Dryocalamus chithrasekarai Vidanapathirana & Pushpamal & Wickramasinghe 2020, sp. nov

Autor: Vidanapathirana, L. J. Mendis Wickramasinghe Dulan Ranga, Pushpamal, Vishan, Wickramasinghe, Nethu
Rok vydání: 2020
Předmět:
DOI: 10.5281/zenodo.3704867
Popis: Dryocalamus chithrasekarai, sp. nov. (Figs 1���4, 7, Table 1) Holotype. NMSL-NH 2019.26.01 (Figs. 2, 3), adult female, SVL 328 mm, Uda Pawanalla Police Post, Sripada (Peak Wilderness), Ratnapura District, Sabaragamuwa Province, Sri Lanka (06��47���42.3������N, 080��27���40.4������E; elevation 655 m a.s.l.), coll. Mendis Wickramasinghe & Dulan Ranga Vidanapathirana, 5 November 2009. Paratype. DWC 2019.05.03 (Fig. 4), juvenile male 199 mm SVL, from Kanneliya, Koralegama, Panangala, Galle, Southern Province, Sri Lanka, (06��14���52.5��� N, 080��19���48.6��� E; elevation 45 m a.s.l.), coll. Vishan Pushpamal, 18 June 2017. Diagnosis. We assign the new species to the genus Dryocalamus because it possesses the following characteristics: costal scales at midbody 13���15; loreal touching eye; broad and keeled ventrals, which are raised on the sides; divided subcaudals, which are raised on the sides. Dryocalamus chithrasekarai sp. nov., can be easily distinguished from all its congeners by the combination of the following characters: (1) the absence of a preocular scale; (2) loreal in contact with supraocular; (3) costal scales in 15 straight rows; (4) posterior margin of nuchal band appears flat; (5) white solid bands on anterior body, which appear somewhat circular centrally; (6) checkered appearance on posterior lateral body where consecutive bands coalesce at the ventrolateral margin; (7) banding present throughout the anterior venter; and (8) tail region consistently dark. Description of holotype. The holotype is an adult female with a snout-vent length of 328 mm and a tail length of 108 mm. Head oval in shape (Fig. 2A), depressed (Fig. 2B), distinct from neck (Figs. 2A & C); snout rounded in dorsal, lateral and ventral views. Body slender, subcylindrical in cross-section. Dorsals smooth, in 15/15/15 straight rows, of uniform shape (almost as long as wide, rhomboid); vertebral scale row (Fig. 2D) and outer row not enlarged (Fig. 2E); individual apical pits prominent on the three scale rows on mid-dorsum between second and third white crossbars from head (weaker towards posterior body); 1 preventral, 228 keeled ventrals (Fig. 2F), raised on the sides; cloacal shield divided; 99 divided subcaudals (Fig, 2G); caudal reduction: 11 to 7 (from the 2 nd SC), to 6 (from the 6 th SC), to 5 (from the 22 nd (L) and 21 st (R) SC) to 4 (from the 24 th SC), to 3 (from the 65 th SC), to 2 (from the 67 th SC); 7/7 supralabials, the 3 rd and 4 th in contact with the eye, the 6 th being longest in longitudinal axis, the 7 th widest in the transverse axis; 1/1 loreals, length equal to height, in contact with nasal, prefrontal, supraocular, eye, and 2 nd and 3 rd supralabials; no preocular; nasal divided, with suture meeting with first supralabial; naris in prenasal; 2/2 postoculars, lower one larger than upper one, which is in contact with supraocular, parietal and upper anterior temporal, while lower one touches the two anterior temporals and 4 th and 5 th supralabials; 2+2 / 2+2 temporals (Fig. 3A); rostral distinctly wider than high, visible in dorsal view; single pair of internasals, wider than long, shorter than prefrontals; single pair of prefrontals, wider than long, extending far onto sides of head to about level of center of eye; frontal pentagonal, longer than wide, longer than its distance from rostral, but shorter than parietals; supraoculars narrow, smaller than frontal; a single pair of parietals, longer than wide (Fig. 3B); 8/8 infralabials, first pair in contact behind mental, first four touching anterior chinshield, 4 th and 5 th in contact with posterior chinshield, 5 th largest; 2 pairs of chinshields, anterior pair longer and slightly wider than posterior pair; no invasive gulars between the chinshields (Fig. 3C); eye large, with slightly vertical-elliptical pupil, diameter of eye less than distance between anterior margin of eye and tip of snout, eye diameter slightly greater than distance from anterior margin of eye to naris. Colour in alcohol (holotype). Except nuchal band, which covers posterior third of parietals, entire head light brown dorsally. Ground colour light brown, with cream-coloured bands (32 on body, not counting nuchal band, 22 on tail). In anterior 18 bands, cream colour is solid, with outer margins scalloped and wider ventrolaterally, centrally with a somewhat circular appearance. Bands posterior to 19 th cream band exhibit a dark blotch within the widened base, where adjacent bands coalesce at ventrolateral margin, giving a checkered appearance laterally. The light bands are 2�� scales wide anteriorly, at level of vertebral scale row, decreasing to 2 scales wide towards base of tail. Width of light-brown interspaces decreases gradually caudad: 11 dorsals in vertebral row in the first dark interspace between nuchal band and first cream band, decreasing to 4 dorsals at tail base and from there to tip of tail. Dark areas reaching ventrals in anterior body: hence venter in that region appearing banded. Entire venter colouration cream with darker interspaces beginning in nuchal region; tail venter bears light brown speckles, no bands. Colour in life (paratype). Except for nuchal band, which covers posterior third of parietals, entire head dark brown dorsally. Ground colour jet black, with pure-white bands (32 on body omitting nuchal band, 21 on tail) (Fig. 4 A���B). In anteriormost 18 white bands, the white band is solid, with band-margins scalloped and wider ventrolaterally (Fig. 4B), centrally with a somewhat circular appearance. While posterior bands (caudad of 19 th white band) exhibit a dark blotch within the widened base, where consecutive bands coalesce at ventrolateral margin, resulting in a checkered appearance laterally. The light bands 2�� scales wide at level of vertebral scale row anteriorly, decreasing to 2 scales wide towards base of tail. Width of dark interspaces decreasing gradually caudad: 14 dorsals in vertebral row in first dark interspace between the nuchal band and first white band, declining to 4 dorsals from tail base to tip of tail. The dark interspaces reaching ventrals, giving venter a banded appearance. The entire venter colouration is greyish-white, producing a clouded appearance with darker interspaces beginning in nuchal region, while tail is consistently dark with no bands (Fig. 4C). Notes on paratype. The right eye was absent in the live juvenile male specimen at the time of collection. A 12 mm length of the tail was snipped off and preserved in ���DNA-grade��� ethanol for future molecular studies. The preserved specimen contains 15 white bands on the tail, and 74 (L)/ 75 (R) SC; 8/8 supralabials with the 6 th being the longest, and 7 th the widest; 8/7 infralabials where the 6 th and 7 th scales have been fused to form a single scale on the right side. Etymology. The species is named for Nagamulla Hewage Chithrasekara, in recognition of his efforts to protect the Kanneliya Forest Reserve, where the paratype was collected. The species epithet is a patronym Latinized in the genitive case. Suggested vernacular names. The vernacular names recommended for the species are ���Chithrasekarage gata radanakaya��� and Chithrasekara���s bridle snake in the languages Sinhala (vernacular) and English, respectively. Comparisons. Dryocalamus chithrasekarai sp. nov., is distinguished from its congeners in Sri Lanka as follows: It differs from D. gracilis by the absence (vs. presence) of a preocular scale; having the loreal in contact (vs. not in contact) with the supraocular (Figs. 3A, 5A); the cloacal shield divided (vs. undivided); posterior margin of the nuchal band flat (vs. convex) banding present throughout the anterior venter (vs. not banded, uniform creamy white); and the tail region consistently dark (vs. creamy white) (Figs. 2, 4, 5 B���C). The new species is distinguished from D. nympha by the absence (vs. presence) of a preocular scale; having the loreal in contact (vs. not in contact) with the supraocular (Figs. 3A, 6A); having 15 (vs. 13) costals; banding present throughout the anterior venter (vs. not banded, uniform creamy white); and the tail region consistently dark, with no white bands (vs. uniformly creamy white) (Figs. 2, 4, 6 B���C). Dryocalamus chithrasekarai sp. nov. is distinguished from D. davisonii (Blanford, 1878), to which it bears a superficial resemblance, by the absence (vs. presence) of a preocular scale, having the loreal in contact (vs. not in contact) with the supraocular, and having 15 (vs. 13) costals. It is distinguished from D. philippinus (Griffin, 1909), D. subannulatus (Dum��ril, Bibron & Dum��ril, 1854) and D. tristrigatus (G��nther, 1858) by the absence (vs. presence) of a preocular scale, having the loreal in contact (vs. not in contact) with the supraocular, the cloacal shield divided (vs. undivided), a banded appearance on the venter throughout the anterior body, and the tail region consistently dark, bearing no white bands (vs. entire venter and tail cream white, unbanded). Remarks. Although D. chithrasekarai sp. nov., is described from only two specimens, we have observed the species also at Kalubowitiyana (06��19���58.9���N, 080��24���09.5���E), Morawaka (06��15���58.9���N, 080��28���36.4���E) and Runakanda (06��27���15.1���N, 080��19���29.0���E) (Figs. 7 A���C), in addition two individuals from Sinharaja [06��26���18.1���N, 080��25���22.3���E (Fig. 7D) and 06��26���18.1���N, 080��26���40.6���E], all of which lie in the ���rain��� forests of the island���s south-western wet zone quadrant. All five individuals were identified in the field on the basis of the unique banded ventral coloration and the absence of a preocular scale.
Published as part of Vidanapathirana, L. J. Mendis Wickramasinghe Dulan Ranga, Pushpamal, Vishan & Wickramasinghe, Nethu, 2020, A new species of Dryocalamus (Serpentes: Colubridae) endemic to the rainforests of southwestern Sri Lanka, pp. 248-260 in Zootaxa 4748 (2) on pages 249-254, DOI: 10.11646/zootaxa.4748.2.2, http://zenodo.org/record/3698755
{"references":["Blanford, W. T. (1878) Notes on some Reptilia from the Himalayas and Burma. Journal of the Asiatic Society of Bengal, 47 (2), 125 - 131.","Griffin, L. E. (1909) A list of snakes found in Palawan. Philippine Journal of Science, 4, 595 - 601.","Dumeril, A. M. C., Bibron, G. & Dumeril, A. (1854) Erpetologie generale ou Histoire Naturelle complete des Reptiles. Vol. 9. Roret, Paris, 474 pp. https: // doi. org / 10.5962 / bhl. title. 100816","Gunther, A. (1858) Catalogue of Colubrine snakes of the British Museum. Printed by order of the Trustees, London, xvi + 281 pp."]}
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