Gloydius chambensis Kuttalam & Santra & Owens & Selvan & Mukherjee & Graham & Togridou & Bharti & Shi & Shanker & Malhotra 2022, sp. nov.

Gloydius chambensis sp. nov.

urn:lsid:zoobank.org:act: 3FC261AB-C7DD-4E7F-92F6-0FBC5607B46C

Figs 7–9

Halys himalayanus Günther, 1864: 393, pl. 24 fig. a (only specimens from Chamba District).

Ancistrodon himalayanus – Boulenger 1896: 424, fig. 125. — Smith 1943: 495–496, fig. 157.

Agkistrodon himalayanus – Gloyd & Conant 1990: 255–264, pl. 14, 31, 38, 52 figs 20–23.

Agkistrodon himalayana – Underwood 1999: 3–8.

Gloydius himalayanus – McDiarmid et al. 1999: 305. — Gumprecht et al. 2004: 20–21, figs i–iii (p. 64), i–iii (p. 65). — Wallach et al. 2014: 310.

Diagnosis

Gloydius chambensis sp. nov. can be identified by the number of gular scales in contact with the infralabial scales (4–5, mean 4.17), number of sublabial scales (9–10, mean 9.57) and the proportion of the first temporal scale covered by the postocular stripe (covering less than a quarter of the temporal scale).

Differential diagnosis

Gloydius chambensis sp. nov. can be distinguished from its sister species, G. himalayanus, by the lower number of gular scales in contact with the infralabial scales (4–5, mean 4.17, compared to 5–6, mean 5.67, in G. himalayanus), a higher number of sublabial scales, r (9–10, mean 9.57, compared to 6–9, mean 7.97, in G. himalayanus) and a lower proportion of the first temporal scale covered by the postocular stripe (covering less than a quarter of the temporal scale, compared to more than a quarter in G. himalayanus).

Both Gloydius chambensis sp. nov. and Gloydius himalayanus can be distinguished from all other congeneric species by a very distinct or sharp canthus rostralis (Gloyd & Conant 1990), from the Gloydius halys complex by having 21 mid-body dorsal rows (vs 22 or 23 rows) (Shi et al. 2018), from G. rubromaculatus, G. strauchi and G. huangi Wang, Ren, Dong, Jiang, Shi, Siler, & Che, 2019 by having a pointed snout and triangular head (vs a blunt snout and rounded head) (Shi et al. 2017, 2018; Wang et al. 2019) and from G. angusticeps and G. monticola by having a matte dorsal texture (vs a glassy texture with a metallic lustre) (Shi et al. 2018; Wang et al. 2019).

Etymology

The specific epithet ‘ chambensis ’ means ‘from Chamba’ in reference to the species being distributed in Chamba District. The suggested common name is the ‘Chamba Pitviper’.

Type material

Holotype INDIA • ♂ adult; Himachal Pradesh, Chamba District, Bhanjraru; 10 Jul. 2018; 32.83909° N, 76.14932° E; alt. 1738 m; Sourish Kuttalam, Vishal Santra, John Benjamin Owens, Vipin Dhiman, Anita Malhotra, Nilanjan Mukherjee, Stuart Graham and Anatoli Togridou leg; found dead on the road; GenBank: OP422588, OP450868, OP407966, OP518269; Voucher Specimen R259 (DNA reference number 18.13); HARC R259 (collection of the High Altitude Research Centre, Solan, Himachal Pradesh).

Holotype description

The holotype HARC R259 is an adult male with a snout-vent length of 34 cm and a tail length of 8.6 cm (total length = 42.6 cm). The width of the head is 13.84 mm and the length of the head is 19.21 mm. The diameter of the eye is 2.78 mm. The head is distinctly triangular and the canthus rostralis is sharp and conspicuous.

Scalation

The holotype has one scale between the nasal scale and the loreal heat-sensing pit, one scale between the loreal pit and the preocular scale, and two postocular scales. The supraocular scale has a completely smooth outer edge. The border of the internasal scales and prefrontal scales is distinctly convex or curved (vs a concave or flat border in eastern populations in Himachal Pradesh). There are seven supralabial scales with the third supralabial scale in contact with the lower postocular scale. The penultimate supralabial scale is fused with the last temporal scale. The specimen has 10 infralabial scales. It has four gular scales in contact with the infralabial scales (not including from the enlarged chin shields). The dorsal scales are in 25:21:17 rows, with heavy keeling on all the dorsal scales. The number of ventral scales is 164 and the number of subcaudal scales is 42.

Coloration in life (Fig. 7)

Paired distinct dark-coloured stripes start from the posterior head scales and extend down the neck and dorsolateral surface as far as the 20 th ventral scale. The postocular stripe is a thin, dark brown stripe that begins from the rear edge of the eye and continues onto the two temporal scales, impinging slightly on the last supralabial scale. The lower edge of the ocular stripe is bordered by a white line. The longer of the two ocular stripes ends in line with the 4 th ventral scale. A total of 24 crossbands on the dorsal surface of the body. These are a dull mud-brown colour, with some having a darker inner border. There are also blotches all along the lateral sides of the body that are broken extensions of the crossbands. The ventral scales are glossy, with many scales having blotches with white edges on the ends of the scale, similar to those on the lateral surface. The background dorsal coloration is a dull mud-brown colour with a matte texture. The posterior half of the tail is lighter in colour.

Variation

Whilst the holotype shares most characters with the rest of the specimens of Chamba, there are some differences. In the scale counts, the holotype has a higher number of ventral scales (164 vs 158–161). In coloration, it differs in the number of crossbands found on the body (24 vs 29–39). The first two scale reductions (25 to 23 and 23 to 21) occur closer to the head (the reduction from 25 to 23 scales occurs at 14.94% vs 5%–8%; 23 to 21 scales at 21.34% vs 8%–11%).

Taxonomic remarks

All specimens that were examined and diagnosed to be Gloydius chambensis sp. nov. were specimens from the field study site. Apart from the deposited holotype, none of the other field specimens were found dead. Our collecting permits did not allow us to ethically euthanise live individuals for this study. Hence, no paratype has been designated.

Distribution and habitat

Gloydius chambensis sp. nov. is distributed across the Chamba and associated valleys, which has an elevational range from 400 m to 5500 m. The major river system of the valley is the Ravi River (Ghosh & Chhibber 1984). The valley is isolated by two ranges, the Pir Panjal Range to the north and northwest and the Dhauladhar Range to the south and southeast (Fig. 1). The specimens were found in habitat primarily consisting of alpine scrub and pine forests, with a ground layer of thick pine needle litter (Fig. 9). The habitat was interspersed with occasional boulders and rock faces. Almost all the specimens were found close to rural households, and anecdotal interactions with the local villagers indicate that this is the venomous snake that is most commonly seen in the region and that causes the most bites to people in the valley (Fig. 10). Some studies have noted that bites can result in pain, swelling, bruising, and bleeding (Khan & Tasnim 1986; Raina et al. 2014).