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| Rhododendron jiucaipingensis Jian Xu & M. T. An, in Hu, Xu, An, Yu et Lu, 2026. |
Abstract
Rhododendron jiucaipingensis Jian Xu & M. T. An, sp. nov. (Ericaceae), a new species of R. subgen. Hymenanthes, subsect. Argyrophylla, from northwestern Guizhou, China, is described and illustrated. It is an evergreen shrub 1.5–3.0 m tall, characterized by green, densely white-tomentose current-year branchlets, leaves crowded at branch apices (5.5–9.5 × 2.5–4.0 cm) with 8–11 pairs of lateral veins, 10 stamens, and cylindric capsules 1.2–2.0 cm long. The new species is morphologically most similar to R. hypoglaucum and R. argyrophyllum, but it is readily distinguished by having densely white-tomentose current-year branchlets, fewer lateral veins (8–11 pairs), a double-layered white indumentum on the abaxial surfaces of young leaves, and 10 stamens. Phylogenetic analysis based on a whole-genome SNP dataset robustly resolves R. jiucaipingensis as a distinct lineage within subsect. Argyrophylla, positioned as sister to the monophyletic clade of five congeneric species with high support (SH-aLRT = 100%, UFBoot = 100%). This molecular evidence, congruent with diagnostic morphological characters, supports the recognition of R. jiucaipingensis as a species new to science.
Key words: Ericaceae, Flora of China, morphology, phylogeny, taxonomy
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| Rhododendron jiucaipingensis Jian Xu & M. T. An, sp. nov. A. Cliff habitat; B. Older branches; C. Current-year branchlet and its dense white tomentum (inset); D. Mature leaf and its short, brown tomentum on the abaxial surface (inset); E. Adaxial surface of young leaf; F. Abaxial surface of young leaf and long white glandular hairs of it (inset); G. Flowering plant; H. Anatomical diagram of the flower and leaf; I. Stamens and their white stiff hairs at the filament base (inset); J. Calyx; K. Ovary; L. Capsule and its colorless stellate hairs (inset); M. Capsule in longitudinal section (Photographs by Jian Xu) |
Diagnosis. Rhododendron jiucaipingensis belongs to subgen. Hymenanthes and is similar in morphology to R. hypoglaucum and R. argyrophyllum, but can be distinguished from R. hypoglaucum by its current-year branchlets and young petioles being densely covered with indumentum (vs. glabrous), and its pedicels being densely white-villous (vs. glabrous). It further differs from R. hypoglaucum in having fewer lateral veins (8–11 pairs vs. 10–14 pairs), an ovary sparsely covered with colorless stellate hairs (vs. glabrous), and typically 7-loculed capsules (vs. 6-loculed). Compared to R. argyrophyllum, the new species is distinguished by its acuminate leaf apex (vs. obtuse), fewer stamens (10 vs. 12–15), and the presence of colorless stellate hairs on the ovary (vs. white short tomentum). Additionally, R. jiucaipingensis is characterized by its restricted cliff habitat at higher elevations (2,400–2,700 m).
Etymology. The specific epithet jiucaipingensis refers to the type locality, Xingfa Township (Jiucaiping), Hezhang County, Bijie City, Guizhou, China.
Vernacular name. The Chinese name is jiǔ cài píng dù juān (韭菜坪杜鹃).
Hong-Fen Hu, Jian Xu, Ming-Tai An, Jiang-Hong Yu, Xing Lu. 2026. Rhododendron jiucaipingensis (Ericaceae), A New Species from Guizhou, China. PhytoKeys 275: 15-26. DOI: doi.org/10.3897/phytokeys.275.183519 [19 May 2026]