Begonia mendumiae M.Hughes in Edinburgh J. Bot. 63(2-3): 196. 2006

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Begonia Section

  • Petermannia

Diagnosis

  • A Begonia siccacaudata J.Door. foliis magis pilosis et magis asymmetricis differt. - Type: Sulawesi, Gorontalo, Gunung Ali, growing on almost vertical rock face in heavy shade, 200 m, 28 iv 2002, M. Mendum, H.J. Atkins,M.F. Newman, Hendrian & A. Sofyan 240 (holo E). (Four new species of Begonia (Begoniaceae) from Sulawesi. Edinburgh J. Bot. 63.: 191-199. 2006.)

Description

  • Creeping pubescent herb to c.20 cm high. Stem rhizomatous, c.7 mm across with scattered hairs; internodes 5-10 mm.

    Stipules broadly lanceolate, 10 × 8 mm with a filiform extension at the tip, fimbriate on the keel. Petioles 5-10 cm long with scattered hairs, pink. Leaves very asymmetric, up to 9 cm long from base to tip, up to 6 cm wide, midrib 4-5.5 cm, ovate with an acute tip, venation palmate-pinnate, scattered with pinkish red hairs, margin shallowly sinuate-dentate with a fringe of short hairs, cordate at the base, lobes sometimes overlapping, deep green in the centre and around the margin with darker mottling on the veins, a paler band running inside the margin.

    Inflorescence bisexual, terminal, protogynous; bracts ovate to sub-orbicular, c.4 mm long.

    Male flowers borne distally to the female in a monochasial cyme with up to three sub-umbellate clusters (actually very compressed cymes) of 6-8 flowers, subtended by 2 bracts with no others visible; tepals 2, suborbicular, c.12 × 12 mm, base cordate becoming truncate at maturity, pale dusky pink; stamens 35, orange, anthers c.0.75 mm long, dehiscing through slits more than half as long as the anther, filaments c.three times as long, slightly fused at the base.

    Female flowers borne singly at the base of the inflorescence, subtended by two bracteoles c.5 mm from the base of the ovary; pedicel c.1.5 cm long; tepals 5, sub-equal, broadly ovate-lanceolate, slightly fimbriate, dusky pink, outer pair 15 × 12 mm, inner three 14 × 6-11 mm; styles 3, twice spirally twisted, orange, deciduous; ovary 13 × 12 mm with 3 equal wings, deep dull-red, truncate across the apex, with scattered hairs, placentation axillary, placentae bifid, wings rounded at the base and acute at the tip.

    Fruit c.13 × 12 mm, drying pale brown, dehiscent; capsule oval, 8 × 5 mm. 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

  • This species was observed growing on a almost vertical rock face, in full shade, at 200 m above sea level.

Conservation

  • Proposed IUCN category: VU D2. (Four new species of Begonia (Begoniaceae) from Sulawesi. Edinburgh J. Bot. 63.: 191-199. 2006.)

Distribution

Asia-Tropical:, Sulawesi (Sulawesiendemic)
Endemic to Indonesia, Sulawesi, North Sulawesi.

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

Etymology

  • It is named in memory of the late collector, Mary Mendum. (Four new species of Begonia (Begoniaceae) from Sulawesi. Edinburgh J. Bot. 63.: 191-199. 2006.)

Notes

  • I have diagnosed this species against Begonia siccacaudata as it is the only other Sulawesi species with anything like a similar habit, but it differs greatly in terms of inflorescence structure. Begonia mendumae has a sub-umbellate male inflorescence, whilst B. siccacaudata bears its male flowers in a comparatively lax thyrse. (Four new species of Begonia (Begoniaceae) from Sulawesi. Edinburgh J. Bot. 63.: 191-199. 2006.)

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., West to east dispersal and subsequent rapid diversification of the mega-diverse genus Begonia (Begoniaceae) in the Malesian archipelago i...)