Contributions to Zoology, 77 (1) – 2008Johan van Rooijen; Gernot Vogel: An investigation into the taxonomy of Dendrelaphis tristis (Daudin, 1803): revalidation of Dipsas schokari (Kuhl, 1820) (Serpentes, Colubridae)

To refer to this article use this url: http://ctoz.nl/vol77/nr01/a05

Taxonomy

Dendrelaphis schokari (Kuhl, 1820) n. comb. (Figs. 5, 6, 7, 8)

next section

Dipsas schokari Kuhl, 1820

Dendrophis helena Werner, 1893

Remarks. The synonymy-list is restricted to references in which data on numbers of ventral scales and subcaudal scales are given as these characters are diagnostic. Two currently recognized synonyms of D. tristis, Leptophis mankas (Bell, 1826) and Dendrophis maniar (Boie, 1827) can not be referred to either D. tristis or D. schokari and will be subjected to further research.

FIG2

Fig. 5. Dendrelaphis schokari, Sri Lanka, neotype RMNH 842.

Material examined. Sri Lanka: NMW 23669:2, NMW 24382:2, NMW 24382:3, NMW 24382:4, MNHN 1890.0065, NMW 23669:1, RMNH 842, RMNH 7066 (1), RMNH 7066 (2), BMNH 1933.12.6.12, BMNH 1969.2781; SMF 62076, SMF 62074, SMF 18672, MHNG 1198.52, MTKD D 10646, MTKD D 10440, MTKD D 15438, MHNG 1199.57, MHNG 1198.54, SMF 70286, MHNG 762.73, MHNG 1198.51, MHNG 1198.55, MHNG 1198.53, MHNG 1198.50, SMF 32366, SMF 70285; India (Malabar Coast): MNHN 244; India (Kottayam, Travancore): BMNH 1924.10.13.15, BMNH 1924.10.13.14; India (Punkanaad, Travancore): BMNH 1924.10.13.12, BMNH 1924.10.13.13; unknown locality: RMNH 7081 (1), RMNH 7081 (2), RMNH 7081 (3), RMNH 7081 (4), RMNH 7081 (5).

Neotype. RMNH 842; collector: Frank, 1853, locality: “Ceylon”, now Sri Lanka. (Figs. 5,6)

Type locality (by designation of a neotype). “Ceylon”, now Sri Lanka.

FIG2

Fig. 6. Dendrelaphis schokari, Sri Lanka, neotype RMNH 842, left side of the head.

Diagnosis. A species of Dendrelaphis, characterized by the combination of: (1) vertebral scales enlarged but smaller than the dorsals of the first row; (2) 155-177 ventrals; (3) 105-127 divided subcaudals; (4) 15 dorsal scale rows at midbody; (5) anal shield divided; (6) 1 loreal scale; (7) 2 supralabials touching the eye; (8) a short first sublabial that touches 2 infralabials; (9) 4 to 7 temporal scales; (10) 2 to 3 postoculars; (11) maximum total length 119.0 cm; (12) TAIL/TL 0.30-0.34; (13) an interparietal spot is absent (rarely rudimentarily present); (14) the presence of a light ventrolateral stripe; (15) the presence, in most specimens, of a vertebral stripe.

FIG2

Fig. 7. Dendrelaphis schokari, living specimen from Sri Lanka. Photograph by Ruchira Somaweera.

Description of the neotype. Adult female; SVL 51.0 cm; TAIL 22.5 cm; 161 ventrals (2 preventrals); 113 subcaudals, all divided; anal shield divided; 1 loreal scale (L+R); 9 infralabials (L+R); first infralabials touch at the mental groove; first sublabial touches infralabials 6 and 7 (L+R); 9 supralabials (L+R), supralabials 5 and 6 touch the eye (L+R); 2 postoculars (L+R); temporal formula: 2+2 (L+R); dorsal formula: 15-15-11; vertebral scales enlarged but smaller than the scales of the first dorsal row; width of the dorsal scale at the position of the middle ventral 2.1 mm; eye-diameter 4.9 mm (L+R); distance anterior border of eye to posterior border of nostril 4.5 mm (L+R); a dark postocular stripe starts behind the eye, covers only the lower quarter of the temporal region and ends at the edge of the jaw; a vertebral stripe, formed by yellow spots on the vertebral scales, starts behind the head and is no longer visible after the level of the 34th ventral scale; an interparietal spot is absent; a faint light ventrolateral line is present, not bordered by black lines; ground color brown, based on the color of unshed skin; supralabials and throat yellow; ventrals yellow anteriorly, yellowish-green posteriorly.

FIG2

Fig. 8. Dendrelaphis schokari, living specimen from Sri Lanka. Photograph by Ruchira Somaweera.

Variation and comparison with Dendrelaphis tristis (Daudin, 1803). Descriptive statistics with regard to D. tristis and D. schokari are provided in Table 3.

Sexual dimorphism. D. schokari exhibits sexual dimorphism in the number of dorsal scale rows one head-length before the anal shield (P < 0.00001, χ2 test). All male specimens have 9 dorsal scale rows at this position whereas 75% of the female specimens have 11 dorsal scale rows at this position.

Distribution. The examined specimens of D. schokari originated from Sri Lanka and the Western Ghats (South-West India), areas that have been shown to be biogeographically closely related (Das, 1995).

Dendrelaphis tristis (Daudin, 1803) (Figs. 9, 10, 11)

Coluber tristis Daudin, 1803

Dipsas schokari Kuhl, 1820 (part.)

Dendrophis scandens Boie, 1827

Dendrophis chairecacos Boie, 1827

Dendrophis boii Cantor, 1839

FIG2

Fig. 9. Dendrelaphis tristis, Calcutta, neotype SMF 58442.

Material examined. Sri Lanka: BMNH 1955.1.9.80, BMNH 93.10.6.1, BMNH 1972.2183, ZMA 21563, SMF 18671, SMF 32367; India (Bengals): RMNH 843 (1), RMNH 843 (2), RMNH 843 (3), RMNH 843 (4), RMNH 843 (5); India (Calcutta): NMW 23686:6, NMW 23686:7, SMF 58442, SMF 58071; India (Darjeeling): BMNH 72.4.17.342, BMNH 1909.3.9.12; India (Bombay): ZMA 14120(2), BMNH 69.8.28.126, ZMA 14120(1); India (Madras): SMF 18634, SMF 18595; India (no exact locality): BMNH 52.10.4.18, MHNG 1553.8; Bengals/Myanmar: NMW 23669:5, NMW 23669:3.

Neotype. SMF 58442 collector: H. Schetty, locality: Calcutta, India. (Figs. 9,10)

Type locality (by designation of a neotype). “Calcutta, India” (original type locality: “Hyderabad”).

FIG2

Fig. 10. Dendrelaphis tristis, Calcutta, neotype SMF 58442, left side of the head.

Diagnosis. A species of Dendrelaphis, characterized by the combination of: (1) vertebral scales enlarged but smaller than the dorsals of the first row; (2) 178-198 ventrals; (3) 121-136 divided subcaudals; (4) 15 (rarely 13) dorsal scale rows at midbody; (5) anal shield divided; (6) 1 loreal scale; (7) 2 supralabials touching the eye; (8) a short first sublabial that touches 2 infralabials; (9) 5 to 8 temporal scales; (10) 2 postoculars; (11) maximum total length 115.0 cm; (12) TAIL/TL 0.30-0.33; (13) a bright (rarely rudimentary) interparietal spot; (14) the presence of a light ventrolateral stripe; (15) the presence, in most specimens, of a vertebral stripe.

FIG2

Fig. 11. Dendrelaphis tristis, Bombay, ZMA 14120(2), note the interparietal spot on top of the head.

Description of the neotype. Adult male; SVL 45.0 cm; TAIL 21.5 cm; 185 ventrals (2 preventrals); 134 subcaudals, all divided; anal shield divided; 1 loreal scale (L+R); 11 infralabials (L+R); first infralabials touch at the mental groove; first sublabial touches infralabials 6 and 7 (L+R); 9 supralabials (L+R), supralabials 5 and 6 touch the eye (L+R); 2 postoculars (L+R); temporal formula: 2+2+2 (L), 2+1+2 (R); dorsal formula: 15-15-9; vertebral scales enlarged but smaller than the scales of the first dorsal row; width of the dorsal scale at the position of the middle ventral 1.9 mm; eye-diameter 3.8 mm (L), 3.9 mm (R); distance anterior border of eye to posterior border of nostril 3.2 mm (L+R); a postocular stripe starts behind the eye and covers approximately 30% of the temporal region; a vertebral stripe, formed by a light colour of the vertebral scales and edges of adjoining dorsal scale rows, starts behind the head and is no longer visible after the level of the 17th ventral scale; an interparietal spot is present; a light ventrolateral line is present, bordered above by a thin dark line; ground color brown; supralabials, throat and ventral scales off-white.

FIG2

Table 3. Descriptive statistics for D. tristis and D. schokari. Mean and range are shown in case of continuous quantitative variables (EYED-VSTRIPE). Median and range are shown in case of discrete quantitative variables (VENT-POC). In case of qualitative variables (VERT-LSTRIPE), the percentage of specimens possessing the indicated charateristic is shown. EYED, EYEN and TAIL are SVL-adjusted values.

Variation and comparison with Dendrelaphis schokari. Descriptive statistics with regard to D. tristis and D. schokari are provided in Table 3.

Sexual dimorphism. Like D. schokari, D. tristis exhibits sexual dimorphism in the number of dorsal scale rows one head-length before the anal shield (P = 0.0003, χ2 test). 85% of the females have 11 dorsal scale rows at this position whereas 90% of males have 9 dorsal scale rows at this position.

Distribution. The examined specimens of D. tristis originated from Sri Lanka, Western Ghats (Bombay), Eastern Ghats (Madras), Northeast India and Myanmar. Daudin’s type originated from Central India (Hyderabad). Boulenger (1894) provides a record from North-West India (Sind). His record is unambiguous given the mentioned ventral and subcaudal counts (185 and 127 respectively). According to Shrestha (2001), D. tristis also occurs in Nepal. Unfortunately, Shrestha did not provide diagnostic data on his record. However, the occurrence of D. tristis in Nepal is plausible given the verified presence of this species in North-East India. In summary, D. tristis ranges from Sri Lanka northward through most of India to Myanmar whereas the distribution of D. schokari is restricted to Sri Lanka and South-west India (Western Ghats) As such, D. schokari appears to have a limited distribution in comparison with D. tristis. This is in agreement with data provided by Boulenger (1894) and Wall (1909, 1921a, 1921b). These authors mention high ventral and subcaudal counts, consistent with D. tristis, for specimens from northern regions and mention both high and low ventral and subcaudal counts, consistent with a combination of D. tristis and D. schokari, for specimens from southern regions.