Tuesday, May 17, 2022

[Botany • 2020] Begonia tjiasmantoi (Begoniaceae, sect. Petermannia) • A New Species from West Sulawesi, Indonesia


Begonia tjiasmantoi Ardi & D.C.Thomas

in Ardi & Thomas, 2020. 

A new species, Begonia tjiasmantoi Ardi & D.C.Thomas is described from Mamasa, West Sulawesi, Indonesia. The species is endemic to West Sulawesi and belongs to Begonia section Petermannia. A provisional conservation assessment indicates a Critically Endangered status.  

Keywords: new species, critically endangered, conservation assessment, a new species, endangered status

Begonia tjiasmantoi Ardi & D.C.Thomas.
A. Habit; scale bar: 5 cm. B. Stipule; scale bar: 5 mm. C.Male inflorescence; scale bar: 10 mm. D. Male inflorescence and female flower; scale bar: 10 cm. E. Male flower, front and side view; scale bar: 5 mm. F. Female flower, front view; scale bar: 5 mm. G. Infructescence; scale bar: 10 mm. H. Ovary cross-section, axile placentation and bilamellate placentae; scale bar: 2 mm.
A–H from WI 562. Photos: W.H. Ardi. 

Begonia tjiasmantoi Ardi & D.C.Thomas spec.nov. 
§ Petermannia

Begonia tjiasmantoi has a rhizomatous stem, male and female flowers with yellow tepals and male flowers with relatively few stamens (22‒24). This character combination differentiates it from other Sulawesi Begonia species. The rhizomatous growth habit of Begonia tjiasmantoi is similar to the growth habit of the orange-tepalled B. ignita C.W.Lin & C.I.Peng, but B. tjiasmantoi can be differentiated by its strongly asymmetric, ovate toelliptic leaves (8–11 × 3.5–5.5 cm); cymose-paniculate male inflorescence with subumbellate partial inflorescences with up to 6 flowers; yellow male flower tepals that are relatively small (6–8 ×7.5–8.5 mm) and have few stamens (22–24);female flowers with shorter pedicels (3–4 mm), 5(–6) yellow tepals, and a cylindrical seed-bearing part of the fruit. Begonia ignita has symmetric or subsymmetric cordiform leaves that are larger (7–12 × 6.5–11 cm); racemose-cymose male inflorescence with monochasial partial inflorescences with up to 3 flowers; orange male flower tepals that are larger in size (10–15 × 9–11mm), more stamens (35–45); female flowers with longer pedicels (6–13 mm), 4 (or rarely 2, 3 or 5)orange tepals, and an ellipsoid seed-bearing part of the fruit. 

Etymology. The species epithet refers to Wewin Tjiasmanto, the Chairmain of the Tjiasmanto Conservation Fund, who has generously supported the Sulawesi Begonia Project. 

 
Wisnu Handoyo Ardi and Daniel C. Thomas. 2020. Begonia tjiasmantoi, A New Species from West Sulawesi. Reinwardtia. 19(2); 61‒65. DOI: 10.14203/reinwardtia.v19i1.3848