Begonia natunaensis subsp. sarawakensis S.Julia & Kiew, 2018

Yiing, Ling Chea, Sang, Julia & Kiew, Ruth, 2018, Begonia species (Begoniaceae) from Gunung Penrissen, Sarawak, Borneo, including two new species and a new subspecies, Phytotaxa 381 (1), pp. 12-21 : 17-20

Begonia natunaensis subsp. sarawakensis S.Julia & Kiew , subsp. nov. ( Figures 3 & 4 )

Similar to Begonia natunaensis subsp. natunaensis in having peltate leaves with long petioles and long cymoselybranched inflorescences but differing in its lamina with purple-brown blotches above and strongly bullate and puckered in the basal quarter with large aeroles that give the lamina a conspicuous cobweb-like pattern.

Type:— MALAYSIA. Borneo, Sarawak, Padawan District : Gunung Penrissen , 3 December 2017, Julia et al. SFC 5589 (holotype SAR!; isotype KEP!) .

Rosette herb, up to 7 leaves per plant. Rhizomatous stem to 13 cm long, 5–14 mm thick, brown or reddish brown, minutely pubescent, terete, internodes 2–7 mm long, slightly swollen at the nodes. Stipules triangular, 18–20 × ca. 8 mm at the base tapering to ca. 6 mm midway up stipule, keeled, margin entire, apex setose, seta to 10 mm long, glabrous, persistent. Leaves alternate, peltate, lamina held vertically; petioles greenish, reddish brown on lower half, 6.5–26 cm long, 3–8 mm thick, terete, glabrous; lamina green above with dark brown blotches between the tertiary veins, paler green beneath also with purplish blotches, glabrous, in life succulent, glossy, suborbicular, 6.3–12 × 7–13.5 cm, petiole attachment 2.5–6.3 cm from the base, both sides of the leaves almost equal in width, margin minutely toothed, teeth turned back at the vein endings, margin slightly recurved, covered with soft white hairs, reddish, apex acuminate, 1.2–1.5 long; venation palmate, 6–7 veins radiating from the petiole attachment, strongly raised above, flat or slightly raised beneath, branching 3–5 times, veins pale green on both surfaces, lateral veins on either side of the midrib 2–3 veins, tertiary veins sclariform at the base, strongly bullate and lamina appearing puckered, reticulation laxer towards the margin, prominent on both surfaces. Inflorescences protandrous, 2–3 inflorescences per plant, axillary in the uppermost leaves, 15–44 cm long, paniculate, male and female flowers on separate or on the same branch, peduncle reddish to pale green, glabrous, 10.5–38.5 cm long. Bracts reddish, triangular, 17–25 × 5–6 mm, margin entire, apex setose, seta 5–8 mm long, persistent; lower bracteoles triangular, 15–20 × 4–6 mm, upper bracteoles lanceolate, 4–8 × 2–3 mm, persistent. Male flowers: pedicel reddish or greenish, 5–10 mm long, glabrous; tepals 2, whitish, 7–8 × 7–9 mm, base cordate, margin entire, apex rounded; stamens 40–48, cluster globose, sessile; filaments lemon yellow, ca. 1 mm long; anthers lemon yellow, obovate, ca. 1 × 0.6 mm, apex emarginate. Female flowers: pedicel whitish, 10–11 mm long, glabrous; ovary whitish or greenish white, sometimes pinkish, wings 3, equal, greenish, 5–7 × 10 mm, tip acute, locules 3, placenta 1 per locule; tepals 2, white, rounded, 4–7 × 5–7 mm, margin entire, apex rounded; styles 3, lemon yellow, ca. 2 mm long, divided to base, anchor-shaped; stigma lemon yellow, papillose forming a continuous twisted band. Fruits more than 5 per infructescence, pale green, glabrous, ca. 10 × 12–15 mm, locules 3, wings 3, 6–7 mm wide, slightly unequal, broadly acute proximally and distally, thinly fibrous, dehiscing between locule and wing; pedicel slightly pendent, 10–13 mm long, glabrous, greenish.

Distribution: —Endemic in Borneo, Sarawak, Padawan District, Gunung Penrissen, known only from the type locality.

Habitat: —Growing on mossy, shaded, high vertical sandstone cliff faces constantly wet from dripping water, locally common and covering the rock face at about 1100 m elevation. The largest plants grew in more shaded areas.

Etymology: —Named for the Malaysian state, Sarawak, where it grows to contrast it with the other subspecies that grows on Natuna Island, Indonesia.

Notes: —The Sarawak taxon is described as a subspecies rather than as a variety because it is geographically distinct and disjunct from B. natunaensis that grows in Natuna Island, about 200 km northeast of Borneo (Lin et al. 2014). Although both subspecies grow in similar habitats (on wet and mossy sandstone cliffs), they are found at different elevations: 100 m on Natuna Island and at 1100 m on Gunung Penrisssen.

The great majority of begonias in Borneo belong to sect. Petermannia . This species has a rhizomatous habitat, protandrous inflorescences and an undivided placenta and is placed in sect. Jackia as the section is currently understood. However, it is unlike any of the other Bornean species with peltate leaves in its robust habit and large, thin leaves. Rather, it is similar to the commonly cultivated B. goegoensis N.E.Br (1882: 71) from Indoensia.

6. Begonia padawanensis C.W.Lin & C.I-Peng, Nord. J. Bot. 33 (2015) 558. Type: — MALAYSIA. Borneo. Sarawak. Padawan District , 01°7 ′ N 110°16 ′ E, 28 Aug 2013, C.W. Lin 559 (holotype SAR n.v.; isotypes HAST, KEP n.v., TAIF).

Sect. Ridleyella .

Distribution: —Endemic in Padawan District, Sarawak. Besides Gunung Penrissen, this species, according to the GPS figures given for the type locality, was also collected near Kampung Annah Rais, which is also on the foothills of Gunung Penrissen.

Specimens examined:— MALAYSIA. Borneo, Sarawak, Padawan District: Gunung Penrissen, 3 December 2017, Julia et al. SFC 5588 (SAR!, KEP!).

Habitat: —Lowland to lower montane forest on wet and mossy or dry sandstone cliffs or large boulders at 200- 1100 m elevation.

Etymology: —Named for the district from where it was first collected.

Notes: —This is a distinctive small creeping begonia with a short stem, slightly oblique, pale green, obovate or spathulate leaves, 3–4.5 × 2.3–3 cm that have an unequal, slightly cordate base. Due to its rhizomatous stem, threelocular ovary and each locule with an undivided placenta, it is placed in sect. Ridleyella .

Figures

FIGURE 3. Begonia natunaensis subsp. sarawakensis A. Habit; B. Rhizome with stipules; C. Leaf margin showing reflexed hairs; D. Upper leaf surface; E. Lower leaf surface; F. Inflorescence; G. Male flower; H & I. Female flower; J. Infrutescence; K. Cross-section of capsule. All photos from SFC 5589 by Ling Chea Yiing.

FIGURE 4. Map of the localities of Begonia natunaensis. Natuna Island, locality of B. natunaensis subsp. natunaensis and Gunung Penrissen, Sarawak, locality of B. natunaensis subsp. sarawakensis.