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| Vincetoxicum phucanhense T.T.H. Nguyen & T.H. Bui, in Nguyen, Le, D.B. Tran, T.B. Tran et Bui, 2026 |
Abstract
Vincetoxicum phucanhense (Apocynaceae, Asclepiadoideae), a new species from Vietnam, is described, illustrated, and compared with three morphologically similar species: Vincetoxicum flexuosum (R.Br.) Kuntze, V. harmandii (Costantin) Meve & Liede, and V. tengii (Tsiang) Meve & Liede. V. phucanhense differs from V. flexuosum in having shorter pedicels, very sparsely hairy sepal margins (vs. glabrous), a larger corolla, broadly elliptic pollinia (vs. globose), longer fruits, and longer seeds. It also differs from V. harmandii in having shorter petioles, smaller leaf blades, glabrous adaxial leaf surfaces (vs. hairy), and a larger corolla. In comparison with V. tengii, V. phucanhense can be distinguished by its larger corolla, corolla coloration (yellow, pink, or red vs. greenish), and broadly elliptic pollinia (vs. globose). A key to the 14 species of Vincetoxicum recorded in Vietnam is provided.
Key words: Asclepiadeae, Phu Canh, Phu Tho, Tylophora, Tylophorinae
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| Vincetoxicum phucanhense. A. Habitat; B, C. Flowering branches; D. Magnified portion of branch showing one row of pubescence; E. Adaxial leaf surface; F. Abaxial leaf surface; G. Inflorescence. Photos by D.B. Tran. |
Vincetoxicum phucanhense T.T.H. Nguyen & T.H. Bui, sp. nov.
Diagnosis. Vincetoxicum phucanhense differs from V. flexuosum by its shorter pedicels (4.0–7.6 mm vs. 14.0–16.0 mm), sparsely hairy sepal margins, larger corolla (7.2–9.6 mm diam, vs. 4.0–6.0 mm), broadly elliptic pollinia, longer fruits (109–123 mm vs. 40–80 mm), and longer seeds (9.2–9.5 mm vs. 6.0–8.0 mm). It is distinguished from V. harmandii by having shorter petioles (3–8 mm vs. 10–20 mm), smaller leaves (9–42 × 4–18 mm vs. 45–75 × 25–45 mm), glabrous adaxial leaf surfaces, and larger corolla (7.2–9.6 mm diam. vs. 4–5 mm). From V. tengii, it differs by its larger corolla (7.2–9.6 mm diam. vs. 5–7 mm) and differently colored corolla, as well as the broadly elliptic rather than globose pollinia.
Thi Thanh Huong Nguyen, Ngoc Han Le, Duc Binh Tran, The Bach Tran and Thu Ha Bui. 2026. Vincetoxicum phucanhense (Apocynaceae, Asclepiadoideae), A New Species from Vietnam. PhytoKeys. 279: 27-34. DOI: doi.org/10.3897/phytokeys.279.203612 [04 Sep 2026]
