Trachischium fuscum Blyth 1854, sp. nov

Autor: Raha, Sujoy, Das, Sunandan, Bag, Probhat, Debnath, Sudipta, Pramanick, Kousik
Rok vydání: 2018
Předmět:
DOI: 10.5281/zenodo.5990875
Popis: Redescription of Trachischium fuscum Blyth, 1854 (Fig. 4A) Talukdar et al. (1980) designated ZSI7044 as the lectotype of Trachischium fuscum. They provided a redescription but it was brief and contained some ambiguous (such as number of VEN) and erroneous (namely SVL and TAL) information. Moreover, it lacked morphometric details and description of the novel characters used in this paper (such as 4SCW/L and 5SCW/L) used to separate T. sushantai sp. nov from T.fuscum. The aforesaid reasons necessitate the inclusion of a redescription of the lectotype of T. fuscum along with an analysis of variation in paralectotypes and non-type materials of T. fuscum. Redescription was based on the lectotype of Trachischium fuscum (ZSI7044): Adult male; SVL 325 mm and TAL 52 mm (not 305 mm and 49 mm respectively as reported by Talukdar et al. [1980]); TAL/TL ratio is 0.14; head small (HL 9.8 mm, 3.2 % of SVL), wider than its height (HW and HH 6.6 mm and 5.1 respectively); head indistinct from neck; eye small (ED 1.3 mm, 13.3 % of HL); ESN 3.7 mm; rostral slightly broader than high (width and height of rostral 1.2 mm and 1.1 mm respectively); internasals paired, much shorter than the undivided PF; length of the pentagonal frontal shield (3.6 mm) greater than its distance from the end of rostral (1.9 mm), wider than supraoculars; parietals (length 5.6 mm) longer than frontal; 1 pre- and 1 post-ocular; loreal twice wider than high; nasals divided and very small; SL (R/L) 6/6, 1 st smallest, 6th largest, 3rd and 4th touching the eye; IL (R/L) 6/6 of 4 are in contact with the genials; anterior genials longer than posterior genials; TEMP (R/L) 1+2/1+2; dorsal scales smooth except those on the basal region of tail which are keeled, DSCH:M: V 13:13:13; VEN 156; anal divided; SC 35 pairs, those one anterior half on tail around twice wider than long with 4SCW/L 2.46 and 5SCW/L 1.88. Blyth (1854) described the colour as follows ���Of an iridescent dull black colour throughout, the ventrals slightly margined paler.��� Now the specimen has become uniformly brown, with paler margins at the trailing edge of VEN still being evident. Variations. Range of morphometric and meristic data of paralectotypes and other non-type specimens of T. fuscum are presented in Table 1. Head and dorsal scalation in this species shows almost no variation except that in ZSI18693 there is only one 1 posterior TEMP on right side. Smith (1943) reported the range of VEN as 150���165 (the lowest VEN count reported by Sharma [2007] is 132 which is most probably erroneous). The highest VEN count made by us was 169 in ZSI19120. Range of SC reported by Smith (1943) was 28���42. In ZSI18679, there are 44 pairs of SC. ZSI7059 (collected from Darjeeling) exhibits several anomalous ventral scales (Figure 4B). In this specimen, split VEN, incomplete VEN and fused VEN are present sporadically among normal VEN. This anomaly results from abnormalities on vertebrae and ribs (e.g. Shine et al. 2005; Mebert 2011). This specimen also has divided PF. Wall (1909b) found one specimen from Darjeeling which got 9 of its anterior SCs undivided. We found undivided SC in three specimens, including one paralectotype (ZSI7051). The dorsum coloration (in preservative) varies from dark brown to almost jet black. Juveniles, as reported by Wall (1909b) and Smith (1943), have longitudinal stripes and an incomplete collar over nape. Here we would like to mention that there is another specimen from Jammu deposited in ZSI general collection (ZSI25651 B) with divided nasal, VEN 150, SC 35 (first 4 undivided, rest distinctly wider than long, not regular hexagon/rhomboid shaped), SVL 227 mm and TAL 45 mm (TAL 19.8 % of SVL) and black dorsum. It can be seen that this specimen can be easily distinguished from the holotype of T. sushantai sp. nov. and we currently refer it to T. fuscum as we could not find any differences in characters from other T. fuscum of eastern Himalaya that we have studied. Distribution. T. fuscum was found from the states of Jammu & Kashmir, northern West Bengal, Uttarakhand, Sikkim, Assam and eastern Arunachal Pradesh in India, east and central Nepal and Bhutan border area (G��nther 1860; Boulenger 1893; Annandale 1904; Wall 1909b; Smith 1943; Agarwal et al. 2010; Wallach et al. 2014; also see the references contained in Wallach et al. 2014). We currently regard one specimen from Jammu as T. fuscum. Also see comments on Ablabes gilgiticus. Wall (1924) regarded the locality Khasi hills (Meghalaya state) to be questionable. Natural history. T. fuscum is a montane snake and it is found between 920 and 2590 meters above sea level (Wallach et al. 2014). This snake species is semi-fossorial and live under stones and leaf litter in montane deciduous forests (Wall 1909b; Das, 2002; Agarwal et al. 2010). Though Das (2002) stated that these snakes become active after sunset, Wall (1909b) frequently found it during daytime in Darjeeling. They feed on earthworms and are of very gentle disposition (Wall 1909b). T. fuscum has a sex ratio that is skewed toward females. The specimens studied by us contained 14 males and 19 females (ratio 1:1.36). Wall (1909b) reported 37 males and 51 females among 88 specimens of which he determined the sex. A similar type of skewed sex ratio was reported for T. guentheri by Wall (1909b) and Chettri et al. (2009). The clutch size of T. fuscum was reported to be 3���6 (Wall 1909b). We found 9 eggs in ZSI19120 (from Gopaldhara, Darjeeling, West Bengal) (Figure 4C). This is the highest number of eggs reported for any Trachischium spp. to date. Hatchlings of this species were seen by Wall (1909b) in Darjeeling in July.
Published as part of Raha, Sujoy, Das, Sunandan, Bag, Probhat, Debnath, Sudipta & Pramanick, Kousik, 2018, Description of a new species of genus Trachischium with a redescription of Trachischium fuscum (Serpentes: Colubridae: Natricinae), pp. 549-561 in Zootaxa 4370 (5) on pages 553-555, DOI: 10.11646/zootaxa.4370.5.6, http://zenodo.org/record/1147357
{"references":["Blyth, E. (1854) Notes and descriptions of various reptiles, new or little known. Journal of the Asiatic Society of Bengal, 23, 287 - 302.","Talukdar, S. K., Sanyal, D. P. & Duttagupta, B. (1980) Redescription of and lectotype designation for Calamaris fusca Blyth, 1854 [Serpentes: Colubridae]. Bulletin of Zoological Survey of India, 3, 93 - 95.","Smith, M. A. (1943) The Fauna of British India, Ceylon and Burma, including the whole of the Indochinese sub-region. Reptilia and Amphibia. Vol. 3. Serpentes. Taylor & Francis, London, xii + 583 pp.","Sharma, R. C. (2007) The fauna of India and the adjacent countries. Reptilia. Vol. III. Serpentes. Zoological Survey of India, Kolkata, 410 pp.","Shine, R., Lankilde, Wall, M. & Mason, R. T. (2005) The fitness correlates of scalation asymmetry in garter snakes Thamnophis sirtalis parietalis. Functional Ecology, 19, 306 - 314. https: // doi. org / 10.1111 / j. 1365 - 2435.2005.00963. x","Mebert, K. (2011) Introduced and Indigenous Populations of the Dice Snake (Natrix tessellata) in the Central Alps - Microgeographic Variation and Effect of Inbreeding. Mertensiella, 18, 71 - 79.","Wall. F. (1909 b) Notes on snakes from the neighbourhood of Darjeeling. Journal of the Bombay Natural History Society, 19, 337 - 357.","Gunther, A. (1860) Contribution to a knowledge of the reptiles of the Himalaya mountains. Proceedings of the Zoological Society of London, 28, 148 - 175.","Boulenger, G. A. (1893) Catalogue of snakes in the British Museum (Natural History). Volume 1. Containing the families Typhlopidae, Glauconiidae, Boidae, Ilysiidae, Uropeltidae, Xenopeltidae and Colubridae, British Museum (Natural History), London, xiii + 448 pp, 28 pls. https: // doi. org / 10.5962 / bhl. title. 54273","Annandale, N. (1904) Additions to the collection of oriental snakes in the Indian Museum. Journal of the Asiatic Society of Bengal, 73, 207 - 211.","Agarwal, I., Mistry, V. & Athreya, R. (2010) Preliminary checklist of reptiles of the Eaglenest wildlife sanctuary, west Kameng district, Arunachal Pradesh, India. Russian Journal of Herpetology, 17, 81 - 93.","Wallach, V., Williams, K. L. & Boundy, J. (2014) Snakes of the world: a catalogue of living and extinct species. CRC Press, Boca Raton, xxvi + 1209 pp. https: // doi. org / 10.1201 / b 16901","Wall, F. (1924) A hand-list of snakes of the Indian empire. Part II. Journal of the Bombay Natural History Society, 29, 59 - 878.","Das, I. (2002) A photographic guide to snakes and other reptiles of India. New Holland Publishers (UK) Ltd., London, 144 pp.","Chettri, B., Bhupathy, S. & Acharya, B. A. (2009) Morphometrics and aspects of breeding biology of Trachischium guentheri Boulenger, 1890 (Serpentes: Colubridae) in north Sikkim, eastern Himalaya, India. Russian Journal of Herpetology, 16, 177 - 182."]}
Databáze: OpenAIRE
Externí odkaz: