Wednesday, November 15, 2017

[Botany • 2017] Spiranthes himalayensis • A New Species (Orchidaceae, Orchidoideae) from Asia


Spiranthes himalayensis Survesw., Kumar & Mei Sun

 Surveswaran, Kumar & Sun, 2017 

Abstract
Spiranthes himalayensis is described here as a new species based primarily on molecular phylogenetic evidence followed by morphological comparison with other Asian Spiranthes species. It is distributed widely from southern India to tropical China. Phylogenetic analysis shows its close affinity to S. nivea which is endemic to Taiwan. Morphologically, the new species looks close to S. sinensis and S. hongkongensis. S. himalayensis is an allogamous species which can be differentiated from its allies on the basis of pubescent plant body, floral bract longer or of the same length as that of ovary, petals with blunt apex, labellum width around hypochile same as the width of epichile, epichile widely flabellate or semi-tunicate, column length equal to or more than 1.5 mm, clavate operculum attached to the column on the broader part by an arm-like extension emerging from the upper part of column and a well developed rostellum partitioning the stigma and pollinarium.

Keywords: Karnataka, Manipur, Orchid, Spiranthes hongkongensis, Spiranthes nivea, Spiranthes sinensis, Tamil Nadu, Yunnan, India, China




Spiranthes himalayensis Survesw., Kumar & Mei Sun, sp. nov.

Diagnosis: Spiranthes himalayensis Survesw., Kumar & Mei Sun sp. nov. is similar to S. hongkongensis, S. nivea and S. sinensis, but can be differentiated on the basis of its allogamous mode of reproduction from S. hongkongensis and S. nivea which are both autogamous. It can also be easily separated from S. nivea by its pubescent body. Other morphological distinctions separating this new species from S. hongkongensis, S. nivea and allogamous S. sinensis include: floral bract longer or of the same length as the ovary, petals with blunt apex, labellum width around hypochile is same as the width of epichile, epichile widely flabellate or semi-tunicate, column length equal to or more than 1.5 mm, clavate operculum attached to the column on the broader part by an arm-like extension emerging from the upper part of column and a well-developed rostellum separating the stigma from the pollinarium.

Habitat: Marshy areas near mountain streams or on bunds of paddy fields (Fig. 2A) where water is stagnant. Plants were usually found growing on clayey soil along with grasses.

Etymology: The specific name refers to the mighty Himalayan mountain range which is an important geographical feature in Asia. The samples collected for this study were not from the Himalayas. However, based on herbarium records and communication with other researchers, it is believed that this species is widespread in the lower altitudes of Himalayas. The evolutionary origin of this species and other Asian Spiranthes are to be further elucidated.

Currently known locations of distribution: India (Karnataka, Manipur & Tamil Nadu) & China (Yunnan and most likely Hainan (see taxonomic notes for details)).

Figure 2. Habitat and habit of Spiranthes himalayensis Survesw., Kumar & Mei Sun, sp. nov.
A
Habitat (type location) - along the bunds of paddy fields B Habit of S. himalayensis C Close-up of the inflorescence showing white coloured flowers with densely covered glandular hairs.

Figure 3. Spiranthes himalayensis Survesw., Kumar & Mei Sun, sp. nov.
A
Complete plant B Inflorescence C Floral bract D Dorsal sepal E Lateral sepal F Petal G Ovary with column and labellum H Close-up showing the glandular hairs on flower and ovary I Side view of labellum J Top view of labellum K Side view of ovary with column L Front view of ovary and column M Front view of pollinarium N Side view of pollinarium.
Note: The pinkish/bluish hue on petals of S. himalayensis is due to the black background in the plates while the flowers appear fully white in natural light. 

Figure 4. Comparison of morphological characters of allied species.
A Spiranthes himalayensis: 1 Close-up of inflorescence 2 A flower 3 Floral bract 4 Dorsal sepal 5 Lateral sepal 6 Petal 7 Ovary with column and labellum 8 Labellum (side view) 9 Labellum (top view) 10 Close-up showing glandular hairs on labellum and ovary 11 Ovary with column (side view) 12 Ovary with column (ventral view)
B S. sinensis: 1 Close-up of inflorescence 2 A flower 3 Floral bract 4 Dorsal sepal 5 Lateral sepal 6 Petal 7 Ovary with column and labellum 8 Labellum (side view) 9 Labellum (top view) 10 Ovary with column (side view) 11 Ovary with column (ventral view)
 C S. hongkongensis: 1 Close-up of inflorescence 2 A flower 3 Floral bract 4 Dorsal sepal 5 Lateral sepal 6 Petal 7 Ovary with column and labellum; 8. Labellum (side view) 9 Labellum (top view) 10 Close-up showing glandular hairs on labellum and ovary 11 Ovary with column (side view) 12 Ovary with column (ventral view)
D S. nivea: 1. Close-up of inflorescence; 2. A flower 3 Floral bract 4 Dorsal sepal 5 Lateral sepal 6 Petal 7 Ovary with column and labellum 8 Labellum (side view) 9 Labellum (top view) 10 Close-up showing glandular hairs on labellum and ovary 11 Ovary with column (side view) 12 Ovary with column (ventral view).
Note: The pinkish/bluish hue on petals of S. himalayensis, S. nivea and S. hongkongensis is due to the black background in the plates while the flowers appear fully white in natural light.


 Siddharthan Surveswaran, Pankaj Kumar, Mei Sun. 2017. Spiranthes himalayensis (Orchidaceae, Orchidoideae) A New Species from Asia. PhytoKeys. 89; 115-128.  DOI: 10.3897/phytokeys.89.19978


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