Cyrtodactylus chamba, Agarwal & Khandekar & Bauer, 2018

Agarwal, Ishan, Khandekar, Akshay & Bauer, Aaron M., 2018, A new bent-toed gecko (Squamata: Gekkonidae: Cyrtodactylus) from the Western Himalayas, Himachal Pradesh, India, Zootaxa 4446 (4), pp. 442-454 : 445-451

Cyrtodactylus chamba sp. nov.

Cyrtodactylus sp. Chamba ( Agarwal et al. 2014a)

Figs. 2–8

Holotype. BNHS 2332 , adult male, from near Chamba (32.47656° N, 76.21076° E; ca. 1130 m asl.), Chamba District , Himachal Pradesh state, India, collected by T. Khichi and I. Agarwal, 0 4 June 2011.

Paratypes. BNHS 2330, BNHS 2331 & BNHS 2333 adult male, adult female, and juvenile male, same collection data as holotype. BNHS 2334–2335 , adult females, Chamba (32.55826° N, 76.126333° E; ca. 960 m asl.), other collection data same as holotype .

Etymology. The specific epithet is the name of the type locality of the species and is used as a noun in apposition. Cyrtodactylus chamba sp. nov. is only known from around Chamba, in the Chamba Valley, Himachal Pradesh, India.

Suggested common name. Chamba bent-toed gecko

Diagnosis and comparison with regional congeners. Cyrtodactylus chamba sp. nov. may be distinguished from all regional congeners by a combination of small body size (SVL up to 63.1 mm), 9–12 SL, 8–10 IL, 33–43 MVSR, relatively short digits and lamellae; heterogeneous dorsal scalation of small granular scales intermixed with enlarged (3– 4X granules) circular, conical and feebly keeled tubercles in 13–15 rows; tubercles extending to proximal one third of tail; five precloacal pores in males; no enlarged femoral scales; no enlarged series of subcaudals, a dorsal colour pattern of 5–7 irregular, broad, dark bands with much narrower, light interspaces.

Cyrtodactylus chamba sp. nov. can be distinguished by the presence of five precloacal pores on males from Altiphylax stoliczkai (males without pores); Cyrtopodion mansarulum and Cyrtodactylus fasciolatus (both femoral and precloacal pores present on males); and the species in which males have a relatively large precloacal pore series— Cyrtodactylus battalensis (8–10 PcP), C. dattanensis (9–10 PcP), C. nepalensis (10 PcP). The dorsal colour pattern of irregular dark bands with much narrower light interspaces in life and 20–23 subdigital lamellae under the 4th toe (n=5) in Cyrtodactylus chamba sp. nov. differentiate it from C. mintoni (dorsal pattern of narrow black crossbars, 17 lamellae under toe IV; n =1). The five precloacal pores in males of the new species (n=3) overlap with the counts of C. lawderanus (4–9 precloacal pores on males, average 6.8, n=14, only two males from eastern Himachal Pradesh with fewer than six pores) and C. himalayanus (4–8 precloacal pores in males, average 6.0, n=9, only two males with fewer than six pores). Cyrtodactylus chamba sp. nov. can be distinguished by its dorsal scalation (homogeneous granular scales intermixed with 13–15 rows of larger, circular, conical, faintly keeled tubercles; 9–10 granules around each enlarged tubercle at midbody) and the condition of the original tail (TL> SVL) from C. lawderanus (heterogeneous granular scales intermixed with 11–15 rows of larger, circular, flattened tubercles; 7–8 granules around each enlarged tubercle at midbody; TL <SVL). Cyrtodactylus chamba sp. nov. is smaller (SVL up to 63.1 mm) and has fewer scales across the belly (33–43, mean 36.8) than C. himalayanus (SVL up to 72.6 mm, 41–43 MVSR, mean 41.8), besides having a narrower head (HW/HL 0.69, 0.67–0.71 vs. 0.73, 0.71–0.76).

Description of holotype. Holotype in good condition except for a few artefacts of preservation: small longitudinal incision on the right side of the belly to collect tissue, tail slightly sigmoid, a few folds of skin on the gular region and a single fold on the right running from front of eye to behind nostril ( Fig. 2 , 3 ). Adult male, snout to vent length 55.8 mm. Head length ~ one fourth SVL (HL/SVL ratio 0.26), wider than long (HW/HL ratio 0.70), somewhat depressed (HH/HW ratio 0.59), distinct from neck; loreal region not inflated, interorbital area flat, canthus rostralis not prominent; snout slightly less than half head length (SE/HL ratio 0.43), slightly less than 2X OD (OD/SE ratio 0.54); scales on canthus rostralis, forehead, loreal region, and snout homogeneous, flat and juxtaposed, those on canthus rostralis largest, those on interorbital region with smaller and granular scales, intermixed with a few slightly enlarged, rounded tubercles; occipital and temporal region with much smaller, granular scales intermixed with irregularly arranged slightly larger rounded tubercles. Eye ~ one fourth head length (OD/HL ratio 0.23); pupil vertical with crenelated margins; supraciliaries decreasing in size towards posterior and anterior edge of orbit, those above and anterior to mid-orbit largest; ear opening oval, obliquely oriented; eye to ear distance more than eye diameter (OD/EE ratio 0.77). Rostral wider than deep, partially divided dorsally; bordered posteriorly by single large supranasal on either side, separated by two small scales (internasals); rostral in contact with SL I, nasals, supranasals and an internasal; nostrils semi-circular, laterally oriented, posterior half covered by nasal pad, each in broad contact with rostral and also in contact with supranasal, SL I and two postnasals; three to four scale rows separate orbit from supralabials; mental wider than long, triangular, three pairs of well-developed postmentals, inner pair longer than the rest and in broad contact with each other behind the mental; inner postmentals bordered by mental, IL I, second postmental and small gular scales; second postmental bordered by inner and outer postmental, IL I and IL II, and two to three gular scales on either side; supralabials 11 (7)/ 12 (8) on each side, bordered by a row of large, flat, slightly elongated scales; infralabials 10/9, IL II to IL VI bordered by a row of enlarged scales, largest anteriorly; interorbital scale rows across narrowest point of frontal bone ca. 35. ( Fig. 3 )

Trunk slightly less than half SVL (TRL/SVL ratio 0.45) with ventrolateral folds; dorsal scales heterogeneous, mainly rounded granules intermixed with irregularly arranged, slightly enlarged (3– 4X granule size) circular tubercles, bluntly conical and feebly keeled throughout, more conical towards flanks ( Fig. 4 ); tubercles extend from behind occiput to proximal one third of tail length, those on head and nape smaller than on dorsum; enlarged tubercles on tail weakly pointed and elongate; tubercles in approximately 13 longitudinal rows at mid-body; 32 tubercles in paravertebral row from occiput to mid-sacrum. Ventral scales larger than dorsals, smooth, imbricate to subimbricate, 35 mid-body scale rows across the belly; gular region with small granular scales, except 1–3 rows of larger, flat, juxtaposed scales bordering mental, postmentals and infralabials. Scales in precloacal region enlarged, five precloacal pores in a continuous series forming an obtuse angle, 4–5 rows of enlarged scales between pore bearing row and vent, no enlarged femoral scales or femoral pores; no precloacal groove; prominent hemipenial bulge ( Fig. 5 ). Three to four rows of enlarged scales between pitted precloacal scales and vent, larger than the largest ventrals and pitted precloacal scales.

Fore and hind limbs relatively slender; forearm (FL/SVL ratio 0.14) and crus (CL/SVL ratio 0.17) relatively short; digits relatively short, strongly inflected at each joint, all bearing robust, recurved claws; subdigital lamellae widened beneath basal phalanx; basal lamellae series: 3–4–5–6–5 (right manus) and 4–5–5–8–7 (right pes); distal lamellae series: 6–8–10–10–8 (right manus) and 8–9–11–10–12 (right pes); interdigital webbing absent on manus, rudimentary between digits I to IV of pes; relative length of digits (measurements in mm in parentheses): I (2.5) <II (3.6) <V (4.1) <III (4.3) <IV (4.6) (right manus) and I (3.2) <II (4.3) <III (5.6) <V (5.8) <IV (6.0) (right pes); scales on palm of manus and sole of pes smooth, rounded; scales on forelimb heterogeneous, enlarged tubercles absent—flat, weakly pointed, smooth sub-imbricate scales on upper arm and anterior forearm, other regions with granular scales, venter of limbs covered by smaller granular scales; scales on hind limbs heterogeneous, dorsal part of thigh and shank with larger, conical granular scales intermixed with scattered, enlarged, slightly conical, feebly keeled tubercles, which are denser on shank than thigh, anterior portion of thigh and ventral aspect of hind limb with enlarged, smooth, imbricate scales.

Tail original, rounded, without distinct median furrow, tapering. Dorsal scales at the base of tail granular, gradually becoming flatter, subimbricate posteriorly, increasing in size toward lateral aspect, intermixed with 4–6 slightly enlarged, weakly keeled tubercles on first two to four whorls; ventral scales larger than dorsal, imbricate, smallest on tail base and anterior one-third of tail; median row with irregularly enlarged subcaudals; two enlarged postcloacal spurs on left side.

Colouration in life. ( Fig. 6 ) Dorsal ground colour of head, body and limbs and tail base light sand-brown, rest of tail with more yellow. Top of head and rostrum with C-shaped, oblong and irregular dark brown blotches; blotches on occiput forming indistinct brown and darker brown anterior border of nuchal band, which has a narrow black posterior outline bordered by a few lighter tubercles; nuchal band contiguous with dark brown post-orbital streak that connects to a pre-ocular streak through the orbit; labials finely dotted with black, with 5–7 indistinct cross-bars formed by light grey pigment with fine black spots and ochre patches, the ochre more prominent on the SL; superciliary scales straw-yellow, darker above mid-orbit; six irregular dorsal bands separated by narrow lighter interspaces, each broadly made up of a narrow anterior border of light markings and tubercles, followed by darker blotches that lead into dark markings outlined posteriorly by a narrow posterior border of light markings and tubercles; first band between forelimb insertions, fifth between hind limb insertions and sixth on tail base; indistinct lighter mid-vertebral line on back and tail base; limbs spotted with black and a few lighter tubercles; tail faintly suffused with ochre, original portion with alternating light and dark markings, the dark markings with lighter interspaces, fading to yellow-brown with darker blotches on the regenerated portion; venter white, each scale with a few fine black dots, underside of limbs lightly marked and tail heavily marked with yellow and brown markings. Iris with copper, bronze and grey.

Colouration in preservative. ( Fig. 2 ) Colours considerably faded with lighter markings almost entirely lost, lighter tubercles indistinct against faded ground colour. Margins of only a few bands partially distinguishable, dorsal pattern of indistinct bands and small irregular blotches.

Variation. The paratypes are similar in pattern to the holotype except the total number of dark dorsal bands varies from 6–7 and the ground colour in life is suffused with yellow, grey, peach or brown ( Fig. 7 , 8 ). BNHS BNHS 2330 is a juvenile that has a complete tail with 10 dark and 10 white bands following the dark postsacral band; darker markings of original tail may be spotted with black BNHS 2231, 2233; regenerated tail in BNHS 2234–2335 with black spots. The number of tubercles on the first few whorls of the original tail varies from 5–8. Table 3 summarizes mensural and meristic variation in the type series.

Distribution and Natural History. Cyrtodactylus chamba sp. nov. is known only from the vicinity of the town of Chamba, Himachal Pradesh, India at elevations between 960–1130 m asl. The Chamba Valley lies along

the course of the Ravi River, between the high mountains of the Dhauladhar Range to the south and Pir Panjal to the north. The species was encountered during a single night of fieldwork in late summer around Chamba. These scansorial, nocturnal geckos were spotted by eye shine on loose stone walls in the town and rocks in a small stream. The only other gecko we spotted in Chamba was Hemidactylus malcolmsmithi .

Figures

FIGURE 2. Dorsal view (A), ventral view (B) of Cyrtodactylus chamba sp. nov. (holotype BNHS 2332). Scale bars 10 mm.

FIGURE 3. Head of Cyrtodactylus chamba sp. nov. (holotype BNHS 2332), dorsal (A), lateral (B) and ventral (C) view. Scale bars 10 mm.

FIGURE 4. Details of dorsal pholidosis of Indian Cyrtodactylus (Siwaligekko) species (top to bottom). Cyrtodactylus chamba sp. nov. (holotype BNHS 2332), C. himalayanus (CES09/1314) and topotypical C. lawderanus (CES09/1344).

FIGURE 5. Precloacal region of Cyrtodactylus chamba sp. nov. (holotype BNHS 2332)

FIGURE 6. Indian Siwaligekko species in life (top to bottom): Cyrtodactylus chamba sp. nov. (holotype BNHS 2332), C. himalayanus (CES09/1314) and C. lawderanus (CES09/1344).

FIGURE 7. Type series of Cyrtodactylus chamba sp. nov. (from right to left, BNHS 2330, 2331, 2333–2335)

FIGURE 8. Type series of Cyrtodactylus chamba sp. nov. in life, BNHS 2330 (top left), BNHS 2331 (top right), BNHS 2333 (bottom left), BNHS 2334 (bottom right).