicel white, c. 3 mm long; ovary white, sometimes tinged pink, elliptic, ovary including the wings 7–8 × 5–8 mm, glabrous, wings 3, equal, locules 3, placentas 2 per locule; tepals 5 or rarely 6, white, sometimes tinged pink, glabrous, outer four tepals broadly elliptic, 9–10 ×

4 mm, margin entire, apex acute, inner one or two tepals lanceolate, 7–8 × 2 mm; styles

3, pale yellow, c. 3 mm long, divided to base, anchor-shaped; stigma pale yellow, papillose forming a continuous twisted band. Capsules elliptic, broader than long, 3–8 × 6–12 mm, glabrous, locules 3, placentas 2 per locule, wings 3, unequal, acute proximally, rounded distally, 2–4 mm wide, thinly fibrous, dehiscing between the locule and wing, pendent on thin pedicels, 1–1.2 cm long.

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

Habitat. On a steep slope above a stream in disturbed mixed dipterocarp forest.

Etymology. Latin, insolitus (‘unusual’), referring to the combination of the terminal inflorescence and habit of the ‘pubescens group’.

Although Begonia insolita is at present known from only one specimen, it is sufficiently distinct to be described as a new species. Although it resembles members of the ‘ Begonia pubescens Ridl. group’ in being a low, hairy begonia with non-oblique leaves, the short petiole not at an angle with the midrib and the venation pinnate, it is unique in the combination of its being glabrous and in the inflorescence being terminal whereas in the ‘pubescens group’ the short inflorescences are produced from many leaf axils lower down the stem. Among members of the ‘pubescens group’, which include Begonia hexaptera Sands , B. hullettii Ridley and B. magentifolia Kiew & S.Julia , B. insolita is most similar to B. tinjanii in being glabrous, but it differs in several other characters (see diagnosis above).

This new species also superficially resembles Begonia incompta Kiew , but B. insolita is much smaller in its habit (15 cm tall versus 87 cm tall) and has shorter internodes, 0.5–3 cm (versus 4–8 cm long); narrowly ovate stipules, c.5 × 3 mm (versus lanceolate, 8–16 × 2.5–4 mm); shorter petioles, 3–7 mm (versus (8–) 20–30 mm long); much smaller leaves, 5.5–9 × 2.3–3 cm (versus 12.5–22 × 5–7.5 cm); and much smaller capsules, 3–8 × 6–12 mm (versus 16–24 × 14–18 mm).

Figures

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

Figure 6. Begonia insolita C.Y.Ling & S.Julia, sp. nov. A, Habit; B, stipule; C, male inflorescence and capsule; D, bracteole; 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 5584, taken by C. Y. Ling.