Begonia bayae S.Julia & Kiew, 2016

Sang, Julia & Kiew, Ruth, 2016, Begonia (Begoniaceae) from Batang Ai National Park and vicinity, Sarawak, Borneo, including six new species, Phytotaxa 252 (1), pp. 17-30 : 22-23

4. Begonia bayae S.Julia & Kiew , spec. nov. ( Figure 3 )

Section Petermannia

Diagnosis: —Similar to Begonia amidalae C.W.Lin & C.-I Peng in its habit and leaf shape but it is different in being a smaller plant with stem to 20 cm tall (vs. stem 30–100 cm tall in B. amidalae ), lamina plain olive green, margin serrate (vs. lamina dark green with silver patches, margin entire to inconspicuously dentate), inflorescences with fewer male flowers (vs. inflorescences much-branched with more than 30 flowers), male flowers with small tepals ca. 3 × 3 mm and ca. 18 stamens (vs. male tepals 5–6 × 4–5 mm and 7–11 stamens).

Type: — MALAYSIA. Borneo. Sarawak. Lubok Antu District: Batang Ai National Park, Lubang Baya , Bebiyong Mit trail, adjacent to the Ranger Post , 1°18’00”N and 112°04’10”E, 200 m, 2 August 2015, Julia et al. SFC 2762 (holotype SAR!; isotypes KEP!, SNP!) .

Erect begonia to 20 cm tall, flowering at ca. 4 cm tall, whole plant glabrous. Stems dark brown, little-branched, woody, 4–5 mm thick, internodes 1.5–3.5 cm long, thicker at nodes. Stipules pale green, lanceolate, 5–8 × 2 mm, margin entire, keeled, apex acuminate, acumen 1–2 mm long, caducous. Leaves alternate, distant, not oblique, slightly asymmetrical, held more or less horizontally; petioles dark brown, 0.5–1.2 cm long, slightly grooved above; lamina plain olive green above, paler beneath, in life slightly succulent, matt, slightly asymmetric, narrowly ovate to almost elliptic, slightly falcate, 9.5–14 × 3.3–5 cm, broad side 1.7–3.5 cm wide, base slightly rounded on the broader side, cuneate on the narrower side, sometimes unequal, basal lobes scarcely developed, margin serrate, apex acuminate, acumen 1.2–1.5 cm long; venation pinnate, veins greenish above, dark brown near the leaf base beneath, 3–5 veins on either side of the midrib, prominent on both surfaces. Inflorescences protogynous, axillary in the upper leaf axils, racemose, rachis scarcely branched, 5–12.5 cm long with 1– 2 female flowers below and 2–4 cymules of male flowers at the apex. Bracts pale green, linear, ca. 11 × 2 mm, margin entire, caducous; bracteoles similar to bracts but smaller, 3–4 × 1–2 mm, caducous. Male flowers with greenish or yellowish green pedicels, 3–4 mm long; tepals 2, yellowish green, oval, ca. 3 × 3 mm, margin entire, apex rounded; stamens ca. 18, cluster conical, subsessile; filaments pale yellow, 0.6–1 mm long; anthers pale yellow, obovate, ca. 0.8 × 0.4 mm, apex emarginate. Female flowers with pale green or yellowish green pedicels, 7–9 mm long, glabrous; ovary pale green, ovoid, 6–7 × 8–12 mm, glabrous, wings 3, subequal, locules 3, placentas 2 per locule; tepals 5, pale green or yellowish green, glabrous, outer 4 tepals elliptic, 6–7 × 3–4 mm, margin entire, apex acute, inner tepal narrowly elliptic, ca. 5 × 2 mm, margin entire, apex acute; styles 3, pale yellow, 2–3 mm long, divided to base, shallowly Y-shaped; stigma pale yellow, papillose forming a continuous twisted band. Capsules single or in a pair, pale green, ovate, 8–10 × 10–18 mm, glabrous, locules 3, wings 3, equal, almost rounded proximally, truncate with rounded wings tips distally, 3–6 mm wide, thinly fibrous, dehiscing between locule and wing; pedicel fine and thread-like, pendent, 7–13 mm long.

Etymology: —Latin, bayae = of the crocodile; name derived from the type locality ‘Lubang Baya’ in local Iban language which means ‘crocodile hole’.

Distribution: — MALAYSIA. Borneo. Sarawak. Endemic in Sarawak. So far only known from Lubang Baya in Batang Ai National Park.

Habitat: —Lowland mixed dipterocarp forest below 200 m elevation, on slopes above the river bank.

Proposed conservation status: —Least Concern as the species occurs within a Totally Protected Area and their habitat is not threatened by any local disturbance.

Figures

FIGURE 3. Begonia bayae. A & B. Habit; C. Inflorescence with female flowers and male buds; D. Male flowers; E. Female flowers; F. Cross section of ovary.All photos from SFC 2762 by Julia Sang (A–E) and Ling Chea Yiing (F).