Begonia melinauensis S.Julia & Kiew, 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 : 19-21

8. Begonia melinauensis S.Julia & Kiew , spec. nov. ( Figure 11 )

Sect. Petermannia

Most similar to Begonia niahensis K.G. Pearce (2003: 77) from Niah National Park, in the positioning of the leaves that are held vertically with elongated tip pointing downwards but it is different in its larger leaves to ca. 20.5 × 22.5 (not 20 × 16.6 cm) with petioles to 16 cm long (not ca. 5 cm) and shallowly dentate and serrulate margin (not distinctly serrate margin) and longer inflorescences 10–12.5 cm long (not 3–8 cm).

Type: — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park, Clearwater Water Cave , 4 Oct 2007, Julia et al. S 99219 (holotype SAR!, isotypes E!, KEP!, K!) .

Shrubby cane-like begonia to 1.5 m tall. Indumentum on stem, leaves and petioles in life is softly velvety with dense unbranched short multicellular hairs, when dried hairs shrinking and leaf appearing glabrescent; young leaves white with dense fawn hairs. Stems conspicuously woody, often branched, pale yellow to green to dark brown, in life 8 mm diameter, when dried 4–8 mm and ridged, internodes 3–12 cm long, conspicuously swollen. Stipules reddish green or dull green or brownish, with a distinct midrib, narrowly lanceolate, 20–25 × 5–9 mm, margin entire, apex acute, caducous. Leaves alternate, distant, held vertically. Petioles with a reddish brown indumentum, 5–7 cm long, terete. Laminas dull green or yellowish green above, paler beneath, softly velvety in life, stiffly thinly papery when dried, oblique, broadly ovate, 12.5–16.5 × 12–17 cm, asymmetric, broad side 9–15.5 cm, base slightly cordate, basal lobes 2.5–9.5 cm, margin distantly and shallowly dentate or sometimes regularly serrate, apex strongly acuminate, acumen to 1.5–4 cm long. Venation palmate, main veins red until the first dichotomy, 2 pairs at base, plus a further 4–6 veins, branching twice before reaching the margin, impressed above and the lamina sometimes bullate, beneath very prominent, softly bristly with long brown hairs and slightly red or reddish brown. Inflorescences axillary, rosy red, erect and longer than petioles, racemose, protogynous, 4.5–9.5 cm long, peduncle 2–4 cm long, with one or, if with two pairs of female flowers, then pairs ca. 2 cm apart, male flowers above on a spike 2–6 cm long. Bract pair elliptic, with short hairs, 15–20 × 6–8 mm, margin entire, persistent; uppermost bracts of male flower pale green with a distinct midrib, almost rounded, with short hairs, ca. 10 × 9 mm. Male flower: pedicel deep red, 5–11 mm; tepals 2, rosy magenta or deep pink, with short hairs outside, ovate, 4.5-6 × 4 mm, margin entire, apex broadly acute; stamens more than 50, cluster globose, stalk 0.6–0.8 mm long; filaments 1–1.2 mm long; anthers pale yellow, oblong, 1–1.2 × 0.5 mm, apex emarginate. Female flower: pedicel rosy red, ca. 7 mm long, with short hairs; ovary greenish red, oblong, ca. 19 × 7 mm, wings 3, pale green, equal, locules 3, placental branches 2 per locule; tepals 5, rosy pink in lower half, pale greenish white towards the tip, elliptic, ca. 18 × 9 mm, outer one smaller, ca. 15 × 4 mm margin toothed towards apex, apex acute; styles 3, yellow, 3–4 mm long, free to base, bifurcating with the ultimate branches broadly U-shaped and curled at the tips; stigma pale yellow, papillose, forming a continuous twisted band. Fruits pendent; pedicel 7–13 mm long, minutely hairy, stiff and recurved; capsule green, oblong slightly wider at the tip, 20–35 mm long, 12–20 mm wide, minutely hairy, locules 3, wings equal, rounded proximally, truncate distally, 4.5–6 mm wide, papery, dehiscing between the wings and locules. Seeds barrel-shaped, ca. 0.3 mm long, collar cells more than half the seed length.

Distribution: — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park and Gunung Buda National Park. Endemic in the Melinau limestone. Found on the limestone hills along Sungai Melinau Paku and Gunung Buda.

Habitat: —Lowland limestone forest, up to 200 m elevation, on limestone boulders or at the base of vertical cliffs, in light shade or sometimes in exposed areas.

Etymology: —The species is named after the Melinau limestone.

Additional specimens examined (paratypes): — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park – boardwalk to Deer Cave , Julia et al. S 99204 ( KEP, L, SAR, SING); Batu Pajang , Runi et al. S 63526 ( SAR); South of Sungai Melinau Paku ca. 1.5 km from Base Camp , Hansen 1 ( E, SAR); 2 km of Sungai Melinau Paku , Nielsen 5 ( AAU, SAR); South of Camp 1, Hansen 313 ( SAR) . Gunung Buda National Park – Gunung Buda, Burtt B 8329 ( E, SAR) .

Notes: —This species belong to a striking group of handsome limestone begonias that are very distinctive in the field particularly in habit, positioning of the leaves and lamina surface features but are more difficult to distinguish in the herbarium. Among these species, B. melinauensis closely resembles B. niahensis in its positioning of the leaves. The elongated tips probably function as a drip-tip. The shrubby species forms massive thickets.

Figures

FIGURE 11. Begonia melinauensis. A. habit with vertically arranged leaves; B. opened female flower; C. male flowers; D. fruits. Photos from S 99219 by Julia Sang.