Sunday, March 29, 2020

[Botany • 2020] Dischidia phuphanensis (Apocynaceae: Asclepiadoideae) • A New Species of Dischidia from North-eastern Thailand

Dischidia phuphanensis Chatan & Promprom

in Promprom & Chatan, 2020. 


Dischidia phuphanensis Chatan & Promprom, a new species from north-eastern Thailand, is described and illustrated. The new species is similar to D. tonkinensis Costantin, but is distinguished by the shape of its leaves, the apices of the staminal corona lobes, the colour of the corolla and the absence of a corolline corona. The distinguishing characters of similar species are discussed. A key for the identification of those species in Thailand without pitcher-like leaves is provided.

Keywords: Marsdenieae, plant diversity, taxonomy

Figure 2. Dischidia phuphanensis Chatan & Promprom
A Branch with leaves and inflorescences B bud C flower D dissected flower with half of corolla removed E calyx from abaxial side F gynostegium (side view), with coronal lobes removed G gynostegium (from above) H pollinarium I pistil J pistil (style-head removed) K follicle L seed 
A–J drawn by Wannachai Chatan from W. Chatan 2489, and K, L from W. Chatan 2904.

Figure 1. Dischidia phuphanensis Chatan & Promprom
A Plant climbing on rock B plant climbing on branches of shrub 2–3 m tall C branches and leaves D inflorescence E follicle (nearly mature) F dehiscent follicle. 
Photographed by Wannachai Chatan from W. Chatan 2489 (A–D) and W. Chatan 2904 (E, F). 

Dischidia phuphanensis Chatan & Promprom, sp. nov.

Diagnosis: Dischidia phuphanensis is most similar to D. tonkinensis, but the new species differs from the latter in its elliptic or narrowly elliptic or slightly oblanceolate leaves (leaves in D. tonkinensis are ovate to ovate elliptic, rarely obovate), apex of corona lobes obtuse (with tips pointing downward in D. tonkinensis), yellow base of the corolla tube and light yellow or white apices of the lobes (white or orange-yellow corolla tube and lobes in D. tonkinensis) and the absence of a corolline corona (corolline corona present in D. tonkinensis). (Figures 1, 2)

Distribution: The new species is endemic to Thailand and is known only from the type locality, Phu Pha Yol National Park, Sakon Nakhon Province, north-eastern Thailand (Figure 3).

Ecology: This new species grows in both slightly open and in shaded areas in mixed deciduous forest at an elevation of 300–400 m.

Etymology: The specific epithet of Dischidia phuphanensis refers to its type locality, the Phuphan mountain range.

Vernacular name: Thao Rag Noi - เถารักน้อย

 Wilawan Promprom and Wannachai Chatan. 2020. A New Species of Dischidia (Apocynaceae, Asclepiadoideae) from North-eastern Thailand.  PhytoKeys. 144: 23-30. DOI: 10.3897/phytokeys.144.47977