Xylophis mosaicus, Deepak & Narayanan & Das & Rajkumar & Easa & Sreejith & Gower, 2020

Deepak, V., Narayanan, Surya, Das, Sandeep, Rajkumar, K. P., Easa, P. S., Sreejith, K. A. & Gower, David J., 2020, Description of a new species of Xylophis Beddome, 1878 (Serpentes: Pareidae Xylophiinae) from the Western Ghats, India, Zootaxa 4755 (2), pp. 231-250 : 235-242

Xylophis mosaicus sp. nov.

( Figs. 2 , 3 , 4 , 5A ; Table 2 , 4 )

urn:lsid:zoobank.org:act:167A87BF-8379-4D5E-8C90-13BBCAA0A7C8

Diagnosis. Xylophis mosaicus sp. nov. is distinguished from X. stenorhynchus (and its putative synonym X. indicus ) and X. captaini in having 13 instead of 15 dorsal scale rows at midbody, in having relatively long prefrontals and short, rectangular internasals versus relatively short prefrontals and broad, squarish internasals, and in lacking a pale (off-white) collar behind the head. The new species differs from X. perroteti (and its synonym X. microcephalum ) in having the posterior pair of genial scales in midline contact (versus posterior pair of genial scales separated along the midline by the first ventral scale) ( Figs. 5A,B , 6F ).

Holotype. BNHS 3577 ( Figs. 3 & 4 ), female, collected close to Eravikulam hut in Eravikulam National Park, Kerala, India (10.274357°N, 77.085782°E, 2,400 m elevation) by Sandeep Das on 3rd December 2015. See map in Fig. 2 .

Paratypes (n = 4). BNHS 3579 , female, collection details as for holotype; BNHS 3580 , female and BNHS 3578 , male, collected by Sandeep Das from Eravikulam National Park (10.204640°N, 77.083096°E, 2221m elevation) and (10.196156° N, 77.067111° E, 2230 m elevation) respectively on 28th April 2017 ( Fig. 7 A–L). BMNH 88.1.27.42 ( Fig. 7 M–P), male, collected by W. Davison prior to 1889 from Anamalai Hills , ‘4,700 ft’ (= 1433 m).

Referred specimens (n = 9). Coordinates provided in this section are estimated from online maps because none is associated with original collection data. BMNH 93.4.18.17, female, High ranges, Travancore , collected by H.S. Ferguson; BNHS 1756 , male, Perumal Malai, Palani Hills, 10.268535° N, 77.541410° E, 1600 m elevation (in present-day Kodaikanal, Tamil Nadu) collected by A. Novorro SJ on 14 th June 1956; BNHS 3128 and BNHS 3126 , males and BNHS 3124 , female, Eravikulam National Park, Kerala (10.170929° N, 77.054943° E, 2250 m elevation) collected by Clifford Rice on 28 August 1980, 23 rd June 1987 and 13 th November 1980, respectively; BNHS 2871 , female, Munnar ( Anamalai Hills ) (10.091893° N, 77.064851° E, 1550 m elevation) collector; BNHS party on 13 th April 1970. BNHS 1751 , male, Kallar ( Anamalai Hills ), collected by Frank Wall on February 1925. ZSIK 19410 , male, collected by Frank Wall, Palani Hills ( Kodaikanal ) on an unknown date; ZSIK 25123, female, collected by Romulus Whitaker, Kodaikanal Ghat, Tamil Nadu 1982. These are considered referred rather than paratype specimens because of imprecise locality data and imperfect specimen condition.

Description of holotype. Some morphometric and meristic data are given in Table 4 . Female. Specimen in good condition, preserved in loose coil with head outside and tail inside, colours have not noticeably faded; ca. 7.5 and 11.9 cm longitudinal ventral incisions into coelom extending back from points ca. 27 mm and 15 mm, respectively, behind snout tip.

Body subcylindrical, dorsoventrally flattened. Head not (or barely) wider than anterior end of body. Head narrows steadily in dorsal and ventral views, with very slightly convex edges. Head narrow (HL 11.6 mm), subtriangular with bluntly rounded tip in dorsal view, broader (HW 7.0 mm) than tall (HH 6.1 mm), gradually tapering from the posterior of parietal to snout tip in lateral view. Rostral very short in dorsal view, slightly shorter than 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 undivided, but notched on upper posterior margin. External naris inverted comma shaped. Left and right nasals not in contact, each subequal in area to the intervening rostral. Paired internasals subtriangular in shape, little larger than nasals and rostral, much smaller than prefrontals. Paired prefrontals little shorter than length of frontal. Five supralabials; third and fourth contacting spectacle. First supralabial very small and, apart from second supralabial, contacts only rostral and nasal ( Fig. 5A . First supralabial wedging into the margins of nasal and rostral). Second supralabial a small, rectangular, thin strip contacting nasal, one large scale between spectacle and nasal, and first and third supralabials. Third and fifth supralabial longer than tall, fourth taller than long, fifth largest. Third and fourth supralabials in contact with approximately and slightly hexagonal 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, slightly shorter (2.8 mm) than prefrontals (3.2 mm) in length. Irregularly hexagonal frontal notably longer (3.8 mm) than broad (3.0 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 smaller, less elongate postocular (also pentagonal).

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. 5A ). Mental short, broad, with tripartite anterior end ( Fig. 4B & 5A ). Six infralabials. First infralabials 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. Inside of mouth uniform, pale off-white in preservation. Teeth small, evenly sized, retrorse, straight to very gently recurved with pointed tips. Teeth barely protruding from surrounding soft tissue and difficult to count but approximately 26 on left maxilla.

Dorsal scales in 13 rows from at least as far anterior as level with sixth ventral, maintained up to posteriormost ventral. Dorsals generally regularly arranged; lowest five dorsal rows on either side larger than three middorsal rows. All body scales macroscopically smooth and glossy, lacking keels. Ventral scales 141, all similarly proportioned except for anteriormost ventral (with anterior projection). Ventrals generally have curved (convex) posterior margins, but much less so on first ventral.Anal shield undivided, longer than the last ventral, its margin overlaps two small, irregular scales on either side in addition to pair of larger subcaudals medially. Subcaudals paired, 16. Tail terminates in sharply tapering terminal scute, with a distinct groove dorsally. Total length 373 mm, tail length 33 mm, tail/total length ratio 0.1. Tail with somewhat flattened venter. Anteriorly with eight to nine dorsal scale rows, reducing to about six at mid tail, two (plus two posteriormost subcaudals) surrounding base of terminal scute.

Colouration in preservative. Body and tail scales all moderately iridescent, ventral scales highly iridescent. Most head and tail scales also moderately iridescent, but very small, unpigmented anterior supra- and infralabials appear matt. Overall, specimen is various shades of grey mottled with dark brown. Several irregular black/dark gray spots, mostly covering entire dorsal scale present more or less densely all along the body and tail. Posterior part of body with narrow pale longitudinal lines, lower one on the lateral edges of the ventrals and another on the upper edges of the first dorsal scale row. Ventral scales under head much paler than body ventrals and subcaudals. First seven ventrals much paler than the rest. Body ventrals and subcaudals with extensive patches of dark gray or black markings on a pale venter. These patches are mostly regular, always a pair of dark dots on lateral edges of ventrals plus one median or (more often) two paramedian patches. Upper surface of head darker than lower and lateral surfaces. Dark head color extends as a stripe on either side, from behind the anterior temporal, terminating near posterior edges of fifth supralabials. Posterior region of first supralabials until anterior half of fifth supralabials pale. Another, broader, posteriorly tapering stripe starts from posterior temporals and terminates near the fourth dorsal scale row level with the second ventral on either side. Mentum, first two and partly the third infralabials, and anterior portion of anterior genials each with a dark patch.Anterior genials each with two other, smaller dark patches on posterolateral edges.

Variation in paratypes. See Table 4 for variation in meristic and morphometric features. Paratypes generally in moderate to good condition; all with single incisions into the coelom except BMNH 88.1.27.42 (two incisions into coelom). BMNH 88.1.27.42 and BNHS 3578 with midventral incisions into base of tail, latter specimen with both hemipenes removed. Paratypes typically match holotype description except where noted here. BNHS 3577 has narrower head, almost as tall as broad. Anterior margin of rostral slightly concave in BNHS 3579. Rostral subequal to rostral-prefrontal distance in dorsal view in BMNH 88.1.27.42. Paired internasals semicircular and first infralabials as long as tall in BNHS 3578. Number of dorsal scale rows level with first subcaudals and level with middle of tail 6–7 and 6–7 in BNHS 3579, 11 and 6 in BNHS 3578, 8–10 and 6 in BNHS 3580; 10 and 6 in BMNH 88.1.27.42. Anterior supra- and infralabials of BMNH 88.1.27.42 mottled with darker pigmentation, shiny rather than matt. Dorsum of BNHS 3580 paler ( Fig. 8A ), with clearer, more checkerboard-like pattern than holotype and other two paratypes. Dorsum and venter of BNHS 3579 darkest ( Fig. 8C ), without any pale spots or patches on both dorsum and venter and lacking pale longitudinal lateral lines; the few pale areas on this specimen are diffuse, on subcaudals 3 and 4, first two ventrals, under the chin, and on infralabials 4 and 5. Pale longitudinal line along upper edge of first dorsal scale row absent in BMNH 88.1.27.42.

Comments on referred specimens. ZSI 25123 is the only specimen without distinct spots on the body, and it overall has a more reddish brown dorsum, though its scalation matches that of other X. mosaicus sp. nov. specimens. BMNH 93.4.18.17 collected by H. S. Ferguson morphologically matches with the new species, and the collection locality is mentioned as high ranges which could be Anamalais. BNHS 3128, BNHS 3126, BNHS 3124 were partially dehydrated, they are all darker in coloration. Both BNHS 2871 and BNHS 1756 are in good condition, BNHS 2871 has a long incision along the venter.

Etymology. The specific epithet mosaicus is in reference to both the mosaic-like nature of the colour pattern of the new species, and the mosaic-like nature of the high elevation shola forest patches (within a grassland matrix) in which it is found. For nomenclatural purposes, the species epithet is considered a noun in apposition.

Suggested common name. Anamalai wood snake (English). Anamalai mannooli vannan pambu (Tamil). Pul mannooli pambu (Malayalam).

Distribution, natural history and conservation. Xylophis mosaicus sp. nov. is presently known only from high elevations (above 1,500 m) in the southern Western Ghats. The three currently known localities, based on recent and historic collections, are Eravikulam National Park (Anamalai Hills) ( Fig. 9A,B ) and Meeshapulimala and Kodaikanal (Palani Hills). The Anamalai and Palani locations are approximately 35 km apart. Given this restricted and patchy distribution and (as far as is known) association with grassland-shola habitats, Xylophis mosaicus sp. nov. might qualify for an IUCN Red List threatened category, but further work is required to test the apparent patchiness and habitat requirements, as well as to generate more information on the ecology of this species.

One of the female specimens (BNHS 3579) collected on 3rd December 2015 was gravid and was kept under observation in captivity for a short period. It fed on live earthworms that were provided. On 21st December 2015 it laid seven eggs and the snake was found sitting coiled on top of the eggs ( Fig. 10 ) for five days, after which it moved away. Eggs were 21.2 mm ± 3.0 mm long and 10.6 mm ± 1 mm wide.

All encounters of X. mosaicus sp. nov. (in total seven) from Eravikulam National Park during 2015–2018 were in grasslands except for one specimen that was found under a rotten log along with a Uropeltis sp. in a shola forest patch in Turners Valley. One individual was sighted in the grasslands of Meeshapulimala, 13 km southwest of Eravikulam National Park.

Figures

FIGURE 2. Distribution of Xylophis perroteti and X. mosaicus sp. nov. in the Western Ghats based on specimens examined in this study. Type locality of X. mosaicus sp. nov. is shown with a red arrow.

FIGURE 3. The holotype of Xylophis mosaicus sp. nov. (BNHS 3577). A. dorsal view and B. ventral view. Scale bar = 10 mm.

FIGURE 4. Head of the holotype of Xylophis mosaicus sp. nov. (BNHS 3577).A. dorsal, B. ventral C. right lateral view and D. left lateral view. Note the wide first ventral that does not separate the posterior genials. Scale bar = 10 mm.

FIGURE 5. Line drawings showing head scalation: A. Xylophis mosaicus sp. nov. (holotype:BNHS 3577), B. Xylophis perroteti (holotype: MNHN-RA 7300). Note the relationship between the first ventral (colored grey) and genials (colored yellow).

FIGURE 6. Xylophis perroteti (BNHS 3582) recently collected from Nigiri Hills (A–D) and the holotype of Xylophis microcephalum (BMNH 1946.1.12.38) from ‘Madras’ (E–H). Note the narrow first ventral separating the posterior genials. Scale bar = 10 mm.

FIGURE 7. Heads of paratypes of Xylophis mosaicus sp. nov. (A–D. BNHS 3578, E–H. BNHS 3579, I–L. BNHS 3580, M–P. BMNH 88.1.27.42). Note the wide first ventral that does not separate the posterior genials. Scale bar = 10 mm.

FIGURE 8. Xylophis mosaicus sp. nov. showing colour in life. A. Paratype BNHS 3580, B. Uncollected specimen from Eravikulam National Park. C. Paratype BNHS 3579.

FIGURE 9. Grassland and shola habitat of Xylophis mosaicus sp. nov. in Eravikulam National Park, Kerala.A. Anaimudi peak and surroundings, B. Campamala and surroundings.

FIGURE 10. Xylophis mosaicus sp. nov. (paratype BNHS 3579) in captivity, observed coiled around its freshly laid eggs.

Tables

TABLE 4. Merestic and morphometric (in millimeters) character data for Xylophis mosaicus sp. nov. Head length = distance between snout tip and back of lower jaw. The format ‘X-Y’ is used to denote the shortest distance between features X and Y.

Voucher no	BNHS- 3577	BNHS- 3578	BNHS- 3579	BNHS- 3580	BNHS- 3128	BNHS- 3124	BNHS- 3126	BMNH 88.1.27.42	BNHS- 2871	BMNH 93.4.18.17	ZSIK- 19410	ZSIK- 25213	BNHS- 1756	BNHS-1751
Type status	Holotype	Paratype	Paratype	Paratype				Paratype
Sex	female	male	female	female	male	female	male	male	female	female	male	female	male	male
DSR	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13	13:13:13
Ventral	141	131	138	138	128	139	133	130	136	140	135	142	140	147
Subcaudal	16	31	20	17	34,33	18,19	33	30	22,21	17	29	18	19	12,13
SL	5,5	5,5	5,5	5,5	5,5	5,5	5,5	5,5	5,5	5,5	5,5	5,5	5,5	5,5
IL	6,6	6,6	6,6	6,6	6,6	6,6	6,6	6,6	6,6	6,6	6,6	6,6	6,6	6,6
SVL	372.5	292.8	327.1	272.8	310.7	183.4	245.0	256.2	301.0	362.2	232.8	403.0	310.0	218.3
TL	33	61	36	26	60	16	42	52	34	33	44	33	29	19
HL	13.7	9.5	10.7	11.5	10.2	6.8	7.5	10.9	9.6	14.1	8.7	12.9	9.4	9.1
HW	7.2	5.2	6.7	5.9	6.6	5.9	5.8	7.3	6.5	8.0	4.2	6.9	6.8	damaged
SW	1.9	1.6	2.6	1.9	1.7	1.2	1.8	1.7	2.0	2.3	1.3	2.2	2.1	damaged
FW	3.0	2.7	3.4	3.0	3.3	2.3	2.8	2.9	3.2	3.4	2.1	3.2	2.9	damaged
PF	2.3	2.0	2.0	2.0	2.1	1.4	1.8	1.9	1.9	2.5	1.7	2.2	1.9	damaged
IN	0.8	0.7	0.5	0.8	0.7	0.5	0.5	0.9	0.7	1.0	0.7	1.1	0.8	damaged
Fr-S	4.6	2.7	3.3	3.1	3.3	2.6	2.7	3.2	2.9	4.0	3.1	3.5	3.4	damaged
1+2 IL	1.9	1.6	1.8	2.0	1.7	1.2	1.4	1.6	1.5	1.7	1.4	1.9	1.5	1.4
3 IL	2.0	1.6	1.7	1.6	1.8	1.2	1.2	1.7	1.5	1.9	1.4	1.8	1.7	1.1