Wednesday, December 14, 2016

[Botany • 2016] Nervilia mekongensis | ว่านแผ่นดินเย็นแม่โขง • Studies in Asian Nervilia (Nervilieae, Epidendroideae, Orchidaceae) VI: A New Species from Thailand, Cambodia, Laos and Vietnam


Nervilia mekongensis S.W.Gale, Schuit. & Suddee, sp. nov. 

B. Flowering plant in habitat. D and E. Close-up of flower.

Photo C taken by T. Sando at the type locality in eastern Thailand, photo B taken by N. Karnsunthad in Mae Ping National Park, Lamphun Province, northern Thailand, and photo E taken by K. Souvannakhoummane in Luang Prabang Province, northern Laos.

Nervilia mekongensis S.W.Gale, Schuit. & Suddeesp. nov. 
 A. Inflorescence emerging above ground. B and C. Flowering plant in habitat. D and E. Close-up of flower. F. Seed capsules. G. Plants in leaf emerging above ground. H. Large colony of plants in leaf.


Photos A, C, D and F–H taken by T. Sando at the type locality in eastern Thailand, photo B taken by N. Karnsunthad in Mae Ping National Park, Lamphun Province, northern Thailand, and photo E taken by K. Souvannakhoummane in Luang Prabang Province, northern Laos.


Abstract

A new species of the terrestrial orchid genus Nervilia is described and illustrated from material collected at several localities in the Greater Mekong region of Southeast Asia. The multi-flowered inflorescence bearing relatively large flowers with a pubescent lip, and the many-veined, cordate-reniform leaf blade that is held well above ground level, place Nervilia mekongensis in section Nervilia. Despite being superficially similar to N. aragoana, a widespread species of tropical Asia and Australasia, it is most closely affiliated to N. fordii, a species known from southern China and Thailand. It is distinguished by its stout inflorescence and lip that is broadest midway along the hypochile and which has acute, forward-projecting side-lobes and a short, ovate mid-lobe. A conservation assessment plus taxonomic notes are provided.

Keywords: Nervilieae, Epidendroideae, Orchidaceae, Monocots, Asia




Distribution:— We confirmed herbarium material of Nervilia mekongensis from eastern and northern Thailand, northern Laos, eastern Cambodia, and northern and southern Vietnam. Plants photographed by Naruemol Karnsunthad in Mae Ping National Park in Lamphun Province, northern Thailand, were also verified as belonging to this species (Fig. 1B).

Ecology:— At the type locality in eastern Thailand, Nervilia mekongensis grows in dry deciduous forest dominated by Shorea siamensis. In northern Thailand and Laos, it occurs in dry deciduous forest on limestone, and in Cambodia it is found in open deciduous forest, growing together with the terrestrial orchids Eulophia spectabilis (Dennst.) Suresh and Geodorum siamense Rolfe ex Downie. In Vietnam, it grows in open secondary scrub and grasslands at the edge of disturbed forest on eroded limestone ridges. It is known throughout an elevational range of 250–1,000 m.

Phenology:— Flowering April to June, in leaf from July until November. 


Etymology:— Named for the Mekong River, which flows through all four range countries and supports the enormous biodiversity of the region.

Vernacular name:— Thai: ว่านแผ่นดินเย็นแม่โขง (Wan phaen din yen mekong).


Stephan W. Gale, André Schuiteman, Santi Watthana, Tomoki Sando, Keooudone Souvannakhoummane, Leonid Averyanov and Somran Suddee. 2016. Studies in Asian Nervilia (Nervilieae, Epidendroideae, Orchidaceae) VI: Nervilia mekongensis, A New Species from Thailand, Cambodia, Laos and Vietnam.
 Phytotaxa. 247(4); 267–273. DOI:  10.11646/phytotaxa.247.4.4


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