Hemidactylus easai, Das & Pal & S & Palot & V & Narayanan, 2022

Das, Sandeep, Pal, Saunak, S, Siddharth, Palot, Muhamed Jafer, V, Deepak & Narayanan, Surya, 2022, A new species of large-bodied Hemidactylus Goldfuss, 1820 (Squamata: Gekkonidae) from the Western Ghats of India, Vertebrate Zoology 72, pp. 81-94 : 81

Hemidactylus easai sp. nov.

Figs 3 , 4 , 5A , 6 , 7

Holotype.

ZSI/WGRC/IR.V/3471 (Figs 2 - 5A , 6A , 7A ) adult male, from Attapadi, Palakkad district, Kerala, India (11.146397°N, 76.65939°E, 530m asl), collected by Muhamed Jafer Palot and Sandeep Das on 12 June 2020.

Paratypes (n=3).

ZSI/WGRC/IR.V/3472 (adult male), BNHS 3103 & BNHS 3104 (adult females), collections details same as the holotype (Figs 5B-C , 6 & 7B ).

Etymology.

The specific epithet is a patronym honouring Dr P. S. Easa, former director of Kerala Forest Research Institute, Thrissur, Kerala for his contributions towards wildlife research, conservation and management, primarily in the Western Ghats over the last four decades and for mentoring SD. We suggest Easa’s rock gecko as common name.

Diagnosis.

A large-sized gecko of the genus Hemidactylus , snout-vent length up to SVL 107 mm (n=4). Dorsal pholidosis heterogeneous, composed of roughly circular, granular scales intermixed with much enlarged, fairly regularly arranged longitudinal rows of 17 or 18 striated subtrihedral tubercles at midbody (Fig. 5A-C ). 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. 20-23 tubercles in paravertebral rows; ventrolateral folds distinct; 41 or 42 transverse ventral scale rows at mid-body. Digits with enlarged scansors, lamellae in straight transverse series; 2-5 undivided basal lamellae beneath first finger and 2-5 beneath first toe; 0 or 1 undivided basal lamellae beneath fourth toe; 10-12 lamellae (including undivided and divided) beneath first finger and 10 or 11 beneath first toe; 11-13 lamellae (including undivided and divided) beneath fourth finger and 13 beneath fourth toe; males with series of 24-30 femoral pores on each side separated by 2-4 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 6-8 large, keeled, striated, posteriorly pointed tubercles. Dorsal coloration dull-brown with a series of four or five transverse pale saddles from occiput to sacrum, tail with distinct alternating light and dark bands.

Description of holotype.

The holotype, an adult male, (SVL 105.8 mm) well preserved and is in good condition. Head short (HL/SVL 0.30), slightly elongate (HW/HL 0.76), not strongly depressed (HH/HL 0.41), distinct from neck. Loreal region slightly inflated, canthus rostralis indistinct (Fig. 4C ). Snout short (SE/HL 0.46); slightly longer than twice eye diameter (OD/SE 0.45); scales on snout, canthus rostralis, forehead and inter-orbital region heterogenous, mostly granular and conical; scales on the snout and canthus rostralis much larger than those on occiput, forehead and inter-orbital regions. Eye small (OD/HL 0.19); pupil vertical with crenulated margins; supraciliaries small, mucronate, gradually increasing in size towards the front of the orbit, largest about one-third the way from anterior edge of orbit. Ear opening elliptical (greatest diameter 2.2 mm); a row of small pointed tubercles above the ear; eye to ear distance slightly greater than the diameter of eye (EE/OD 0.71). Rostral wider than deep (RL/RW 0.65), partially divided dorsally by a weakly developed rostral groove; two internasals, 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 two postnasals on either side; 4-6 rows of scales separate orbit from supralabials. Mental triangular; two well-developed postmentals, the inner pair smaller (3.3 mm) than the mental (4.4 mm), and in strong contact with each other (1.1 mm) behind mental, outer pair shorter (1.7 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 six small gular scales on each side; outer postmentals bordered by infralabial II on the right and separated by a large scale on the left, inner postmental, and five gular scales on both side along with one large scale on the right side between the third infralabial and the outer postmental; four to five additional rows of scales below infralabials III to VIII are enlarged and weakly imbricate. Supralabials (on both sides) to mid orbital position nine, to angle of jaw 11 on right and left; infralabials 9 on each side. Body relatively stout (BW/SVL 0.20), ventrolateral folds distinct.

Dorsal pholidosis heterogeneous, composed of subcircular granular scales intermixed with enlarged, fairly regularly arranged strongly keeled, pointed tubercles in 18 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 12-15 small granules with 2-5 granules between two longitudinally adjacent enlarged tubercles (3-6 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 dorsal granular scales, smooth, imbricate, slightly larger on precloacal and femoral region than on chest and abdominal region; midbody scale rows across belly 42; 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 subequal 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, except those on knee flat, imbricate, intermixed with enlarged, conical tubercles, which are larger on thigh compared to shank; anterior aspect of thigh with flatter scales, posterior aspect with granular scales. Twenty-five and twenty-four pores in an enlarged row of femoral scales on left and right side respectively, 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 0.15); tibia short (CL/SVL 0.17); 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: 11-12-12-12-12 (left manus), 10-13-12-12-11 (right manus) (Fig. 4E ), 10-14-13-13-12 (left pes), 10-14-13-13-13 (right pes) (Fig. 4F ). Relative length of digits (measurements in mm in parentheses): I (5.8) < II (6.7) < III (7.2) < IV (7.4) < V (8.1) (left manus); I (3.9.) < V (9.2) < IV (8.4) < II (8.3) < III (8.2) (left pes).

Tail regenerated; 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 4-10 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 (Fig. 3D ). Two subequal rounded postcloacal spurs on each side are much smaller than dorsal tubercles at midbody (Fig. 3D ).

Variations in the paratypes.

Variations in the paratypes in some of the meristic and mensural characters are provided in the Table 2 . Two paratypes are females. BNHS 3104 has an incomplete tail and partially broken in BNHS 3103 at the base, but intact (Fig. 6B ). Internasals in BNHS 3103 are separated by two small scales. In ZSI/WGRC/IR.V/3472 & BNHS 3104 outer post mental on the left side is in contact with the third supralabial and a distinct small scale is present between the mental and the inner post mental on the right side in ZSI/WGRC/IR.V/3472. Skin in the frontal region of the head in BNHS 3104 is slightly damaged but intact (Fig. 6C ). In life, all the paratypes were comparatively lighter in dorsal colouration and this, however, is not significant in preservative.

Color in life (based on holotype).

Dorsal aspect of the body, uniformly brownish with four indistinct transverse bands from the neck to the hind limb insertion and two on the tail, bordered by discontinuous black patches (Fig. 7A ). Dorsal aspect of the head without any dark markings in the parietal and frontal region. A preorbital yellow streak extends from the posterior of the naris to the anterior of the eye on both sides. Ventral aspect of the head mostly cream coloured with light brown mottling on the gular region and mental, infralabials, post mentals and few other adjacent scales mottled with dark brown. Fore and hindlimbs brownish speckled with irregular black patches on the dorsal side. Ventral aspect of the body, forelimbs and hindlimbs predominantly cream coloured with sprinkled and or mottled with brown colour.

Comparison with other members of Hemidactylus prashadi group.

Hemidactylus easai sp. nov. differs from the other large-bodied congeners by several non-overlapping morphological characters. It can be distinguished by the presence of 24-30 femoral pores (FP) separated by 2-4 pore-less scales (vs. 21 FP separated by two pore-less scales in H. kolliensis ; 19-21 FP separated by 13-14 pore-less scales in H. acanthopholis ; 22-24 FP separated by 3-6 pore-less scales in H. hunae ; 16-18 FP separated by 13-14 pore-less scales in H. sirumalaiensis ; 17-22 FP separated by 10-11 pore-less scales in H. vanam ; 21-24 PF separated by four pore-less scales in H. sushilduttai ; 15-19 FP separated by 3 pore-less scales in H. depressus ; 17-18 FP separated by 5 pore-less scales in H. siva ; 7-9 FP separated by 1-3 pore-less scales in H. triedrus ; 11-15 FP separated by 1-3 pore-less scales in H. sahgali ; 7-8 FP separated by 3 pore-less scales in H. whitakeri ; 21-24 FP separated by 5-7 pore-less scales in H. kimbulae ; 15-19 FP separated by 6 pore-less scales in H. aaronbaueri , 17-18 FP separated by 7 pore-less scales in H. tamhiniensis ,18-21 FP separated by 4 pore-less scales in H. kangerensis ); by the presence of 16-18 rows of moderately keeled subtrihedral tubercles (vs. 22-24 in H. paaragowli ; 14-16 in H. prashadi ; 15-16 in H. kolliensis and homogeneous dorsal pholidosis with no enlarged tubercles in H. scabriceps ); .

From the closely related Hemidactylus graniticolus , H. easai sp. nov. can be differentiated by the presence of moderate to strongly keeled tubercles on the dorsum (vs. weakly keeled or smooth tubercles on the dorsal aspect) (Fig. 5 ); enlarged tubercles on the two most medial parasagittal rows subconical, strongly keeled (vs. tubercles on the two most medial parasagittal rows flattened, smooth to weakly keeled); dorsal pholidosis of tail with slightly larger granular, striated scales and longitudinal series of 6-8 large, keeled, striated, posteriorly pointed tubercles (vs. dorsal pholidosis of tail with small, imbricate, striated scales and a series of four enlarged, keeled weakly striated and flattened tubercles).

Distribution and natural history notes.

Hemidactylus easai sp. nov. is currently known only from the type locality in the Kerala parts of the Western Ghats. The type series was collected from human settlements, inside buildings on the banks of the river Bhavani, which originates from the Nilgiri Hills of Western Ghats (Fig. 8 ), flows very close to Silent Valley National Park and joins the Cauvery River near Tamil Nadu. The locality is a rain shadow area dominated by dry zone vegetation interspersed with riparian vegetation. The mean annual rainfall in Palakkad district is 2135 mm ( Prasad et al. 2021). The holotype and the paratypes were found at night, actively foraging for insects. Several uncollected individuals of H. easai sp. nov. were observed in human settlements and rock crevices in the vicinity of the type locality. Hemidactylus easai sp. nov. was found in sympatry with Cnemaspis gracilis in the same microhabitat and, H. cf. whitakeri and Cyrtodactylus sp. was also found in the type locality.

The type locality of H. easai sp. nov. is in a close proximity to the Silent Valley National Park (SVNP) but not under any legal protection. It is however possible that the new species is found within the SVNP and adjacent Nilgiris mountain range, given that the habitat is contiguous.

Correct spelling of Hemidactylus paaragowli Srikanthan, Swamy, Mohan & Pal 2018.

Srikanthan et al. (2018), in the original description, included two different spellings, " Hemidactylus paaragowlipaaragowli "(abstract) or " Hemidactylus paaragowli " (keywords, description). However, the original authors or the subsequent authors working on the systematics of Hemidactylus from India did not correct this nomenclatural error but used the name " Hemidactylus paaragowli " ( Mirza et al. 2018; Agarwal et al. 2019a; Lajmi and Karanth 2020; Khandekar et al. 2020). Here in this work, according to the provisions of articles 19.3, 24.2 & 32.2.1 of the International Code for Zoological Nomenclature (ICZN, 1999), we act as the first reviser and choose Hemidactylus paaragowli as the correct spelling since this spelling is used in the formal description part and higher usage (20 times) over the incorrect " Hemidactylus paaragowlipaaragowli " which is cited only once in the abstract of the original description ( Srikanthan et al. 2018).

Figures

Figure 2. ML phylogeny showing the phylogenetic relationships of Hemidactylus easai sp. nov. Numbers at internal branches are posterior probability and ML bootstrap support values, respectively. Sample marked in blue is generated in this study and sample from the type locality of H. graniticolus is marked in red.

Figure 3. Holotype of Hemidactylus easai sp. nov. (ZSI / WGRC / IR. V / 3471) in dorsal (A) and ventral (B) aspect. Scale bar = 10 cm.

Figure 4. Hemidactylus easai sp. nov. (holotype, ZSI / WGRC / IR. V / 3471), 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. Plate showing the dorsal pholidosis of Hemidactylus easai sp. nov. (A, ZSI / WGRC / IR. V / 3471, B. ZSI / WGRC / IR. V / 3472 & C. BNHS 3103) and H. graniticolus (D. BNHS 1850, E. BNHS 1858 & F. BMNH 1946.8.23.76).

Figure 6. Paratypes of Hemidactylus easai sp. nov. in dorsal aspects, A. ZSI / WGRC / IR. V / 3472, B. BNHS 3103, B. BNHS 3104. Scale bar = 10 mm.

Figure 7. Hemidactylus easai sp. nov. showing colour in life, A. Holotype ZSI / WGRC / IR. V / 3471, B. Paratype ZSI / WGRC / IR. V / 3472.

Figure 8. A. Abandoned building from the type locality where holotype was collected and B. General habitat of the type locality of Hemidactylus easai sp. nov.