Begonia tinjanii S.Julia, 2016

Sang, Julia, Kiew, Ruth & Yiing, Ling Chea, 2016, Six new species of Begonia (Begoniaceae) from Central Sarawak, Borneo, Phytotaxa 277 (2), pp. 171-181 : 178-179

5. Begonia tinjanii S.Julia , spec. nov. ( Figure 6 )

Section Petermannia

Diagnosis: —Similar to Begonia rhombipetala S.Julia & C.Y.Ling (2015: 122) in its habit, leaf shape and inflorescence type but it differs in the shorter petiole 0.4–0.9 cm long (vs. 1.2–2 cm long), lamina with basal lobe 2–3 mm wide (vs. basal lobe to 5 mm wide), in its sparsely villous pedicel of male and female flowers (vs. pedicel of male and female flowers glabrous), the dimorphic tepals of male and female flower (vs. isomorphic tepals of male and female flower in B. rhombipetala ) and its fruit narrower, to 8 mm wide with a short pedicel to 4 mm long (vs. fruit to 12 mm wide and pedicel 12–14 mm long).

Type: — MALAYSIA. Borneo. Sarawak. Tatau District: Jelalong, Tinjan SFC 4296 (holotype SAR!, isotype KEP!).

Low herb 18–26 cm tall. Stem green-brown, 5–7 mm thick, glabrescent; internodes 1–2.5 cm long, few-branched, succulent, slightly thicker at nodes. Stipules red brown, keeled, villous on midrib, hairs red-brown, lanceolate, 10–12 × 4 mm, margin entire, apex setose, seta ca. 2 mm long, caducous. Leaves alternate, crowded, slightly falcate but not oblique, held horizontally; petioles red brown, 0.4–0.9 cm long, fleshy, villous on midrib, hairs red-brown, terete; lamina plain, dark green above, magenta beneath, in life succulent, sparsely hirsute above, hairs red brown, rarely glabrous, glabrous beneath, glossy, slightly asymmetric, oblanceolate, (5–)8–12 × (2–) 3–4.5 cm, broad side (1.3–) 1.5– 2.2 cm wide, base cordate, sometimes overlapping, unequal, basal lobes 2–3 mm long, margin dentate, apex acute; venation pinnate, 3–4 veins on either side of the midrib, 1 vein in basal lobe, veins dark green above, magenta and sparsely villose, hairs red brown below, slightly impressed above, prominent beneath. Inflorescences protogynous with male inflorescence on upper leaf axil, 2–3 cm long, peduncle 2–3 mm long, umbellate. Bract red brown, ca. 7 × 4 mm, margin entire, apex setose, seta ca. 1 mm long, keeled, persistent. Bracteole similar to bracts, persistent. Male flowers: pedicel white, (5–)13–15(–20) mm long, sparsely villous, hairs red brown; tepals 4, white; outer 2 tepals orbicular or obovate, 8–12 × 5–10 mm, glabrous except sprinkle or red brown hairs on towards the base, margin entire, apex rounded; inner 2 tepals narrowly elliptic, 6–8 × 1–4 mm, glabrous, margin entire, apex broadly acute, stamens 18–26, subsessile; filaments pale yellow, 1–2.5 mm long; anthers pale yellow, oblong or obovate, 1–2 × 0.5–0.8 mm, apex emarginate. Female inflorescence on lower leaf axils, ca. 2.5 cm long, peduncle 3–4 mm long, umbellate.Bract red brown, narrowly elliptic, 4–9 × 2–3 mm, keel, setose, seta 0.5–1 mm long. Bracteole narrow elliptic, 9–10 × 3 mm, setose, seta to 2 mm long, keeled. Female flowers: pedicel reddish or pale green, 4–8 mm long, sparsely villose, hairs red brown; ovary yellowish green or white, ovoid or oblong, 10–12 × 10–12 mm, sparsely villose, more prominent on the centre, beak to 2 mm long, wings 3, subequal, locules 3, placentas 1 per locule; tepals 5, white, sparsely villous outside, hairs red brown, outer 4 tepals obovate, 9–11 × 4–5 mm, inner tepal narrowly elliptic, ca. 8 × 3 mm, margin entire, apex broadly acute; styles 3, pale yellow, 3–5 mm long, divided to base, anchor-shaped; stigma pale yellow, papillose forming a continuous twisted band. Capsules single or in pairs, ca. 12 × 8 mm, glabrous, locules 3, wings 3, equal, acute proximally and distally, ca. 3 mm wide, thinly fibrous, dehiscing between locule and wing; pedicel straight, ca. 4 mm long.

Etymology: —Named after Tinjan Kuda, Field Assistant at Sarawak Forestry Corporation, who first collected the species.

Distribution: — MALAYSIA. Borneo. Endemic in Sarawak. So far known only from the type locality.

Habitat: —Old logged-over lowland mixed dipterocarp forest.

Proposed conservation status: —Critically Endangered. The species is known only from a single locality that lies outside the network of Totally Protected Areas. The species is threatened by habitat disturbance.

Note: — Begonia tinjanii is atypical of Sect. Petermannia in its undivided placenta but apart from this it conforms with the other characters of Sect. Petermannia .

Figures

FIGURE 6. Begonia tinjanii. A, Habit; B, Flowering plant; C, Stipule; D, Male inflorescence; E, Male flower; F–G, Female flower; H, Cross-section of ovary.All photos from SFC 4296 by C.Y.Ling.