Begonia rambutan Rimi, 2015

Repin, Rimi, Sang, Julia, Kiew, Ruth & Mujih, Handry, 2015, Eleven new species of Begonia (Begoniaceae) from the Crocker Range, Sabah, Malaysia, Phytotaxa 208 (1), pp. 1-20 : 16

10. Begonia rambutan Rimi , spec. nov. ( Figure 11 )

Sect. Petermannia

It is similar to the Begonia cauliflora in its short petioles, non-oblique and sub-symmetric leaves, but it is unique among all Bornean begonia species in its small (6–10 × 13–14 mm) rotund wingless fruit densely covered in long white stiff hairs.

Type:— MALAYSIA. Borneo. Sabah. Papar District: Crocker Range Park, Ulu Kimanis , Trail 11, 1 April 2008, Kinahim et al. KNP 10589 (holotype SNP!; isotype SAN!) .

Semi-erect herb 20–30 cm tall. Stem unbranched, ca. 4 mm thick, slightly woody, green, hispid with white or brown hairs ca. 2 mm long, internodes 0.7–2.7 cm long, swollen at the nodes. Stipules pale green, hispid, lanceolate, 10–18 × 6 mm, keeled, margin hairy, apex setose, seta ca. 1.5 mm long, persistent. Leaves alternate, not oblique, close, held horizontally; petiole green, hispid, 3–7 mm long, slightly grooved above; lamina plain dark green above, pale green beneath, glabrous above, slightly fleshy in life, glossy, obovate, almost symmetric, 8–15 × 3–7 cm, base slightly rounded, basal lobes scarcely developed, margin hairy, minutely toothed in the lower half, finely serrate in the upper half, teeth increasing in size towards the apex, apex acuminate, acumen 1–1.5 cm long; venation pinnate, veins red-green and hairy beneath, 4 on each side of midrib, prominent above, slightly prominent beneath. Inflorescence protogynous, axillary in the lower leaf axils, sometime below the leaves, white, simple cymes, rachis ca. 1 cm long, peduncle ca. 3 mm long. Bracts lanceolate, ca. 20 × 6 mm, margin hairy, apex setose, seta ca. 1 mm long, caducous; bracteoles pale reddish, narrowly lanceolate, ca. 8 × 4 mm, margin entire, caducous. Female flower sessile, white; ovary densely hairy, hairs on a raised base, ca. 4 mm long, ovoid or rotund, ca. 1 × 1 cm, wings not developed, locules 3, placenta bilamellate with few ovules on both surfaces; tepals 5, white, hairy outside, margin entire, apex bluntly acute, outermost tepals, 16 × 12–16 mm, innermost tepals ca. 16 × 11 mm; styles 3, yellow, subsessile, divided at base, Y-shaped with almost flat top; stigma yellow, papillose forming a continuous twisted band. Male flower: pedicel white, ca. 15 mm long; tepals 4, white, glabrous, oval, margin toothed, apex acute, sparsely hairy outside and on the margin, outer tepals 14–15 × 10–12 mm, inner tepals 9–14 × 6–8 mm; stamens ca. 20, cluster globose, sessile; filaments yellow, ca. 2.5 mm long; anthers yellow, narrowly obovate, ca. 1 × 0.3 mm, apex emarginate. Capsule sessile; fruit rotund, 6–10 × 13–14 mm, white when young, brown when ripe, densely hairy, hairs white, on a raised base, locules 3, ribbed (wings not developed). Seed: barrel-shaped, ca. 0.2 × 0.1 mm, columnar cells more than half the length of seed.

Distribution: — MALAYSIA. Borneo. Endemic in Sabah.

Habitat: —River bank, cliff on river bank, secondary forest or primary lowland dipterocarp forest.

Etymology: —Its dense, red, stiffly hairy fruits resemble rambutan, Nephelium lappaceum Linnaeus (1767: 125) , Sapindaceae .

Additional specimens examined: — MALAYSIA. Borneo. Sabah. Papar District: Crocker Range Park – Ulu Kimanis, Trail 1, Kinahim et al. KNP 10581 (SNP); Beaufort District: Crocker Range Park – Ulu Membakut, Geofarry et al. KNP 14582 (SNP); Tawau District: Tawau Hill Park – Trail Utama Barat, Rahimah et al. SP 18007 (SNP).

Notes: —Its fruit is remarkable in resembling a small rambutan, not only in its dense red hairs, but also in lacking wings. Compared with other species, its fruit contains very few seeds. It is not known how it dehisces, if at all, nor how the seeds are dispersed.

Figures

FIGURE 11. Begonia rambutan. A. Habit; B. Male flower; C & D. Female flower with densely hairy ovary; E. Cross-section of ovary. All photos by Kinahim Sampang.