Trimeresurus septentrionalis Kramer, 1977

Vogel, Gernot, Mallik, Ashok Kumar, Chandramouli, S. R., Sharma, Vivek & Ganesh, S. R., 2022, A review of records of the Trimeresurus albolabris Gray, 1842 group from the Indian subcontinent: expanded description and range extension of Trimeresurus salazar, redescription of Trimeresurus septentrionalis and rediscovery of historical specimens of Trimeresurus davidi (Reptilia: Viperidae), Zootaxa 5175 (3), pp. 343-366 : 355-357

Trimeresurus septentrionalis Kramer, 1977

( Figures 1–2 , 8–9 )

Trimeresurus albolabris septentrionalis Kramer, 1977

Trimeresurus septentrionalis — Giannasi et al. 2001

Trimeresurus albolabris septentrionalis —Leviton et al. 2003

Cryptelytrops septentrionalis — Malhotra & Thorpe 2004

Trimeresurus (Trimeresurus) septentrionalis — David et al. 2011

Trimeresurus septentrionalis — Wallach et al. 2014

Specimens Examined (n=18). Holotype MHNG 1404.31 an adult male collected by H. Schnurrenburger between 1962 – 1964 (fide Kramer, 1977) from Pokhara (28˚15’N 83˚55’E; 1500 m asl), Nepal . Other material examined: MHNG 1400.24 – 39 , 1404.2 – 30 , 1404.32 – 47 , from the type locality. CAS 135750 , also from the type locality .

Remarks. Kramer (1977) while describing the new subspecies septentrionalis under T. albolabris , explicitly listed only MHNG 1404.31 as “ Holotypus ”. Whereas eleven other specimens from MHNG, BMNH (now NHMUK) and CHNM were listed only as “Material” unlike MHNG 675.92, 678.7, which were explicitly mentioned as “ Paratypen ” under the taxon insularis . Hence, we hereby confirm that T. albolabris septentrionalis does not have any paratypes and MHNG 1404.31 is the holotype, by monotypy.

Redescription of holotype. An adult male with a subcaudal incision; overall in good condition. Habitus slender; head triangular, flat on top, wider than mid - trunk, snout subovate in profile, bluntly rounded at tip; neck evident, slim compared to mid - trunk; canthus rostralis discernable; tail tapering to a fine point. Scales rather smooth along the lateral aspects of the body; obtusely keeled on dorsal aspect covering the vertebral and paravertebral rows, especially on the hinder half. Rostral slightly visible from above, much reduced; two large internasals that have broad midline contact; head scales rather flat, small; supraoculars bean - shaped, enlarged; right and left ones separated by 10 cephalic scales in line between them; preocular large; subocular elongate, crescent - shaped; postocular 1, very small; SL 11/10, first SL in contact with nasal; 2 nd SL forming anterior margin of loreal pit; 3 rd one large, contacting an elongate presubocular scale that borders the posterior margin of loreal pit; IL 12; mental wider than long; anterior genials larger than posterior series of genials; PV 3; VEN 164, mildly angulate laterally; anal scale 1; SC 79 pairs; DSR: 21:21:15. TL: 633.0 mm (SVL: 486.0 mm, TaL: 147.0 mm); TaL/TL: 23.2%; HL: 25.7 mm; HW: 14.1 mm; ED: 3.6 mm; END: 5.4 mm; ELD: 4.0 mm. Colouration in alcohol bluish overall; dorsum light blue all across the body, except for anterior parts of head that has brownish tinge, similarly the tail ending too has a brownish/brick - red tinge; mental and gular regions cream; venter of a lighter shade of blue than the dorsum; posterior parts of subcaudals with a reddish tinge; a distinct white streak from below the eye to up to jaw angle apparently continuing across neck as a white ventrolateral stripe extending posteriorly till tail base.

Variation. In general, agreeing well with the holotype and showing the following intra - specific variation: SVL: 252 – 701 mm; TaL: 58 – 147 mm; TaL/TL: 18.7 – 23.2% (males), 14.7 – 17.1% (females); HL: 16.3 – 36.8 mm; HW: 10.0 – 22.2 mm; DSR: 21 – 23 (near neck): 21(midbody): 15 – 17 (near tail), anterior rows 22 and 23 on three occasions, posterior rows 16 and 17 on two occasions; PV 1 – 2; V: 164 – 171; SC: 74 – 80 pairs (males), 56 – 66 pairs (females); SL 12; IL 13 – 14; white postocular streak absent on both sides in two male paratypes (out of 4 occasions) ; ventrolateral white stripe dark below, in one male paratype; postocular streak and ventrolateral white stripes absent in all female paratypes and other specimens.

Distribution and Habitat. Trimeresurus septentrionalis occurs in the Siwalik range and lower Himalaya in western and central parts of this mountain range ( Kramer 1977; Regenass & Kramer 1981) in Nepal and India. Recent works on Indian snakes were unable to shed light on this species ( Das 2002; Whitaker & Captain 2004). Subsequent treatments include those by Gumprecht et al. (2004). Recently, T. septentrionalis has been reported from the Kumaon region ( Singh et al. 2017). While definitively known from the western and central Himalayan foothills of India, the presence of T. septentrionalis in Bangladesh is doubtful at best ( Gumprecht et al. 2004).

Figures

FIGURE 1. Map of the Indian subcontinent showing newly recorded / identified distribution records of (i). Trimeresurus salazar (black; field records: squares, specimen records: dots); (ii). T. septentrionalis (white); type localities with a dot in the middle (iii). T. davidi (encircled—corrected locality / X—incorrect locality)

FIGURE 2. Reconstructed phylogeny from three concatenated mitochondrial genes showing the phylogenetic position of T. salazar nested within the clade comprising other members of T. albolabris species complex. The values on nodes show the posterior probability from Bayesian inference and bootstrap values from the maximum likelihood analysis.

FIGURE 8. Trimeresurus septentrionalis Holotype MHNG 1404.31 from Nähe Pokhara, Nepal. Photos: Gernot Vogel.

FIGURE 9. Trimeresurus septentrionalis live adult female from Kathmandu, Nepal, showing its diagnostic character of plain grass green colouration without any mix of yellow in it. Photo: Gernot Vogel