A NEW SPECIES OF Dendrelaphis ( SERPENTES : COLUBRIDAE ) FROM THE WESTERN GHATS-INDIA Sectional

A new species of the colubrid genus Dendrelaphis Boulenger 1890 is described from the Western Ghats, India. Dendrelaphis girii sp. nov. resembles Dendrelaphis bifrenalis (Boulenger, 1890) which inhabits Sri Lanka. It differs from the latter predominantly in the absence of a ventrolateral stripe, the much narrower and shorter postocular stripe and the broader snout. The description of D. girii sp. nov. underscores the notion that Sri Lanka and the Western Ghats are faunally more distinct than previously thought.


Introduction
The colubrid snakes of the genus Dendrelaphis Boulenger, 1890 are widely distributed, ranging from Pakistan in the West to the northern and eastern coast of Australia in the East and South and to southern China in the North (Ziegler & Vogel, 1999).Members of the genus Dendrelaphis are slender, diurnal species that are predominantly arboreal and feed mainly on lizards and amphibians.In 1858, Günther recorded a specimen of the genus Dendrelaphis with two loreal shields.It originated from Sri Lanka.He regarded it as a variety of Dendrophis picta (var.C.) (Gmelin, 1789) but pointed out that, in addition to the double loreal shield, the muzzle is elongate in comparison to Dendrelaphis pictus.Boulenger later described the form represented by Günther's specimen as Dendrophis bifrenalis (1890) on the basis of three syntypes.Four years later he elaborated on his initial description on the basis of the same three specimens (Boulenger, 1894).At some point, this species has again been regarded as a subspecies of Dendrelaphis pictus (Meise & Henning, 1932;Mertens, 1934).Ferguson (1895) was the first to record Dendrophis bifrenalis from India and stated that it is not TAPROBANICA VOL.03: NO. 02 uncommon in Trevandrum (today Thiruvananthapuram, Kerala).Subsequently, Wall (1921) confirmed the occurrence of this species in India, namely in Trevandrum and in Travancore (today a part of Kerala).Subsequent works (Smith, 1943;Mahendra, 1984;Sharma, 2007) have not presented new locality records.However, Whitaker & Captain (2004) doubted the occurrence of this species in India, assuming it to be a Sri Lankan endemic.Thus, despite the fact that Ferguson considered this species to be common, it has been recorded only sparsely.Indeed, no Indian specimen could be located by the authors during investigations in the majority of collections in Europe and several collections in the United States.
Recent species descriptions and revalidations suggest that levels of endemism harboured by Sri Lanka as well as the Western Ghats may be substantially higher than currently known (e.g.Mukherjee & Bhupathy, 2007;Van Rooijen & Vogel, 2008;2009;Vogel & Van Rooijen, 2011a).This notion, as well as some observed differences in coloration between the Sri Lankan and Indian sister populations of Dendrelaphis bifrenalis, incited this study into the population systematics of this species.

Materials and Methods
Nineteen museum specimens were examined.This sample represented 13 specimens from Sri Lanka and 6 specimens from the Indian subcontinent.For each examined specimen, 21 characters including aspects of colour pattern, body proportions and scalation were recorded (Table 1).Eye-diameter and distance eye-nostril were measured with a slide calliper to the nearest 0.1 mm.These measurements were made on the left and right side and were subsequently averaged.Snout-vent length and taillength were measured by marking the length on a piece of string and subsequently measuring the position of the mark to the nearest 0.5 cm.Snoutvent length was measured to the posterior margin of the anal plate.The number of ventrals was counted following Dowling (1951).Subcaudals were counted on one side, the terminal scute was excluded.The first sublabial was defined as the scale that starts between the posterior chin shield and the infralabials and that borders the infralabials (see Peters, 1964, fig. 7;Lillywhite, 2008).The last infralabial was defined as the infralabial still covered completely by the last supralabial.The posterior most temporal scales were defined as the scales of which more than half of the area lies in front of an imaginary line that runs from the apex of the last supralabial to the posterolateral corner of the parietal.
Characters were analyzed univariately using either χ 2 (stripe2) or ANCOVA (all others).Characters exhibiting significant or near-significant differences (P<0.1) between the populations were included in a Principal Components Analysis (PCA, e.g.Cramer, 2003).For PCA, morphometric variables were adjusted to a common SVL of 50.5 cm to correct for potential ontogenetic variation between the samples of the species (e.g.Thorpe, 1975Thorpe, , 1983;;How et al., 1996;Turan, 1999).The following allometric equation was applied: X adj = X -β(SVL -SVL mean ) where X adj is the adjusted value of the morphometric variable; X is the original value; SVL is the snout-vent length; SVL mean is the overall mean snout-vent length; β is the coefficient of the linear regression of X against SVL.All statistical analyses were carried out with the software SPSS (2006; SPSS for Windows.Release 14.0.2.Chicago: SPSS Inc.).

Statistical analyses:
Figure 1 shows the results of a PCA based on the characters VENT, SUBC, TAIL, INFR, TEMP, ATEMP, WSNT, STRIPE1, STRIPE2 and NECK.A clear separation of the two sister populations is in evidence.
Table 2 gives descriptive statistics as well as significance-levels of the differences.The most important differences are the lower number of gular scales, the broader snout, the narrower postocular stripe and the rudimentary ventrolateral stripe in D. girii sp.nov.
Taxonomic evaluation: Evidently, the two sister populations differ in several aspects of their morphology and coloration.In addition, the two populations are reproductively isolated due to an extrinsic geographic barrier (the Indian Ocean).Therefore, the two populations are considered to represent separately evolving lineages, and therefore species, in accordance with the general lineage species concept (De Queiroz, 1998, 2007) TAPROBANICA VOL.03: NO. 02   Diagnosis: A species of Dendrelaphis characterized by the combination of: 1) two loreal scales on each side of the head; 2) 15 dorsal scale rows at midbody; 3) enlarged vertebral scales; 4) 166-173 ventrals; 5) 140-147 subcaudals; 6) 8-9 supralabials, 2 supralabials border the eye; 7) 6-8 temporal scales; 8) a long sublabial that touches 2-5 infralabials; 9) 1-3 gular rows; 10) a divided anal shield; 11) relative tail-length 0.36-0.37;12) a black postocular stripe that covers less than a quarter of the temporal region and that barely extends onto the neck; 13) an absent or rudimentarily present pale ventrolateral line.

Etymology:
We want to dedicate this species to Varad Giri, the curator of the herpetological collection of the Bombay Natural History Society.He contributed enormously to the knowledge of the Indian reptiles by his own research and by making the BNHS collection easily available for all kind of researchers.
Description of the holotype (Fig. 2 & 3): Adult male; dissected; body very slender; snout-vent length 65.3 cm; tail-length 37.3 cm; relative tail length 0.36; head distinct from neck; head-length 23.1 mm; snout width 5.5 mm; pupil round; eyediameter 4.45 mm (left/right averaged); distance eye-nostril 4.85 mm (left/right averaged); 169 ventrals; 147 subcaudals; dorsal scales in 15-15-11 rows; 9 supralabials, 5th and 6th border the eye; 9/10 infralabials, infralabials 1-5 touch the first chinshield, infralabials 5 and 6 touch the second chinshield; 1 preocular; 2 postoculars; 2 loreals, anterior one larger than posterior one and more elongate; temporal formula 2:1:2:2 (L), 2:2:1:2 (R); first sublabial touches infralabials 6 through 9; vertebrals moderately enlarged, with straight posterior margin, width of the vertebral scale at the position of the middle ventral scale 2.8 mm; anal divided; parietal scales bordered posteriorly by 4 scales (not being temporal scales).Ground colour of body and tail bluish-grey mixed with brown (depending on the upper layer of the skin, which is partly damaged), the upper head brown (preservation artefact); supralabials whitish; 7th -9th supralabials with dark dorsal margins, the preocular dark on its ventral part; a black postocular stripe starts behind the eye, covers only a small part of the temporal region, and extends to the upper jaw with a few spots behind the ankle of the jaw; no ventrolateral line present, belly and underside of the tail uniform whitish.3. Other important characters agree with features of the holotype.Range: Dendrelaphis girii sp.nov.inhabits the Western Ghats, South India.It was found in the states of Karnataka, Tamil Nadu and Maharashtra.
There are several differences between Dendrelaphis girii sp.nov and D. bifrenalis.The most obvious one is the light ventrolateral line, which is present in D. bifrenalis and missing or very faint in Dendrelaphis girii sp.nov.(see Fig. 3, 4).The postocular stripe is much broader in D. bifrenalis.In D. bifrenalis there are black oblique bars in the neck region of some, but not all specimens (8 specimens out of 12 in our data) (see Fig. 3-5).This pattern is not sex related.It is absent in D. girii sp.nov.For Dendrelaphis girii sp.nov.we had only 1 male, so it is not possible to compare the sexual dimorphism in this character.The snout of Dendrelaphis girii sp.nov. is much broader than that of D. bifrenalis.Dendrelaphis girii sp.nov.has, on average, fewer subcaudals and more ventrals than D. bifrenalis, but the ranges broadly overlap.

Discussion
Dendrelaphis girii sp.nov. is undoubtedly a sister species of D. bifrenalis.Both species exhibit a double loreal shield, a unique character within the genus, and are phenetically very similar in other aspects of morphology as well.Possibly, the common ancestor of both species dispersed across the land bridge between India and Sri Lanka that came into existence due to Pleistocene lowering of sea levels (e.g.Voris, 2000;Pethiyagoda, 2005).Subsequent isolation would have provided the opportunity for independent evolution of the sister populations.
The Western Ghats and Sri Lanka together have been designated as one of the biodiversity hotspots of the world (Mittermeier et al., 2005) and are known to host a high level of endemism among reptiles (e.g.Das, 1996;Ishwar et al., 2001;Mittermeier et al., 2005;Gunawardene et al., 2007).Recent species descriptions suggest that biodiversity as well as the level of endemism harboured by this area may be substantially higher than currently known (e.g.Pethiyagoda, 2005;Wickramasinghe et al., 2007;Mukherjee & Bhupathy, 2007).This notion is underscored by recent insights into the taxonomy of the genus Dendrelaphis: one Sri Lankan endemic, D. schokari Kuhl, 1820 was resurrected from synonymy (Van Rooijen & Vogel, 2008), one South Indian species, D. chairecacos Boie, 1827, was resurrected from synonymy (Van Rooijen & Vogel, 2009), and two new species, D. ashoki Vogel & Van Rooijen, 2011a and D. girii sp. nov. (this report) have now been described from the Western Ghats.Furthermore, these results add to the notion that the faunas of Sri Lanka and the Western Ghats are more distinct than previously recognized (e.g.Bossuyt et al., 2004).

Table 1 :
List of morphometric, meristic and coloration characters used in this study and their abbreviations

Table 2 :
Morphological and coloration characters of Dendrelaphis girii spec.nov and D. bifrenalis.Values of snoutwidth are SVL-adjusted.Coll. the same as holotype.

Table 3 :
Morphological and coloration characters of the types of Dendrelaphis girii sp.nov.