Begonia divergens 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 : 12-14

5. Begonia divergens Kiew & S.Julia , spec. nov. ( Figure 7 )

Sect. Petermannia

It is similar to Begonia kachak K.G. Pearce (2003: 74) from Niah National Park in its thick rhizome, large and rounded leaves with widely spaced veins and in its inflorescences with one or two pairs of female flowers at the base and a long raceme of male flowers above. It differs from this species in its much larger leaves with a glabrous petiole 9–25 cm long and a lamina 10.5–18.5 × 14–23 cm (compared with a bristly petiole 2–17 cm long and lamina 7.5–12.5 × 7.5–15 cm in B. kachak ) and larger capsule 14–23 × 10–16 mm (not ca. 19 × 16 mm).

Type: — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park – Sungai Terikan, 16 April 2012, Julia et al. SFC 2812 (holotype SAR!; isotypes SAR!, K!, KEP!, L!, E!, SING!, SAN!) .

Creeping or scrambling rhizomatous herb 60–90 cm tall, sometimes rooting at nodes. Whole plant glabrous. Stems sometimes branching, greenish brown, reddish green or pale green, woody, swollen at nodes, internodes 2–6.5 cm long, 4–11 mm diameter. Stipules pale green or reddish green, lanceolate, (11–)17–18 × 5–7 mm, entire, apex setose, soon caducous and leaving a circular scar. Leaves alternate, distant and horizontal. Petioles: reddish, (6.5–)15–17(–24) cm, succulent and grooved above. Laminas plain green above, paler beneath, glossy when fresh, succulent in life, thinly papery when dried, slightly oblique, broadly ovate to rotund, (8.5–)13–14(–21) × 12–19(–25) cm, asymmetric, broad side 6.5–10(–16) cm, base cordate but not overlapping, basal lobes rounded, 0.5–3.5 cm, margin sometimes reddish, slightly scalloped and scarcely toothed between the acute vein endings, apex narrowly acuminate. Venation palmate-pinnate, main veins green, reddish at the base on upper leaves surface, 2 pairs of veins at base, 2 pairs along midrib and 3–4 veins in basal lobe, branching twice before reaching the margin, plane above, prominent beneath. Inflorescence axillary, reddish, erect and usually shorter than petioles, racemose, unbranched, protogynous, 8–17(–26) cm long with two female flowers below and many male flowers in a cluster above. Peduncle red, (4–) 7.5–16 cm long. Bract pair broadly oval, 10–15 × 6–12 mm, margin entire, apex rounded and slightly acute and mucronate, whitish transparent, persistent. Uppermost bracts: pale green, ovate, ca. 10 × 6 mm, margin entire, caducous. Male flower: pedicel red, 8–12 mm long; tepals 2, white or palest pink, broadly oval, 5–8 × 7–8 mm, margin entire, apex rounded or emarginate; stamens 35–40, cluster ca. 3.5 mm across, globose, stalked to 1 mm long; filament lemon yellow, 4 mm long; anthers bright yellow, oblong, ca. 1 × 0.5 mm, apex emarginate. Female flower: pedicel rosy red, 10–14 mm long; ovary pale green, reddish towards apex, oblong, 10–13 × 7–9 mm, wings 3, 2– 4 mm wide, unequal, locules 3, placental branches 2 per locule, bright red, many ovules on both surfaces; tepals 5, pale pink or cream-coloured with a faint pink tinge, broadly oval, 6–9 × 7 mm, margin entire, apex rounded; styles 3, lemon yellow, 3–4 mm long, bifurcating; stigma yellow, papillose forming a continuous twisted band. Fruits pendent; pedicel 10–14 mm long, stiff and recurved; capsule pale green, oblong, slightly narrowed proximally, truncate distally, 15–20 × 13–16 mm, glabrous, locules 3, wings unequal, larger wing 5 mm wide, locule 3, stiffly papery, splitting between the wings and locules. Seeds barrel-shaped, 0.3–0.4 × 0.1–0.2 mm, collar cells more than half of the seed length.

Distribution: —Borneo, Sarawak, Marudi District, Gunung Mulu National Park and Gunung Buda National Park. Endemic in the Melinau limestone. Widespread, collected from Clearwater Cave, Bukit Berar, Melinau Gorge, Gunung Api, Lobang Cina, Sungai Terikan, Bukit Agung, Gunung Buda but not yet from Gunung Benarat.

Habitat: —Common. Climbing on the base of shaded vertical cliff faces or rooted in soil pockets on limestone boulders at 130–150 m elevation or on mossy rocks in lower montane limestone forest at 830–1150 m on Gunung Api.

Etymology: —This species is named for its characteristic widely diverging veins.

Additional specimens examined (paratypes): — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park – Unspecified locality, Abang Mohtar S 49652 ( K, KEP, L, MO, SAN, SAR), Julaihi S 86819 ( KEP, SAN, SAR); Melinau Gorge , Burtt B 8238 ( E, SAR); Burtt & Wood B 2301 ( E, SAR), Chai S 38929 ( A, K, KEP, L, MO, SAN, SAR), Lewis 333 ( SAR), Lewis 316 ( SAR); Bukit Berar, Chai S 39504 ( K, KEP, L, SAN, SAR); Sungai Berar, Kiew RK 458 ( KEP); Lobang Cina, Abang Mohtar & Othman S 49417 ( K, KEP, L, SAR); Gunung Api, Gua Batu, Anderson S 30756 ( A, E, K, L, SAR), Chai S 30400 ( K, L, SAR), Chai S 30439 ( K, SAR), Lehmann S 29437 ( K, SAR), Sirukit & Mohd. Azam SFC 3010 ( SAR), SFC 3007 ( K, KEP, L, SAN, SAR, SING); Near boardwalk to Deer Cave , Julia et al. S 99206 ( K, KEP, SAR), Bukit Agung, Julia SFC 2816 ( E, K, KEP, L, SAR), Julia et al. SFC 2823 ( SAR) . Gunung Buda National Park – Gunung Buda, Burtt B 8331 ( E, SAR), Julia et al. SFC 2827 ( E, SAN, SAR, SING) .

Notes: —This common species shows some differences between populations. For example, plants from Gunung Buda have a more pronounced scalloped margin compared to scarcely toothed margin for plants from Lobang Cina and Sungai Terikan; while those from Clearwater Cave and Bukit Berar have more rounded, less oblique leaves and smaller leaves (ca. 10.5 11 cm) compared to those from Sungai Terikan (15.5–17 × 16– 18.5 cm).

Figures

FIGURE 7. Begonia divergens. A. habit; B. inflorescence with female flower and young buds of male flowers; C. closeup of female flower; D. inflorescence with a pair of fruits and many flowers opening. Photos from SFC 3010 by Connie Geri.