Begonia baikoides S.Julia & C.Y.Ling, 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 : 173-175

2. Begonia baikoides S.Julia & C.Y.Ling , spec. nov. ( Figure 3 )

Section Petermannia

Diagnosis: —Similar to Begonia baik C.W.Lin & C.-I.Peng (2014: 1) in its creeping habit, small size and leaf shape, rugose upper surface, in its indumentum and male flower with 4 tepals. However, it differs in the lamina having a ciliate margin and the basal lobes scarcely developed, 0.8–1 cm long (vs. a glabrous margin with well-developed basal lobes 2–3.3 cm long in B. baik ), broad stipules 12–16 × 13–16 mm (vs. 17–20 × 8 mm), shorter inflorescences 4–5 cm long (vs. ca. 7.5 cm) and fewer stamens 16–17 (vs. 25 in B. baik ).

Type: — MALAYSIA. Borneo. Sarawak. Kapit District: Bukit Ngingit, Jacqueline et al. SFC 5871 (holotype SAR!, isotype KEP!).

Creeping herb with erect apex 6–11 cm tall. Indumentum of stems, stipules, petioles, upper lamina surface and lower veins densely hirsute with magenta hairs, ca. 3 mm long. Stems green to brown, unbranched, succulent, 4–5 mm thick, internodes 1–4 cm long, slightly thicker at nodes. Stipules pale green tinged red at base, broadly ovate, 12–16 × 13–16 mm, keeled, margin ciliate, apex acute or rounded, persistent. Leaves alternate, distant, oblique, held horizontally; petioles pale green, 1.5–4.8 cm long, terete or slightly grooved above; lamina dark green to green-brown above, paler towards the margin, maroon to reddish beneath, in life succulent, surface pimply above, each pimple tipped by a long hair, matt, asymmetric, ovate, 5–8.5 × 4.5–6.5 cm, broad side 3.5–4.5 cm wide, base cordate, sometimes overlapping, basal lobes 0.8–1cm long, margin dentate and ciliate, slightly undulating, apex acuminate, acumen 0.8–1 cm long; venation pinnate-palmate, veins concolorous above, pale brown beneath, 3 pairs radiating from base, 3 veins on either side of the midrib, 1–2 veins in basal lobe, slightly impressed above, prominent beneath. Inflorescences protogynous, axillary in upper leaf axils, racemose to 4–5 cm long, peduncle hirsute, hairs white, ca. 2.5 cm long. Bracts pale green, tinged red at base, ovate, 14–20 × 9–16 mm, margin ciliate, persistent; bracteoles to 4 pairs, lower bracteoles similar to bracts, pale green tinged reddish at base, 9–12 × 8–12 mm, upper bracteoles white to pale green, oval, 5–7 × 12 mm, margin ciliate, apex emarginate, persistent. Male flowers: pedicel white, 5–6 mm long, glabrescent; tepals 4, white, glabrous, outer 2 tepals broadly ovate, 8–10 × 6–8 mm, margin ciliate, hairs white, apex broadly acute to rounded; inner 2 tepals lanceolate, 6–8 × 1.5–2 mm, margin entire, apex broadly acute to rounded; stamens 16–17, cluster globose, subsessile; filaments pale yellow, ca. 1 mm long; anthers pale yellow, obovate, ca. 1 × 0.5 mm, apex emarginate. Female inflorescence 4.5–5 cm long. Bract and bracteoles similar in shape and size as in male inflorescence, bracteoles 4–7 pairs, white, margin ciliate. Female flowers: sessile, enclosed by 2–3 bracteoles; ovary white or pale green, broadly elliptic, 5–5.5 × 10–11 mm, hirsute, hairs white, wings 3, unequal, locules 3, placenta 2 per locule; tepals5, white inside, white to pale green outside, glabrous, outer 3 tepals broadly elliptic, 9–10 × 7–8 mm, margin ciliate, apex acute, inner 2 tepals slightly smaller, lanceolate, 6–8 × 3–4 mm; styles 3, pale yellow, ca. 3 mm long, divided to base, anchor-shaped; stigma pale yellow, papillose forming a continuous twisted band. Capsules not seen.

Etymology: —Latin, - oides = similar to Begonia baik .

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

Habitat: —Old logged-over forest with dense forest cover, on rocky surface of sandstone boulders.

Notes: — Begonia baikoides and B. baik are similar in their small creeping habit and leaves. Both grow in similar habitats creeping on moss-covered vertical sandstone rock faces. They are attractive plants in their small size, broadly ovate almost rotund leaves that are dark green above and deep rosy brown beneath. The hispid red hairs on the upper leaf surface are raised on minute pointed pimples giving it a rough appearance.

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

Figures

FIGURE 3. Begonia baikoides. A, Habit; B, Close-up of upper surface of leaf; C, Close-up of lower surface of leaf; D, Magenta hairs on leaf surface; E, Stipule; F, Male inflorescence; G–H, Male flower; I, Female inflorescence; J. Cross-section of ovary.All photos from SFC 5871 by C.Y.Ling.