Research Article |
Corresponding author: Pratyush P. Mohapatra ( pratyush.m@zsi.gov.in ) Academic editor: Uwe Fritz
© 2021 Surya Narayanan, Pratyush P. Mohapatra, Amirtha Balan, Sandeep Das, David J. Gower.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Narayanan S, Mohapatra PP, Balan A, Das S, Gower DJ (2021) A new species of Xylophis Beddome, 1878 (Serpentes: Pareidae) from the southern Western Ghats of India. Vertebrate Zoology 71: 219-230. https://doi.org/10.3897/vz.71.e63986
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We reassess the taxonomy of the Indian endemic snake Xylophis captaini and describe a new species of Xylophis based on a type series of three specimens from the southernmost part of mainland India. Xylophis deepaki sp. nov. is most similar phenotypically to X. captaini, with which it was previously confused. The new species differs from X. captaini by having a broader, more regular and ventrally extensive off-white collar, more ventral scales (117–125 versus 102–113), and by lack of flounces on the body and proximal lobes of the hemipenis. Phylogenetic analysis of mitochondrial 16S DNA sequences strongly indicates that the new species is most closely related to X. captaini, differing from it by an uncorrected pairwise genetic distance of 4.2%. A revised key to the species of Xylophis is provided.
Hemipenis, Kanyakumari, molecular phylogeny, snakes, taxonomy, Xylophiinae
The fossorial snakes of the genus Xylophis Beddome, 1878 (Pareidae: Xylophiinae) are endemic to the Western Ghats region of peninsular India. The genus comprises four currently recognised species, namely X. perroteti Duméril, Bibron and Duméril, 1854, X. stenorhynchus (Günther, 1875), X. captaini Gower and Winkler, 2007, and X. mosaicus Deepak, Narayanan, Das, Rajkumar, Easa, Sreejith and Gower, 2020 (
We generated DNA sequence data for the mitochondrial 16S rRNA gene (16S) for one Xylophis specimen (ZSI-CZRC-V-7218) from Melpuram, Kanyakumari district, Tamil Nadu, India. Genomic DNA was extracted from liver tissue stored in absolute ethanol at –20C, using the DNeasy (QiagenTM) blood and tissue kit. We amplified a partial sequence of 16S using the primers 16Sar-L and 16Sar-H and reported protocols (
DNA sequence data for mitochondrial 16S rRNA gene used in phylogenetic analyses. All data previously published except for Xylophis deepaki sp. nov.
Species | Voucher | GenBank # | Corresponding GenSeq Nomenclature |
Xylophis captaini (Pareidae: Xylophiinae) |
|
MK340909 | genseq-1 16S |
Xylophis deepaki sp. nov. (Pareidae: Xylophiinae) | ZSI-CZRC-7218 | MW832840 | genseq-1 16S |
Xylophis mosaicus (Pareidae: Xylophiinae) |
|
MN970035 | genseq-1 16S |
Xylophis perroteti (Pareidae: Xylophiinae) |
|
MN970037 | genseq-3 16S |
Xylophis perroteti (Pareidae: Xylophiinae) | CES 2016b | MK340908 | genseq-3 16S |
Xylophis perroteti (Pareidae: Xylophiinae) |
|
MN970036 | genseq-3 16S |
Xylophis stenorhynchus (Pareidae: Xylophiinae) | CAS 17199 | MK340907 | genseq-4 16S |
Pareas monticola (Pareidae: Pareinae) | ADR 507 | MN970033 | — |
Pareas cf. formosensis (Pareidae: Pareinae) | CHS 886 | MK194290 | — |
Achalinus rufescens (Xenodermidae) | CHS 868 | MK194279 | — |
Xenodermus javanicus (Xenodermidae) |
|
AF544810 | — |
Bayesian (BI) phylogenetic analysis was carried out with MrBayes 3.2 (
In addition to the materials of the species described here, we examined the type material of all species of Xylophis, including junior synonyms, except for X. perroteti for which we relied on data and photographs presented by
Catalogue numbers for voucher specimens bear the following prefixes:
Meristic and morphometric (in mm) character data for Xylophis deepaki sp. nov. † indicates data from
Registration number | ZSI-CZRC-7218 |
|
ZSI-SRC-VRS-287 |
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†CSPT/S 77A & B |
Specimen status | Holotype | Paratype | Paratype | Referred specimen | Referred specimens |
Sex | Male | Male | Male | Female? | Male & Female |
DSR | 15:15:15 | 15:15:15 | 15:15:15 | 15:15:15 | 15:15:15 |
SL | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 |
IL | 5/5 | 5/5 | 5/5 | 5/5 | 5/5 |
TL | 136 | 112 | 125 | 115 | 176–199 |
tL | 16 | 10.4 | 15.4 | — | 10–16 |
W | 3.4 | 3.1 | 3.7 | — | 4.62–4.70 |
V | 123 | 120 | 123 | c.125 | 117–118 |
SC | 23 | 22 | 20 | 16 | 13–18 |
HL | 4.3 | 3.8 | 4.4 | — | 4.75–4.93 |
Hw | 3.6 | 2.9 | 3.7 | — | 4.27–4.55 |
F-Snt | 1.4 | 1.5 | 1.5 | — | 1.87–1.99 |
PrfL | 0.6 | 0.6 | 0.6 | — | 0.51–0.65 |
F-Snt ÷ PrfL | 2.1 | 2.5 | 2.3 | — | 3.06–3.60 |
FL | 2.6 | 1.9 | 2.1 | — | 2.51–2.55 |
Fw | 1.8 | 1.8 | 2.0 | — | 2.23–2.33 |
PaL | 2.2 | 2.0 | 2.5 | — | 2.47–2.62 |
Both ML and BI analyses recovered the same set of relationships (Fig.
Uncorrected pairwise distances for mitochondrial 16S rRNA gene among samples used in the phylogenetic analyses.
Species | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | |
1 | Xylophis captaini | ||||||||||
2 | Xylophis deepaki sp. nov. | 0.042 | |||||||||
3 | Xylophis mosaicus | 0.095 | 0.086 | ||||||||
4 | Xylophis perroteti BNH S3582 | 0.109 | 0.102 | 0.051 | |||||||
5 | Xylophis perroteti CES2016b | 0.101 | 0.096 | 0.046 | 0.000 | ||||||
6 |
Xylophis perroteti |
0.110 | 0.107 | 0.055 | 0.000 | 0.006 | |||||
7 | Xylophis stenorhynchus | 0.086 | 0.080 | 0.063 | 0.074 | 0.070 | 0.077 | ||||
8 | Pareas monticola | 0.148 | 0.150 | 0.112 | 0.090 | 0.114 | 0.090 | 0.117 | |||
9 | Pareas cf. formosensis | 0.119 | 0.119 | 0.069 | 0.087 | 0.083 | 0.089 | 0.091 | 0.093 | ||
10 | Achalinus rufescens | 0.126 | 0.130 | 0.119 | 0.137 | 0.132 | 0.138 | 0.112 | 0.141 | 0.136 | |
11 | Xenodermus javanicus | 0.149 | 0.151 | 0.126 | 0.151 | 0.151 | 0.151 | 0.136 | 0.124 | 0.147 | 0.098 |
Xylophis perroteti
–
Xylophis captaini
– Gower and Winkler, 2007 [in part];
India, Tamil Nadu: close to Marthandam, 8°20.610’N, 77°13.092’E, 56 m a.s.l., plantation, 23 November 2016, Surya Narayanan and Pratyush P. Mohapatra leg., see map in Fig.
Holotype male, spirit preserved, with hemipenis in a separate vial, ZSI-CZRC-V-7218 (Figs
The new species is assigned to the genus Xylophis based on the anterior-most (three) pairs of infralabial shields reduced to narrow strips, together much smaller than large pair of anterior chin (genial) shields. Xylophis deepaki sp. nov. is small (maximum known total length 199 mm), with 15 dorsal scale rows at midbody, 117–125 ventrals (n=6), 13–23 subcaudals (n=6), internasal length almost equal to the prefrontal length, a thick and ventrally near-complete off-white collar, and mostly smooth hemipenial body and lobes.
Xylophis deepaki sp. nov. differs from X. perroteti (including its putative synonym X. microcephalum, see
The new species differs from X. stenorhynchus (and its putative synonym X. indicus, see
Xylophis deepaki sp. nov. differs from its superficially most-similar congener and closest relative, X. captaini, in having more ventral scales, 117–125 (vs. 102–113), a wide off-white collar band that extends onto the ventral surface (vs. narrow and dorsally restricted collar band), lacking a dark lateroventral line on the third dorsal scale row on each side (vs. present in X. captaini) and in having a largely smooth hemipenis with a protrusion on the hemipenial body (vs. proximal half of each lobe having about eight, approximately transverse fleshy flounces and lacking a protrusion on the body). The new species differs from congeners by an uncorrected pairwise DNA-sequence difference of 4% in mitochondrial 16S.
Some morphometric and meristic data are given in Table
Back of head slightly wider than anterior of the neck and narrowing steadily anteriorly thereafter. Head short, 4.3 mm, and high, 2.6 mm, with steeply domed snout in lateral view. Snout abruptly tapering to blunt, rounded tip in dorsal view. Rounded rostral short in dorsal view, much shorter than the distance between it and prefrontal scales. Nasals undivided, not in contact with each other and each smaller than the rostral that separates them anteriorly. Naris subcircular, situated in the anterior part of the nasal. Paired internasals large, much larger than the nasals and rostral. Prefrontals distinctly larger than the internasals in area and slightly longer along the midline suture (0.7 mm vs. 0.5 mm between internasals). Frontal kite-shaped with the anterior margin slightly convex, noticeably longer (2.6 mm) than broad (1.8 mm) and almost as long as the parietals. Parietals longer than wide, with short midline contact (0.4 mm), much shorter than midline contact between internasals and between prefrontals.
Five supralabials, third and fourth contacting eye; first very small, contacting second supralabial, rostral and nasal; second is a thin strip contacting the nasal, loreal and adjacent supralabials; third taller than long, contacting loreal and adjacent supralabials; fourth slightly larger than the third, contacting postocular, anterior temporal and adjacent supralabials; fifth largest, touching anterior and lower posterior temporal as well as fourth supralabial. Eyes small with a subcircular pupil. One supraocular and one postocular on each side, subequal in size. One anterior temporal, larger than two subequal posterior temporals. Mental short, broad, with a tripartite anterior end. Anterior two infralabials short and thin, second slightly larger. The length of first two infralabials together shorter than the third, and in lateral view falling notably short of halfway along the length of anterior genials. Fourth and fifth infralabials much larger. Pair of anterior genials, large, meeting substantially along the midline. Posterior pair of genials much smaller, contacting briefly along the midline, largely divided by the intervening anteriormost ventral. First unpaired midventral scale (= first ventral, here) between posterior genials, larger than the subsequent ventrals, longer than wide and the subsequent ventral scales are wider than long. Body subcylindrical, ventral surface slightly flattened, Dorsal scales in 15 rows at the level of fifth ventral until the posteriormost ventral. Dorsal scales macroscopically smooth, regularly arranged, evenly sized across the body and apical pits absent. Ventrals scales 123 in number, all similarly proportioned except for anteriormost ventral. Anal shield undivided, larger than the last ventrals, its posterior margin overlaps six scales on each side, including the subcaudals. Subcaudals in 23 pairs. Tail terminates in bluntly tapering, apical, spine-like scute.
Scales on the body and tail iridescent. Head scales match this, except for some of the anterior supralabials and infralabials. Overall, the specimen is in shades of brown mottled with off-white and with a distinct off-white collar. Ventral surface paler and less mottled than dorsum, and first three ventrals and adjacent scales mottled off-white continuation of the collar. The main body of each ventral and subcaudal scale are fairly uniform, pale brown, sometimes with an indistinct dark proximal margin anteriorly and off-white margin posteriorly. Upper and sides of the head and body-tail junction are darkest parts of the animal, notably darker than the body. Dorsal head scales generally dark brown with distinct irregular off-white mottling on all scales except for darker frontal. First two supralabials and first three infralabials off-white with a small brown patch only on the second supralabial. Other lateral head scales brownish with very little pale mottling except for a substantial off-white patch on the anterior part of the lower posterior temporal. Collar band off-white, approximately two scales wide with slightly irregular anterior and posterior edges, extends laterally on both sides and connected ventrally where it is two to three scales wide but somewhat broken by brown mottling. Three distinct dark lines on the dorsal surface, running from behind the collar to tail tip, all more than half a dorsal scale wide, being one scale wide at the body-tail junction. Distinct dark dorsal stripe up to almost one scale wide, medially along the middorsal line, narrowly breaking the pale collar mid-dorsally. Middorsal line confined to the midline (eighth) scale row and the pair of dorsolateral lines confined to the 5th dorsal scale row on each side. Three thin, indistinct ventrolateral lines run along the first three dorsal scale rows of each side, becoming feeble and almost invisible at the level of approximately the 30th ventral. Between dark longitudinal lines, scales are various shades of mottled pale brown and off-white. In life, the colouration is almost the same as in the preserved condition except for the pale collar which has faded in ethanol-preserved specimens.
Hemipenis (Fig.
See Table
This species is named in honour of the Indian herpetologist Dr Deepak Veerappan, in recognition of his substantial, 21st Century contributions to herpetology, including work on Xylophis systematics. We suggest the common name Deepak’s wood snake (English).
Based on the limited current knowledge, Xylophis deepaki sp. nov. is endemic to Tamil Nadu, known from only a few locations along the south-western slopes of the southernmost part of the Western Ghats. Apart from Melpuram, Pathukani, Ambadi estate, and Ashambu hills in Kanyakumari District (vouchered specimens), X. deepaki is also known from Kulashekaram, Keeriparai and Thadikarankonam, Kanyakumari District of Tamil Nadu (uncollected, live observations), at elevations of 86–245 m a.s.l.. This region receives an annual rainfall of ca. 1500–2600 mm (
The holotype (ZSI-CZRC-V-7218) and paratype-1 (ZSI-SRC-VRS-287) along with three other individuals (uncollected) were found in a private plantation area consisting of mixed coconut and plantain crops (Fig.
Currently, X. deepaki sp. nov. is not reported from any protected areas and all the known records are from human-modified landscapes such as plantations, except for the record from Ashambu hills.
Xylophis spp. are not protected under any schedules of the Indian Wild Life (Protection) Act, 1972. We encourage additional studies on their taxonomy, ecology and evaluation of their conservation status of these snakes, which might aid in future amendment of the Act.
This revised key is based on that presented by
1 | Dorsal scales in 13 rows at midbody; supraocular notably larger than postocular; six or more infralabials | 2 |
– | Dorsal scales in 15 rows at midbody; supraocular and postocular shields subequal in size; five infralabials | 3 |
2 | First ventral separates the posterior genials and contacts the anterior genials | X. perroteti (including its putative junior subjective synonym X. microcephalum) |
– | Posterior genials in midline contact, preventing contact between first ventral and anterior genials | X. mosaicus |
3 | Ventrals 120–135; prefrontal shields much longer than internasals; second infralabial notably longer than first, the two together being about as long as the third infralabial | X. stenorhynchus (including its putative junior subjective synonym X. indicus) |
– | Ventrals 106–125; prefrontals and internasals subequal in midline length; second infralabial only marginally longer than first, the two together being shorter than the third infralabial | 4 |
4 | Ventrals 102–113; pale collar restricted to dorsum; hemipenis body with large flounces | X. captaini |
– | Ventrals 117–125; pale collar extends onto venter; hemipenis body without flounces | X. deepaki sp. nov. |
Our description of X. deepaki sp. nov. increases the total number of currently recognised Xylophis species to five, excluding the two putative synonyms X. microcephalum and X. indicus (see
Classification of Xylophis under the newly described subfamily Xylophiinae (family Pareidae) based largely on molecular phylogenetics (
During this study, it was drawn to our attention (V. Deepak, pers. comm.) that the numbers of subcaudals of
As per our present understanding, X. deepaki sp. nov. is the only species of Xylophis to occur at the far southern end of the Western Ghats, where it is restricted to low and mid-elevations of the southwestern slopes of this mountain range. However, it should be noted that previous confusion with X. captaini, and lack of dedicated Xylophis surveys (other than those reported by
In addition to new materials reported here, we have identified some of the Xylophis captaini specimens (
The authors have no funding to report.
The authors have declared no competing interests exist.
SN thanks Dr Aravind Madyastha (ATREE, Bengaluru) and SB thanks Dr Aneesh Embalil for support and making lab facilities available; Rahul Khot, Saunak Pal, Vithoba Hegde, Shyam Jadhav for extending full support during the visits to