Begonia yiii Kiew & S.Julia, 2013

Sang, Julia, Kiew, Ruth & Geri, Connie, 2013, Revision of Begonia (Begoniaceae) from the Melinau Limestone in Gunung Mulu National Park and Gunung Buda National Park, Sarawak, Borneo, including thirteen new species, Phytotaxa 99 (1), pp. 1-34 : 28-29

13. Begonia yiii Kiew & S.Julia , spec. nov. ( Figure 16 )

It is distinguished from Begonia imbricata Sands (1990: 64) in its smaller bracts 10–15 × 5–10 mm (not 12–20 × 13–21 mm), by its stamens 35–40 (not 25–28) and the smaller fruits 10–12 × 14–18 mm on a short pedicel 8–18 mm (not 18 × 16 mm with a pedicel 30–33 mm long) and its fruits wider than long, ca. 8 mm long and 14–15 mm wide (not longer than wide, 17–20 mm long, 5–8 mm wide).

Type: — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park, Hidden Valley , 21 March 1990, Yii & Talib S 58706 (holotype SAR!; isotype KEP!) .

Succulent or straggling herb, 20–50 cm tall, flowering at 12 cm tall. Indumentum on the stem, petiole and underside of the veins ferrugineous. Stems 2.5–4 mm diameter when dried, branched, reddish, woolly white pubescent; internodes 1.3–5.5(–7.3) cm long. Stipules light green, ovate, 7–20 × 6–10 mm, apex setose, persistent. Leaves alternate, distant, reddish or dark green on the lower surfaces, dark green above, either plain above sometimes with rows of white spots between the veins, coalescing in parts; in life young leaves pink. Petioles 1–2.5(–2.5) cm long, dark red, hairy. Laminas slightly oblique, broadly ovate, 7–13.5 × 3–7.5, asymmetric, broad side 2.3–4.2 cm wide, base rounded not enlarged, with white pubescent, apex bluntly rounded to caudate; venation palmate-pinnate with 2 basal veins and another 2–3 displaced pairs along the midrib, veins red to deep red on lower surface, hairy. Inflorescences axillary, erect and longer than the petioles, cymose, protogynous, 5.5–12(–15) cm long, peduncle pink or reddish, (2–)3.5–5.5(–10) cm long, with shite hairs. Bracts in pairs, pink or light green to white at the tip, ovate or lanceolate, 10–15 × 5–10 mm, persistent. Uppermost bracts almost white with a distinct midrib, ovate, slightly oblique, 8–15 × 4–9 mm, margin entire with sparse hairs, persistent. Male flower: pedicel pink, 2–4 mm; tepals 4, white, broadly elliptic, outer tepals ca. 8 × 9 mm, inner ones smaller, ca. 3 × 4–5 mm, glabrous, margin entire; stamens yellow, 35–40, cluster globose, stalk ca. 0.5 mm long; filament ca. 0.5 mm long, anthers pale yellow, narrowly obovate, ca. 1.0 × 0.8 mm, apex emarginate. Female flower: pedicel ca. 4 mm, pink, sparsely hairy; ovary white flush very light pink, broadly elliptic, 5 × 4 mm, wings 3, subequal, locules 3, placental branches 1 per locule; tepals 5, white, elliptic, outer tepals 5–6 × 4–5 mm, inner one smaller, ca. 4 × 3 mm, margin entire; styles 3, 2 mm long, free to the base, bifurcating with yellow stigma forming a continuous twisted papillose band. Fruits pendent, single or in pairs, glabrous; pedicel 8–18 mm long, stiff and recurved; capsule ca. 8 mm long, 14–15 mm wide, green, glabrous; wings 3, subequal, thinly papery, 5–8 mm wide at the widest point, dehiscing between the wings and locules. Seeds barrel-shaped, ca. 0.4 × 0.2 mm, collar cells more than half the length of the seeds.

Distribution: — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park. Endemic in the Gunung Mulu National Park but not confined to limestone; on limestone collected from Hidden Valley and opposite Long Bala on Sungai Melinau and from non-limestone habitats on Gunung Mulu and Sungai Melinau Paku.

Habitat: — In limestone forest sometimes growing in creeks, at elevation 200–900 m. More common in lower montane forest on Gunung Mulu (Yii & Abu Talib S 58205 , S 58224) at 1180–3000 m elevation and in forest on shale at 300–850 m elevation .

Etymology: —Named after Yii Puan Cheng, the Forest Ranger at Forest Department Sarawak (1976– 1994) and who first collected this species.

Additional specimens examined (paratypes): — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park – Opposite Long Bala, Yii & Talib S 58811 ( K, KEP, L, SAR); unspecified locality, Lai & Jugah S 44160 ( KEP, SAR), Martin S 38153 ( L, K, KEP, MO, SAN, SAR), Martin S 38188 ( K, L, SAR), Martin S 37057 ( E, L, SAR); Camp 3, Gunung Mulu , Yii & Talib S 58224 ( K, KEP, L, SAR), Yii & Talib S 58203 ( K, KEP, L, SAR), Chai S 36457 ( L, K, KEP, SAR), Burtt & Woods B 2120 ( E, SAR), Burtt & Woods B 2086 ( E, SAR); Path from Melinau Paku, Anderson S 4519 ( K, L, SAR), Anderson S 4518 ( K, L, SAR), Path from sub-camp 2 to sub-camp 3, Lewis 301 ( SAR); path from sub-camp 1 to sub-camp 2, Lewis 278 ( SAR), Lewis 279 ( SAR); sub-camp 2, Lewis 294 ( SAR); ridge above Melinau Gorge, Kiew RM 450 ( KEP) .

Notes: — Begonia yiii is a distinctive species in its persistent bracts that are relatively large and pink or light green contrasting with the green foliage, in the rather few stamens (22–28), and in its fruits that are deltoid in outline with the wings that grow beyond the point of attachment of the style. It shares these characters with B. imbricata from Gunung Kinabalu, Sabah. They both have similar foliage in the lamina being glabrous and scarcely oblique and the petiole being short and hairy. However, B. yiii is distinct in the characters given above.

Sands (1990) placed B. imbricata in sect. Bracteibegonia but Doorenbos et al. (1998) corrected this and placed it in sect. Petermannia . Begonia yiii also exhibits characters typical of sect. Petermannia species (erect stem, asymmetric leaves with palmate-pinnate venation, protogynous inflorescences and fruits with three locules and more or less equal dry wings). It is atypical in its unbranched placenta and to a lesser extent its male flowers with four tepals (not always a consistent character in either section). If Doorenbos et al. (1998) are followed, B. yiii would be placed in sect. Reichenheimia , but otherwise would be quite atypical of this section. Until more specimens become available for examination to confirm the number of placenta branches, we refrain from assigning B. yiii to any section.

Figures

FIGURE 16. Begonia yiii. A. Habit showing variegated leaves; B. variation in leaf shape; C. male flower bud; D. open male flower; E. stamen cluster; F. stamen; G. female flower; H. style and stigma; I. Fruit; J. TS ovary; K. seeds. A from S 58706; B from S 58811, C–F from S 58224; G & H from RK 279; I–K from S 44160, drawn by Joseph Pao.