Begonia sessilifructa S.Julia & Kiew, 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 : 30-32

12. Begonia sessilifructa S.Julia & Kiew , sp. nov.

Similar to Begonia kiamfeei Kiew & S.Julia in its creeping habit, hirsute petioles and long inflorescences but differs in having smaller stipules, 3–5 × 2–3 mm (versus 8–13 × 4–6 mm); uppermost bracteoles persistent and studded with glandular knobs (versus caducous bracteoles with entire margins); fewer stamens, c.14 (versus 26–30); subsessile female flowers with hispid ovary (versus female flower with a pedicel to 8 mm long and a glabrous ovary); and fruit subsessile (versus fruit stalk 6–13 mm long).

– Type: Malaysia, Borneo , Sarawak, Julau District , Sungai Mujok, Sungai Sugai (near boundary of Lanjak Entimau Wildlife Sanctuary), 1°44′03′′N, 112°05′53′′E, 24 v 2016, Ling & Dino SFC 5953 (holotype SAR!, isotype KEP!). Figure 13 .

Creeping herb. Stem and petioles hirsute, stipules and lamina hispid, hairs reddish, sometimes whitish, 1.5–2 mm long. Stems 5–18 cm long, little branched, red brown, internodes 1–3.5 cm long, 2–3 mm thick, slightly thicker at nodes, rooting at nodes. Stipules pale green or brownish, ovate, 3–5 × 2–3 mm, margin entire, apex setose, seta to 2 mm long, caducous. Leaves oblique, held horizontally; petioles reddish or greenish, 2–5.5 cm long, terete; lamina plane, sparsely bristled, plain green above, pale green beneath, in life slightly succulent, asymmetrical, ovate, 4–7.5 × 4–6.5 cm, broad side 2.5–4.5 cm wide, base unequal, cordate, overlapping (when dry appearing peltate), basal lobe 1.5–2.5 cm long, margin dentate, apex acuminate, acumen 0.5–0.8 cm long; venation palmate-pinnate, pale green, above reddish towards the base, 3–5 veins on either side of the midrib, branching twice towards the margin, 2 or 3 veins in basal lobe, slightly impressed above, prominent beneath. Inflorescences erect, axillary, opposite the leaf, cymose paniculate, 7–19 cm long, red brown with sparse reddish hairs, peduncle 3.5–7 cm long, first branch with a single female flower, upper branches with a row of up to 17 pairs of bracteoles, each subtending 1 or 2 male flowers; bracts pale green, ovate, 5–6 × 3–4 mm, margin entire, apex acuminate, acumen to 1 mm long, persistent; lower bracteoles similar to bracts but smaller, 2–4 pairs, margin entire, pale green or reddish, 2–4 × 2 mm, apex setose, seta to 1 mm long, reddish, pinkish or greenish, ovate, 1–3 × 1–4 mm, margin studded with glandular knobs, persistent. Male flowers: pedicel 5–10 mm long white or pinkish, tepals 4, white or pinkish outside, white inside, glabrous, margin entire, apex broadly acute or rounded, outer two tepals broadly ovate, 5–7 × 4–5 mm, inner two tepals oblanceolate, 3–5 × 2 mm, stamens c.14, cluster globose, subsessile, filaments 1–1.2 mm long; anthers lemon yellow, obovate, c.0.8 × 0.5 mm, apex emarginate. Female flowers: subsessile, ovary white or pale green, broadly ovate, 4–5.5 × 12–16 mm, densely hispid on the locules, hairs red, 1–2 mm long, wings 3, equal, 4–6 mm wide, locules 3, placentas 2 per locule, tepals 5, white, pinkish or pale green outside, white or pinkish inside, glabrous outside and inside, margin entire, apex rounded, outer four tepals obovate, 5–7 × 4 mm, inner tepal oblanceolate, 5–7 × 2 mm, styles 3, yellow, c. 1 mm long; stigma lemon yellow, anchor-shaped, papillose. Capsules subsessile, single, pale green with red hispid hairs on locules, 6–7 × 15–17 mm, locules 3, placentas

2 per locule, wings 3, equal, broadly acute proximally and distally, 5–6 mm wide, dehiscing between the locules and wings.

Distribution. Malaysia ( Sarawak). To date, known only from Lanjak Entimau Wildlife Sanctuary (see Figure 1 ), where the species is widely distributed. This species occurs both within and outside the boundaries of the TPA of Lanjak Entimau Wildlife Sanctuary.

Habitat. Riparian forest along the main river at elevation to 131 m; growing on steep slopes with clayey soil.

Etymology. Latin, sessilis (‘stalkless’), fructus (‘fruit’).

Additional specimen examined. MALAYSIA. Sarawak: Julau District – Lanjak Entimau Wildlife Sanctuary, Sungai Igan , 25 v 2016, Ling & Dino SFC 5968 ( KEP!, SAR!) .

Subsessile female flowers and capsules are seldom encountered in Bornean begonias. Also striking in Begonia sessilifructa are the regular row of upper bracteoles with male flowers that are produced on the upper branches of the inflorescence.

In its creeping habit, this species resembles Begonia dinosauria C.W.Lin & C.I Peng , but B. sessilifructa differs in its plane lamina surface, shorter stem, 5–18 cm long (versus conspicuously bullate lamina surface, longer stem, 15–40 cm long); ovate stipules, 3–5 × 2–3 mm, with an entire margin (versus ovate-triangular larger stipules, 7–12 × 3.5–8 mm with a denticulate margin); shorter petioles, 2–5.5 cm (versus 4.5–8 cm); bracts with entire margin (versus ciliate margin); tepals of male flower smaller, outer two tepals 5–7 × 4–5 mm and inner two tepals 3–5 × 2 mm (versus tepals of male flower larger, outer two tepals 13–17 × 7–10 mm and inner two tepals 11–16 × 2–4 mm); fewer stamens, c.14 (versus 30–40); and subsessile female flowers (versus stalked female flower with pedicel to 3–5 mm long).

Figures

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

Figure 13. Begonia sessilifructa S.Julia & Kiew, sp. nov. A and B, Habit; C, stipule and stem; D, juvenile leaf upper surface; E, inflorescence; F, male flower; G and H, female flowers; I, capsule; J, cross-section of ovary. All photographs taken by C. Y. Ling: A–F and I, Ling & Dino SFC 5953 (the type specimen); G–H and J, Ling & Dino SFC 5968.