Begonia umbratica 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 : 24-26

11. Begonia umbratica S.Julia , spec. nov. ( Figure 14 )

Sect. Petermannia

It is most similar to Begonia melinauensis in its glabrescent leaves that are velvety in life but it differs in its stems that are not woody, in its larger stipules (ca. 30 × 8 mm), leaves that are held horizontally, have longer petioles (usually 7–16 cm) and a shorter acumen (to 1.5 cm long) and a shorter inflorescence (2–3 cm long) compared with B. melinauensis that has a conspicuously woody stem, stipules to 25 × 9 mm, leaves held vertically with a shorter petiole 5.5–7 cm long, longer acumen to 4 cm and inflorescences 4–9.5 cm long.

Type: — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park, Bukit Agung , 16 April 2012, Julia et al. SFC 2814 (holotype SAR!; isotypes E!, K!, KEP!, L!, SAR!) .

Shrubby cane-like begonia 1 m tall, often bushy and branched. Indumentum on stem, leaves and petioles in life softly velvety with dense unbranched short multicellular hairs; young leaves pale green with dense fawn hairs. Stems ridged, robust, succulent, red brown, in life 8–10 mm diameter, when dried 5–7 mm, glabrous; internodes 2.5–8 cm long. Stipules glabrous, reddish green or rosy red, with a distinct midrib, lanceolate, ca. 30 × 8 mm, margin entire, apex pointed, caducous. Leaves alternate, distant, held horizontally, slightly velvety beneath. Petioles with a reddish brown indumentum, (5–) 7–16 cm long, grooved. Laminas matt, dark green above, paler beneath, very slightly softly velvety in life with stiff white hairs on the upper surface, glabrous below, thinly papery when dried, oblique, broadly ovate, 13–20 × 11.5–21 cm, asymmetric, broad side 7–14 cm, base slightly cordate, basal lobes 1.5–3 cm, margin shallowly dentate or finely toothed, apex acute or acuminate, acumen to 1.5 cm long. Venation palmate, 2–3 pairs at base, plus a further 4–5 veins, branching 2– 4 times before reaching the margin, on lower surface main veins red until the first dichotomy, red at base of the veins on upper surface impressed above, beneath very prominent, glabrous. Inflorescences axillary, erect and shorter than petioles, racemose, protogynous, 3–4 cm long, peduncle ca. 1.5 cm long, with 1– 3 female flowers, and above a spike 2–6 cm long of male flowers. Bract pair broadly elliptic, hairy, brownish pink or rosy red, 30–35 × 10–14 mm, margin entire, persistent; uppermost bracts pinkish brown or dull green, with distinct midrib, elliptic, sparsely, ca. 25 × 12 mm. Male flower: pedicel white, 6–7 mm long; tepals 2, pinkish or greenish or lemon yellow, glabrous, elliptic, ca. 6 5 mm, margin entire, apex almost rounded; stamens pale yellow, 41–45, cluster conical, stalk ca. 1 mm long; filaments ca. 1mm long; anthers pale yellow, obovate or oblong, 0.8–1 × 0.5 mm, apex emarginate. Female flower (young): pedicel reddish, ca. 2 mm long, sparsely hairy; ovary reddish, elliptic, ca. 8 × 3 mm, wings 3, brownish red, unequal, locules 3, placental branches 2 per locule; tepals 4–5, pink, outer one smaller, narrowly ovate, ca. 8 × 6 mm, inner one bigger, ovate, ca. 10 × 8 mm, margin entire, toothed towards apex, apex acute; styles 3, pale yellow, 1 mm long, free to base, bifurcating with the ultimate branches broadly U-shaped and curled at the tips; stigma pale yellow, glabrous, twisted at the end. Fruits pendent, 1 per axil with a further 2 produced singly above; pedicel 7–10 mm long, glabrous, stiff and recurved; capsule reddish or greenish, oblong slightly wider at the tip, 25–32(–40) mm long, 11–15 (–20) mm wide, glabrous, locules 3, wings unequal, cuneate proximally, truncate distally, 3–5(–9) 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: —Borneo, Sarawak, Marudi District, Gunung Mulu National Park and Gunung Buda National Park. Endemic in the Melinau limestone.

Habitat: —In lowland limestone forest. Growing on limestone-derived soil at the base of vertical cliffs or on steep scree slope with a guano layer or in wet and shaded conditions at 102–220 m elevation.

Etymology: —Its name denotes the shady conditions in which it grows in the undergrowth of limestone forest.

Additional specimens examined (paratypes): — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park – Boardwalk to Deer Cave , Julia et al. S 99203 ( SAR), Julia et al. S 99205 ( SAR), Julia et al. S 99202 ( SAR); Boardwalk to Clearwater Cave , Julia et al. S 99220 ( SAR); Bukit Berar , Julia et al. S 99213 ( SAR), Julia et al. S 99214 ( SAR) . Gunung Buda National Park – Gunung Buda, Chai S 39468 ( A, E, MO, L, K, KEP, SAN, SAR) .

Notes: —Although B. umbratica and B. melinauensis grow sympatrically they would not be confused because their foliage is distinct: in B. umbratica , the leaves are held horizontally on longer petioles and have an acute apex compared with those of B. melinauensis that are held vertically on shorter petioles and have a conspicuously attenuated apex.

Figures

FIGURE 14. Begonia umbratica. A. habit; B. leaves and a single female flower; C. inflorescence with fruit and male flowers; D. female flower. Photos from SFC 2814 by Connie Geri.