[Botany • 2026] Mitreola luongii (Loganiaceae) • A New Species from Limestone Hill in northern Vietnam

Abstract

A new species of Mitreola (Loganiaceae), M. luongii, is described from limestone area in Tuyen Quang Province, northern Vietnam. Morphologically, it is most similar to M. crystallina, but can be distinguished by its shrub habit, up to 1 m tall (vs. herb, up to 60 cm tall), having terminal and axillary inflorescences (vs. terminal), shorter internode 1.5–5.5 cm long (vs. 6–8 cm long), shorter peduncles 0.5–1.5 cm long (vs. ca. 6 cm long), smaller leaf size 5.5–10.5 × 2–4.5 cm (vs. 15–20 × 5–7 cm) and longer corolla tube 4–4.5 mm long (vs. 4 mm long).

Eudicots, Du Gia National Park, Flora, Gentianales, hornpods, Indochina, taxonomy

Mitreola luongii.  A. Habit, B–C. Flowering branches, D. Abaxial leaf surface, E. Terminal and axillary inflorescences, F. Corolla, front view, G. Corolla, lateral view, H. Partly dissected flower, showing stamens, style and stigma. I. Opened corolla, showing inner hairs and stamens, J. Pistil. Photos: A by Quoc Trong Pham, B & E by Phetlasy Souladeth, C, D, F–J by Shuichiro Tagane.

Mitreola luongii Moriwak., Tagane & V.S.Dang, sp. nov.  

Diagnosis:—Mitreola luongii is most similar to M. crystallina of China in having light-purple corollas, but can be readily distinguished by its shrub habit, up to 1 m tall (vs. herb, up to 60 cm tall), terminal and axillary inflorescences (vs. terminal), shorter internode 1.5–5.5 cm long (vs. 6–8 cm long), shorter peduncles 0.5–1.5 cm long (vs. ca. 6 cm long), smaller leaf size 5.5–10.5 × 2–4.5 cm (vs. 15–20 × 5–7 cm) and longer corolla tube 4–4.5 mm long (vs. 4 mm long). (Table 1). 

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Etymology:—The species epithet honors Mr. Vuong Dinh Luong, director of Du Gia National Park, who has made significant contributions to biodiversity conservation in the park. 

Vernacular name:—Tiểu mạo Vương Đình Lương