Thursday, January 11, 2018

[Botany • 2018] Dregea taynguyenensis • A New Species (Apocynaceae, Asclepiadoideae) from Vietnam


Dregea taynguyenensis T.B. Tran & Rodda

in Tran, Van, Thu, Choi, Eum & Rodda, 2018

Abstract

The new species Dregea taynguyenensis from Vietnam is described, illustrated and compared with the other Dregea species occurring in Vietnam and neighbouring countries D. cuneifolia, D. sinensis, D. volubilis and D. yunnanensis. Dregea taynguyenensis differs from these species by the leaf blade secondary veins number, calyx lobes shape, and corolla lobes size.

Keywords: Asclepiadaceae, Marsdenieae, Southeast Asia, Wattakaka, Eudicots



Dregea taynguyenensis T.B. Tran & Rodda, spec. nov. 

Dregea taynguyenensis is most similar to D. cuneifolia due to the elliptic-oblong leaf blades, cuneate at base and acuminate at apex. The former is distinguished from the latter by having 7–10 secondary veins each side of midrib (vs. 5–6 in D. cuneifolia), calyx lobes lanceolate to linear (vs. ovate) and corolla lobes 10.2–12.6 × 5.3–6.4 mm (vs. c. 4 × 4 mm).

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Etymology:— The specific epithet refers to the type locality, Tay Nguyen area in Vietnam.. 

Distribution and ecology:— Dregea taynguyenensis is only found in Vietnam, Gia Lai province, Tay Nguyen area where it grows in sunny places in secondary forest, in association with Bidens pilosa Linnaeus (1753: 832), Jasminum lanceolarium Roxburg (1820: 97), Maclurodendron oligophlebium (Merrill 1923: 246) T.G. Hartley (1982: 13), Mallotus paniculatus (Lamarck in Lamarck & Poiret 1786: 207) Müller Argoviensis (1865: 34), Melicope pteleifolia (Champion ex Bentham in Bentham 1851: 330) T.G. Hartley (1993: 521). 

FIGURE 1. Dregea taynguyenensis. Flowering branch in the habitat of the type locality. Photograph by T.B. Tran (9 June 2011).
FIGURE 2. Dregea taynguyenensis. A, Leaf blade, abaxial side (left), adaxial side (right); B, Inflorescence with flower buds; C, Flowering branch; D, Inflorescence with greenish flowers; E, Inflorescence with flowers yellowish flushed purple. Based on T.B. Tran et al. Bach 0906201101 (HN), photographs by T.B. Tran (9 June 2011). 

The Bach Tran, Hai Do Van, Ha Bui Thu, Sangho Choi, Sangmi Eum and Michele Rodda. 2018. Dregea taynguyenensis (Apocynaceae, Asclepiadoideae), A New Species from Vietnam. Phytotaxa. 333(2); 267–273. DOI: 10.11646/phytotaxa.333.2.11


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