Begonia ramosissima 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 : 21-23

9. Begonia ramosissima Kiew & S.Julia , spec. nov. ( Figure 12 )

Sect. Petermannia

Begonia ramosissima most resembles B. chaiana Kiew & S.Julia (2007: 210) from the limestone hills in Kuching Division, but it is different in its shorter petioles 5–10 mm (not 15–22 mm long), in its leaves that are not oblique (compared with slightly oblique leaves with a rounded basal lobe 5–10 mm long in B. chaiana ), shorter inflorescences 2–5.5. cm long (not 6–9.5 cm long), its 15 mm-long fruit pedicel (not ca. 7 mm long), smaller capsule ca. 13 × 12 mm (not ca. 15 × 20 mm) and narrower wings, 3 mm wide (not ca. 8 mm).

Type: — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park, Deer Cave , 12 November 1981, Lai & Jugah S 44176 (holotype SAR!; isotype KEP!) .

Slender much-branched herb to 30 cm tall. The whole plant glabrous. Stems reddish, succulent, 3 mm thick when dried, branching to form a spreading canopy; internodes 2–4 cm long. Stipules caducous. Leaves alternate, distant, greenish. Petioles 5–10 mm, hairy. Laminas bright green above, pale green beneath, glabrous on both surfaces except on the midrib and veins, thinly papery when dried, not oblique, slightly asymmetric, elliptic, 10–12 × 3–4.5 cm, narrow to the base or rounded, base sometimes unequal, broadly rounded on one side and cuneate on the narrow side, margin doubly shallowly dentate, apex acuminate, acumen to 1–1.5 cm long. Venation palmate-pinnate with a basal pair and 4–5 veins displaced veins along the midrib, slightly prominent on both sides. Inflorescences axillary, red, erect and longer than petioles, racemose, protogynous, 2–5.5 cm long, peduncles 1.5–2.3 cm long, with small male flowers. Bract caducous. Male flowers: pedicel 3–7 mm; tepals 2, pinkish white, broadly elliptic, 5–7 × 4–6 mm, glabrous, margin entire; stamens yellow, 15–25, cluster globose, stalk ca. 0.2 mm long; filaments 0.8–1 mm long, anthers pale ovate, 0.5–1 × 0.3 mm, apex rounded. Female flowers: not seen. Fruits single; pedicel 13–15 mm long, stiff and recurved; capsule 12–13 × 12 mm long, narrow proximally, truncate distally, greenish, glabrous, locules 3, placental branches 2 per locule, wings equal, 3–4 mm wide at the widest point, thinly papery, dehiscing between the wings and locules. Seeds barrel-shaped, ca. 0.2 × 0.1 mm, collar cells half the length of the seed.

Distribution: — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park. Endemic in the Melinau limestone. Habitat: —In lowland limestone forest and also in alluvial mixed dipterocarp forest. Etymology: —It takes its name from its characteristic much-branched habit. Additional specimen examined (paratype): — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park – Sungai Medalam, Yii S 39915 (A, MO, K, KEP, SAN, SAR).

Notes: — Begonia ramosissima is a very distinctive species in its slender branching habit and narrow, not oblique, scarcely asymmetric thin leaves. In this habit, it most resembles B. chaiana from the Padawan limestone in the Kuching Division.

Figures

FIGURE 12: Begonia ramosissima. A. branched habit; B. male inflorescence; C. male flower bud; D. open male flower; E. stamen cluster; F. stamens; G. Fruit; H. TS ovary; I. seeds. All from S 44176, drawn by Joseph Pao.