 |
| Rhododendron mulunense Y.S.Huang & X.X.Mao, in Hou, Huang, Luo, Chen et Mao, 2026. |
Abstract
Rhododendron mulunense, a new species of Rhododendron (Ericaceae) within subsect. Maddenia in sect. Rhododendron and endemic to karst areas of Guangxi and Guizhou Province, SW China, is described and illustrated. The new species most closely resembles R. wumingense, particularly in scale density on the abaxial leaf surface and in flower color and shape, but can be readily distinguished by its hairless shoots and leaves, larger tubular-funneled corolla, and longer and thinner white tube flushed with pink. According to the IUCN Red List Categories and Criteria, the threatened status of the new species is assessed as “Endangered, EN C2a(i), D.” We provide detailed documentation of its morphological characteristics, geographical distribution, digitized holotype voucher, and comparative photographs, along with a diagnostic table. An identification key is provided as a primary tool to enable taxonomic discrimination of this species from its congeners.
Key words: Conservation, morphology, Rhododendron mulunense, Rhododendron wumingense, taxonomy
 |
| Rhododendron mulunense. A. The habitat of this new species in type localities; B. Flowering plants; C. Leaves; D–F. Flowering branchlets, inflorescences, and flowers; G, H. Dissection of corolla; I. Flower buds; J. Stamens and style; K. Styles and ovaries; L. Dissection of ovary; M. Stigmas; N. Poorly developed stamens; O. Normal stamens; P, Q. Anther abaxial and adaxial surface; R. Tube base; S. Flower bud scales; T. Dehiscent capsule. Photographs by Yu-Song Huang. |
Rhododendron mulunense Y.S.Huang & X.X.Mao, sp. nov.
Diagnosis. Resembles Rhododendron wumingense Fang but distinguishable by the absence of indumentum on young shoots, leaf margins, and petioles (vs. sparsely setose), longer and larger leaves (4.2–7.4 × 2.3–3.8 vs. 3.5–4.5 × 1.8–2.4 cm), relatively sparser scales on abaxial leaf surfaces (1–4 vs. 1–3 × their own diameter apart), corollas that are tubular funneled (vs. broadly funneled), longer and wider (5.9–7.5 × 4.7–7 vs. 3.1–4.5 × 3.3–4.9 cm) with slender tubes (2.9–3.9 × 0.5–1.2 vs. 1.9–2.5 × 1.7–2.4 cm), outer surface of corolla tubes white flushed with pink (vs. yellowish green) and pubescent but not scaly (vs. sparsely scaly and hairless) (Figs 1, 2, 4; Table 1).
Etymology. The specific epithet of this newly described species refers to its type localities at Guangxi Mulun National Nature Reserve, part of the South China Karst landscape registered in UNESCO’s World Heritage List.
Vernacular name. Simplified Chinese: 木论杜鹃;
Chinese pinyin: mù lùn dù juān.
Ying Hou, Yu-Song Huang, Liu-Juan Luo, Zheng-Ren Chen, Xing-Xing Mao. 2026. Rhododendron mulunense (Ericaceae), A New Species from the Karst Mountains of Guangxi and Guizhou Provinces, China. PhytoKeys. 269: 99-112. DOI: doi.org/10.3897/phytokeys.269.175011 [08-01-2026]
