Begonia acidulenta 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 : 19-21

1. Begonia acidulenta S. Julia & Kiew , spec. nov. ( Figure 2 )

Section Petermannia

Diagnosis: —This species resembles Begonia roseopunctata Kiew (2015: 146) in its equally striking leaf pattern: young plants have leaves with white or sometimes pink spots, in older plants the white spots coalesce into lines between the veins, and in still older plants the leaves are plain green. It is also similar in its habit, leaf shape, paniculate inflorescences and fruits but it is different in having larger stipules 15–17 × 3–6 mm (vs. 6 × 2 mm in B. roseopunctata ), longer petioles 4.3–8.5 cm long (vs. 1.5–2.2 cm long) and larger laminas 14–22 × 10.5–17 cm (vs. 10.5–13.5 × 9–9.5 cm), larger bracts, 7–10 × 2–4 mm (vs. bracts ca. 4 × 2 mm), relatively longer inflorescences (7–) 18.5–28 cm long (vs. inflorescences (5–) 7–13 cm long), male flowers with 56–59 stamens (vs. male flowers with ca. 26 stamens), female flowers with a larger ovary, 9–14 × 11–17 mm (vs. ovaries 6–8 × 5–10 mm) and capsules with wings 6–10 mm wide (vs. narrower wings, 3.5–4.5 mm wide in B. roseopunctata ). In addition, the maculation is usually white and coalesces into broad white bands between the veins in B. acidulenta in contrast to B. roseopunctata where the spots remain more discrete.

Type: — MALAYSIA. Borneo. Sarawak. Lubok Antu District: Batang Ai National Park, Sungai Bebiyong Besai , 1°18’40’’N and 112°04’00”E, 198 m, 2 August 2015, Julia et al. SFC 2759 (holotype SAR!; isotype KEP!) .

Cane-like begonia, whole plant glabrous. Stems 20–50 cm tall, little-branched, deep red, slender, 4–6 mm thick; internodes 4–13.5 cm long. Stipules pale green or dull red, broadly lanceolate, 15–17 × 3–6 mm, margin entire, apex setose, seta to 4 mm long, persistent. Leaves distant, held more-or-less horizontally, oblique; petioles deep red, 4.3–8.5 cm long, succulent; lamina of young plants green with white or pink spots or with lines of coalescing spots between veins above and a band of pink or white around the margin, leaves of older plants have broad white stripes between the veins, and in flowering plants the leaves are plain green above, paler beneath, thinly succulent, drying papery, asymmetric, broadly lanceolate, (14–)21–22 × 10.5–17 cm, broad side (8–) 11–12 cm long, base cordate, unequal, basal lobe 1.5–3 cm long, margin minutely toothed, apex acuminate, acumen (1.5–) 4.5–5.5 cm long; venation palmate-pinnate with 3–4 veins at the base and 3–4 veins on either side of the midrib, branching towards the margin, concolorous, slightly impressed above, prominent beneath. Inflorescences protogynous, axillary in upper leaf axils, paniculate, (7–) 18.5–28 cm long, peduncle 4.5–9 cm long, with 1–3 lateral branches ca. 2 cm long below, each branch with a pair of female flowers, above richly cymosely branched with many male flowers. Bracts pale green, lanceolate, 7–10 × 2–4 mm, margin entire, keeled, apex acuminate, acumen to 2 mm long, persistent; bracteoles similar but smaller, caducous. Male flowers with dull red pedicels, 2–4 mm long; tepals 4, pale yellowish green, margin entire, apex rounded or broadly acute, outer 2 tepals oval, 4–6 × 4–5 mm, inner 2 tepals narrowly oval or elliptic, 3–4 × 2–3 mm, stamens 56–59, cluster conical, sessile, filaments ca. 0.8 mm long, anthers pale yellow, obovate or oblong, ca. 0.8 × 0.5 mm, apex emarginate. Female flowers with pale green pedicels, 8–10 mm long, ovary pale green, 9–14 × 11–17 mm, wings 3, equal, 4–6 mm wide, locules 3, placenta 2 per locule, tepals 5, pale green, outer 4 tepals elliptic or broadly ovate, 7–11 × 4–7 mm, margin entire, apex broadly acute, inner tepal smaller, elliptic, 6–10 × 3–4 mm, styles 3, pale green, 3–4 mm long; stigma brownish, shallowly Y-shaped, papillose forming a continuous twisted band. Capsules in life pale green, 13–15 × 12–28 mm, locules 3, wings 3, equal, rounded proximally, truncate distally with a pointed tip, 6–10 mm wide, dehiscing between the locules and wings; pedicel pendent, stiff, 12–25 mm long.

Etymology: —Latin, acida = acid; - ulenta = full of, referring to leaves being sufficiently acid to be used to polish silver.

Distribution: — MALAYSIA. Borneo, Sarawak. Endemic in Sarawak, as yet known only from Batang Ai.

Habitat: —Lowland mixed dipterocarp forest below 200 m elevation, on earth slopes above river banks in deep to light shade.

Additional specimen examined: — MALAYSIA. Borneo. Sarawak. Lubok Antu District: Batang Ai National Park, Sungai Bebiyong Besai, 2 August 2015, Julia et al. SFC 2761 (KEP, SAR, SNP).

Notes: —It is a striking species when young with its variegated leaves but it loses its attraction as an ornamental species as the adult leaves are plain green. Some populations observed in the field have almost non-oblique leaves.

Henry & Schneiter (2009) and the local Iban in the Batang Ai area (August 2015, pers.comm.) reported that the sour young leaves of this species are commonly used to flavour food by the Iban community in Batang Ai. In addition, Henry & Schneiter (2009) illustrated on page 45 a variegated begonia that is clearly B. acidulenta and on page 44 show a local informant demonstrating the preparation of Begonia 2 leaves (S 99559) for polishing silver utensils by pounding them with hard clay soil.

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

2. Begonia amidalae C.W.Lin & C.-I. Peng (2014: 129). Type:— MALAYSIA. Borneo , Sarawak. Lubok Antu District , Batang Ai , 5 July 2013, C.W. Lin 547 (holotype SAR n.v.; isotypes E, HAST, KEP, TAIF).

Distribution: — MALAYSIA. Borneo. Sarawak. Endemic in Sarawak; known only from Batang Ai in Lubok Antu District.

Habitat: —In lowland mixed dipterocarp forest at 100–200 m elevation in valleys on steep slopes or on stream banks.

Notes:—The species was collected from forest areas outside the Batang Ai National Park boundary (Lin, C.W. pers.comm.). So far no record of this species has been recorded within the Park boundary.

Proposed conservation status: —Data Deficient. The species was previously recorded from the forest outside the park boundary and their occurrence within the park boundary is yet to be ascertained.

3. Begonia anserina C.W.Lin & C.-I Peng (2014) 136). Type:— MALAYSIA, Sarawak: Lubok Antu District , Batang Ai , 5 July 2013, C.W. Lin 548 (holotype SAR n.v.; isotypes E, HAST, KEP, TAIF).

Distribution: — MALAYSIA. Borneo. Sarawak. Endemic in Sarawak; known only from Batang Ai in Lubok Antu District.

Habitat: —In lowland mixed dipterocarp forest at 180–194 m elevation in light shade in forest above river banks or in undulating forest.

Additional specimen examined: — Malaysia, Borneo, Sarawak, Lubok Antu District, Batang Ai National Park, Sungai Bebiyong Besai, 2 August 2015, Julia et al. SFC 2757 (KEP, SAR, SNP).

Notes: —The species is common on forest along Sungai Bebiyong Besai where it grows together with B. edgariana and B. compacta .

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

Figures

FIGURE 2. Begonia acidulenta. A. Habit showing flowering plant with plain leaves; B. Juvenile plant with pink variegated leaves; C. Young plant with whitish variegated leaves; D. Stipule; E. Male inflorescence; F. Female flower; G. Fruit and young female flower; H. Cross section of fruit. All photos from SFC 2759 by Julia Sang (A–G) and Ling Chea Yiing (H).