Begonia magentifolia 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 : 17-19

7. Begonia magentifolia Kiew & S.Julia , spec. nov. ( Figure 10 )

Sect: Petermannia

It most resembles Begonia stichochaete K.G. Pearce (2003: 78) from Niah National Park but it is different from this species in its more robust habit with stems to 3–5 mm diameter (not 5–9 mm), bristles to 5 mm long (not ca. 2 mm) and internodes 1–1.5 cm long (not 2.5–5 mm) with smaller stipules (ca. 12 × 3 mm not ca. 17 × 11 mm); narrower laminas 10–12.5 × 3.7–4.5 cm (not 11–19 × 7.5–10 cm) with the broad side measuring 2–2.5 cm wide (not 6–7.5 cm) and the basal lobe 3–5 mm long (not 1.7 cm); smaller bracts ca. 3 × 1 mm (not ca. 13 × 10 mm) and uppermost bracts 2 0.5 mm (not 12 × 12 mm). In addition, Begonia stichochaete has erect panicles to 3.4 cm long, whereas in B. magentifolia one, almost sessile, male flower is produced per leaf axil.

Type: — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park, boardwalk to Clearwater Water Cave , 4 Oct 2007, Julia et al. S 99215 (holotype SAR!; isotypes K!, KEP!, L!) .

Small, unbranched erect herb. Stems wiry, green, 10–50 cm long, 3–6 mm diameter when dry, internodes 1– 1.5 cm long in the upper part of the stem and to 2.5–4 at the base of stem; stem, stipules and petioles densely covered in long brown bristles ca. 5 mm long. Stipules magenta, narrowly lanceolate, 9–15 × 3–4 mm, midrib thick, margin entire, apex setose, to 4 mm long, persistent. Leaves alternate, distant. Petioles: brownish, (4–) 7–17 mm long, terete. Laminas dark jade green above, reddish magenta below, sometimes green on both surfaces and then paler beneath, hairy on both surfaces, scattered hairs uniseriate, ca. 1 mm long, frequent above, less dense beneath, papery when dried, not oblique (petiole does not form an angle with the midrib), unequally lanceolate, (9.5–)10–16.5 × (2.5–) 3.7–4.5 cm, slightly asymmetric, broad side 2–2.5 cm, base unequal, rounded, basal lobes 3–5 mm, margin ciliate and minutely serrate, apex acute to slightly acuminate. Venation pinnate, lateral veins, 4–6 pairs, impressed above when fresh, when dry prominent above and beneath. Inflorescences axillary with one flower per axil. Bracts ovate, ca. 3 × 1 mm, margin entire, caducous; uppermost bracts: magenta, lanceolate, ca. 2 × 0.5 mm. Male flower: pedicel 8–12 mm long; tepals 2, white or palest pink, broadly oval, 10–12 × 9–12 mm, margin entire, apex rounded; stamens 23–25, cluster ca. 3 mm across, globose, stalked to 1 mm long; filament ca. 2 mm long; anthers yellow, oblong, ca. 0.1 × 0.5 mm, apex emarginate. Female flower: sessile; ovary scarlet, globose, ca. 13 × 13 mm; wings 3, ca. 2 mm wide, equal; locules 3, placental branches 2 per locule; tepals 5, isomorphic, sparsely hairy outside, pink, elliptic, 2–4 × 2– 3 mm, margin entire, apex rounded; styles 3, 2 mm long, free to base and bifurcating with the ultimate branches broadly U-shaped; stigma papillose, forming a continuous twisted band. Fruit: ovary scarlet, 8–9 mm, wings ca. 2 mm wide. Seeds barrel-shaped, 0.2–0.3 × 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: —Lowland limestone forest, on limestone derived soil, at 100–140 m elevation or on nonlimestone areas on sandy banks above the river or on steep slopes on shale formation in mixed dipterocarp forest.

Etymology: —The species is named for its striking deep magenta-coloured lower leaf surface.

Additional specimens examined (paratypes): — MALAYSIA. Borneo. Sarawak. Marudi District: Gunung Mulu National Park – Sungai Melinau Paku, Stone 136 28 ( SAR) ; Gunung Mulu, Burtt & Woods B 2070 ( E, SAR) ; Ulu Sungai Berar, Anderson S 39363 ( L, SAR) ; Sungai Berar, Kiew RK 485 ( KEP), RK 493 ( KEP) , Lewis 310 ( SAR) ; Gua Rusa, Argent & Kerby 813 ( E, SAR) .

Notes: — Begonia magentifolia is striking in its hispid stem and petiole and in its dark jade green leaves with red hairs on the upper surface and the rich magenta lower surface. It belongs to a distinct group of begonias in sect. Petermannia that have a short, unbranched stem, very short petioles and non-oblique leaves where the petiole does not form an angle with the midrib. Among this group that includes B. berhamanii Kiew (2001: 254) , B. caulifora Sands (1990: 68) , B. pubescens Ridley (1906: 254) and B. stichochaete K.G.Pearce , it most resembles Begonia stichochaete from the Subis limestone in the Niah National Park. In Sarawak, this group of species is infrequent on limestone substrates.

Figures

FIGURE 10. Begonia magentifolia. A. habit; B. single male flower in leaf axil. Photos from S 99215 by Connie Geri.