Begonia watuwilensis Girm. in Reinwardtia 13(1): 70. 2009

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Content

Begonia Section

  • Petermannia

Diagnosis

Description

  • Stems erect, terete, rooting at base, dark red to violet, glabrous to pubescent, swollen at the nodes, branching, 0.5-0.8 cm in diameter, internodes 3-12 cm long, 50-100 cm tall.

    Stipules 1-2 x 0.8-1.2 cm, broadly triangular, margin entire, apex acuminate, caducous. Leaves petiole red to dark red, glabrous to pubescent, terete, 1-5.5 cm long; lamina glabrous to pubescent on both sides, broadly ovate, strongly asymmetric, base oblique, lobes not overlapping, margin biserrate, apex acuminate, 9-17 x 4.5-11 cm, broad side 3-7 cm wide, narrow side 1.5-4 cm long wide, basal lobe 2-6 cm long; venation palmate-pinnate, 1-2 pairs at the base, 5 pairs along the midrib, 2-3 in the basal lobe, branching towards the margin, veins impressed above, prominent beneath.

    Inflorescences bisexual, terminal, cymose, an up to 6-times branched dichasium, somewhat pendant, glabrous to pubescent, protandrous, male and female flower inflorescences with basal male and female flowers distal, ca. 30-32 male flowers and ca. 32 female flowers every peduncle, peduncles reddish green. Bracts glabrous, reddish, broadly ovate, rather translucent.

    Male flowers pedicels white, 0.3-1 cm long; tepals 4, white or pink, margin entire, apex rounded, outer tepals broadly ovate, 10-14 x 7-13 mm, the inner two oblong, 8-9 x 2-3 mm; stamens yellow, ca. 80-95, forming a narrow fan, filaments pale yellow, 1.5-2 mm long, anthers yellow, oblong to narrowly obovate, 2.5-3 mm long, apex notched, opening by slits along the sides, almost as long as the anthers.

    Female flowers pedicels white, 6-7 mm long; ovary pink, with 3 white equal wings, 3 locular; placentae axillary, bifid; tepals 5, white, glabrous, the larger ones up to 15 x 7-9 mm, broadly elliptic, the smallest one narrowly elliptic, 15 x 4 mm; styles 3, golden yellow, forked once, 4 mm long.

    Fruits dehiscent capsules, reddish green, on a 10-15 mm long pedicel, with 3 equal wings, broadly triangular, acuminate at the base, widest at the apex, 10-15 x 5-7 mm (without wings); stigmas caducous. Seeds barrel-shaped, ca. 0.3-0.5 mm long, collar cells more than half the seed length. (Girmansyah, D., Wiriadinata, H., Thomas, D.C. & Hoover, W.S., Two new species and one new subspecies of Begonia (Begoniaceae) from Southeast Sulawesi, Sulawesi, Indonesia in Reinwardtia 13(1). 2009)
  • Perennial, monoecious herb, up to c. 150 cm tall; stems erect or semi-erect, slightly woody at base, all above-ground vegetative parts with microscopic glandular hairs, otherwise glabrous or with a sparse indumentum of white trichomes, c. 0.5–1.5 mm
    long. Stem branched; internodes 2.5–16 cm long, terete, green, red or brownish. Leaves alternate; stipules caducous, 12–29 × 6–12 mm, oblong, ovate or elliptic, acuminate, setose, seta to 3 mm long, margin entire, green, translucent at margin; petioles c. 1–8.2 cm long, terete, red; lamina basifixed, 8.5–29.5 × 3–16.5 cm, very asymmetric, ovate, elliptic, or sometimes oblong, base obliquely cuneate to cordate, lobes not overlapping, apex acute, margin distantly dentate to serrate, the teeth bristle-pointed, adaxial surface dark green, sometimes with a whitish to pale greenish band running along the margin, abaxial surface pale green or reddish, venation pinnate to palmately-pinnate, secondary veins craspedodromus. Inflorescences pendent, racemose-cymose with several protandrous, dichasial partial inflorescences, each many-flowered, peduncles 2.2–4 cm long, bracts obovate or suborbicular, 6–14 × 6–13 mm, pale greenish to pinkish. Male flowers: pedicels (3–)7–22 mm long, white, glabrous; tepals 4, unequal, the outer larger 8–14 × 4–15, suborbicular to broadly ovate, the inner smaller 6–12 × 2–4 mm, oblong, narrowly elliptic or narrowly obovate, margin entire, apex rounded, white, white tinged with pink, or pink, sometimes with the outer tepals white and the inner pink, glabrous; androecium of 15–23 stamens, yellow, filaments c. 0.5–1 mm long, slightly fused at the very base, anthers c. 1–1.5 mm long, obovate, dehiscing through unilaterally positioned slits c. 1/2 as long as the anthers. Female flowers: pedicels (7–)11–24 mm long, glabrous, green-reddish; tepals 5, unequal, white, white tinged with pink, or pale pink, unequal and the four outer larger, 10–18 × 7–12 mm, elliptic to obovate, the inner smaller, 8–17 × 3–6 mm, elliptic, glabrous; ovary subglobose, 8.5–10 × 6–8 mm (excluding the wings), pinkish, glabrous, locules 3, placentation axile, placentae bilamellate, wings 3, subequal to unequal, usually one larger and two smaller, or sometimes two larger and one smaller, base rounded, apex truncate, widest at the apex (larger wings up to 13 mm), style basally fused, 3-branched, each stylodium bifurcate in the stigmatic region, stigmatic surface a spirally twisted papillose band, yellow to orange. Fruits: pedicels thin and hanging, up to 2.9 cm long, seed bearing part subglobose, 8–15 × 5–9 mm (excluding the wings), glabrous, dehiscent, splitting along the wing attachment, wing shape as for ovary, larger wing up to 14 mm wide (widest point at apex). Seeds barrel-shaped, c. 0.3 mm long. (Thomas, D.C., Bour, A. & Ardi, W.H., Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species in Gardens' Bulletin Singapore 70(1): 163-176. 2018)

Habitat

Conservation

  • Provisional IUCN conservation assessment. Endangered EN B1ab(iii),B2ab(iii). Begonia watuwilensis is known from only two localities: lowland karst rainforest in Matarombeo and upland rainforest on Gunung Watuwila, which lie about 100 km apart. None of the collection localities are in legally protected areas, and some anthropogenic disturbance by agriculture (oil palm plantations) was observed in Matarombeo at the periphery of the habitats. The small EOO and AOO in combination with only few collection localities and observed threats warrant an Endangered (EN) status. The Abuki mountain range in between the two localities is botanically very poorly explored, and this species is likely more widespread, but even if it is present in suitable limestone habitats in between Matarombeo and Gunung Watuwila, its EOO would remain < 5000 km2.

Distribution

Endemic to Southeast Sulawesi, Sulawesi, Indonesia. Known from only two localities: Gunung Watuwila and Matarombeo (Fig. 1). (Thomas, D.C., Bour, A. & Ardi, W.H., Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species in Gardens' Bulletin Singapore 70(1): 163-176. 2018)

Etymology

Notes

  • The placement in section Petermannia has been confirmed by chloroplast DNA sequences (see Thomas et al. 2012, J. Biogeogr. 39: 98-113). [Note by D.C. Thomas, 6/8/2013]
  • The protandrous inflorescences with basal male flowers and several distal female flowers of Begonia watuwilensis are very unusual in Begonia sect. Petermannia. Most species in this section show two-flowered or single-flowered female inflorescences or partial inflorescences, which are either basal to male partial inflorescences in a mixed protogynous inflorescence, or separate from the male inflorescences. However, there are several variations of this typical inflorescence morphology (see Irmscher, 1914; Doorenbos et al., 1998). Despite the very unusual inflorescences, Begonia watuwilensis can be placed in Begonia section Petermannia, based on the presence of 3-locular ovaries with axillary, bilamellate placentae, five-tepaled female flowers and four-tepaled male flowers, and the lack of specialized underground organs like tubers or rhizomes. The sectional placement is also supported by chloroplast DNA sequences (unpublished data). (Girmansyah, D., Wiriadinata, H., Thomas, D.C. & Hoover, W.S., Two new species and one new subspecies of Begonia (Begoniaceae) from Southeast Sulawesi, Sulawesi, Indonesia in Reinwardtia 13(1). 2009)
  • Begonia watuwilensis does not have separate female and male inflorescences or partial inflorescences, which differentiates it from the vast majority of species in the large section Petermannia (but see B. divariacta Irmsch. (Irmscher, 1953), and possibly also B. gracilicyma Irmsch. ex M.Hughes (Hughes et al., 2009)). Its partial inflorescences are protandrous dichasia with basal male and distal female flowers. However, some morphological features (the lack of specialised underground organs such as rhizomes and tubers, unilaterally opening anthers, and 3-loculed capsules with bilamellate, axile placentation) as well as cpDNA sequence data (see Thomas et al., 2012) allow placement of this species in section Petermannia.
    The new collections of Begonia watuwilensis from Matarombeo indicate that this species is more widespread and has a wider ecological amplitude than previously thought. It was previously known from only a single collection from Gunung Watuwila, where it was collected from slopes in upland forest (at c. 1000 to 1200 m altitude). The new collection localities in Matarombeo lie c. 80 km northeast of Gunung Watuwila, and the species occurs here in lowland rainforest on limestone at c. 100 to 200 m altitude. The material of some individuals from Matarombeo also has some quantitative (e.g. larger leaves, longer pedicels of male and female flowers) and qualitative morphological characters (fruits with unequal wings, leaf laminas with a white band running in parallel to the margin) which deviate from the original description. The amended description above is based on measurements of living material from the type locality cultivated at Bali Botanic Gardens, as well as measurements of the newly available material from Matarombeo. It also incorporates measurements from the original description by Girmansyah et al. (2009), except for the androecium. The androecium was described as consisting of ‘c. 80–95 stamens’ with ‘2.5–3 mm long’ anthers, which open by ‘slits along sides’ (Girmansyah et al., 2009), but this is inconsistent with our observations from the holotype, cultivated material from the type locality (vouchered as Thomas & Ardi 09-55), and the material form Matarombeo, which has flowers with 15–23 stamens, and c. 1 to 1.5 mm long anthers dehiscing through unilaterally positioned slits. (Thomas, D.C., Bour, A. & Ardi, W.H., Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species in Gardens' Bulletin Singapore 70(1): 163-176. 2018)
  • Begonia watuwilensis has protandrous inflorescences, which separates it from the vast majority of species in the large section Petermannia (see Moonlight et al. 2018; Thomas et al. 2018). (Ardi, W.H., Chikmawati, T., Witono, J.R. & Thomas, D.C. (2018). A synopsis of Begonia (Begoniaceae) of Southeastern Sulawesi including four new species. Phytotaxa 381.1: 027-050.)

Specimens

  • INDONESIA. Sulawesi, Southeast Sulawesi: North Kolaka, 17 Mar. 2006, H. Wiriadinata et al. Deden 574 (BO); North Kolaka, Ranteangin subdistrict, Tinukari village, 04 Aug. 2009. A.Hidayat et al. AH 4149 (BO); North Kolaka, Ranteangin subdistrict, Tinukari village, 17 Dec. 2009, E.A. Widjaja & Agus Suyadi EAW 8881 (BO); Matarombeo, close to Mataraki bridge, 117 m, 18 Feb. 2017, W.H Ardi WI 169 (BO, KRB, SING); Matarombeo, Telaga biru, ca. 14 km west of Mataraki bridge, 115 m, 19 Feb. 2017, W.H. Ardi WI 171 (BO, KRB, SING); Matarombeo, ca. 20 km W of Mataraki bridge, 194 m, 19 Feb. 2017, W.H Ardi WI 177 (BO, KRB, SING); cultivated at Bali Botanic Garden from material collected on Mt. Watuwila, 4 Apr. 2009, D.C Thomas & W.H. Ardi DCT 09-55 (BO, E). (Ardi, W.H., Chikmawati, T., Witono, J.R. & Thomas, D.C. (2018). A synopsis of Begonia (Begoniaceae) of Southeastern Sulawesi including four new species. Phytotaxa 381.1: 027-050.)