Habenaria agasthyamalaiana (Orchidaceae), a new terrestrial orchid from the Southern Western Ghats, India

Abstract

Habenaria agasthyamalaiana, a new species of terrestrial orchid is described from Shendurney Wildlife Sanctuary of Agasthyamalai biosphere reserve, a part of the South-western Ghats. This species is morphologically similar to Habenaria crinifera. Detailed description and photographs are provided for identification of this new taxon. Key wordS: Agasthyamalai, Kerala, Kollam, New species, Shendurney wildlife sanctuary, Western Ghats doi: http://dx.doi.org/10.15517/lank.v19i2.38612 Received 27 June 2019; accepted for publication 19 July 2019. First published online: 14 August 2019. Licensed under a Creative Commons Attribution-NonCommercial-No Derivs 3.0 Costa Rica License. Introduction. The mountain chain of the Western Ghats biogeographic zone older than the Himalaya has geomorphic features of immense importance with unique geology, flora and fauna and ecology. The Western Ghats forest ecosystem moderates the tropical climate of the region and has an exceptionally high level of biological diversity and endemism. It is recognized as one of the world’s eight ‘hottest hotspots’ of biological diversity along with Sri Lanka. The Western Ghats is an “Evolutionary Ecotone” and the region demonstrates speciation related to the breakup of the ancient landmass of Gondwanaland and is hence considered as a cradle for biological evolution. More than 7,000 of the plant species have been recorded from the Western Ghats with the number of endemics estimated to be 2,253 (Nayar et al. 2014). The historical human presence in the Western Ghats makes it an area of high conservation interest (Joshi et al. 2017). The region harbors two Biosphere Reserves, 15 National Parks, 52 Wild Life Sanctuaries, nine Tiger Reserves and 39 UNESCO World heritage sites. During the recent orchid exploration in the Shendurney Wildlife Sanctuary, Kerala, a part of the Agasthyamalai biosphere reserve in the southern Western Ghats, the first author located an interesting Habenaria population. This entity was morphologically similar to Habenaria crinifera Lindl., however we studied it because of significant morphological differences. Habenaria Willdenow (1805: 5) (Orchidinae, Orchidoideae, Orchidaceae) is a large genus of approximately 883 terrestrial species (Govaerts et al. 2018) distributed throughout the tropical and subtropical regions of the Old and New World (Pridgeon et al. 2001), with centers of diversity in Brazil, southern and central Africa and East Asia (Kurzweil & Weber 1992). Most species are perennial, geophytes, with a growth associated with a wet season followed by a dormant period in the form of an underground root tuber during the dry season (Batista et al. 2013). There are 69 species reported in India and 39 of them are found in the Western Ghats, with 22 being endemic (Nayar et al. 2014, Kumar et al. 2016). Kerala is also one of the biodiversity rich state harboring 258 orchid species of which 29 species of Habenaria (Nayar et al. 2014). Specimens of this entity were collected and measurements were made using fresh material. The flowers were dissected and examined under the Stereozoom microscope SZ61 and description was written. The entity is characteristic by conspicuous flowers, a tripartite lip with a bifurcate midlobe which is shorter than lateral lobes. The specimen was compared with the allied species Habenaria crinifera and Habenaria plantaginea Lindl. (Table 1). Based on the examination of a fresh specimen and comparison with the known species of the genus, we conclude that our taxon represents new undescribed species which is described here.