Hemidactylus pakkamalaiensis Narayanan, Christopher, Raman, Mukherjee, Vimalraj, Deepak, 2023

Narayanan, Surya, Christopher, Peter, Raman, Kothandapani, Mukherjee, Nilanjan, Prabhu, Ponmudi, Lenin, Maniezhilan, Vimalraj, Sivangnanaboopathidoss & Deepak, V., 2023, A new species of rock-dwelling Hemidactylus Goldfuss, 1820 (Squamata: Gekkonidae) from the southern Eastern Ghats, India, Vertebrate Zoology 73, pp. 499-512 : 499

Hemidactylus pakkamalaiensis Narayanan, Christopher, Raman, Mukherjee, Vimalraj, Deepak sp. nov.

Figs 3 , 4 , 5 , 6

Holotype.

BNHS 2907 (Figs 3 , 4 , 6A ) adult male, collected from Pakkamalai Hill, Gingee Hills range, Villupuram district, Tamil Nadu, India (12.164819°N, 79.250909°E, 335m asl) by Peter Christopher and Surya Narayanan on 27 November 2022.

Paratypes (n = 4).

BNHS 2908 & BNHS 2909 (adult males), BNHS 2910 & BNHS 2911 (adult females), collections details same as the holotype (Figs 5 , 6B ).

Etymology.

The specific epithet is a toponym named after its type locality Pakkamalai Hill. We suggest an English name Pakkamalai rock gecko and a Tamil name ப ாக்கமைல ப ாைறப்பல்லி.

Diagnosis.

A large-sized gecko of the genus Hemidactylus , snout-vent length up to a maximum SVL of 109 mm (n = 5). Dorsal pholidosis heterogeneous, composed of roughly circular, granular scales intermixed with much enlarged, fairly regularly arranged longitudinal rows of 19-22 striated subtrihedral tubercles at midbody. Enlarged tubercles on the two most medial parasagittal rows are small, subconical, strongly keeled and rounded, gradually increasing in size and becoming conical towards flanks, last two to three rows on flanks smaller, conical. Two well-developed pairs of postmentals, the inner pair longer than the outer pair and mental, and in broad contact behind the mental. Paravertebral rows with 21-24 tubercles; 34-38 transverse ventral scale rows at mid-body. Digits with enlarged scansors, lamellae in straight transverse series; two or three undivided basal lamellae beneath first finger and two or three beneath first toe; one or two undivided basal lamellae beneath fourth toe; ten or 11 lamellae (including undivided and divided) beneath first finger and nine or ten beneath first toe; 12 or 13 lamellae (including undivided and divided) beneath fourth finger and 12-14 beneath fourth toe; males with series of 19-21 femoral pores on each side separated by four or five pore-less scales. Original tail depressed, oval in transverse section with a median dorsal furrow; scales on the tail slightly larger than dorsals, striated, with longitudinal series of 4-8 large, keeled, striated, posteriorly pointed tubercles. Dorsal colouration dull-brown with a series of four or five transverse pale saddles from occiput to sacrum, tail with distinct alternating light and dark bands.

Comparison with other members of prashadi group.

Hemidactylus pakkamalaiensis sp. nov. differs from the other large-bodied congeners by several non-overlapping morphological characters. It can be distinguished by the presence of 19-21 femoral pores (FP) separated by 4 or 5 pore-less scales in males (vs. 23-28 FP separated by 1-3 pore-less scales in H. graniticolus ; 19-21 FP separated by 13 or 14 pore-less scales in H. acanthopholis Mirza & Sanap, 2014; 26-28 FP separated by 7-9 pore-less scales in H. hunae Deraniyagala, 1937; 16-18 FP separated by 13 or 14 pore-less scales in H. sirumalaiensis Khandekar et al., 2020; 17-22 FP separated by 10 or 11 pore-less scales in H. vanam Chaitanya et al., 2018; 15-19 FP separated by three pore-less scales in H. depressus Gray, 1842; 17 or 18 FP separated by five pore-less scales in H. siva Srinivasalu et al., 2018; 7-9 FP separated by 1-3 pore-less scales in H. triedrus (Daudin, 1802); 11-15 FP separated by 1-3 pore-less scales in H. sahgali Mirza et al., 2018; 7 or 8 FP separated by three pore-less scales in H. whitakeri Mirza et al., 2018; 15-19 FP separated by six pore-less scales in H. aaronbaueri Giri, 2008; 17 or 18 FP separated by seven pore-less scales in H. tamhiniensis Khandekar et al., 2021; 18-21 FP separated by four pore-less scales in H. kangerensis Mirza et al., 2017; 24-30 FP separated by 2-4 pore-less scales in H. easai ; 14-15 FP separated by 11 pore-less scales in H. hegdei Pal & Mirza, 2022); by the presence of 19-22 rows of moderately keeled subtrihedral tubercles in both sex (vs. 16 or 17 in H. sushilduttai Giri et al., 2017; 12-14 in H. kimbulae ; 15 or 16 in H. kolliensis ; 17 or 18 in H. easai ; 18-20 in H. kangerensis ; 14-16 in H. hunae ; 16 in H. siva ; 16-18 in H. sushilduttai ); presence of 34-38 transverse ventral scale rows at mid-body in both sex (vs. 40-13 in H. hunae , 41 or 42 in H. easai ; 40-46 in H. graniticolus ; 28-30 in H. kangerensis ; 30-33 in H. sushilduttai ; 27-30 in H. siva ); dorsal pholidosis heterogeneous with enlarged tubercles (vs. dorsal pholidosis homogeneous with no enlarged tubercles in H. scabriceps ).

Description of holotype (BNHS 2907).

The holotype, an adult male, (SVL 104 mm) is well preserved. Head short (HL/SVL 0.29), slightly elongated (HW/HL 0.66), not strongly depressed (HH/HL 0.29), distinct from neck. Loreal region slightly inflated, and canthus rostralis indistinct (Fig. 4C ). Snout short (SE/HL 0.40); slightly longer than twice eye diameter (OD/SE 0.45); scales on the snout, canthus rostralis, forehead and inter-orbital region heterogeneous, mostly granular and conical; scales on the snout and canthus rostralis much larger than those on occiput, forehead and inter-orbital regions; skin in the frontal slightly damaged. Eye small (OD/HL 0.18); pupil vertical with crenulated margins; supraciliaris small, mucronate, gradually increasing in size towards the front of the orbit, largest about one-third the way from the anterior edge of orbit; a few supraciliaris in the suprocular region in the left eye damaged and missing. Ear opening elliptical (2.8 mm); a row of small keeled tubercles above the ear.

Rostral scale wider than deep (RL/RW 0.68), partially divided dorsally by a weakly developed rostral groove; nasals, enlarged and separated by three small scales; one supranasal on each side, smaller than internasals; two diminutive postnasals on each side; rostral in contact with nasal scale, supralabial I, internasals and the anterior small scale separating the internasals; nostrils small (0.8 mm), oval; nasal scale surrounded by supranasal, internasal, rostral, supralabial I and three postnasals on either side; five (on the anterior) and three (on the posterior) rows of scales separate orbit from supralabials.

Mental triangular; two well-developed pair of postmentals, the inner pair smaller (3.4 mm) than the mental (4.6 mm), and in strong contact with each other (1.2 mm) behind mental, outer pair shorter (2.2 mm) than the inner pair and separated from each other by inner pair (Fig. 4B ). Inner postmentals bordered by mental, infralabial I and II on left and right, outer postmental and 10 small gular scales on each side; outer postmentals bordered by infralabial II on the right and left, inner postmental, and five gular scales on the right and six gular scales in the left along with two other large scales between the gular scales and the infralabials; one to three additional rows of scales below infralabials III to VIII are enlarged and weakly imbricate. Supralabials (on both sides) to mid orbital position 10, to angle of jaw 12 on right and left; infralabials 10 and nine on right and left side, respectively. Body relatively stout (BW/SVL 0.22), ventrolateral folds not very distinct.

Dorsal pholidosis heterogeneous, composed of subcircular granular scales intermixed with enlarged, fairly regularly arranged strongly keeled. Pointed tubercles in 21 longitudinal rows, extending from occiput to tail, that are heterogeneous in shape and size; enlarged tubercles on the two most medial parasagittal rows slightly smaller than rest on dorsum and the rows most broadly spaced from one another, gradually increasing in size and becoming conical towards flanks, last two rows on flanks slightly smaller than medial parasagittal rows and strongly conical; each enlarged tubercle surrounded by a rosette of 13-16 small granules with 2-5 granules between two longitudinally adjacent enlarged tubercles (5-11 between parasagittal rows at midbody); enlarged tubercles on nape and shoulder smaller and conical, those on occiput and the temporal region still smaller, conical.

Ventral scales larger than granular scales on the dorsum, smooth, imbricate, slightly larger on precloacal and femoral region than on chest and abdominal region; midbody scale rows across belly 34; gular region with small, granular scales, becoming slightly larger and imbricate on anterior and lateral aspect. Scales on palm and sole smooth, imbricate, subcircular; scales on the dorsal aspect of upper arm slightly smaller than the last row of enlarged tubercles on dorsum, flat, weakly pointed, imbricate, keeled; dorsal aspect of forearm with smaller, granular scales, intermixed with a few enlarged, conical tubercles, those on anterior aspect are smooth, flat, imbricate; scales on dorsal part of thigh and shank granular, imbricate, intermixed with enlarged, conical tubercles, which are larger on thigh compared to shank that are subequal to those tubercles in the dorsal aspect of the body; anterior aspect of thigh with flatter scales, posterior aspect with granular scales.

Twenty pores in an enlarged row of femoral scales on both sides, separated medially by a diastema of four pore-less scales; subequal row of enlarged scales anterior to pore-bearing scales (Fig. 4D ). Fore and hind limbs relatively short, stout; forearm short (FL/SVL 0.13); tibia short (CL/SVL 0.15); digits moderately short, strongly clawed; all digits of manus and digits I-IV of pes indistinctly webbed; terminal phalanx of all digits curved, arising angularly from distal portion of expanded lamellar pad, half or more than half as long as associated toepad; scansors beneath each toe in a straight transverse series, divided except for distal and four to five basal scansors on digit I: 10-13-13-12-13 (left manus), 10-12-13-12-13 (right manus) (Fig. 4E ), 10-13-13-13-13 (left pes), 10-14-13-13-13 (right pes) (Fig. 4F ). Relative length of digits (measurements in mm in parentheses): I (6.8) <II (8.7) <III (8.3) <IV (8.2) <V (8) (left manus); I (6.8) <V (9.6) <IV (8.7) <II (9.3) <III (6.6 damaged) (left pes).

Tail complete regenerated (about 30% of the tail original); depressed, flat beneath, verticillate, with well-defined median furrow; scales on the dorsal aspect of tail subimbricate, larger than granules on dorsum, with a series of 4-6 much enlarged, strongly pointed, moderately keeled tubercles; ventral scales enlarged, imbricate, median row (subcaudal plates) covering almost entire base of the tail, bordered laterally by two or three rows of larger pointed, smooth, imbricate scales; those close to vent small, smooth, flat and imbricate. Two indistinct postcloacal spurs on each side, much smaller than dorsal tubercles at midbody.

Variations in the paratypes.

Variations among the meristic and morphometric characters in the paratypes are provided in the Table. 2. Two paratypes BNHS 2910 & 2911 are females. BNHS 2909 has a very short tail among all the type series. Up to eight enlarged tubercles in the tail in paratype BNHS 2909. postcloacal spur distinct in paratypes BNHS 2908 & BNHS 2909. Other differences include the number of undivided lamellae at the base of pes and manus that varies between three (BNHS 2908) to five (BNHS 2910 & BNHS 2911) in the paratypes and occasionally in the middle in BNHS 2910 & 2909. Gular scales that are in contact with the outer postmental much larger on the right side in BNHS 2909. The total number of the gular scales contacting the outer postmentals vary between eight and thirteen.

Colour in life and preservative (based on holotype).

Dorsal aspect of the body, uniformly brownish with three indistinct transverse bands from the neck to the hind limb insertion and one on the tail, bordered by discontinuous brownish patches extending towards the lateral side of the body (Fig. 6A ). Dorsal aspect of the head is brownish with inconspicuous white markings on the parietal and neck region. Ventral aspect of the head is mostly cream-coloured with light brown mottling on the gular region and mental, infralabials, post mentals and a few other adjacent scales mottled with dark brown. Fore and hindlimbs are brownish speckled with irregular black patches and a few scattered brownish-yellow spots on the dorsal side. Ventral aspect of the body, forelimbs and hindlimbs predominantly cream coloured with sprinkled and or mottled with brown colour. In preservative, the overall colouration is the same as in life except in dark transverse bands on the dorsum that became less prominent.

Distribution and natural history.

Hemidactylus pakkamalaiensis sp. nov. is currently known from the Gingee Hills cluster. This species is nocturnal and appears to be locally abundant. In addition to the collected specimens, we encountered 56 live individuals in and around the collection site during our four-day fieldwork. All the specimens in the type series were gathered from rock boulders within a limited area at the type locality, mostly after 19:00 hrs. These hills are predominantly formed of granitic rock boulders and feature native vegetation, including thorny scrub jungle, moist deciduous forest, and tropical dry evergreen forest ( Arulappan et al. 2015).

Figures

Figure 3. Holotype of Hemidactylus pakkamalaiensis sp. nov. (BNHS 2907) in the dorsal (A) and ventral (B) view. Scale bar = 10 mm.

Figure 4. Hemidactylus pakkamalaiensis sp. nov. (Holotype, BNHS 2907), A head in dorsal view, B ventral view, C lateral view, D view of the femoral region, E ventral view of right manus and F right pes. Scale bar = 10 mm.

Figure 5. Paratypes of Hemidactylus pakkamalaiensis sp. nov. in dorsal view, A BNHS 2908, B BNHS 2909, C BNHS 2910, D BNHS 2911. Scale bar = 10 mm.

Figure 6. Dorsolateral view of the A holotype (BNHS 2907) and B one of the paratypes (BNHS 2911) of Hemidactylus pakkamalaiensis sp. nov. in life from Pakkamalai Hill, Tamil Nadu, India.