Dendrelaphis proarchos ( Wall, 1909 )

Parmar, Dikansh S., Thakur, Mehul N., Agarwal, Ishan, Ganesh, S. R. & Vogel, Gernot, 2024, Report of stray sightings of Dendrelaphis proarchos (Wall, 1909) (Serpentes: Colubridae) in Surat, Gujarat, western India, Zootaxa 5433 (2), pp. 231-248 : 234-240

Dendrelaphis proarchos ( Wall, 1909)

( Figs. 1–4 ; Tables 1–3 )

Material examined (n=1 preserved, 6 uncollected). BNHS 3553, adult male, collected on 29 th July 2016 from Navjivan Hyundai , Surat, Gujarat (21.1711°N 72.8308 °E) by Pratik D. Shinde, Mehul N. Thakur and Dikansh S. Parmar. The uncollected specimens (n=6): individual 1, adult male, collected on 18 th May 2015 from Udhna BRC (21.1564°N 72.8442°E); individual 2, adult male, collected on 10 th October 2017 from Abhva (21.1210°N 72.7659°E); individual 3, adult male, collected on 17 th February 2020 from Chandni chowk Piplod (21.1659°N 72.7748°E); individual 4, adult male, collected on 27 th February 2020 from Agam shopping center Vesu (21.1358°N 72.7713°E); individual 5, adult male, collected on 15 th March 2020 from Navsari bazaar Water works (21.1882°N 72.8225°E); individual 6, adult female, collected on 4 th April 2020 from Jash residency Vesu (21.1467°N 72.7697°E), all rescued from Surat by Pratik D. Shinde, Mehul N. Thakur, and Dikansh S. Parmar .

Diagnosis of Surat specimens. The Surat specimens exhibit the following characters ( Table 2 ): (1) vertebral scales distinctly enlarged, larger than the dorsals of the first row; (2) 185–194 ventrals; (3) 139–142 divided subcaudals in complete tails; (4) 15 dorsal scale rows at midbody; (5) cloacal shield undivided in all individuals (i.e., 100% undivided cloacal shield); (6) one loreal scale; (7) three supralabials touching the eye; (8) a moderate first sublabial that touches two infralabials; (9) 11–12 temporal scales; (10) preoculars 1 or 2; (11) 2 or 3 postoculars; (12) maximum total length 1150 mm; (13) a black temporal stripe that does not starts on the postnasal or loreal, but starts on the center of the eye follows postoculars (middle or second postocular) covers the majority of the temporal region and extends onto the neck; (14) vertebral stripe absent, (15) a distinct, bright ventrolateral stripe bordered by one black line at the bottom; (16) dorsal instertitial color blue; (17) tongue color red with black tip.

Description of BNHS 3553. A summary of the morphometrics, scalations, and coloration characters of the individuals from Surat is given in Table 2 . TBL 1065 mm; SVL 735 mm; tail 330 mm; 189 ventrals (2 preventrals); 120 divided subcaudals in incomplete tail; cloacal shield undivided; one loreal scale; 10/11 (L/R) infralabials; first infralabials touch at the mental groove; 3 sublabials, first sublabial (medium sized) touches only 6 and 7 (L and R) infralabials, 9 supralabials, supralabials 4,5,6 (L), 4,5,6 (R) touch the eye (fourth with posterior corner); preoculars 2 (L), 1 (R) two preoculars on left side second preocular below the first one is very small and one preocular on right side, three postoculars, postoculars are almost equal in length except the top most postocular which is slightly larger than other two postoculars; temporal formula: 2+2+2 (L), 2+2+2 (R) (shape and size of upper temporals varies, first temporal is smallest second is longest and third is thickest but infra temporals are almost uniform in shape and size); dorsal formula: 15:15:9; vertebral scales enlarged, larger than the scales of the first dorsal row; both width and length of the dorsal scale at the position of the middle ventral 4.3 mm; eye–diameter 5.6 (L), 5.6 (R) mm; distance anterior border of eye to posterior border of nostril 4 mm distance from center of the eye to posterior border of nostril is 6.1 mm, distance between eye to snout 6.5 mm, rostral length 2.5 mm, rostral width 4 mm snout width measured between the nostrils 3.6 mm; head length 22.8 mm; head length from snout to posterior border of each parietal shield is 18 mm, head width 9 mm, interorbital distance 8 mm, length of parietal shield 7 mm, width of parietal shield 5 mm, length of frontal 7 mm, width of frontal 3 mm, length of prefrontal 3.5 mm, width of prefrontal 4.1mm, length of internasal 3 mm, width of internasal 3.1 mm, second and third supralabials are completely in contact with loreal but only the anterior corner of the fourth supralabial is indistinctly in contact with loreal on the left side and distinctly in contact with loreal on the right side, loreal is in contact with postnasal, preocular and prefrontal, but not in contact with internasal, loreal is separated from internasal by contact of postnasal with prefrontal, first supralabial is in contact with rostral and both nasal scales but second supralabial is in contact only with one nasal scale i.e., postnasal, a black stripe starts from the center of the eye, but on scales it is seen on the second (middle) postocular scale, covers the majority of the temporal region and extends onto the neck where it fades away; a distinct bright ventrolateral line present, bordered by one black line at the bottom which begins after the black stripe that fades at neck; ground color olive-brown, based on color of unshed skin; supralabials yellowish and throat yellowish and white ( Figure 2 ). Inter-scale color blue and tongue colour red with black tip.

Field Observations of Surat specimens. These specimens were rescued from human habitations in Surat city of Gujarat state, western India, on the shore of the Arabian Sea. Rescue calls of this species were obtained mainly from heavily populated and traffic-laden areas with few trees or vegetation, surrounded by buildings in and around the Surat city. Quick and alert, they puffed up their throat and fore-body revealing blue inter-scale skin when threatened. One individual opened its mouth and repeatedly struck, but most individuals of the species were generally mild tempered and calmed down on handling. They fed readily on live geckos as Hemidactylus murrayi Gleadow, 1887 and frogs as Minervarya agricola (Jerdon, 1853) , and juvenile Hoplobatrachus tigerinus ( Daudin, 1803) .

Comparisons to other Dendrelaphis species. Morphologically, D. proarchos is characterized as having the following features with respect to the Surat specimens presented in this study (fide Vogel & van Rooijen 2011a; Biakzuala et al. 2022): ventrals 173–198 (185–194 in Surat snakes); subcaudals 131–156 (139–142 in Surat snakes); midbody scales 15:13–15:9–11 (15:15: 9–11 in Surat snakes); cloacal shield single only in 40% of individuals (single 100% in Surat snakes); supralabials 8–10 (9 in Surat snakes); sublabials 4–10 (4–6 in Surat snakes); temporals 5–16 (11–12 in Surat snakes); postoculars 2–3 (2–3 in Surat snakes); the horizontal diameter of the eye not exceeding 5.1 mm (<5.6 mm in Surat snakes); the maximum width of the vertebral scale at the position of the middle ventral 4.1 mm (5 mm in Surat snakes). Regarding coloration, a bright, light ventrolateral stripe bordered by one or two black lines vs. a bright ventrolateral stripe, bordered by one black line at the bottom, which begins after the black stripe that fades at the neck. The subcaudal counts (139–142) and relative tail lengths (33.3–34.3%) of Surat snakes having complete tails fully match the corresponding values of D. proarchos (131–163; 33.0–36.0%) as reported by Biakzuala et al. (2022) based on 25 specimens comprising both the sexes.

Only a few species of Dendrelaphis with black postocular stripes occur in Peninsular India, though they are restricted to the mesic, forested hill ranges ( Vogel & van Rooijen 2011a,b; Aengals et al. 2022). These congeners include D. ashoki , D. bifrenalis , and D. girii . None of these three species are known to be found in Dangs or anywhere in the Gujarat region ( Vogel & van Rooijen 2011a,b; Aengals et al. 2022). The Surat snakes differ from D. ashoki in having more ventral scales 185–194 (vs. 164–180), fewer subcaudal scales 139–142 (vs. 151–162), postocular 5 or 6 (vs. 4); infralabials touching first sublabials 4–6 (vs. 7–10); undivided cloacal scale (vs. divided); larger eye diameter 5.6 (vs. 4.6); larger maximum width of the vertebral scale at the position of the middle ventral 5 (vs. 3.1); STRIPE 1 ventrolateral stripe bright, bordered by one black line (vs. ventrolateral stripe dull, not bordered by black lines); BS-EYE black stripe on the eye present (vs. absent); BS-PNPRO black stripe absent in between post nasal and preocular (vs. present). The Surat snakes differ from D. girii and D. bifrenalis in having 1 loreal on each side of head (vs. 2), dorsal scale rows 15:15:9 or 11 (vs. 15–17:15: 11 in D. girii ), supralabials 18 (vs. 14–18 in D. girii ), more ventral scales 185–194 (vs. 166–173 and 167–173, respectively), fewer subcaudal scales 139–142 (vs. 145–155 in D. bifrenalis ), more supralabials in contact with eye 6 (vs. 4); postoculars 5 or 6 (vs. 4 or 6; 4, respectively), temporals 11 or 12 (vs. 6–8 in D. girii ), undivided cloacal scale (vs. divided), larger eye diameter 5.6 (vs. 4.9 and 4.3, respectively), larger maximum width of the vertebral scale at the position of the middle ventral 5 (vs. 2.8 and 3, respectively), STRIPE 1 ventrolateral stripe bright, bordered by one black line (vs. ventrolateral stripe dull, not bordered by black lines in D. girii ; ventrolateral stripe bordered by one or two black lines in D. bifrenalis ), STRIPE 2 and the very lengthy postocular stripe extending well into forebody (vs. stripe not surpassing neck in D. girii ), BS-EYE Black stripe present on center of the eye (vs. absent in D. girii ), BS-PNPRO Black stripe absent between postnasal to preocular (vs. present in D. girii and D. bifrenalis ). Thus, the Surat snakes are morphologically closer to D. ashoki (in having long black postocular stripe, 1 loreal) and geographically closer to D. girii (250 airline km between Pune and Surat).

From the two Northeast Indian congeners having black postocular stripes, D. biloreatus and D. cyanochloris , the Surat samples differ in having 15 dorsal scale rows (vs. 13 and 13–16, respectively); 1 loreal on each side of head (vs. 1–2 in D. biloreatus ); cloacal scale undivided (vs. divided); STRIPE 1 ventrolateral stripe bright, bordered by one black line (1) (vs. dull (3) in D. cyanochloris ; absent (4) in D. biloreatus ).

The Surat snakes differ from the South Eeast Asian, D. pictus in having higher count of ventrals 185–194 (vs. 166–178 in D. pictus ); higher count of subcaudals 139–142 (vs. 113–147); undivided cloacal scale (vs. divided); black temporal stripe starting from postocular (vs. starting on postnasal or loreal); larger horizontal eye diameter ranging up to 5.6 mm (vs. not more than 5.0 mm), higher maximum width of the vertebral scale at the position of the middle ventral ranging between 2.3–5.0 mm (vs. 2.0– 3.1 mm). Lastly, they also differ from the only native congener known from Surat, D. tristis , thus: presence of black lateral and ventrolateral longitudinal body stripes (vs. presence of bronze vertebral stripe); tongue red (vs. copper blue); broad, bold black temporal stripe extending well onto neck and forebody (vs. thin black postocular streak not exceeding temporals); enlarged vertebral scales larger than first dorsal row (vs. smaller than or equal to first dorsal row); interparietal spot absent (vs. present or rarely rudimentary); ventrals 185–194 (vs. as low as 178); subcaudals 139–142 (vs. as low as 117); higher maximum width of the vertebral scale at the position of the middle ventral> 5 mm (vs. <3.4); undivided cloacal scale (vs. divided).

Figures

FIGURE 1. Maximum likelihood phylogenic tree of Dendrelaphis based on a partial fragment of 16S with bootstrap support shown at nodes (values <60 not shown). The Surat individual BNHS 3553 (in red) nested within the native Myanmar and Northeast Indian populations of D. proarchos.

FIGURE 2. BNHS 3553 in life Dendrelaphis proarchos from Surat, Gujarat, India. (a) Full body, dorsal view; (b) Head, left side view with black postocular stripe; (c) Head, right side view with black postocular stripe; (d) Head, frontal view, showing its red tongue; (e) Body, lateral view, showing black ventrolateral stripes along body; (f) undivided cloacal scale (profiles of diagnostic features). Photographs by Dikansh S. Parmar.

FIGURE 3. Physical map of Indian subcontinent showing Surat in coastal Gujarat, western India from where we present this report of Dendrelaphis proarchos, and localities (black rectangles) in the natural range of the species in Northeast India and neighboring countries, including its type locality (black star).

FIGURE 4. Live individual here identified as Dendrelaphis cf. proarchos (see Appendix 3) recently rescued by Nature Care NGO from Anand Nursery, Jaipur, Rajasthan, western India. (a) Full body, dorsal view; (b) Anterior and ventrolateral aspects; (c) Head, dorsal and lateral view. Photographs by Rakesh Prajapat.