Hemidactylus quartziticolus, Khandekar & Thackeray & Mariappan & Gangalmale & Waghe & Pawar & Agarwal, 2023

Khandekar, Akshay, Thackeray, Tejas, Mariappan, Rameshwaran, Gangalmale, Satpal, Waghe, Vivek, Pawar, Swapnil & Agarwal, Ishan, 2023, A remarkable new species of gecko (Squamata: Gekkonidae: Hemidactylus) from scrublands at the southern tip of India, Vertebrate Zoology 73, pp. 433-450 : 433

Hemidactylus quartziticolus sp. nov.

Figs 3 , 4 , 5 , 6 , 7

Holotype.

NRC-AA-1256 (AK-R 1215), adult male, from near Jeya Parvathi Amman Kovil, Vallanadu Reserve Forest, Manakkarai (8.6848° N, 77.8696° E; ca. 120 m asl.), Thoothukudi district, Tamil Nadu state, India, collected by Akshay Khandekar, Ishan Agarwal, Swapnil Pawar and team on 12 April 2022.

Paratypes.

(n = 9) NRC-AA-1257 (AK-R 1214), NRC-AA-1258 (AK-R 1218), adult males, same data as holotype; NRC-AA-1259 (AK-R 1220), NRC-AA-1260 (AK-R 1221) adult males, NRC-AA-1264 (AK-R 1216), adult female, same data as holotype except collected from the other side of Jeya Parvathi Amman Kovil, Manakkarai (8.6771° N, 77.8722° E; ca. 90 m asl.); NRC-AA-1261 (AK-R 1206), NRC-AA-1262 (AK-R 1207), NRC-AA-1263 (AK-R 1208), adult males, from Kurumalai Reserve Forest, Kurumalai (9.0919° N, 77.8543° E; ca. 130 m asl.); NRC-AA-1265 (AK-R 1209), adult female, from near Perumal Kovil, Kurumalai (9.0927° N, 77.8519° E; ca. 90 m asl.), Thoothukudi district, Tamil Nadu state, India, collected by same team on 10 April 2022.

Etymology.

The specific epithet is a combination of the German noun “quartz” + the Latin suffix -ite (used to denote rocks and minerals) and the Latin suffix -cola that means inhabitant or dweller of, referring to the quartzite rock formations the new species inhabits.

Suggested Common Names.

Quartzite brookiish gecko or Thoothukudi brookiish gecko.

Diagnosis.

A small-sized Hemidactylus , snout to vent length less than 57 mm (n = 10); a single internasal scale behind rostral and between supranasals. Dorsal pholidosis heterogenous, composed of much smaller, subcircular, smooth and flattened granular scales intermixed with 18 regularly arranged rows of distinctly enlarged, subcircular, strongly keeled and pointed tubercles at midbody; tubercles largest on flanks; 18-20 paravertebral tubercles between forelimb and hindlimb insertions; ventral scales much larger than dorsal body granular scales, smooth, subimbricate, sub-equal from chest to vent, 24-29 scales across belly at mid-body, 48-54 longitudinal scales from fore arm insertions to anterior margin of cloaca; subdigital scansors smooth, mostly divided in oblique series; four lamellae under digit I of manus and pes, six or seven lamellae under digit IV of manus and pes; males with continuous series of 35-38 precloacal-femoral pores (n = 8/10); dorsal scales at tail base heterogeneous, granular scales similar in size and shape to those on mid-body dorsum, gradually becoming larger, pointed and subimbricate posteriorly, intermixed with series of 4-10 much enlarged, keeled, conical tubercles forming whorls; median row of sub-caudals smooth, enlarged, undivided, roughly rectangular, plate-like scales covering almost entire portion of the tail. Dorsal colouration beige to tan, scattered dark blotches on dorsum occasionally forming horizontal X-shaped markings on dorsum.

Comparison with members of the Hemidactylus brookii group.

Hemidactylus quartziticolus sp. nov. can be easily distinguished from the Indian members of the Hemidactylus brookii group based on the following differing or non-overlapping characters: 18 regularly arranged rows of distinctly enlarged, subcircular, strongly keeled and pointed tubercles at midbody (versus enlarged tubercles completely absent from dorsum in H. imbricatus Bauer et al., 2008; tubercles only slightly larger than surrounding granular scales in H. albofasciatus Grandison & Soman, 1963, H. gracilis Blanford, 1870, H. reticulatus Beddome, 1870, and H. vijayraghavani Mirza, 2018; 15 rows of dorsal tubercles at mid-body in H. chikhaldaraensis Agarwal, Bauer, Giri & Khandekar, 2019, 15 or 16 in H. chipkali Mirza & Raju, 2017, H. rishivalleyensis Agarwal, Thackeray & Khandekar, 2020 and H. treutleri , 11-14 in H. flavicaudus , 19 or 20 in H. kushmorensis , 13 or 14 in H. mahonyi , 11-17 in H. parvimaculatus Deraniyagala, 1953, 15-17 in H. sankariensis Agarwal, Bauer, Giri & Khandekar, 2019, 14 or 15 in H. srikanthani , and 6-8 in H. xericolus ); males with continuous series of 35-38 precloacal-femoral pores (versus femoral pores absent, only precloacal pores present in H. albofasciatus , H. gracilis , H. imbricatus , H. reticulatus , H. sataraensis Giri & Bauer, 2008, and H. vijayraghavani ; precloacal-femoral pores series separated medially by more than four poreless scales in H. chikhaldaraensis , H. chipkali , H. mahonyi , H. murrayi Gleadow, 1887, H. rishivalleyensis , H. sankariensis , H. srikanthani , H. tenkatei , H. treutleri , and H. varadgirii Chaitanya, Agarwal, Lajmi & Khandekar, 2019; precloacal-femoral pores series separated medially by at least 1-3 poreless scales in H. brookii , H. gleadowi , H. flavicaudus , H. kushmorensis , H. malcolmsmithi (Constable, 1949), H. parvimaculatus , and H. xericolus ); 24-29 scales across belly at mid-body (versus 31-33 scales across belly at mid-body in H. brookii , 33 in H. chikhaldaraensis , 32-34 in H. gleadowi , 33-42 in H. kushmorensis , 30-35 in H. rishivalleyensis , 33-35 in H. sankariensis , 37 or 38 in H. srikanthani , and 30-33 in H. varadgirii ); four lamellae under digit I and six or seven lamellae under digit IV of both manus and pes (versus five lamellae under digit I of pes in H. brookii ; five lamellae under digit I of manus and pes in H. chipkali ; six lamellae under digit I of manus and pes in H. sankariensis ; five or six lamellae under digit I of pes in H. tenkatei ; six lamellae under digit I of manus and seven under digit I of pes, 10 lamellae under digit IV of manus and 11 under digit IV of pes in H. chikhaldaraensis ; five or six lamellae under digit I and 10 under digit IV of pes in H. kushmorensis , five or six lamellae under digit I of both manus and pes, eight or nine lamellae under digit IV of manus and 8-10 under digit IV of pes in H. mahonyi ; six or seven lamellae under digit I of both manus and pes, nine lamellae under digit IV of manus and 10 under digit IV pes in H. rishivalleyensis ; seven lamellae under digit I of both manus and pes, nine or 10 lamellae under digit IV of manus and 10 under digit IV of pes in H. srikanthani ; six or seven lamellae under digit I, nine lamellae under digit IV of manus and pes in H. treutleri ; and five or six lamellae under digit I of manus and pes in H. varadgirii ).

Description of holotype.

The holotype is in good condition except tail slightly bent towards left, tail tip regenerated, and a 4.7 mm long incision in abdomen for tissue collection (Fig. 3A-E ). Adult male, SVL 53.9 mm. Head short (HL/SVL 0.26), moderately elongate (HW/HL 0.79), not strongly depressed (HD/HL 0.42), distinct from neck. Loreal region inflated, canthus rostralis indistinct (Fig. 4A, C ). Snout short (ES/HL 0.42); slightly longer than twice eye diameter (ED/ES 0.49); scales on snout, canthus rostralis, forehead, and inter-orbital region heterogeneous, mostly enlarged and conical; scales on loreal region bordering eye anterior to orbit much larger, more strongly conical, weakly keeled; scales on occiput and temporal region heterogeneous, granular scales intermixed with enlarged, weakly and conical tubercles, enlarged tubercles becoming pronounced, strongly conical and slightly more spaced out on temporal region (Fig. 4A, C ). Eye small (ED/HL 0.20); pupil vertical with crenulated margins; supraciliaries small, mucronate, gradually increasing in size towards front of the orbit (Fig. 4C ). Ear opening oval (greatest diameter 1.5 mm); eye to ear distance greater than diameter of eye (EE/ED 1.70). Rostral wider (2.1 mm) than high (1.3), divided dorsally by a weakly developed rostral groove for about half of its length; two enlarged supranasals, separated from each other by a single, slightly smaller internasal; upper postnasal present, lower postnasal absent on either side; rostral in contact with nostril, first supralabial, supranasals and internasal; nostrils small (0.4 mm), oval; surrounded by supranasals, rostral, first supralabial and upper postnasal on either side; a single row of scales separate orbit from supralabials on each side. Mental subtriangular, slightly wider (2.2 mm) than high (1.9 mm); two pairs of well-developed postmentals, both roughly rectangular; the inner pair slightly shorter (1.5 mm) than the mental, and in strong contact with each other (0.9 mm) below mental, outer pair slightly smaller (1.1 mm) than inner pair and separated from each other by five small, granular chin scales below inner pair (Fig. 4B ). Inner postmentals bordered by mental, infralabial I and II, outer postmental on either side and five small, granular chin scales below; outer postmentals bordered by inner postmental, infralabial II and seven chin scales on left and five on right side; two rows of enlarged, slightly elongate scales below second to fourth infralabials, inner row bordering infralabial with scales slightly larger and elongate than lower row; rest of the gular region with small, subcircular, smooth, more or less flattened, granular scales, becoming slightly larger and imbricate on lateral aspect on either side (Fig. 4B ). Twelve supralabials up to angle of jaw and eight at mid-orbital position on either side; nine infralabials up to angle of jaw and seven at mid-orbital position on both sides (Fig. 4C ).

Body relatively stout (BW/SVL 0.24), trunk relatively short (TRL/SVL 0.43), without ventrolateral fold on either side (Fig. 5A-C ). Dorsal pholidosis heterogenous, composed of much smaller, subcircular, smooth and flattened granular scales intermixed with 18 regularly arranged rows of distinctly enlarged, subcircular, strongly keeled and pointed tubercles at midbody; tubercles increasing in size up to flank and then gradually decreasing ventrolaterally; 19 paravertebral tubercles between limb insertions on either side (Fig. 5A-C ). Enlarged tubercles on nape and shoulder slightly smaller and conical than those on parasagittal rows, those on occiput still smaller and blunt (Figs 2A , 3A ). Ventral scales much larger than granular scales on dorsum, smooth, subimbricate, subequal from pectoral region to cloaca; 27 transverse ventral scales across belly at mid-body; 48 longitudinal scales from forearm insertion to anterior margin of cloaca (Fig. 5B ). A continuous series of 35 precloacal-femoral pores on the lower-most enlarged row of femoral scales (Fig. 4D ).

Scales on palm and sole similar in size or marginally larger than dorsal body granules, subcircular, smooth and flattened; those on dorsal aspect of forearm heterogenous, composed of granular scales intermixed with enlarged tubercles that are similar to the enlarged tubercles on dorsum in shape and size, weakly keeled and pointed; scales on dorsal aspect of palm and wrist much larger than those on granular scales on body dorsum, smooth, flattened and subimbricate; scales on ventral aspect of forearm granular, smooth, marginally larger than dorsal body granules (Fig. 2A, B ). Scales on dorsal aspect of thigh and shank heterogenous, consisting of granular scales intermixed with enlarged, weakly keeled and pointed tubercles except those on knee slightly smaller; scales near limb insertions granular, slightly smaller than dorsal body granules; scales on dorsal aspect of sole heterogeneous, slightly larger, flattened, smooth, subimbricate scales intermixed with slightly enlarged weakly keeled and weakly pointed tubercles; scales on ventral aspect of thigh and shank similar to body ventrals, subequal, smooth and subimbricate on thigh and imbricate on shank (Fig. 2A, B ).

Fore and hind limbs relatively short, stout; forearm short (FL/SVL 0.11); tibia short (CL/SVL 0.13); digits moderately short, strongly clawed; all digits of manus and digits I-IV of pes indistinctly webbed at base; terminal phalanx of all digits curved, arising angularly from distal portion of expanded lamellar pad, half or more than half as long as associated lamellar pad; scansors beneath each digit in oblique series (the number of undivided basal lamellae excluding apical lamella in parentheses): 4(1)-6(0)-7(1)-7(1)-6(1) (left manus; Fig. 4E ), 4(1)-6(0)-7(1)-7(1)-6(1) (right manus); 4(1)-7(1)-7(1)-7(1)-6(1) (left pes; Fig. 4F ), 4(1)-7(1)-7(1)-7(1)-6(1) (right pes). Relative length of digits (measurements in mm in parentheses): IV (3.9)> III (3.4) = V (3.4)> II (3.0)> I (2.1) (left manus); IV (4.7)> III (4.2)> V (3.9)> II (3.4)> I (2.7) (left pes).

Tail original except tip (15.4 mm) which is regenerated, depressed, flat beneath, verticillate, with median furrow; tail equal to snout-vent length (TL/SVL 1.00; Fig. 2C-E ). Dorsal scales at tail base and on original tail heterogeneous, granular scales similar in size and shape to those on mid-body dorsum, gradually becoming larger, pointed and subimbricate posteriorly, intermixed with series of 4-10 much enlarged, keeled, conical tubercles forming whorls; tubercles in ventrolateral aspect weakly keeled to smooth; 10 enlarged tubercles in first three whorls, eight in fourth whorl, seven in fifth and sixth whorls, six in 7-11 whorls; rest with four enlarged tubercles (Fig. 2C-E ). Ventral scales at tail base subequal, smooth, imbricate, slightly larger than midbody ventral scales; three subequal, smooth postcloacal spurs on each side, smaller than dorsal tubercles at mid-body; slightly increasing in size posteriorly; rest of original tail with large, undivided, roughly rectangular, plate-like subcaudal scales (median row) covering almost entire portion of the tail; median row bordered laterally by one or two rows of large, smooth, imbricate scales (Fig. 2D, E ).

Colouration in life (Fig. 6A).

Dorsal ground colour of head, body, limbs and tail brown. Two short preorbital streaks anterior to eye; postorbital streaks distinct, upper terminating on temporal region and lower extending onto neck to form a discontinuous collar. Labials with fine black spots and ochre streaks. Head, body and tail with black blotches - few scattered on head, four along vertebral midline between limb insertions - with two X-shaped markings running through spots across centre of back and anterior to hindlimb insertions, and one incomplete X-shaped marking at forelimb insertions; tail with about 11 narrow, black markings which may be paired spots, single spots or crossbars; limbs with dark reticulation and digits with a few crossbars. Venter off-white.

Variation and additional information from paratypes (Figs 6B, C, 7A, B).

Mensural and meristic data for the type series is given in Table 3 and 4 respectively. There are eight adult male and two adult female specimens, SVL ranging from 47.0-55.9 mm. All specimens resemble the holotype male (NRC-AA-1256) except for the following variations: inner postmental bordering infralabial I and II on left and infralabial I on right side in NRC-AA-1264, inner postmental bordering infralabial I and II on right and infralabial I on left side in NRC-AA-1261 and NRC-AA-1263, inner postmental bordering infralabial I on either side in NRC-AA-1262 and NRC-AA-1265; chin scales bordering inner postmental (six in NRC-AA-1257, NRC-AA-1260, four in NRC-AA-1264, NRC-AA-1263, three in NRC-AA-1258). Outer postmental bordering infralabial II on left and infralabial I and II on right side in NRC-AA-1264, outer postmental bordering infralabial I on right and infralabial I and II on left side in NRC-AA-1261 and NRC-AA-1263, outer postmental bordering infralabial I and II on either side in NRC-AA-1262 and NRC-AA-1265; chin scales separating left and right outer postmental below inner pair (six in NRC-AA-1257, NRC-AA-1260, four in NRC-AA-1258, NRC-AA-1263. Seven paratypes (NRC-AA-1257, NRC-AA-1264, NRC-AA-1258, NRC-AA-1259, NRC-AA-1260, and NRC-AA-1265) have an original and complete tail, marginally or slightly longer than body (TL/SVL 1.12, 1.03, 1.04, 1.12, 1.14, 1.07 respectively), NRC-AA-1261 and NRC-AA-1262 with complete but partially regenerated tail, and NRC-AA-1263 with partially incomplete tail (Fig. 7A, B ). Dorsal ground colouration varies from light pinkish to ochre-brown; dorsal colour pattern varies from series of X-shaped markings to indistinct cross-bars to spots; 12-15 dark markings on original tail; regenerated tail mottled brown.

Distribution and Natural history.

Hemidactylus quartziticolus sp. nov. is known from the type locality Vallanadu Reserve Forest and an additional locality 45 km north, Kurumalai Reserve Forest, both in Thoothukudi District, Tamil Nadu, India (Fig. 1 ). Both localities have low (<310 m asl.), narrow quartzite ridges with exposed rocks along the ridgeline, and generally stony soil and low, scrubby vegetation (Southern Thorn Forests: 6A/DSI; Champion and Seth 1968) (Fig. 8A-C ). The team of five visited these two areas on one night each from about an hour before sunset to two hours after sunset. At Vallanadu, the new species was found in abundance (>15 in one hour). Individuals were seen on quartzite rock formations approximately 0.5-2.0 meter height above from the ground. All the female individuals we spotted (n = 5) were gravid, and only a single subadult individual was observed during the entire survey. Sympatric lizards encountered during the survey were Hemidactylus cf. frenatus , H. cf. leschenaultii , H. cf. acanthopholis , H. cf. scabriceps , Eutropis cf. carinata , Psammophilus cf. dorsalis , and Calotes versicolor (Daudin, 1802). At Kurumalai it had been raining and was drizzling when we visited and only four individuals of the new species were observed. Two paratypes (an adult male and gravid female) were seen about 50 cm above the ground on the wall of a small temple situated among the quartzite rock formations, and the other two individuals were observed on rocks about 1-2 m above the ground. Sympatric congeners at Kurumalai includes Hemidactylus cf. frenatus , H. cf. leschenaultii , H. cf. triedrus , Eutropis cf. carinata , Psammophilus cf. dorsalis , and Calotes versicolor .

Figures

Figure 1. Elevation map showing the distribution of the new species and other members of the Hemidactylus brookii group distributed in peninsular India (stars, new species; triangles, Hemidactylus gleadowi clade; circles, Hemidactylus murrayi clade; diamonds, Hemidactylus malcolmsmithi - Hemidactylus parvimaculatus clade; squares, ground-dwelling clade). The type locality is marked for H. murrayi.

Figure 2. Left, inset, backbone maximum likelihood phylogeny of Indian Hemidactylus with major groups marked in different colours; Hemidactylus quartziticolus sp. nov. is marked by a red rectangle within the Hemidactylus brookii group (see Table S 1 for GenBank accession numbers). Main figure, Maximum Likelihood phylogeny of the Hemidactylus brookii group of Indian Hemidactylus based on the ND 2 gene. Posterior Probability = 1 / bootstrap support ≥ 75 shown at nodes, outgroups not shown.

Figure 3. Hemidactylus quartziticolus sp. nov. (holotype, NRC-AA- 1256): A dorsal view of body, B ventral view of body, C dorsal view of tail, D ventral view of tail, and E lateral view of tail. Scale bars 10 mm; photos by Akshay Khandekar.

Figure 4. Hemidactylus quartziticolus sp. nov. (holotype, NRC-AA- 1256): A dorsal view of head, B ventral view of head, C lateral view of head, D view of cloacal region showing precloacal-femoral pores and post cloacal spurs, E ventral view of left manus, and F ventral view of left pes. Scale bars 5 mm; photos by Akshay Khandekar.

Figure 5. Details at mid-body of Hemidactylus quartziticolus sp. nov. (holotype, NRC-AA- 1256): A dorsal view, B ventral view, and C lateral view. Scale bars 5 mm; photos by Akshay Khandekar.

Figure 6. Hemidactylus quartziticolus sp. nov. in life: A male, holotype NRC-AA- 1256, B female, paratype NRC-AA- 1264, and C uncollected juvenile. Photos by Akshay Khandekar.

Figure 7. Paratype series of Hemidactylus quartziticolus sp. nov. from left to right: NRC-AA- 1257 - NRC-AA- 1265, A dorsal view, and B ventral view. Scale bar 10 mm; photos by Akshay Khandekar.

Figure 8. Habitat of Hemidactylus quartziticolus sp. nov.: A general habitat at the type locality, B quartzite rock formation on which individuals of the new species were seen at the type locality, and C general habitat at Kurumalai, from where a few paratypes of the new species were collected. Photos by Akshay Khandekar (A and B), and Ishan Agarwal (C).