Cyrtodactylus aravindi, Narayanan & Das & Balan & Tom & Divakar & Kp & Hopeland & Deepak, 2022

Narayanan, Surya, Das, Sandeep, Balan, Amirtha, Tom, Roshin, Divakar, Nitin, Kp, Rajkumar, Hopeland, P. & Deepak, V., 2022, A new species of Cyrtodactylus (Reptilia: Gekkonidae) from the southern Western Ghats of India, Vertebrate Zoology 72, pp. 729-743 : 729

Cyrtodactylus aravindi sp. nov.

Figures 3 -6

Type locality.

Muppandal, Nagercoil, Kanyakumari dis-trict, Tamil Nadu, India (8.260862°N, 77.557513°E, 108 m above sea level).

Holotype.

ZSI-R 28275, adult male collected from Muppandal, Nagercoil, Kanyakumari district, Tamil Nadu, India (8.260862°N, 77.557513°E, 108 m above sea level) collected by P. Hopeland and Amirtha Balan on 4 April 2022 (Figs 3 , 4 , 6A ).

Paratypes (n=5).

ZSI-R 28276 (adult male), ZSI-R 28277 (adult female), ZSI-R 28278 (adult male), ZSI-R 28279 (subadult male) collections details same as the holotype (Figs 5A-D ); ZSI-R 28280 (adult female) collected from Thuckalay, Kanyakumari district, Tamil Nadu, India (8.285148°N, 77.379105°E, 371 above sea level) collected by Roshin Tom & Sandeep Das on 7 August 2021 (Figs 5E and 6B ).

Etymology.

The specific epithet is a patronym honouring Dr N. A. Aravind, Senior Fellow at ATREE, Bengaluru, India for his support towards herpetological research. Aravind is a malacologist who has also contributed to amphibian systematics and his lab support has been instrumental in our research for the past few years. We suggest a common name for the new species as Aravind’s ground gecko.

Diagnosis.

A small-sized Cyrtodactylus , SVL less than 45 mm (n =6); body moderately stout, limbs and digits short, slender; dorsal pholidosis on trunk homogeneous with smooth and granular scales; 16-20 dorsal midbody scale rows across trunk contained within one eye diameter; 33-36 ventral scales across belly; precloacal groove, enlarged precloacal and femoral scales, precloacal or femoral pores absent in both the sexes. Tail without a series of enlarged median subcaudal scales. Subdigital scansors smooth, entire (except one or two on some digits divided), unnotched; 5 or 7 basal 7 or 8 distal on digit IV of the manus. Dorsal pattern with a single thick band medially between the fore and hind limb insertions and a single moderatly sized spot posterior to the band. Post-occipital collar complete extending from the posterior margin of one orbit to the other, no regular spots on the flanks. Venter tan brown with irregular dark mottling.

Description of Holotype.

Morphometric and merestic data are provided in Table 2 . Adult male. Specimen in good condition, and a small piece (3mm) of the tail was removed from the posterior end for DNA extraction (Fig. 3 ). Body relatively slender (BW/AGL 0.42), trunk almost half of SVL (AGL/SVL 0.47) without ventrolateral folds. SVL 40.7 mm, head short (HL/SVL 0.31), wide (HW/HL 0.64), not strongly depressed (HD/HL 0.32), as broad as body (HW/BW ratio 1.01), and distinct from neck. Loreal region slightly inflated, canthus rostralis not prominent. Snout less than half the head length (ES/HL 0.37), slightly longer than eye diameter (ED/ES 0.61); scales on snout, canthus rostralis, and loreal region large, subcircular, smooth and, weakly conical; much larger than granular scales on the forehead and interorbital region; occipital and temporal region with smaller, smooth granules. Eye small (ED/HL 0.23); pupil vertical with crenate margins; supraciliaries short, larger anteriorly, not elongate; interorbital scale rows across narrowest point of frontal 12 or 13; 33-38 scale rows between left and right supraciliaries at mid-orbit. Ear-opening oval, small (EL/HL 0.09); eye to ear distance similar to eye diameter (EE/ED 1.06). Rostral wider (1.9 mm) than deep (1.1 mm), incompletely divided by weakly developed rostral groove dorsally covering more than half of its height; a single enlarged supranasal on each side, more than twice the size than postnasals, separated from each other by a single enlarged internasal on the snout; two subequal postnasals, much smaller than supranasals; rostral in contact with nostril, supralabial 1, supranasals, internasals, and postnasals on either side; nostrils rounded, directed outwards, covering most of the nasal scale; four or five rows of smaller scales separate the orbit from the supralabials. Mental enlarged, triangular, wider (2.6 mm) than long (1.9 mm); one pair of postmentals, slightly longer (1.3 mm) than mental, in strong contact with each other below mental; sublabials half the size of postmentals; chin shields bordering postmentals and infralabials flat, smooth, smaller than outermost postmentals, rest flattened, small, smooth; two or three rows of enlarged elongated scales separating gular scales from infralabials. Nine supralabials up to angle of jaw and seven at midorbital position on each side; eight infralabials up to angle of jaw and seven infralabials at midorbital position on both sides.

Dorsal pholidosis on trunk homogeneous; granular scales smooth to feebly keeled. Granular scales on occiput and nape slightly smaller than those on body dorsum; granular scales on flank slightly larger than those on dorsum. Ventral scales larger than granular scales on dorsum, smooth, subimbricate, subequal from chest to vent; 33 ventral scales across belly between lowest rows of granular scales on flank. Scales on throat slightly smaller than those on belly; gular region with much smaller. No enlarged precloacal or femoral scales, no precloacal or femoral pores; no precloacal groove. Scales on palm and soles granular, smooth, rounded; scales on dorsal aspects of limbs heterogeneous in shape and size; mixture of small, granules similar to dorsum and many smooth flattened and imbricate scales which are much larger than granules on the body dorsum.

Forelimbs and hindlimbs slightly long, slender (LAL/SVL 0.14; CL/SVL 0.15); digits short, slender, with a strong, recurved claw, moderately inflected, distal portions laterally compressed. Series of unpaired lamellae on basal portion of digits except one or two which on some digits which are paired, separated from narrower distal lamellae by a single large lamella at the inflection; basal lamellae series: 3-6-6-6-5 right manus, 3-6-7-9-6 right pes, 3-6-5-6-3 left manus; 3-6-7-9-6 left pes; distal lamellae series: 8-7-9-8-7 right manus, 9-9-10-9-10 right pes, 7-7-9-8-7 left manus; 9-8-10-9-10 left pes. Relative length of digits (measurements in mm in parentheses): IV (3.0)> III (2.7)> II (2.6)> V (2.3)> I (1.7) (right manus); IV (3.9)> III (3.6)> V (3.5)> II (3.1)> I (1.9) (right pes).

Original tail circular in cross-section, relatively thick, tapering gradually to tip, unsegmented, slightly shorter than snout-vent length (TL/SVL ratio 0.81). Scales on dorsal aspect of tail base similar to body dorsum; scales on dorsal aspect of tail large flat, slightly elongated, smooth, and imbricate, becoming larger towards the lateral aspect, largest on ventral side, but not forming median row of transversely enlarged subcaudal scales. Three and two small, smooth, subequal, conical postcloacal spurs on the right and left side of the tail base, respectively; prominent hemipenal swelling, flap of skin covering cloacal aperture

Colouration.

Dorsal head pattern has six distinct dark spots; one spot in the frontal region that is slightly narrow; two dark elongated spots between the occiputs just parallel to the supraciliaries and three dark spots in the parietal region, the one in the middle much longer than the other two. All the markings on the head are distinctly separated from each other. Laterally a dark streak through the eye and continues as dark postocular stripes that connect to form the collar band. Labials are mostly whitish with some dark markings on the first four labials and the area below the eye. Ventral aspect of the body pale with irregular black mottling mostly towards the flank and with dark spots in the trunk region. Ventral aspect of the head has numerous thick streaks on infralabials grading into a thin dark network in the gular region; ventral aspect of tail is dark with some scattered light scales. Dorsal colour heterogeneous, creamish white to brown, one thick dark-brown band on the mid-body extending into the lateral sides where it becomes broader, covering the region between the fore and hind limb insertions; and one dark brownish prominent spot behind the band mid dorsally (between the band and sacral region). Tail dorsum is darker with irregular black mottling and one dark spot (roughly bell-shaped) at the tail base. The area between the collar band and the band is much lighter than the area between the band and tail base. Limbs are brownish with irregular black mottling and the thigh has a few small scattered dark streaks. Collar is dark brown and roughly inverted bell-shaped. In preservative, the creamish colour turned slightly paler.

Variations among the paratypes.

Mensural and meristic data for the type series are given in Table. 2. Paratypes of both male and female specimens range in SVL from 28.7-44.7 mm. All paratypes resemble the holotype in overall morphology except as follows: Two internasals in ZSI-R 28280. The scales between outer postmentals are five (three large and two small) in ZSI-R 28279, two in ZSI-R 28276, four in ZSI-R 28278 and two in ZSI-R 28280. The position on the outer postmentals is slightly lower in ZSI-R 28276, ZSI-R 28277 and ZSI-R 28279. The outermost postmental on the left side is covered by four scales. Tail incomplete in ZSI-R 28277 and ZSI-R 28279 (less than 10mm was cut for the DNA extraction). Tails of all the paratypes original except in ZSI-R 28278 that has regenerated from the base of the tail but complete. In colouration, the frontal spot and parietal spot (middle one) are much narrower in ZSI-R 28276 and the parietal spot (middle one) narrower in ZSI-R 28276, ZSI-R 28277 and ZSI-R 28280. Head markings are feeble or inconspicuous in ZSI-R 28278 and ZSI-R 28279. The dorsal band does not extend into the flank covering the whole area between fore and hindlimb insertion in ZSI-R 28277, ZSI-R 28279 and ZSI-R 28280. The collar band in all the paratypes differ from that of the holotype posteriorly; in ZSI-R 28278 and ZSI-R 28279 it is somewhat a straight line, slightly notched inwards in ZSI-R 28276 and ZSI-R 28280 and roughly V-shaped in ZSI-R 28277. Paratype ZSI-R 28280 has one small dark spot between the collar band and middorsal band and the dark spot in the tail base is medially divided in ZSI-R 28278 and ZSI-R 28280.

Comparison with the members of the Cyrtodactylus collegalensis complex.

Cyrtodactylus aravindi sp. nov. can be differentiated from all the members of the Cyrtodactylus collegalensis complex by the presence of a single band on the dorsum (Vs. three pairs of dark spots that may be fused forming horizontal 8 shaped markings in C. collegalensis two broad dark bands on dorsum in C. rishivalleyensis , three rows of irregular blotches in C. srilekhae ), two broad dark bands on dorsum in C. speciosus , 4-6 pairs of spots on dorsum in C. varadgirii ). From the closely related Sri Lankan species C. yakhuna including its variety " Cyrtodactylus zonatus " the new species can be differentiated by a combination of characteristics, presence of a single dark band and a single dark spot anterior to the hindlimb insertions on the dorsum (Vs. one or two dark bands on the dorsum (the posterior mark is much larger making it look like a band than a spot)); the dorsal band is always in mid-dorsum i.e. its edges on both ends are equally spaced between the fore and hindlimb insertions (Vs. the band is always on the anterior of the body, more closely to the forelimb insertion). Additionally, Cyrtodactylus aravindi sp. nov. has higher number of ventral scales across belly (MVSR) 33-36 compared to C. collegalensis (27-29) and C. speciosus (29-34).

Distribution and Natural History.

Cyrtodactylus aravindi sp. nov. is currently known from the two locations 20 kilometres from each other in straight-line distance in the Agasthaymalai hill range in the southern Western Ghats of India. The type locality is in the rain shadow region with very high winds on the eastern slopes of the Western Ghats close to the Aralvaimozhi pass (Fig. 7A ) and Thuckalay is situated more towards the western slopes at the southernmost end of the Western Ghats (Fig. 7B ) receiving an annual rainfall of about 600-900 mm and 900-1200 mm, respectively ( Pascal et al. 2004). Cyrtodactylus aravindi sp. nov. is a nocturnal species and the type series was collected from the ground at night between 19:30-22.00 hrs. The holotype and the four paratypes (ZSI-R 28276-ZSI-R 28279) were all collected from a small area (ca. 60 acres) in the type locality, an isolated southern tropical dry evergreen scrub forest patch, the woody trees Tamarindus indicus , Ficus religiosa and other shrubs with some history of agriculture about two decades ago. At both sites, Cyrtodactylus aravindi sp. nov. appears to be a rather uncommon species. The holotype (ZSI-R 28275) was collected from the bottom of a shrub, ZSI-R 28277 was collected from leaf litter covered by a Banyan tree, paratypes ZSI-R 28276, ZSI-R 28278 and ZSI-R 28279 were found in the mud path covered by vegetation consisting of bushes and grasses. Paratype ZSI-R 28280 was collected from hilly terrain mainly composed of rubber plantations intermixed with coffee and coconut plantations. In both locations the new species is found in sympatry with a few geckonids namely: Hemidactylus acanthopholis Mirza & Sanap, 2014, H. leu-shnualiti Duméril & Bibron, 1836, H. parvimaculatus Deraniyagala, 1953 and H. triedrus (Daudin, 1802).

At the type locality, individuals were seen in the months of October (2021) and April (2022). They were not recorded in the months of November-December (2021) and May (2022) when field effort was made at Muppandal as a part of the ecological study commissioned by the landholder Dohnavur Fellowship. This species seems to occur in lower density in open scrub habitat but prefers areas with high grass, shrub and tree cover with open edges.

At the type locality, agriculture was practised in the past but with the absence of intervention in over two decades, ecological succession has occurred. But when agriculture was paused, wind farms had been set up and run for over two decades since. Currently, both the known locations of C. aravindi sp. nov. do not fall under any protected area network. However, the type locality Muppandal is set at less than one kilometre from the border of Kanyakumari Wildlife Sanctuary but is isolated by the linear infrastructure of highways in the East, West and North among other landuse. It also demonstrates the role private properties like Dohnavur Fellowship can play in conservation of lesser-known or lesser charismatic species outside the protected area networks in southern Tamil Nadu state.

Figures

Figure. 3. A Dorsal (upper) and B ventral (lower) aspects of the holotype (ZSI-R 28275) of Cyrtodactylus aravindi sp. nov. Scale bar = 10 mm.

Figure. 4. Cyrtodactylus aravindi sp. nov. (holotype, ZSI-R 28275). A head in dorsal view, B ventral view, C lateral view, D ventral view of right manus, and E right pes. Scale bar = 5 mm.

Figure. 5. Dorsal (top) and ventral (bottom) aspects of the paratypes of Cyrtodactylus aravindi sp. nov. A ZSI-R 28276, B ZSI-R 28277, C ZSI-R 28278, D ZSI-R 28279 and E ZSI-R 28280. Scale bar = 10 mm.

Figure. 6. Live images of Cyrtodactylus aravindi sp. nov. A Holotype (ZSI-R 28275), B Paratype (ZSI-R 28280), C uncollected juvenile female from the type locality.

Figure. 7. General habitat of C. aravindi sp. nov. A Muppandal (type locality) and B Thuckalay (paratype locality), Kanyakumari district, Tamil Nadu, India.