Begonia chiasmogyna M.Hughes in Edinburgh J. Bot. 63 (2-3): 193. 2006

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Content

Begonia Section

  • Petermannia

Description

  • Erect softly hairy much branching herb to c.50 cm high. Stem woody at base, sometimes rooting where nodes touch substrate, densely hairy, internodes 5-13 cm.

    Stipules c.10 × 7 mm with a filiform extension at the tip, hairy, semi-persistent. Petioles 2-6 cm long, densely hairy. Leaves very asymmetric, up to 7-17 cm long from base to tip and 3-6 cm wide, midrib 5-13 cm, ovate-lanceolate, venation pinnate-palmate, covered with colourless hairs, margin scalloped and irregularly dentate with a fringe of short hairs, shallowly cordate at the base, pale green.

    Inflorescence bisexual, terminal, protogynous, female flowers occasionally borne separately; bracts ovate, c.3 mm long, fimbriate.

    Male flowers borne in monochasial cymes of c.14 flowers; tepals 2, suborbicular, c.8 × 9 mm, base cordate becoming truncate at maturity, outer surface with a few short colourless hairs, margin slightly fimbriate, white; stamens 45-50, yellow, anthers c.0.75 mm long, dehiscing through short slits near the tip, filaments the same length, slightly fused at the base.

    Female flowers borne in pairs; pedicel c.3 mm long; tepals 4, equal, sub-rhomboid, denticulate, white, c.15 × 11 mm; styles 3, twice spirally twisted, yellow, deciduous; ovary 10 × 14 mm with 3 equal wings, truncate across the apex, scattered with colourless hairs, pale green or pink, placentation axile, placentae bifid, wings rounded at the base and acute at the tip.

    Fruit c.12 × 16 mm, drying pale brown, dehiscent, capsule oval. Seeds barrel shaped, c.0.3 mm long, collar cells c.2/3 the length of the seed. (Four new species of Begonia (Begoniaceae) from Sulawesi. Edinburgh J. Bot. 63.: 191-199. 2006.)

Habitat & Ecology

  • Stream embankment at 800 m elevation, in full shade. (Ardi, W.H. & Thomas, D.C. 2022: Synopsis of Begonia (Begoniaceae) from the northern arm of Sulawesi and Sangihe Island, Indonesia, including three new species. – Edinburgh J. Bot. 79(Begonia special issue, article 405): 1-50. http://doi.org/10.24823/EJB.2022.405)

Conservation

  • Proposed IUCN category: VU D2. (Four new species of Begonia (Begoniaceae) from Sulawesi. Edinburgh J. Bot. 63.: 191-199. 2006.)
  • Data Deficient (DD). This species is known from three localities: Bogani Nani Wartabone National Park, Gunung Boliohutu, and Gunung Poniki. Although the result of GeoCAT analysis recommend an Endangered status based on the EOO (1064 km2) and AOO (12 km2), the forests in the wider area of the three mountains is very poorly collected, and the species will probably also occur deeper in the forested areas. Because more detailed field observations of habitat conditions, population sizes and local abundance at the collection sites are lacking, we currently assess this species as Data Deficient (IUCN Standards and Petitions Subcommittee, 2019). (Ardi, W.H. & Thomas, D.C. 2022: Synopsis of Begonia (Begoniaceae) from the northern arm of Sulawesi and Sangihe Island, Indonesia, including three new species. – Edinburgh J. Bot. 79(Begonia special issue, article 405): 1-50. http://doi.org/10.24823/EJB.2022.405)

Distribution

Endemic to Indonesia, Sulawesi, Sulawesi Gorontalo.

See specimen tab for map of point distribution data of georeferenced specimens.

Indonesia: endemic to Sulawesi, North Sulawesi and Gorontalo Provinces (Ardi, W.H. & Thomas, D.C. 2022: Synopsis of Begonia (Begoniaceae) from the northern arm of Sulawesi and Sangihe Island, Indonesia, including three new species. – Edinburgh J. Bot. 79(Begonia special issue, article 405): 1-50. http://doi.org/10.24823/EJB.2022.405)

Etymology

  • It is unusual in section Petermannia in the female flowers having four rather than five tepals, the rhomboidal tepals giving a cross-shape to the perianth; hence the epithet chiasmogyna (female cross). (Four new species of Begonia (Begoniaceae) from Sulawesi. Edinburgh J. Bot. 63.: 191-199. 2006.)A
A. Four new species of Begonia (Begoniaceae) from Sulawesi. Edinburgh J. Bot. 63.: 191-199. 2006.

Notes

  • Begonia chiasmogyna is similar to B. gambutensis Ardi & D.C.Thomas in terms of the dense indumentum on the vegetative parts and the cymose male inflorescence. In other characters, however, the two species are distinct. Begonia chiasmogyna can be easily differentiated from B. gambutensis by the colour of the indumentum, because the former species has a white indumentum (not red crimson). Other differentiating characters include the number and shape of the tepals of the female flowers: Begonia chiasmogyna has four obtrullate tepals, whereas B. gambutensis has five obovate tepals (Ardi et al., 2014). (Ardi, W.H. & Thomas, D.C. 2022: Synopsis of Begonia (Begoniaceae) from the northern arm of Sulawesi and Sangihe Island, Indonesia, including three new species. – Edinburgh J. Bot. 79(Begonia special issue, article 405): 1-50. http://doi.org/10.24823/EJB.2022.405)

Molecular Systematics

  • GenBank
  • see Thomas et al., 2012 (Thomas, D.C., Hughes, M., Phutthai, T., Ardi, W.H., Rajbhandary, S., Rubite, R., Twyford, A.D. & Richardson, J.E. 2012: West to east dispersal and subsequent rapid diversification of the mega-diverse genus Begonia (Begoniaceae) in the Malesian archipelago. – Journal of Biogeography 39: 98-113)

Specimens

  • Gorantalo, Nr Gunung Gambuta, 9 iv 2002, M. Mendum, H.J. Atkins, M. Newman, Hendrian, A. Sofyan 46 (E, L); Gorantalo, Gunung Boliohutu, 22 iv 2002, M. Mendum, H.J. Atkins, M. Newman, Hendrian, A. Sofyan 146 (E); Gorantalo, Gunung Boliohutu, 23 iv 2002, M. Mendum, H.J. Atkins, M. Newman, Hendrian, A. Sofyan 167 (holo E) – Type of Begonia chiasmogyna M. Hughes. (Hughes, M. An annotated checklist of Southeast Asian Begonia. 2008)
  • Indonesia. Sulawesi. Northern arm of Sulawesi. Central North Sulawesi: Gorontalo, Gunung Boliohutu, 9 iv 2002, M. Mendum et al. 46 (E, K, L); Gunung Boliohutu, 22 iv 2002, M. Mendum et al. 146 (E). Eastern North Sulawesi: Bolaang Mongondow, Dumoga-Bone National Park, Edward Camp, 28 iii 1985, de Vogel & Vermeulen 6790 (E); Bolaang Mongondow, Gunung Poniki, 30 x 2016, S. Barber et al. BAAK13 (BO, E). (Ardi, W.H. & Thomas, D.C. 2022: Synopsis of Begonia (Begoniaceae) from the northern arm of Sulawesi and Sangihe Island, Indonesia, including three new species. – Edinburgh J. Bot. 79(Begonia special issue, article 405): 1-50. http://doi.org/10.24823/EJB.2022.405)