Begonia gambutensis Ardi & D.C.Thomas in Edinburgh J. Bot. 71(2): 260. 2014

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Begonia Section

  • Petermannia

Diagnosis

  • Differs from other Sulawesi Begonia species by the character combination of a dense crimson indumentum on vegetative parts, male inflorescences showing basal dichasial branching with well-developed internodes and distal monochasial branching, and female flowers with obovate tepals distinctly tapering towards the base. (Ardi, W.H., Ardaka, I M., Hartutiningsih, I Nyoman Lugrayasa & Thomas, D.C. - Two new species of Begonia (Begoniaceae) from Sulawesi, Indonesia)

Description

  • Perennial, monoecious herb with erect stems, to c.60 cm tall, with a dense indumentum of crimson, multicellular, simple trichomes up to c.1.2 mm long and a sparse indumentum of microscopic, glandular trichomes on stems and leaves. Stems branched; internodes c.3–5.5 cm long, reddish. Leaves alternate; stipules caducous, 8–17 × 6–7 mm, asymmetric, oblong to narrowly elliptic, with a slightly prominent midrib abaxially projecting up to c.2 mm at the apex; petioles c.4–9 cm long, red; lamina basifixed, 7–12.6 × 4.8–8 cm, asymmetric, ovate to elliptic, base cordate, lobes sometimes overlapping, apex acuminate, margin serrate to biserrate, undulate, the teeth long bristle-pointed, adaxial surface midgreen and abaxial surface pale green,primary veins 5–8, actinodromous, secondary veins craspedodromous. Inflorescences: protogynous; female inflorescences 2-flowered, one node basal to the male inflorescences or solitary, peduncles 4–7 mm long; male inflorescences distal to the female inflorescences or sometimes solitary, usually branched with 2–3 cymose partial inflorescences, each showing 1–2 basal dichasial branchings and several distal monochasial branchings, the internodes well developed in the basal part, but condensed in the most distal part. Male flowers : pedicels 9–15 mm long; tepals 2, pink, rarely white, 9–16 × 13–21 mm, broadly ovate, base slightly cordate, margin fringed by stiff hairs, apex rounded, abaxially hairy; androecium of c.40–60 stamens, yellow, filaments up to c.1.5 mm long, slightly fused at the very base, anthers up to c.1 mm long, obovate, dehiscing through unilaterally positioned slits > 1/2 as long as the anthers. Female flowers: pedicels 3–4 mm long; tepals (4–)5, whitish-pinkish, unequal, the smallest 8–14 × 5–7 mm, obovate, the larger 21–22 × 15–18 mm, obovate to elliptic, the margin serrulate and fringed with short stiff hairs, abaxially hairy; ovary ellipsoid, hairy, locules 3, placentation axile, placentae bilamellate, wings 3, subequal, narrowly triangular, base rounded, apex truncate, the margin serrulate with teeth extended into multicellular hairs up to c.1 mm long, styles basally fused, 3-branched, each stylodium bifurcate in the stigmatic region, stigmatic surface a spirally twisted papillose band, orange. Fruits : peduncles c.9–13 mm long; pedicels 5–7 mm long; ellipsoid, 14–16 × 5–7 mm (excluding the wings), sparsely to moderately densely hairy, dehiscent, splitting along the wing attachment, wing shape as on ovary, 9–11 mm wide at the widest point (at the apex); seeds ellipsoidal, c.0.3–0.4 mm long, collar cells c.1/5–1/4 of the length of the seed. (Ardi, W.H., Ardaka, I M., Hartutiningsih, I Nyoman Lugrayasa & Thomas, D.C. - Two new species of Begonia (Begoniaceae) from Sulawesi, Indonesia)

Habitat

  • Primary rain forest, forest floor at the side of a river, at c.700 m above sea level.

Distribution

Endemic to Indonesia, Sulawesi, Gorontalo.
See 'Specimens' tab for map of point distribution data of georeferenced specimens.

Etymology

  • The epithet ‘ gambutensis ’ refers to Gunung Gambuta, where the type material was collected.

Notes

  • The complex inflorescence architecture of Begonia gambutensis with basal dichasial branching with well-developed internodes and distal monochasial branching (Fig. 2D) in combination with the crimson indumentum on vegetative parts ( Fig. 2C ), and tepals of the female flowers which conspicuously taper towards the base, separates this species from other Sulawesi Begonia species.
    In molecular phylogenetic analyses on the basis of non-coding plastid DNA data, Begonia gambutensis (accession DCT 09-53) is retrieved in a well-supported clade with the Northern Sulawesi species B. macintyreana and B. chiasmogyna, which is sister to a clade containing the Northern Sulawesi species B. mendumiae , B. capituliformis, B. hispidissima and B. masarangensis (Thomas, 2010 ; Thomas et al. , 2012 ). The complex, many-flowered inflorescences of Begonia macintyreana , which show well-developed internodes as well as basal dichasial branching and distal monochasial branching, are similar to the ones found in B. gambutensis . However, apart from the inflorescence architecture the two species are morphologically dissimilar and the glabrous stems, leaves and generative parts and the somewhat pointed apices of the tepals of Begonia macintyreana separate this species from B. gambutensis . Begonia chiasmogyna has some similarity with Begonia gambutensis with regard to the dense indumentum on vegetative parts, the complex inflorescence architecture with relatively well-developed internodes, and the tepals of the female flowers, which taper conspicuously towards the base (Hughes, 2006 ). However, Begonia chiasmogyna can be easily differentiated from B. gambutensis by the colour of the indumentum (white, not reddish), as well as the number and shape of the tepals of the female flowers (four obtrullate tepals versus five obovate tepals). (Ardi, W.H., Ardaka, I M., Hartutiningsih, I Nyoman Lugrayasa & Thomas, D.C. - Two new species of Begonia (Begoniaceae) from Sulawesi, Indonesia)

Specimens

  • SULAWESI . Gorontalo : Gunung Gambuta (cultivated at Bali Botanic Garden from material collected in the wild), 4 iv 2009, D.C. Thomas & W. Ardi 09-53 (BO, E). (Ardi, W. & Thomas, D.C. Edinburgh J. Bot. 71(2): 259-268. 2014)