Xylophis deepaki, Narayanan & Mohapatra & Balan & Das & Gower, 2021

Narayanan, Surya, Mohapatra, Pratyush P., Balan, Amirtha, Das, Sandeep & Gower, David J., 2021, A new species of Xylophis Beddome, 1878 (Serpentes: Pareidae) from the southern Western Ghats of India, Vertebrate Zoology 71, pp. 219-230 : 219

Xylophis deepaki sp. nov.

Figs 1 , 2 , 3 , 4 , 5A

Xylophis perroteti - Rajendran (1985). [Chresonym]

Xylophis captaini - Gower and Winkler, 2007 [in part]; Ganesh (2010); Ganesh et al. 2012; Bhupathy et al. 2016 [in part] [Chresonym]

Type locality.

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. 2 .

Type specimens.

Holotype male, spirit preserved, with hemipenis in a separate vial, ZSI-CZRC-V-7218 (Figs 3 , 4 , 5A ). Paratype-1, male, collection details as for holotype, ZSI-SRC-VRS-287 (Figs 6 A-D , 5B ). Paratype-2, male, collector unknown, from Potugani junction, Kanyakumari Dist., Tamil Nadu (=Pathugani) (8°28.672'N, 77°13.627'E, 240 m a.s.l), collection date unknown, BNHS 3383 (see Gower and Winkler 2007: 316).

Referred specimens (n = 3).

BNHS 1762, female (?), collected from Ashambu hills, Tamil Nadu is treated as a referred specimen and not a paratype because of the imprecise locality and poor condition of the specimen. CSPT/S 77a and 77b from Ambadi estate, Kanyakumari District, Tamil Nadu (reported as X. captaini by Ganesh et al. 2012) are referred but have not been examined by us.

Diagnosis.

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 Deepak et al. 2020) and X. mosaicus in having 15 rather than 13 dorsal scale rows along most of the body. Additionally, the new species has relatively short prefrontals and broad, squarish internasals (vs. long prefrontals and internasals), and a distinct off-white collar band (vs. absent). The hemipenis of X. deepaki is smooth with few, ill-defined flounces towards the distal end of the lobes (vs. well-defined longitudinal flounces in X. perroteti ) and differs from that of X. mosaicus in having a short, smooth body and lobes (vs. elongated body, ill-defined ‘calyces’ and scattered fleshy papillae on the distal part of the body and the lobes).

The new species differs from X. stenorhynchus (and its putative synonym X. indicus , see Gower and Winkler 2007) in having generally fewer ventrals, 117-125 (vs. 120-135), internasals almost as long as the prefrontals along the midline (vs. substantially shorter than prefrontals), the length of first and second infralabialstogether shorter than the third (vs. about as long as the third infralabial), and a wide off-white collar extending to the ventral surface (vs. narrow and dorsally restricted collar band).

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.

Description of holotype (ZSI-CZRC-V-7218).

Some morphometric and meristic data are given in Table 2 . A male specimen, in good condition, a longitudinal ventral incision into coelom extending from 64th to 67th ventral. The body preserved in a loose coil, slightly dorsoventrally flattened, with a small constriction slightly below the midbody caused by overly tight tying of a field tag. Both hemipenes removed for further preparation, stored with the specimen. Colours have not noticeably faded in preservative.

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. 7 ) 8.5 mm in total length, 53% of the tail length, extending to posterior of the 12th subcaudal. Bilobed and deeply forked, for 37.6% of total length. Apical lobes cylindrical and slightly unequal (length and the maximum width of each lobe: 5.3 and 0.9 mm; 4.6 and 0.8 mm, respectively). Hemipenial body unornamented except for a fleshy protuberance on the sulcal side, slightly proximal to the fork, below the sulcus division. The sulcus bifurcates at almost three quarters along the length of the hemipenial body and runs centro-linearly, terminating distally below the apex. In the fully everted hemipenis, the sulcus canal is not exposed but rather enclosed by the lips. The head appears to be rounded and disk-shaped. Towards the distal end, there are 4-8 oblique, inconspicuous flounces on both sides of the sulcus spermaticus. A few scattered microscopic papillae on the flounces at the distal end.

Variation in paratypes.

See Table 2 for variation in some meristic and morphometric features. Paratypes generally very similar to holotype. Both paratypes generally in moderate to good condition. In ZSI-SRC-VRS-287 the upper posterior temporals slightly smaller on both sides; the posterior pair of genials separated by a macroscopically indistinct thin slither of the first ventral; the third ventral is the first scale that is wider than long. ZSI-SRC-VRS-287 is preserved in a U-shaped loose coil and lacks any incision into the coelom; head slightly narrower (not an artefact of preservation); frontal more domed anteriorly, making the prefrontal appear shorter along the midline in dorsal view; midline contact between parietals slightly longer than between both internasals and both prefrontals; third supralabial wider along the lower margin; pale collar less distinct ventrally. In BNHS 3383, the posterior margin of the anal shield overlaps five rather than six scales on each side, including the subcaudals.

Etymology.

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).

Distribution and natural history.

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 ( Glenna et al. 2018). The lower plains here, including the type locality, are currently dominated by extensive monocultures of rubber ( Hevea brasiliensis Müll.) and partly teak ( Tectona grandis L.) plantations. The natural vegetation of this region is of southern tropical dry deciduous forest with trees such as Haldina cordifolia (Roxb.), Cochlospermum religiosum (L.), Dillenia pentagyna Roxb., Hydnocarpus laurifolia (Dennst.), Hymenodictyon excelsum (Roxb.) and Lannea coromandelica (Houtt.) with mostly red soil and mixed with varying quantity of ferruginous elements (Henry and Swaminathan 1981).

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. 8 ). These animals were found while digging humus-rich, clay mixed red soil in the farmed land. Xylophis deepaki sp. nov. appears to be common within its currently known range. One of us (AB) has encountered as many as eight individuals of Xylophis cf. deepaki . while removing stone debris in a rubber plantation at ca. 14:00hrs in November 2013 at Thadikarankonam, Kanyakumari District, Tamil Nadu and one specimen from Keeriparai, Kanyakumari District, Tamil Nadu was found moving on the surface during rains in a rubber plantation (farmland) at 18:00hrs in October 2014; these records are provisionally treated as likely to be the new species because these localities are close to the type locality of X. deepaki sp. nov. Rajendran (1985) reports a series of Xylophis perroteti found sympatric with Rhinophis travancoricus in Ambadi estates near Pechiparai dam, with four individuals of Xylophis sp. found while digging along a brook; these are very far from the known distribution of X. perroteti and at much lower elevations (see Deepak et al. 2020), and instead might also represent X. deepaki sp. nov. based on the locality. Rajendran (1985) stated that the Xylophis he observed likely fed on termites, but the basis for that is unclear, and as far as we know, no feeding observations have yet been reported. Gower and Winkler (2007) reported earthworms in the guts of two specimens in X. captaini .

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. Bhupathy et al. (2016) predicted X. captaini to occur in Kanyakumari Wildlife Sanctuary and Kalakkad Mundanthurai Tiger Reserve based on the results from environmental niche modelling, where possibilities of sympatric occurrence of the both X. captaini and X. deepaki cannot be ruled out. Additionally, the underlying distribution data for X. captaini used by Bhupathy et al. (2016) included the southernmost records from Gower and Winkler (2007) that are here shown to instead represent X. deepaki sp. nov.

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.

Figures

Figure 1. BI Phylogeny showing the phylogenetic relationships of Xylophis deepaki sp. nov. Numbers at internal branches are posterior probability and ML bootstrap support values, respectively. Scale bar represents substitutions per site.

Figure 2. Distribution of Xylophis captaini and X. deepaki sp. nov. in the Western Ghats based on specimens examined in this study and observations of uncollected animals reported in the text.

Figure 3. Holotype of Xylophis deepaki sp. nov (ZSI-CZRC-V- 7218) in dorsal (A) and ventral (B) views. Scale bar = 10 mm

Figure 4. Head of holotype of Xylophis deepaki sp. nov. (ZSI-CZRC-V- 7218) in dorsal (A), ventral (B), right lateral (C) and left lateral (D) views. Scale bar = 10 mm.

Figure 5. Xylophis deepaki sp. nov. showing colour in life. A. Holotype ZSI-CZRC-V- 7218, B. Paratype ZSI-SRC-VRS- 287.

Figure 6. Views of the head of paratypes of Xylophis deepaki sp. nov. (A-D. ZSI-SRC-VRS- 287, E-H. BNHS 3383); dorsal view (A, E), ventral view (B, F), right lateral view (C, G) and left lateral view (D, H). Scale bar = 10 mm.

Figure 7. Hemipenis of Xylophis deepaki sp. nov. (ZSI-CZRC-V- 7218). (A) sulcate view of left side; (B) asulcate view of left side; (C) sulcate view of the right side; (D) enlarged view of the distal portion of the sulcate side. Scale bar = 1 mm.

Figure 8. Habitat of Xylophis deepaki sp. nov. in Melpuram, Kanyakumari Dist., Tamil Nadu, showing some banana and coconut within rubber plantation.