Sinomicrurus nigriventer Wall, 1908

Mirza, Zeeshan A. & Varma, Vishal, 2020, On the systematic status of Calliophis macclellandi nigriventer Wall, 1908 (Reptilia: Serpentes: Elapidae), Zootaxa 4821 (1), pp. 105-120 : 107-112

Sinomicrurus nigriventer Wall, 1908 comb. nov.

Figs. 3–6

Calliophis macclellandi nigriventer Wall, 1908: 266

Calliophis macclellandi “nigriventer ” Form IV Smith (1943): 425

Sinomicrurus macclellandi univirgatus Smith et al. 2012: 68 (in part)

Holotype. Adult male NHMUK 1948.1 .7.7 Kasauli , Punjab (now Kasauli, Himachal Pradesh, India) ( Fig. 3 ).

Material examined. NHMUK 1946.1 .17.82 (= NHMUK 1937.4.3.14) adult female from Kasuli, Punjab (now Kasauli, Himachal Pradesh, India) ( Figs. 4 & 5 ); NCBS NRC-AA-0005 adult male from Nairaini village , Solan district, Himachal Pradesh (30.7761230°N, 77.0196530°E, elevation 870m, datum WGS84 ), India collected by Vishal Varma on the 2 nd of October 2019 ( Fig. 6 ) .

Diagnosis. A medium sized species of Asian coral snake measuring 364–445mm SVL, 13 dorsal scale rows. Colouration of a broad white chevron mark on the head, with a reddish brown dorsum and a mid-dorsal black vertebral strip extending from the nape to the vent and with three thin bands on the tail, belly white with black smear up to the vent and tail dorsum with a few band-like blotches. No maxillary teeth behind fang. Tail comprising of 8.2–8.8% of total length. Ventral scales 230–235 in males, 251 in a single female, and 26–29 subcaudals. Hemipenis reaching eighth subcaudal plate.

Comparisons. Sinomicrurus nigriventer comb. nov. is here compared with its congeners for non-overlapping or differing characters ( Table 1 ): 13 dorsal scale rows [vs. 15 in S. kelloggi (Pope, 1928) and S. houi Wang, Peng & Huang in Peng et al. 2018 , S. sauteri (Steindachner, 1913) ], a broad white chevron mark on the head [vs. white thin band on the head in S. japonicus (Günther, 1868) and S. hatori (Takahashi, 1930) ]. Sinomicrurus nigriventer comb. nov. is most similar to S. macclellandi and S. peinani Liu, Yan, Hou, Wang, Nguyen, Murphy, Che & Guo, 2020 in bearing 13 dorsal scale rows, 1 + 1 temporal scales and in general colouration, however, it differs in bearing a single dorsal vertebral stripe (vs. rings in S. peinani , S. m. macclellandi , S. m. swinhoei and S. m. iwasakii ), and venter with black smear (vs. black bands or blotches in S. m. macclellandi , S. m. swinhoei, S. m. iwasakii , and S. m. univirgatus). Ventral scales in males 230–235 (vs. 182–212 in S. macclellandi sensu lato, 217 in S. peinani ) ( Smith 1943; Lalremsanga & Zothansiama 2015). A summary of the comparison is presented in Table 1 .

Etymology. The specific epithet “ nigriventer ” belongs to the original description ( Wall 1908) and it is a combination of two words, “niger” meaning black and “venter” for belly referring to the black smeared belly typical to the species. Suggested English vernacular name is Black-bellied coral snake.

Description of holotype. The specimen in general is in good condition of preservation except for the head, which lacks some labial, temporal and part of the parietal scales on the right side. The ventral side of the tail bears a longitudinal incision. Doral surface of head and body brown throughout with a black longitudinal stripe running from the nape to the tail proximally, four band-like blotches on the tail, not complete. Head with a broad white chevron, the scales anterior and posterior to it darker. Ventrally white with irregular black blotches connected to each other along the belly up to the cloacal opening ( Fig. 3 ).

Head short, 7.5 mm; high, 3.7 mm, with steeply domed snout in lateral view, indistinct from neck. Snout tapering to blunt, rounded tip in dorsal view. Rostral subtriangular, visible from dorsal view; wider than deep. Nostrils large, crescent shaped, situated medially, loreal scale absent. Internasals paired, wider (1.4 mm) than long (1.0 mm); smaller than prefrontals. Prefrontals wider (2 mm) than long (1.6 mm); frontal subtriangular, 2.0 mm at the widest anterior border, median length 2.7 mm and posterior width 1.1 mm at suture with supraocular. Parietals 4.0 mm long, each 2.1 mm at its widest anterior, 1.0 mm at its posterior border. Temporals 1+1, posterior temporal larger. Supraocular much larger than preocular; preocular large, higher than wide. Loreal wider than long, the one on the right fused with nasal, a small one of the left side. Postoculars two, equal in size. Eye circular, 1.0 mm diameter with a rounded pupil. Seven supralabials, third and fourth in contact with orbit. First supralabial very small and, apart from second supralabial, contacts only rostral and nasal. Second supralabial small, contacting nasal, first supralabial, third supralabial and remotely in contact with the preocular. Third to seventh supralabial scales much larger than the anterior ones, subequal. Fifth supralabial in contact with postocular, fourth + sixth supralabials and temporals. Mental short, broad, triangular. Two anterior infralabials short and small, third infralabial and subsequent ones larger. Fifth and sixth infralabials much larger than the rest, larger in comparison with the pair of posterior genials. Anterior genials more than twice as long (1.9 mm) as wide (0.9 mm), posterior genials 2.0 mm long and 0.8 mm wide. Posterior pair separated by one row of scales.

Body sub-cylindrical, ventral surface marginally flattened. Dorsal scales imbricate, regularly arranged, evenly sized, lacking apical pits, arranged in 13 rows across body. All body scales smooth lacking keels and glossy. Ventral scales 230 (+2 pre-ventrals). Anal shield divided, similar in size to last ventral scale, its posterior margin overlaps with four small, irregular scales on right and five on left, in addition to pair of larger subcaudals medially. Subcaudals 29, paired. Tail tip in a sharp tapering apical spine. SVL 445 mm, tail length 43 mm, tail/total length ratio 0.09.

Dentition of male NCBS NRC-AA-0005. The specimen bears one functional and two accessory fangs in the maxilla and lacks maxillary teeth behind it. Seven functional teeth on the palatine and two on the pterygoid. Six functional dentary teeth.

Variation. Other examined specimens agree with the holotype except for differences noted here: Adult female NHMUK 1946.1.17.82 ( Figs. 4 & 5 ) SVL 432mm, Tail 39mm, ventrals 251 and 26 subcaudals; Adult male NCBS NRC-AA-0005 ( Fig. 6 ) SVL 364 mm, Tail length 33 mm, ventrals 235 and subcaudals 27. The ventral black smearing is more prominent in the males.

Colouration of NCBS NRC-AA-0005. Colouration in preservative ( Figs. 6a & 6b )—The maroon colouration has bleached out and has turned in a shade of brown and the pinkish shade of ventral scales has turned off-white with a slight yellow tinge. Colouration in life ( Figs. 6c & 6d )—Dorsal scales in a shade of maroonish brown with a single vertebral black stripe. Head shield namely, internasals, prefrontals anterior 1/4 th of the frontals and half of the supraoculars black; rest of the frontal, posterior supraoculars, anterior portion of parietals, postoculars, anterior temporal and suporalabials 5 to 7 creamish with diffused light brown patches on the frontal and parietals. Posterior parts of parietals, posterior temporal and adjoining scales blackish brown eventually fading into a lighter shade of brown finally turning maroonish brown. Scales glossy and iridescent. Tail dorsum with four thin bands. Ventrally pinkish with black irregular smearing starting from the third ventral scale reaching the anal plate. Tail with remotely placed black blotches ventrally.

Figures

FIGURE 3. Sinomicrurus nigriventer comb. nov., holotype, NHMUK 1948.1.7.7, adult male, (a) dorsal aspect, (b) ventral aspect. Scale bar 10mm.

FIGURE 4. Sinomicrurus nigriventer comb. nov., NHMUK 1946.1.17.82, adult female, (a) dorsal aspect, (b) ventral aspect. Scale bar 10 mm.

FIGURE 5. Sinomicrurus nigriventer comb. nov., NHMUK 1946.1.17.82, adult female, images of head scalation, (a) dorsal aspect, (b) ventral aspect, (c) right lateral aspect.

FIGURE 6. Sinomicrurus nigriventer comb. nov., NCBS NRC-AA-0005, adult male, (a & c) dorsal aspect, (b & d) ventral aspect. Scale bar 10 mm.