Begonia mekonggensis Girm. & Wiriad. in Reinwardtia 13(1): 70. 2009

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Begonia Section

  • Petermannia

Diagnosis

  • Inflorescentia subumbellata Begoniae guttapilae et Begoniae ozototrichi affinis, sed praeclare habitu dioico distinguitur. - Type: Indonesia, Sulawesi, Southeast Sulawesi, Kabupaten Kolaka, Kecamatan Ranteangin, Desa Tinukari. Gunung Mekongga, 18 Maret 2006, Deden Girmansyah, Deden 579 (Holotype BO!, Isotype US, L, K, E). (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)

Description

  • Stems erect, terete, rooting at base, brownish red, glabrous, swollen at the nodes, branching, 0.4-0.5 cm in diameter, internodes 3-6 cm long, up to 50 cm tall.

    Stipules glabrous, narrowly triangular, margin entire, apex acuminate, persistent, pale yellow, 1.7-2.1 x 0.6-0.8 cm. Leaves petiole dark red, glabrous, terete, 2-5 cm long; lamina glabrous on both sides, oval, asymmetric, base slightly oblique, lobes not overlapping, margin biserrate, apex acuminate 6-14 x 3-7 cm, broad side 2.5-5 cm wide, narrow side 1.5-2.5 cm wide, basal lobe 1-1.5 cm long; venation palmate-pinnate, 1-2 pairs of veins at the base, 2-3 pairs along the midrib, 1-3 in the basal lobe, branching towards the margin, veins impressed above, prominent beneath.

    Inflorescences unisexual (plants dioecious), axillary, dichasial, somewhat pendant, glabrous, peduncles reddish green. Bracts glabrous, green, boatshaped, rather translucent, persistent, ca. 1 x 0.5 cm.

    Male flowers pedicels reddish-white, 2-2.5 cm long; tepals 2, white or reddish, margin entire, apex rounded, 1.1 x 1.1-1.9 cm; stamens yellow, forming a narrow fan, filaments pale yellow, 1-1.5 mm long, anthers yellow, broadly obovate, 1-1.5 mm long, apex notched, opening by slits along the sides, almost as long as the anthers.

    Female flowers pedicels white, 3-5 mm long; ovary reddish green, with 3 equal wings, 1.2-1.9 cm long, 3 locular, placentae axillary, bifid; tepals 5, white to reddish, broadly elliptic, glabrous, up to 15-16 x 6-12 mm, styles 3, orange, forked once, 5 mm long.

    Fruits dehiscent capsules, green, on 3-5 mm long pedicels, with 3 equal wings, broadly triangular, acuminate at the base, widest at the apex, ca. 8 x 14 mm; stigmas caducous. Seeds barrel-shaped, ca. 0.4-0.45 mm long, collar cells less 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)

Habitat

  • Secondary forest at 700 to 800 m asl.

Conservation

  • Endangered EN B2ab(iii). Begonia mekongensis is known from only a few localities including lowland rainforest in the Mangkutana-Pendolo devide and upland rainforest on Gunung Mekongga, which lie about 180 km apart. The collections from Mangkutana-Pendolo are from the periphery of a legally protected area, the Faruhumpena Forest Reserve. The small EOO (7,168 km2) and AOO (28 km2) in combination with only few collection localities warrant an Endangered (EN) status. (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.)

Distribution

Indonesia; endemic to Sulawesi, so far only known from three localities (Gunung Mekongga, Mangkutana-Pendolo divide and Rantepao-Palopo divide). (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.)

Etymology

  • The epithet "mekonggensis" is composed of Mekongga, a reference to Gunung Mekongga where the type material was collected, and "-ensis" (Latin: originating from). (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)

Notes

  • Begonia mekonggensis is one of several putatively dioecious species which are found in Sulawesi: B. guttapila D.C.Thomas & Ardi in Thomas et al. (2009: 234), B. rantemarioensis D.C.Thomas & Ardi in Thomas et al. (2011: 240), B. sanguineopilosa D.C.Thomas & Ardi in Thomas et al. (2011: 243), and B. torajana D.C.Thomas & Ardi in Thomas et al. (2011: 246). A comparison of the salient features of Begonia mekonggensis with allied species is shown in Table 2. (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, Ranteangin District, Tinukari Village, 03 Aug. 2009, Agus Rinai et al. AR 012 (BO); North Kolaka, Ranteangin District, Tinukari Village, 07 Aug. 2009, A. Hidayat et al. AH 4187 (BO); North Kolaka, 19 Mar. 2006, H. Wiriadinata et al. 588 (BO); North Kolaka, Ranteangin District, Tinukari Village, 29 June 2011, E.A. Widjaja EAW 9693 (BO).