Oligodon melaneus Wall, 1909

Das, Abhijit, Gower, David J., Narayanan, Surya, Pal, Saunak, Boruah, Bitupan, Magar, Sanjay, Das, Sanjib, Moulick, Soumabrata & Deepak, V., 2022, Rediscovery and systematics of the rarely encountered Blue-bellied kukri snake (Oligodon melaneus Wall, 1909) from Assam, India, Zootaxa 5138 (4), pp. 417-430 : 421

Oligodon melaneus Wall, 1909

Figs. 1–3 , Tables 1–2 .

Wall (1909) provided relatively detailed descriptions of the two syntypes. We note differences between Wall’s and our observations in the text and Table 2 , and provide the first photographs of the syntypes ( Figs. 2 and 3 ), but otherwise focus on a more detailed description of the new specimen because it was collected more than 260 km from the type locality.

Lectotype. BMNH 1910.12 .31.3 ( Fig. 2 ), a female specimen from Tindharia (ca. 26.85660°N, 88.34442°E; 823 m elevation), Darjeeling District, West Bengal state, India, collected July 1908. This specimen is here designated as the lectotype because it is the best preserved of the two syntypes.

Specimen in very good condition; ventral incision into coelom ca. 25 mm to ca. 40 mm from vent, midventral incision ca. 14 mm into anterior end of tail; 329 mm total length (snout–vent length 280 mm, tail length 49 mm); head length 10.4 mm; head width 5.6 mm.

Lepidosis . 7,7 supralabials but on the right side the 2 nd and 3 rd and the 6 th and the 7 th supralabial are incompletely distinct (partially ‘fused’). The 3rd and 4th supralabials in contact with the spectacle covering the eye. Partly subdivided nasal contacts 1 st and 2 nd supralabial. 1,1 preocular; 7,7 infralabials; 1+2,1+2 temporals; 2,2 postoculars; dorsal scales in 17-15-15 rows; 159 ventrals; 39 subcaudals.

Colouration in preservative. Body colour brown; top of the head without typical Oligodon markings, same colour as dorsum; rostral cream; supralabials heavily speckled with dark brown, paler edged; postoculars and temporals (see Fig. 2 ) unpatterned; infralabials and genial region cream with four dark brown spots medially; anterior ventral scales are edged with dark brown; posterior to the thirteenth ventral, colouration uniform dark brown throughout to vent. Subcaudals dark brown with paler centres.

Paralectotype. BNHS 958 (fide Wall 1924; Fig. 3 ), a male specimen from the same locality and date of collection as the lectotype .

Specimen dehydrated to some extent and possibly moulting when it was fixed; outer layer of most head shields and some body scales missing; 312 mm total length (snout–vent length 261 mm, tail length 51 mm); head length 9.1 mm; head width 5.3 mm; adult male.

Lepidosis . 7,7 supralabials with the 3 rd and 4 th in contact with the eye. Partly subdivided nasal contacts 1 st supralabial only. 1,1 small preocular; 7,7 infralabials; 1+2, 1+2 temporals; 2,2 postocular; dorsal scales in 17-15-15 rows; 152 ventrals; 43 subcaudals.

Colouration in preservative. Body colour dark grey merging to greyish on the flanks; individual scales finely speckled with black on a grey background. Venter grey and iridescent; ventral scales finely speckled with black, less densely on the anterior part of the body than on the posterior of the body and subcaudals ( Fig. 3 ).

Figures

FIGURE 1. Phylogenetic relationships of Oligodon melaneus.A) ML phylogeny with bootstrap support values, B) BI phylogeny with Bayesian posterior probability support values.

FIGURE 2. Designated lectotype of Oligodon melaneus (BMNH 1910.12.31.3). Photographs by Kevin Webb. Scale bar increments in mm.

FIGURE 3. Paralectotype of Oligodon melaneus BNHS 958. Photographs by Saunak Pal. Image not to scale.