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Begonia balgooyi in Gard. Bull. Singapore 70(1): 164. 2018
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Diagnosis
- This species has palmately compound leaves, which are rare in section Petermannia. Of the palmately compound-leaved species in the section (Begonia insueta D.C.Thomas & Ardi, B. oligandra Merr. & L.M.Perry, B. polilloensis Tebbitt and B. rachmatii (Tebbitt) it is most similar to the Philippine B. polilloensis, but differs from it in its longer petioles (3.5–7.5 cm vs 0.7–2 cm), longer pedicels of the male flowers (10–34 mm vs c. 6 mm), and the different shape of the petals of the male flowers (suborbicular to broadly ovate vs elliptic). (Thomas, D.C., Bour, A. & Ardi, W.H. 2018: Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species. – Gardens' Bulletin Singapore 70(1): 163-176)
Description
- Perennial, monoecious herb, up to c. 25 cm tall; stems prostrate to semi-erect, rooting at the nodes when in contact with the substrate, with microscopic glandular hairs and a sparse to moderately dense indumentum of multicellular whitish hairs, c. 0.5–1 mm long, on above-ground vegetative parts. Stem branched, internodes 1.5–5.5 cm long, red or reddish-greenish. Leaves alternate; stipules semi-persistent, 4–7 × 3–4.5 mm, ovate to elliptic, acuminate, setose, seta to 3 mm long, margin entire, translucent, reddish-greenish; petioles 3.5–7.5 cm long, adaxially shallowly channelled, concolourous with the stem; lamina basifixed, palmately compound, 5–9.5 × 3.5–7 cm, ovate to elliptic, with 3–6 leaflets, 1.5–6 × 0.8–3 cm, the smallest asymmetrical, the larger symmetric to slightly asymmetric, ovate to elliptic, margin serrate to pinnatisect (divided up to c. 80% to the midrib), teeth bristle-pointed, base cuneate or rounded, apex acuminate, adaxial surface green with reddish or greenish veins, sparsely hairy inbetween the veins or glabrous, abaxial surface pale green, sparsely to moderately hairy on the veins only, veins reddish, leaflet venation pinnate, secondary veins craspedodromus. Inflorescences protogynous; female flowers solitary, often one node basal to male inflorescences or separate, peduncles c. 1 mm long, green-reddish, glabrous, bracts similar to stipules, c. 3–6 × 2.5–4 mm, ovate, midrib prominent, setose, seta up to 1.5 mm long; male inflorescences monochasial cymes with 3–10 flowers, peduncles 3–19 mm long, reddish, glabrescent, bracts similar to stipules, c. 4–6 × 2–3 mm, ovate, midrib prominent, setose, seta to 1.5 mm long. Male flowers: pedicels 1–3.4 cm long, whitish, whitish tinged with pink, to reddish, sparsely hairy to glabrous; tepals 2, white or white tinged with pink, 7–10 × 8–13 mm, suborbicular to broadly ovate, base slightly cordate, apex rounded; androecium of c. 46–50 stamens, yellow, filaments up to c. 0.5 mm long, slightly fused at the very base, anthers up to c. 1 mm long, obovate, dehiscing through unilaterally positioned slits c. 1/2 as long as the anthers. Female flowers: pedicels 3–7 mm long, green-reddish, glabrous; tepals 5, white, unequal, the four larger outer 6–9.5 × 4–7 mm, ovate to elliptic, the smaller inner one 6–8 × 3–4 mm, elliptic; ovary ellipsoid, 3–6 × 3 mm (excluding wings), red, glabrous, locules 3, placentation axile, placentae bilamellate, wings 3, subequal, pale green, base rounded or cuneate, apex truncate, style basally fused, 3-branched, each stylodium bifurcate in the stigmatic region, stigmatic surface a spirally twisted papillose band, orange. Fruits: peduncles c. 1–2 mm long, pedicels 3.5–9 mm long, ovary ellipsoid, 8–10 × 3.5–5 mm (excluding the wings), sparsely hairy, dehiscent, splitting along the wing attachment, wing shape as for ovary, up to 10 mm at the widest point (apically). Seeds barrel-shaped, c. 0.2 mm long. (Thomas, D.C., Bour, A. & Ardi, W.H. 2018: Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species. – Gardens' Bulletin Singapore 70(1): 163-176)
Habitat
- Growing terrestrially on steep slopes or river embankments in lowland and upland rainforest, in dense shade, on limestone soils, at c. 50–1200 m altitude (Thomas, D.C., Bour, A. & Ardi, W.H. 2018: Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species. – Gardens' Bulletin Singapore 70(1): 163-176)
Conservation
- Provisional IUCN conservation assessment. Endangered EN B1ab(iii),B2ab(iii).
Begonia balgooyi is known from only three collections from three localities of lowland and upland rainforest on limestone: Mangolo, Gunung Watuwila and Matarombeo, only the former of which has some legal protection as a Nature Recreation Park. Only single populations were observed in Mangolo and Matarombeo, and some anthropogenic disturbance by agriculture (oil palm, cacao and clove plantations) at the periphery of the habitats were noted. The Abuki mountain range in between the three localities is botanically very poorly explored and this species is likely more widespread. However, even if it is present in suitable limestone habitats in between Mangolo, Gunung Watuwila and Matarombeo, its Extent of Occurrence (EOO) would remain < 5000 km2. The small EOO and Area of Occupancy (AOO), in combination with only few collection localities and observed threats, warrant an Endangered (EN) status. (Thomas, D.C., Bour, A. & Ardi, W.H. 2018: Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species. – Gardens' Bulletin Singapore 70(1): 163-176)
Distribution (General)
- Endemic to Southeast Sulawesi, Sulawesi, Indonesia. Known from only three localities: Mangolo Nature Recreation Park, Gunung Watuwila, and Matarombeo (Fig. 1). (Thomas, D.C., Bour, A. & Ardi, W.H. 2018: Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species. – Gardens' Bulletin Singapore 70(1): 163-176)A
Etymology
- This species is named in honour of Max Michael Josephus van Balgooy; a pre-eminent expert on the Malesian flora, who extensively collected in the region and led a major Indonesian-Dutch expedition to Sulawesi in 1979 (see Baas et al., 2012). (Thomas, D.C., Bour, A. & Ardi, W.H. 2018: Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species. – Gardens' Bulletin Singapore 70(1): 163-176)B
Notes
- Begonia balgooyi is a very distinct species in Begonia section Petermannia on account of its palmately compound leaves. It can be easily differentiated from other palmately compound-leaved species in the section (Begonia insueta D.C.Thomas & Ardi, B. oligandra Merr. & L.M.Perry, B. polilloensis Tebbitt and B. rachmatii Tebbitt [see Tebbitt, 2005; Thomas et al., 2011]). Begonia insueta from Sulawesi and B. oligandra from New Guinea are morphologically dissimilar to B. balgooyi. They are much more robust and taller plants with unequal ovary wings. Begonia rachmatii from Sulawesi differs from B. balgooyi in having many-flowered, complex inflorescences (cymose-racemose) usually composed of multiple monochasial partial inflorescences (vs single few-flowered monochasia), fewer stamens (15–30 vs 46–50), and subsessile fruits (pedicels 1–2 mm vs 3.5–9 mm long). Differential characters of Begonia polilloensis are outlined in the diagnosis above. (Thomas, D.C., Bour, A. & Ardi, W.H. 2018: Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species. – Gardens' Bulletin Singapore 70(1): 163-176)
- Begonia balgooyi is distinct in Begonia section Petermannia on account of its palmately compound leaves, and it can easily be differentiated from the other two palmately compound-leaved species in the section from Sulawesi: Begonia insueta D.C.Thomas & Ardi [2011: 230] is a much more robust plant and has characteristic fruits with much longer pedicels (to 19 mm long) and unequal wings; B. rachmatii Tebbitt (2005: 101) has many-flowered cymoseracemose male inflorescences composed of multiple monochasial partial inflorescences, 15–30 stamens per male flower, and subsessile fruits (pedicels 1–2 mm), while B. balgooyi has male inflorescences comprised of single fewflowered monochasia, male flowers with 46–50 stamens, and longer fruit pedicels (to 9 mm long) (Thomas et al. 2018). In its growth habit and inflorescence morphology, Begonia balgooyi is closest to the simple-leaved Begonia flacca. (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 Tenggara: Tawanga, B. Watuwila, c. 1200 m, 24 Mar 1929, Kjellberg 1010 (BO); N of Linomoyo, Matarombeo, Anoa forest, 86 m, 15 Feb 2017, Ardi 157 (BO, KRB, SING). (Thomas, D.C., Bour, A. & Ardi, W.H. 2018: Begonia of the Matarombeo karst, Southeast Sulawesi, Indonesia, including two new species. – Gardens' Bulletin Singapore 70(1): 163-176)