Discussion |
In an era of mass extinctions (Dubois, 2003), new species descriptions are indicative of the yet undocumented biological wealth of the Western Ghats. Recent studies in the Western Ghats also have emphasized that amphibians are the best surrogates for conservation priority regions (Das et al. 2006) and Philautus is considered as an indicator of fragmented forests for its patchy distribution (Gururaja et al. 2007).
Type localities of 21 species of Philautus from the Southern India has marked differences in their distribution, both spatio-temporally. Sixteen species from southern (8°–12°N), five from central (12°–16°N) and none from northern Western Ghats (16–21°N) (Figure 4 and Table 3). Chronologically too, eight species between 1850-1900, two species between 1900-1950 and from 2000 onwards 11 species have been described. The spatial distribution trend of species discovery can be attributed to a) biogeography of the region (viz., southern Western Ghats bestowed with more evergreen forests, greater number of rainy days, higher altitudes [and hence more wet and cool habitats], more protective areas (nature reserves/parks/sanctuaries) than central or northern Western Ghats); b) higher per cent endemism (restricted geographical ranges) in amphibians of Western Ghats (Aravind et al. 2007); whereas temporal pattern is attributed to c) recent taxonomic revisions of the genus Philautus (Bossuyt & Dubois, 2001) d) considering Sri Lankan and Western Ghat Philautus as phylogenetically disjunct population (Bossuyt et al. 2004; Manamedra–Arachchi & Pethiyagoda, 2005) leading to more split in earlier combined Philautus group from the subcontinent (Chaitra et al. 2004); e) renewed interest in this genus as indicator species of diversity hotspots/fragmentation/decline, etc., leading to accidental new discoveries (Gururaja et al. 2007) and f) charismatic nature of these tiny frogs compelling researchers to look for them (Aravind et al. 2007). However, this spatio-temporal pattern necessitates further systematic research on the distribution and biogeography of this genus in particular and amphibians in general from the Western Ghats to acquire insights on distribution and diversity patterns.
The issue of great concern is that many of the species will simply vanish even before they are formally detected and identified, as there is a tremendous pressure generated from ever increasing human population and human induced changes in the Western Ghats. This is evident in the present study as Kakkayam Reserve Forest harbors some of the best remaining tropical wet evergreen forest (Nair, 1991), but due to dam construction and other related activities they are getting fragmented and reduced in area. Philautus ochlandrae sp. nov. being very restricted in these forest patches further highlights the need for conservation of this region.
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