Xylophis chenkaruppan, Narayanan & Das & Ghosh & Palot & Umesh & Gower & Deepak, 2025

Narayanan, Surya, Das, Sandeep, Ghosh, Avrajjal, Palot, Muhamed Jafer, Umesh, P., Gower, David J. & Deepak, V., 2025, Hidden in the Sky Islands: A new species of Xylophis Beddome, 1878 (Serpentes: Pareidae: Xylophiinae) from montane habitats of Wayanad in the Western Ghats of India, Zootaxa 5666 (4), pp. 509-528 : 512-521

Xylophis chenkaruppan sp. nov.

urn:lsid:zoobank.org:act:39AA177C-CC39-4DE0-82DA-006936BFBF58

Diagnosis and comparison. A Xylophis with 13 dorsal scale rows at midbody, preocular pentagonal having minimal contact with the eye, posterior genials in midline contact, 126–131 ventral, and 23–38 subcaudal scales. Smaller (presumably younger) individuals are dark in coloration and larger (presumably adult individuals) generally have a reddish-dun dorsum with black mottling and reddish ventrum.

Xylophis chenkaruppan sp. nov. is distinguished from X. stenorhynchus (and its putative synonym X. indicus ), X. captaini and X. deepaki in having 13 instead of 15 dorsal scale rows at midbody, and in having relatively long prefrontals (vs. short). Xylophis chenkaruppan sp. nov. differs from X. perroteti (and its synonym X. microcephalum ) in having the posterior pair of genial scales in midline contact ( Fig. 3A ) (vs. posterior pair of genial scales separated along the midline by the first ventral scale) ( Fig. 3C ). In terms of head scalation, the new species more closely resembles X. mosaicus ( Fig. 3B ) than its sister X. perroteti . Xylophis chenkaruppan sp. nov. and X. mosaicus differ in adult colour, having reddish rather than yellowish markings ventrally. Sample sizes are not large, but there is also an indication that the new species has fewer ventrals and more subcaudals than X. mosaicus for both males (<131 ventrals and>33 subcaudals, n = 5 versus> 127 and <34, respectively, n = 7) and females (131 and 23 or 24, n = 1 versus> 135 and> 16, n = 6) ( Fig. 4 ).

Holotype. ZSI / WGRC /IR. V.3825 ( Figs. 3A , 5 , 6 ), male, from Vellarimala Hills , Wayanad district, Kerala, India (11.4677°N, 76.1463°E; 1409 m elevation), collected by Muhamed Jafer Palot, Avrajjal Ghosh and Umesh P. on 7th October 2015. See map in Fig. 1 .

Paratypes (n=5). BNHS 3381 & BNHS 3383 , male, BNHS 3382 , female, collection details same as holotype. ZSI / WGRC /IR-V.3826& ZSI / WGRC /IR-V.3827from Kurichyarmala Hills, Wayanad District , Kerala (11.602652°N, 75.968739°E, 1431 m elevation) collected by Muhamed Jafer Palot & Sandeep Das on 30 th January 2010 .

Description of holotype. Some morphometric and meristic data are given in Table 1. Male, specimen in good condition, both hemipenes everted, right hemipenis removed for detailed examination; ventral incision in the midbody, three ventral scales long.

Body subcylindrical, dorsoventrally slightly flattened. Head not (or barely) wider than the anterior end of body. Head narrows anteriorly, steadily in dorsal and ventral views, with very slightly convex edges. Head narrow, subtriangular with bluntly rounded tip in dorsal view, broader (HW 8.3 mm) than tall (HH 5.5 mm), gradually tapering from the posterior of parietal to snout tip in lateral view. Rostral very short in dorsal view, slightly shorter than the distance between it and prefrontal scales. Rostral contacts anterior edges of first supralabials, anterior edges of internasal, and lateral edges of nasal. Rostral falls short of level of ventral edges of anterior supralabials, resulting in small median notch at anterior margin of upper lip. Nasals slightly rectangular, undivided. External naris in the anterior region of the nasal, elliptical. Left and right nasals not in contact, each subequal in area to the intervening rostral. Paired internasals subrectangular, lacking straight edges, broader where they meet, little larger than nasals and rostral, much smaller than prefrontals. Paired prefrontals little shorter than length of frontal. Prefrontal and internasals not in midline contact. Single elongated preocular on either sides, much broader and taller anteriorly and narrower towards the ocular, with minimal contact with spectacle. Five supralabials; third and fourth contacting spectacle. First supralabial very small, contacts only rostral and nasal other than second supralabial ( Fig. 6B ). First supralabial wedging into margins of nasal and rostral. Second supralabial small, rectangular, thin strip contacting nasal, one large scale between spectacle and nasal, and first and third supralabials. Third and fifth supralabials longer than tall, fourth taller than long, fifth largest. Third and fourth supralabials in contact with spectacle. Fourth supralabial also contacts postocular and anterior temporal. Fifth supralabial contacts anterior temporal and lower posterior temporal. Scale between spectacle and nasal pentagonal, elongate, anterior end slightly curved (towards nasal), shorter (1.8 mm) than prefrontals (2.1 mm) in length. Irregularly hexagonal frontal notably longer (3.2 mm) than broad (2.5 mm), and much shorter than paired parietals. Temporals 1 + 2, subequal in size, anterior one wedged between last two supralabials. Small, elongate supraocular (irregularly pentagonal, wider posteriorly) and a smaller, less elongate postocular.

Anterior of lower jaw dominated by large pair of anterior genials meeting along midline mental groove, prevented from reaching margin of mouth by small mental and three very slender infralabials ( Fig. 3C ). Posterior genials in wide contact with each other. Mental short, broad, with tripartite anterior end ( Fig. 3B & 6A ). Six infralabials. First infralabial shortest, broader than long; second larger than first, shorter than third. First two infralabials overlap anterior half of anterior genials; third infralabials overlap posterior half of anterior genials. First unpaired midventral scale (= first ventral, here) lies immediately behind posterior genials, wider than long. Second ventral scale shorter than first, much wider. Dorsal scales in 13 rows from at least as far anterior as level with seventh ventral, maintained up to posteriormost ventral. Dorsals generally regularly arranged; lowest four dorsal rows on either side distinctly larger than the three middorsal rows. All body scales macroscopically smooth, glossy, lacking keels. Ventral scales 130, all similarly proportioned except for anteriormost ventral. Ventrals generally have curved (convex) posterior margins, but much less so on anteriormost ventral. Anal shield undivided, longer than the last ventral, its margin overlaps two small, irregular scales on either side in addition to a pair of larger subcaudals medially. Subcaudals paired, 37 on each side. Tail ends in a sharply tapering terminal scute.

Hemipenis (based on the holotype): Relatively long hemipenis, 31.5 mm in total length, 49% of tail length ( Fig. 7 ). Bilobed and deeply forked, for 34.3% of total length. Apical lobes cylindrical. Hemipenial body unornamented except for few fleshy protuberances. Sulcus bifurcates at almost three-quarters along length of hemipenial body and runs centro-linearly, terminating distally below apex. In fully everted hemipenis, sulcus canal is not exposed but instead enclosed by lips. Towards distal end, 7 or 8 flounces with spine-like projections towards apex.

Variation in paratypes: Some of the variations in the meristic and morphometric characteristics among the paratypes are provided in Table 1. ZSI / WGRC /IR-V.3826 & BNHS 3381 preserved in a “U” shaped loose coil. Hemipenis not everted in other male specimens. Midventral incisions in varying lengths in BNHS 3381 , BNHS 3382 and BNHS 3383 , and no incisions in ZSI / WGRC /IR-V.3826 & ZSI / WGRC /IR-V.3827. Prefrontals and internasals in midline contact in BNHS 3381 and BNHS 3383 ( Fig. 8 ). Other main variations based on the coloration are provided below .

Colour in life and preservatives: Based on the specimens collected it is possible that Xylophis chenkaruppan sp. nov. undergoes an ontogenetic colour shift. The larger individuals (ZSI/WGRC/IR.V.3825 & BNHS 3381) are reddish, mostly with dark coloration in the head and tail with dark mottling in the dorsum, with reddish ventrum. Comparatively smaller individuals (BNHS 3383 & ZSI/WGRC/IR-V.3827: Appendix. 2) have fully dark dorsum and ventrum. One other smaller individual (ZSI/WGRC/IR-V.3826) appears to have an intermediate coloration with reddish mid-dorsum with most parts of the anterior and the posterior of the dorsum darkish. It appears unlikely to be a sexual dimorphism because, the female (BNHS 3382) resembles the other larger males in coloration in having reddish dorsum with darker head and tail markings.

In life, holotype ZSI/WGRC/IR.V.3825 was dorsally reddish with scattered black mottles, mostly one dorsal scale wide, darker patches slightly larger on the back of the head, extending posteriorly to the level of the eighth ventral; in the posterior part of the body, the dark spots become larger (two dorsal scales wide) laterally and in the mid dorsum, extending to the tip of the tail, making a trilineate color pattern. Head slightly paler than the body. Ventrum uniformly reddish with whitish margins. Ventral surface of the head and anterior of body with Y-shaped (posteriorly diverging) black marking extending from the first to sixth ventral. Underside of the tail mostly reddish with irregular patches of dark spots, slightly larger in the middle of the tail; tip of the tail fully dark.

Paratypes BNHS 3381 & 3382 largely resembling holotype, except the darker patch on the anterior dorsum much thicker extending up to the level of 20th and 28th ventral, respectively. BNHS 3383 & ZSI/WGRC/IRV.3827 uniformly darker on both dorsum and ventrum except below the head, where scales around the Y-shaped mark paler. Ventral scales completely dark from the level of sixth ventral to the tip of the tail in BNHS 3383 . ZSI/WGRC/IR-V.3826 with reddish dorsum, much darker in the anterior region, with seven black irregularly sized lateral pentagonal shaped markings. In the trilineate marking, the mid dorsal dark line covers up to five dorsal scales anteriorly, gradually becoming narrower posteriorly. In preservative, the reddish colour in ZSI/WGRC/IR. V.3825, BNHS 3381 & 3382 has faded to brown, with dark patches and mottling intact. ZSI/WGRC/IR-V.3826 & 3827 are completely pale in colour, likely an artefact of longtime exposure to natural light.

Etymology: The specific epithet chenkaruppan is a portmanteau of two words from Malayalam language, “Chem” = red and “Karupp” = black, in reference to the red and black dorsal coloration of the new species. For nomenclatural purposes, the specific epithet is treated as a noun in opposition. To be grammatically correct in Malayalam, the “m” of “chem” becomes an “n” when combined with “karupp”. We suggest a common name as “red and black woodsnake”, and a Malayalam name as “ Chenkaruppan”.

Distribution, natural history and conservation

Xylophis chenkaruppan sp. nov. appears to be an uncommonly encountered and narrowly distributed species, currently known only from the Vellarimala and Kurichyarmala Hills, Wayanad, Kerala, at an elevation above 1400 m asl ( Fig. 10 ). The holotype was recovered within a decomposing log in thick canopy-covered forests in Vellarimala. The larger (presumably adult) paratype from the same location was found on the forest floor under a log approximately one km away from the first individual. The two smaller paratypes from Vellarimala were found under the same fallen log, as the paratype. One was recovered immediately after lifting the log, while the other was retrieved while digging loose top soil. Paratypes ZSI/WGRC/IR-V.3826 & ZSI/WGRC/IR-V.3827 were found together below a log within Shola forest at approximately 10:00 am in the Kurichyarmala Hills. Both specimens were partially buried in the soil beneath the decaying log. All the individuals from Vellarimala were collected during the day, between 10:00 am and 3:00 pm. Other reptiles, Including Amphiesma monticola (Jerdon, 1853) , Kaestlea beddomii (Boulenger, 1887) , Ristella cf. travancorica (Beddome, 1870) and Cnemaspis cf. wynadensis (Beddome, 1870) were found sympatrically in both locations.

Figures

FIGURE 1. Map showing the distribution of Xylophis species with 13 dorsal scale rows. Type localities are marked with a black circle. Note that the type locality of X. perroteti is an imprecise location in the Nilgiri Hills.

FIGURE 3. Line drawings partly modified from Deepak et al. (2020) showing variations in head scalation: A. Xylophis chenkaruppan sp. nov. (holotype: ZSI/WGRC/IR.V.3825), B. X. mosaicus (holotype: BNHS 3577), C. X. perroteti (holotype: MNHN-RA 7300).

FIGURE 4. Bivariate plot of numbers of subcaudal versus ventral shields for Xylophis mosaicus (data from Deepak et al. 2020 and Narayanan et al. 2022) and X. chenkaruppan sp. nov. Two specimens of X. mosaicus reported as males (by Deepak et al. 2020) are outliers that require re-examination.

FIGURE 5. Holotype of Xylophis chenkaruppan sp. nov. (ZSI/WGRC/IR.V.3825) from Vellarimala, Wayanad, Kerala, India, with left hemipenis everted. Scale bar = 10 mm.

FIGURE 6. Head of the holotype of Xylophis chenkaruppan sp. nov. (ZSI/WGRC/IR.V.3825). A. dorsal, B. ventral C. right lateral view and D. left lateral view. Scale bar = 10 mm.

FIGURE 7. Right hemipenis of Xylophis chenkaruppan sp. nov. (holotype, ZSI/WGRC/IR.V.3825) stained with Alizarin red. (left) partial sulcate view; (right) partial asulcate view. Scale bar = 1 mm.

FIGURE 8. Heads of four of the five paratypes of Xylophis chenkaruppan sp. nov. A. BNHS 3381, B. BNHS 3382 C. BNHS 3383 and D. ZSI/WGRC/IR-V.3826. Scale bar = 5 mm.

FIGURE 10. Habitat of Xylophis chenkaruppan sp. nov. A. Vellarimala, Wayanad (type locality) and B. Kurichyarmala, Wayanad in Kerala state of India.