Rhododendron mingii Y.P. Ma, L.M. Gao & E.D. Liu, 2023

Liu, Zhenwen, Liu, Ende, He, Deming, Ma, Yongpeng & Gao, Lianming, 2023, Rhododendron mingii (Ericaceae), a new species from Southeast of Yunnan, China, Phytotaxa 619 (1), pp. 97-104 : 98-102

Rhododendron mingii Y.P. Ma, L.M. Gao & E.D. Liu , sp. nov. ( Figure. 1 )

The new species resembles R. genestierianum by flower shape and petal color, but differs from the latter by the much shorter petiole and leaf, densely white powder on outer surface of petal, and slender and erect style ( Table 1 ).

Type:— CHINA. Yunnan: Wenshan Prefecture, Maguan County, Laojun Mountain , ca. 2500 m, 14 May 2019, E.D. Liu, Y. Yang & Y.Y. Li, OYY00214 (holotype: KUN!) .

Shrubs, evergreen, 1–2 m tall; stem and branches glabrous, gray white, bark peeling. Petiole grooved, 2–3 mm long; leaves clustered at stem apex, leathery, oblong-lanceolate, 3–6(8) × 1–2 cm, base cuneate, apex caudate-acuminate, margin slightly revolute and fringed with sparse hairs; abaxial surface pale green, densely white powder, scales sparse, small, circular, about equal in size, brown; adaxial surface green, shiny; midrib grooved adaxially; lateral veins 10–12- paired, usually not obviously reaching the margin. Inflorescence terminal, umbellate, 5–9-flowered. Pedicel 1–1.5 cm, glabrous, white powder; calyx pruinose, rim-like, slightly lobed, 2–3 mm long, persistent; corolla campanulate, fleshy, pruinose, reddish purple, 1.2–1.6 cm long, tube 0.8–1.2 cm long, glabrous; stamens 10, unequal, 0.5–1.5 cm long, shorter than style, filaments glabrous, unequal, 0.4–1.2 cm long, anthers ca. 2 mm long, deep red; ovary scaly; style purple, 1.2–1.5 cm long, glabrous, slender and longer than corolla; stigma small, capitate. Fruit not known.

Distribution and ecology:—To date, Rhododendron mingii has only been found from the type locality of Laojun Mountain, Malipo County, SE Yunnan of China (104°34’E, 22°57’N). It grows in evergreen bushes on the summit of Laojun Mountain at an elevation of ca. 2500 m, co-occurring with R. maguanense Feng (1983: 268) and R. sinofalconeri Balfour (1916: 272) .

Phenology:— Rhododendron mingii flowers from April to May.

Etymology:—The specific epithet is in honor of Prof. Tien-Lu Ming, a taxonomist of the genus Rhododendron .

Notes: —Base on morphological and phylogenetic evidence in the present study, we are still unable to make an accurate subsectional placement for the new species, due to no clear boundaries between subsections Tephropepal and Genestieriana ( Figure 2 ). Morphologically, R. mingii is similar to R. genestierianum , but the most contrasting character distinguishing them is the characteristic of style ( Table 1 ). In general, whether a slender or deflexed style is the key trait to define subsections in section Rhododendron . However, there is exception for the subsection Moupinensia , which is including three species and R. moupinense Franchet (1886: 33) has slender style whereas the remaining two have deflexed styles. The newly discovered R. mingii would further raise the interesting topic regarding the importance of style characteristics in defining subsection or species within section Rhododendron .

Figures

FIGURE 1. Rhododendron mingii A. Flowing branch. B. Close-up view of leaf blade abaxial surface. C. Gynoecium. D. Stamens. E. Opened corolla. F. Habit. (A–E drawn by Y. Luo from the holotype).

FIGURE 2. Maximum Likelihood tree based on the concatenate sequences of the three DNA barcodes (rbcL, matK and ITS) under the General Time Reversible model. Bootstrap values (>50%) are shown along the clades.