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| Rhododendron yombuwurii Hutabarat, Bandjolu & Zulfadli, in Hutabarat, Zulfadli, Bandjolu, Basrul, Hariri, Senatama et Larekeng, 2026. |
Abstract
A new species of Rhododendron subgenus Vireya from Central Sulawesi, Rhododendron yombuwurii, is described. The species is known from material originating from the Tokorondo Range, northwest of Lake Poso, and is currently cultivated at a lower elevation near Saluopa Waterfall, where it grows epiphytically and produces small, bright orange flowers. We provide a detailed morphological description, comparative microscopic observations, notes on distribution, habitat and ecology, and a preliminary conservation assessment. Phylogenetic analyses based on the nuclear ribosomal ITS region support the placement of the species within subgenus Vireya and its distinction from morphologically similar taxa.
Keyword: Flora, Malesia, Mountain flora, Poso, Rhododendron celebicum, Schistanthe, Tokorondo, Wallacea
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| A. Rhododendron yombuwurii thriving and flowering as an epiphyte beneath the canopy of a small tree in Tentena, Central Sulawesi; B. The fresh material of the type specimen PWH1635; C. Flower bud of R. yombuwurii. (Photographed by P.W.K. Hutabarat) |
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| Morphology of Rhododendron yombuwurii Hutabarat, Bandjolu & Zulfadli, sp. nov. A. flowering stem; B. Semi–erect inflorescence; C. Flower bud; D. Glabrescent adaxial leaf; E. Scaly petiole; F. Scaly abaxial leaf; G. Scales on abaxial leaf; H. Narrow funnel–shaped corolla; I. Corolla lobes and stamen position; J. Corolla (inside); K. Androecium and gynoecium; L. Stamen; M. Gynoecium; N. Immature fruit; O. Laxly scaly ovary (Photographed by Zulfadli) |
Rhododendron yombuwurii Hutabarat, Bandjolu & Zulfadli, sp. nov.
Diagnosis: Rhododendron yombuwurii is most closely allied to R. celebicum (Blume) DC. (de Candolle, 1839), and shows affinity to R. impressopunctatum J.J.Sm. (Smith, 1932), and R. vidalii subsp. brachystemon Argent (Argent, 2003). It differs from R. celebicum by its raised midrib and lateral veins (vs. slightly impressed), semi-erect to horizontal inflorescences (vs. pendulous), glabrous calyx externally (vs. densely scaly), and much smaller orange corolla, 17–22 × 12–16 mm (vs. 35–46 × 20–25 mm, pink to red). From R. impressopunctatum it differs in having smaller leaves, fewer-flowered inflorescences, smaller orange corollas, and filaments clustered at the corolla mouth rather than exserted. The species further differs from R. vidalii subsp. brachystemon by its scaly young twigs becoming glabrescent, longer leaves with raised veins, glabrous calyx externally, smaller orange corolla, and a sparsely scaly to nearly glabrescent ovary. Additional distinguishing characters are summarized in Table 1. ...
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| A. Type locality of Rhododendron yombuwurii in the Tokorondo Range, Poso Regency, Central Sulawesi. The red dot marks Saluopa Waterfall, where the type specimen was collected as a cultivated plant, while the yellow circle indicates Petirorano, the presumed original source of the species. B. Saluopa Waterfall, a lower montane site at 560 m elevation, characterized by a cool and humid climate. |
Prima Wahyu Kusuma Hutabarat, Zulfadli, Kurniawan Palindondaya Bandjolu, Basrul, Muhammad Rifqi Hariri, Andhika Senatama and Siti Halimah Larekeng. 2026. Rhododendron yombuwurii (Ericaceae), A New orange-flowered Species of subgenus Vireya from Central Sulawesi, Indonesia. Taiwania. 71(2); 277-283 DOI: 10.6165/tai.2026.71.277 [2026 March 28]
