Dravidogecko tholpalli, Chaitanya & Giri & Deepak & Datta-Roy & Karanth, 2019

Chaitanya, R., Giri, Varad B., Deepak, V., Datta-Roy, Aniruddha & Karanth, Praveen, 2019, Diversification in the mountains: a generic reappraisal of the Western Ghats endemic gecko genus Dravidogecko Smith, 1933 (Squamata: Gekkonidae) with descriptions of six new species, Zootaxa 4688 (1), pp. 1-56 : 30-34

Dravidogecko tholpalli sp. nov.

( Figs 11 A–D, 13G, 15B; Table 7 )

Hoplodactylus anamallensis: Boulenger, 1885

Hoplodactylus anamallensis [non Gecko anamallensis Günther, 1875 ] — Boettger, 1893.

Hemidactylus anamallensis: Bauer & Russell, 1995

Hemidactylus anamallensis [non Gecko anamallensis Günther, 1875 ] — Ganesh, 2010;

Holotype. BNHS 2351 , an adult male, Kodaikanal town (10.2334 °N, 77.4910 °E; ca. 2110 m asl.), Dindigul District , Tamil Nadu, collected by R. Venkitesan and RC on 17 th December, 2016.

Paratypes. Details of collection same as the holotype. BNHS 2352 , BNHS 2353 , ZSIK 2982 , ZSIK 2984 , ZSIK 2985 , ZSIK 2986 —adult males; BNHS 2354 , BNHS 2355 and ZSIK 2983 —adult females.

Type locality. Kodaikanal, Dindigul District, Tamil Nadu.

Summarized description and diagnosis. Snout-vent length up to 52.2 mm (n=10); internasals separated by one smaller scale; two pairs of well-developed postmentals, inner pair longer than the outer; ventral scales counted at midbody, 25–31; precloacofemoral pores, 38–40 (n=7); subdigital lamellae under digit IV of manus, 7 or 8 and under digit IV of pes, 9–11; supralabials 8–11 and infralabials, 8–10 on each side.

Dravidogecko tholpalli sp. nov. can be distinguished from other congeners based on the following characters: number of precloacofemoral pores (PcFP 38–40 versus 45 or 46 in D. anamallensis , 52–56 in D. septentrionalis sp. nov., 36–38 in D. meghamalaiensis sp. nov., 42 or 43 in D. douglasadamsi sp. nov. & 48 in D. smithi sp. nov.); one smaller scale separating the internasals (versus two in D. septentrionalis sp. nov.); first pair of postmentals much longer than the second (2PML/1PML 0.41–0.67 versus only slightly longer, 0.82–0.96 in D. meghamalaiensis sp. nov.).

Genetic divergence (p-distance). Dravidogecko tholpalli sp. nov. exhibits 0.3% intraspecific variation, while it is 16.8% –21.4% divergent from all other congeners ( Table 9 ).

Description of holotype. The holotype is in good condition except, head is slightly tilted towards the right—an artefact of preservation ( Fig 11A ). Body is dorsoventrally flattened with the posterior 3/4 th of tail regenerated.Adult male, SVL 50.9 mm. Head short (HL/SVL 0.26), slightly elongate (HW/HL 0.68), not depressed (HH/HW 0.61), distinct from neck. Loreal region slightly inflated, canthus rostralis indistinct ( Fig 11C ). Snout short (SE/HL 0.40), longer than orbital diameter (OD/SE 0.53); scales on snout, canthus rostralis, inter-orbital region, forehead, occipital and nuchal regions granular and rounded with those on the snout and canthus rostralis being larger ( Fig 11B ). Eye small (OD/HL 0.21); pupil vertical with crenulated margins; supraciliaries small, rounded, directed outwards and uniform in size. Ear opening elliptical (longer diameter 0.7 mm); eye to ear distance longer than diameter of eye (EE/OD 1.46). Rostral wider than deep (RL/RW 0.37), with a distinct rostral groove extending halfway through the scale medially; two large internasals, separated by a smaller, subequal scale, all in broad contact with rostral; two postnasals on either side, slightly smaller than the internasals, the lower in contact with supralabial I; rostral in contact with nasal, supralabial I, internasals and the smaller scale separating the internasals; nostrils about the size of the lower postnasal, roughly circular with nasal pad visible posteriorly; nasal surrounded by internasal, rostral, two postnasals and a small scale separating it from supralabial I on either side; 2–4 rows of scales separate orbit from supralabials at mid-orbital position. Supralabials roughly rectangular, increasing in length anteriorly. Supralabials (to midorbital position) 8 (right), 8 (left); supralabials (to angle of jaw) 10 (right), 10 (left); infralabials (to angle of jaw) 8 (right), 8 (left). Mental triangular; two pairs of well-developed postmentals, the inner pair slightly shorter (1.0 mm) than the mental (1.1 mm), and in strong contact with each other (0.5 mm) behind mental; outer pair distinctly shorter (0.6 mm) than the inner pair, separated from each other by five gular scales that are smaller than postmentals ( Fig 11D ). Inner postmentals bordered by mental, infralabial I & II (barely touching on both sides), outer postmentals and five smaller gular scales; outer postmentals bordered by infralabials I (barely touching on the right) and II, inner postmentals, and smaller gular scales each of dissimilar sizes, four on the right and two on the left sides. Body relatively slender, elongate (TRL/SVL 0.47). Dorsal pholidosis composed of small, rounded granules that are juxtaposed in arrangement, becoming slightly larger, flatter, weakly pointed and sub-imbricate laterally; Ventral scales larger than dorsals, largely homogeneous in shape and size, smooth, flat, sub-imbricate; gular region with smaller, granular, juxtaposed scales; anterior gular scales visibly larger, flatter; scales on femoral region larger than those on chest; precloacal scales larger than scales on femoral region; midbody scale rows across belly 26–28. Non-lamellar scales in the palmar and plantar regions heterogeneous in size, rounded, juxtaposed on palm and sole; scales on dorsal aspect of upper arm larger than granules on dorsum, flat, pointed, sub-imbricate and smooth; dorsal aspect of forearm with smaller, sub-imbricate scales intermixed with a few rounded granules around the elbow; scales on dorsal aspect of hand and digits larger than those on forearm, flat, weakly pointed and imbricate; scales on anterior aspect of thigh large, flat, imbricate and weakly pointed; rest of the dorsal scales on hindlimb smaller, granular and rounded. Scales on dorsal aspect of foot larger than those on shank, flat, weakly pointed and imbricate.

Forearm (FL/SVL 0.10) and tibia short (CL/SVL 0.13); digits moderately short with relatively long terminal phalanges, 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, more than half as long as associated toepad; scansors beneath each toe undivided throughout, in a straight transverse series: 6-7-8-7-7 (left manus), 6- 7-7-8-7 (right manus), 6-8-9-9-7 (left pes), 6-8-9-10 -7 (right pes). Relative length of digits (measurements in mm in parentheses): IV (4.0)> III (3.8)> II (3.5)> V (3.0)> I (2.6, claw broken) (left manus); IV (5.2)> III (4.7)> V (4.6) = II (4.6)> I (3.3) (left pes).

Tail partially regenerated, rounded at the base, flat beneath, tapering posteriorly, covered above uniformly with round, smooth, flat, sub-imbricate scales that become slightly larger laterally; subcaudal scales larger, with an undivided median series of enlarged scales. An uninterrupted series of 38 precloacofemoral pores that are only faintly visible towards the knee ( Fig 13G ).

Variation in paratypes. Inner postmentals in contact with only infralabial I on both sides in all other paratypes. Inner postmentals bordered posteriorly by three gular scales in BNHS 2352 , BNHS 2353 , ZSIK 2982 , ZSIK 2983 and ZSIK 2985 , and by five gulars in BNHS 2354 . Right inner postmental bordered by a small gular scale laterally in BNHS 2355 and ZSIK 2984 . Outer postmentals bordered by 3 gulars in BNHS 2352 (R), 5 in BNHS 2354 (R) and ZSIK 2984 (R) and 6 in BNHS 2355 (R) and ZSIK 2983 (R). Outer postmentals not in contact with infralabials BNHS 2355 (R), ZSIK 2983 (R) and ZSIK 2984 (R). Outer postmentals in contact with both infralabial I and II on both sides in BNHS 2352 , BNHS 2353 , BNHS 2354 , ZSIK 2982 , ZSIK 2985 and ZSIK 2986 . Other morphological variations are listed in Table 7 .

Colour in preservative. Dorsum predominantly light brown mottled with darker, discontinuous streaks from the snout to the base of tail ( Fig 11A ). Similar mottling faintly visible on dorsal aspect of limbs. Neck with a roughly circular, dark blotch flanked by 2 longitudinal streaks on either side. Posterior part of head demarcated by a disctinct saddle-shaped horizontal streak ( Fig 11B ). Inter-orbital region slightly darker than rest of the body with scattered dark-brown granules. Labials paler than rest of the head with faint, darker spots bordering each labial. Supralabials bordered by a dark, roughly triangular streak from nostril to eye. Limbs no different from rest of the dorsum. Tail predominantly grey with darker, longitudinal markings in the regenerated portion. Ventral region uniformly cream coloured. Ventral surface of tail pale, with scattered mid-brown speckling throughout.

Colouration (in life) (based on photographs of an uncollected topotype). Dorsal markings more evident in life ( Fig 15B ). Dorsum pale-brown with darker streaks throughout. Head dorsum pale-brown, snout darker, with a dark streak emanating from snout to eye. Yellow dots on each labial with a scattering of these in the loreal region. Forehead ground colour, interspersed by darker spots. A dark, discontinuous streak emanates from eye up to the forelimb insertion. A dark saddle shaped collar in the occipital region. Six dark streaks along the vertebral region after the collar, followed posteriorly by two saddle shaped markings in the sacral region. Limbs of ground colour with dark spots sprinkled all over. Tail distinctly banded with alternating light and dark portions. Bands more conspicuous after the first three segments. Iris marbled, golden, suffused with prominent dark-brown venation; pupil black with crenulated margins.

Etymology. The specific epithet is a compound noun formed by the combination of two Tamil words from the Sangam era (3 rd century BC—3 rd century AD) that alludes to the ancient divergence and colonization of these geckos in peninsular India. The stem word, ‘ thol ’ (pronounced /ɵɔl/) is an archaic Tamil word for ‘ancient’ and ‘ palli ’ (pronounced /pǝllɪ/) an ancient word still in common parlance, is the Tamil for ‘gecko’.

Suggested Common name. Kodaikanal Dravidogecko .

Distribution. Dravidogecko tholpalli sp. nov. is presently restricted in distribution to Kodaikanal town and its outskirts in the Palani Hills of the southern Western Ghats. They are found in large numbers around the Kodaikanal Lake in the centre of the town, which is surrounded by disturbed evergreen forests. The habitat in the Palani Hills chiefly constitutes moist deciduous and southern tropical wet evergreen forests (B. Balaguru et al. 2016). These habitats are at an altitude of 1600–2000 m asl and receive an average annual rainfall of 1500 mm ( Bhupathy et al. 2009). Other areas in the Palani Hills such as Perumalmalai and Vattakanal are likely to harbour populations of D. tholpalli sp. nov.

Habitat and natural history. The type-series of Dravidogecko tholpalli sp. nov. was collected in Kodaikanal town from abandoned buildings and stone walls near forested areas. Kodaikanal falls under a special case of the Madurai-Pollachi rainfall regime with 0–4 dry months and slightly more (~92) rainy days annually ( Pascal 1982). Other lizards found in sympatry were Cnemaspis sp. , Kaestlea cf. palnica and Salea anamallayana .

Figures

FIGURE 11. Holotype of D. tholpalli sp. nov. A) Full-body dorsal B) Head dorsal C) Head lateral D) Head ventral. Scale bar = 10 mm.

FIGURE 13. Cloacal region showing precloacofemoral pores (indicated by black dots) in the congeners of Dravidogecko. A) D. anamallensis B) D. douglasadamsi sp. nov. C) D. smithi sp. nov. D) D. meghamalaiensis sp. nov. E) D. janakiae sp. nov. F) D. septentrionalis sp. nov. G) D. tholpalli sp. nov. Scale bar = 10 mm

FIGURE 15. A) Dravidogecko smithi sp. nov. (BNHS 2350) from Ponmudi, Tiruvananthapuram, Kerala B) Dravidogecko tholpalli sp. nov. (uncollected specimen) from Kodaikanal town, Dindigul, Tamil Nadu C) Dravidogecko janakiae sp. nov. (uncollected specimen) from Munnar, Idukki, Tamil Nadu.