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INTRODUCTION

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The Western Ghats, a chain of hills of varied width and height running parallel to the western coast of India, is a hotspot of biological diversity (Myers et al., 2000). This region harbors a high proportion of endemic species, especially in lower-vertebrate group such as amphibians, reptiles and fishes (Daniels, 2001; Dahanukar et al., 2004); this endemism has been attributed to the prevailing geographical, climatic and phenological conditions providing the necessary humid environment and habitat (Roelants et al.,2004). Amphibians form an important faunal group of this region, but are incompletely documented (Bossuyt, 2002); some represent disjunct populations that necessitate the integrated morphological and molecular analyses to resolve their phylogeography (Karanth, 2003).

It is quite evident that the Western Ghats, as a part of the Old World region, represent a Cenozoic refugium for old lineages and a unique reservoir of ancient endemic anurans (Duellman, 1999; Roelants et al., 2004). In recent years, there has been increasing interest worldwide in understanding the biogeography and evolutionary lineages of amphibians of the Western Ghats, especially in relation to their links with Madagascar’s fauna and to patterns of amphibian dispersal in the Indian Ocean region (Vences et al., 2003). With the discovery of a new primitive frog, it was established that India had an ancient biogeographical link with the Seychelles, and that amphibian endemism in the region dates back to 150–195 Mya (Biju and Bossuyt, 2003; Dutta et al.,2004). Several lineages may have originated on the Indian subcontinent during the trans-Tethys drift (Bossuyt and Milinkovitch, 2001).

Approximately 500 species of ranids have been recorded in the Oriental realm. To date about 135 species have been recorded from the Western Ghats (Gururaja,2004), of which over 100 (nearly 75%) are endemic to the region. The order Anura is represented by 109 species, including members of the Rhacophoridae. Species of the genus Philautus in the family Rhacophoridae form a unique group because they undergo direct development, wherein the tadpole stage is avoided (Marmayou et al., 2000). Since the recent revision of the genus Philautus (Bossuyt and Dubois, 2001), several new Philautus species have been described from the Western Ghats (Kuramoto and Joshy, 2003; Bossuyt, 2002; Biju and Bossuyt, 2005a, b), which strongly reinforces that this region is a center of amphibian diversity, where many more new species await description (Aravind et al., 2004; Gower et al., 2004). However, this pristine biogeographic reservoir of evolutionary history in the Western Ghats is now threatened by heavy human demographic pressure and interference (Aggarwal, 2004; Dutta et al., 2004), warranting urgent protective measures and a preemptive conservation strategy. We here describe a new species of Philautus and analyze its phylogenetic relationships.Our results further highlight the significance of the Western Ghats as hotspot of amphibian diversity and the need for prioritization of its conservation.

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