Dravidogecko beddomei, Adhikari & Srikanthan & Ganesh, 2023

Adhikari, Omkar Dilip, Srikanthan, Achyuthan N. & Ganesh, S. R., 2023, A new species of Dravidogecko (Squamata: Gekkonidae) from the under-surveyed Periyar Plateau of the Southern Western Ghats in Peninsular India, European Journal of Taxonomy 870 (1), pp. 146-166 : 153-160

Dravidogecko beddomei sp. nov.

urn:lsid:zoobank.org:act:25C54DA6-4089-4FBA-9EF9-D7266E0A2B5A

Figs 1 , 3–6

Summarized description and diagnosis

A species of Dravidogecko endemic to the Periyar Plateau, characterized by the following combination of characters: snout-vent length up to 50.8 mm; two pairs of well-developed postmentals, inner pair longer than mental and outer postmentals, anteriorly in strong contact with mental; bordered by 1 st infralabial scale, mental, outer postmentals and two or three gular scales; ventral scale rows, 31‒33; precloacal-femoral pores 46‒52 (n = 3); subdigital lamellae beneath of digit I: six, and digit IV: eight or nine (manus); subdigital lamellae beneath of digit I: five or six and digit IV: 10 or 11 (pes); supralabials 9–11 and infralabials eight or nine on each side.

Differential diagnosis

Dravidogecko beddomei sp. nov. can be distinguished from all other (allopatric) congeners based on the following characters: number of precloacal-femoral pores 46‒52 (vs 52‒56 in D. septentrionalis , 40‒43 in D. douglasadamsi , 38‒40 in D. tholpalli , 35‒36 in D. janakiae , 36‒38 in D. meghamalaiensis ); ventral scales rows across belly 31‒33 (vs 29‒31 in D. smithi , 25‒31 in D. tholpalli , 24‒30 in D. janakiae , 25‒28 in D. anamallensis ); lamellae on digit IV of pes 10–11 (vs 12 in D. anamallensis ); mental scale is shorter in length than postmental shield, mental scale length / primary postmental shield length 0.8–0.9 (vs 1.0– 1.3 in D. meghamalaiensis ; 1.0– 1.1 in D. douglasadamsi ; 1.1–1.2 in D. smithi ; and 1.0– 1.6 in D. janakiae ).

Genetic divergence (p-distance)

Dravidogecko beddomei sp. nov. is 13.0–22.5% divergent from all other (allopatric) congeners, and 16.2–16.4% divergent from its closest congeners D. meghamalaiensis , 15.2–15.3% divergent from D. smithi and 19.5% divergent from D. douglasadamsi ( Table 2 ).

Etymology

The specific epithet is a patronym coined in genitive singular case, honouring Col. Richard Henry Beddome (1830–1911), the pioneering herpetologist who first surveyed this part of the Western Ghats, the Devar Malai Hills (see Ganesh 2010).

Material examined

Holotype INDIA • adult ♂; “ Suttivezhi Vayal or Vairavankulam hills in the northern edge of Devar Malai , Tenkasi district , Tamil Nadu, India ”; 9°10′32.88″ N, 77°16′17.4″ E; alt. 970 m a.s.l.; Dec. 2011; S. Pal and M. Prabhu leg.; BNHS 2648 ( Fig. 3A–I ).

Paratypes (n = 3) INDIA • 1 adult ♂; “ Kakki Dam, Periyar Forest, Pathanamthitta district , Kerala, India ”; 9°19′31.08″ N, 77°8′40.56″ E; alt. 1030 m a.s.l.; Dec. 2011; S. Pal and M. Prabhu leg.; BNHS 2645 ( Fig. 4A–B ) •

1 adult ♂; same collection data as for preceding; BNHS 2646 ( Fig. 4C–D ) • 1 adult ♀; same collection data as for preceding; BNHS 2647 ( Fig. 4E–F ) .

Other referred specimens (n = 2)

India, 2 adults ♀, sighted in Sivagiri hills (9° 20´59.27˝ N, 77° 19´55.89˝ E; 1100 m a.s.l.), north of Suttivezhi Vayal (type locality) and east of Kakki Dam (paratype locality); April 2008, uncollected ( Figs 5–6 ).

Description of holotype

Holotype is in generally good condition ( Fig. 3 ), well fixed, moderately flat beneath, without ventrolateral folds on both sides of trunk. An adult male; snout-vent length 45.7 mm.

HEAD. Head short in length (28.0% of snout-vent length); relatively broad in width (77.3% of maximum head length); slightly depressed (44.5% of maximum head length), distinct from neck. Loreal region inflated, interorbital region concave, forehead not concave, canthus rostralis indistinct; snout relatively long (55.6% of maximum head width), slightly longer than horizontal diameter of the eye orbit (54.6% of eye orbit to snout tip distance). Scales on snout, forehead, and canthus rostralis rounded and granular; scales on snout larger than those on occipital region and interorbital region; scales on occipital region and interorbital small, rounded, mostly granular. Eyes rounded, small (23.4% of maximum head length); pupil vertically elliptical with crenulated margins; supraciliaries small, gradually decreasing in size posteriorly. Ear opening deep, roughly oval (16.7% of eye orbit to nostril distance); lacking enlarged lobules. Supralabial scale count, 11/10 (left/right), 9 th supralabial on left side and 8 th supralabial on right side are in mid-orbital position, 10 th and 11 th supralabial on left side and 10 th supralabial on right side to the angle of jaw, supralabials are roughly rectangular in shape with slightly convex above. Rostral rectangular with wide convex, fairly visible when viewed dorsally, without a distinct rostral groove. Nostril oval shaped, oriented laterally, touches 1 st supralabial on either sides, single supranasal; two large internasals, separated by single small scale, all in broad contact with rostral; two postnasals on either side, smaller than the internasals, the lower in contact with 1 st supralabial; anteriorly rostral contacting with nasal; nostrils about the size of the lower postnasal, roughly circular; nasal surrounded by internasal, rostral, 1 st supralabial and two postnasals on either side; 1 or 2 rows of scales separate orbit from supralabials at mid-orbital position. Infralabial scale count, 9/9 (left/right); 1 st ‒4 th infralabials slightly larger in size, rectangular in shape; 5 th –9 th infralabials decreases in size posteriorly; the lower edges of 3 rd ‒9 th infralabials are bordered with two rows of enlarged elongated scales. Mental scale triangular; two pairs of well-developed postmentals; primary postmental pair comparatively larger in size to secondary postmental pair, contacting each other, and 1 st infralabial on both sides; secondary pair, not contacting each other, touches 1 st and 2 nd infralabials; both primary and secondary pair bordered by smooth, granular, rounded scales.

BODY. Moderately elongated, axilla to groin distance (43.3% of snout-vent length), dorsally compressed, without ventrolateral folds. Dorsal pholidosis composed of small, flat, granular and rounded scales that are juxtaposed in arrangement, homogeneous in shape. Ventral scales sub-imbricate, smooth, granular, homogeneous in shape and size, larger than dorsal granular scales, ventral scales across belly 32; gular region covered in small granular scales about equal in size to dorsal granules, gradually increasing in size posteriorly, anterior gular scales visibly larger and flatter; scales on femoral region larger than those on sacrum and chest with some precloacal scales being largest; scales on dorsal aspect of upper arm larger than granules on dorsum, flat, smooth, and sub-imbricate; 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, imbricate; scales on dorsal part of thigh and shank heterogeneous in size, flat, weakly pointed and sub-imbricate; largest on anterior aspect of thigh. Scales on dorsal aspect of foot larger than those on shank, flat, rounded and imbricate; non-lamellar scales in the palmar and plantar regions flat and smooth; ones on palm juxtaposed while those on sole sub-imbricate and weakly pointed. Pre-anal groove absent; pre-anal depression absents; an incessant series of 49 precloacal-femoral pores that are indistinct towards the knee.

LIMBS. Fore and hind limbs relatively short, slender, ventral surfaces of limbs covered with uniform, flattened, sub-imbricate scales; forearm short (humoral length is 13.8% of snout-vent length; radius ulnar length is 13.4% of snout-vent length); tibia short (thigh length 16.8% of snout-vent length; crus length is 16.6 snout-vent length); digits moderately short, flattened, with relatively long terminal phalanges, strongly clawed; all digits of manus and digits II–V of pes indistinctly webbed; terminal phalanx of all digits curved, angular from distal portion of expanded lamellar pad, more than half as long as associated toepad; scansors beneath each digit are undivided, in a straight transverse series; lamellae count of left manus – digit I (6), digit II (7), digit III (8), digit IV (9), and digit V (7); lamellae count of left pes – digit I (6), digit II (7), digit III (8), digit IV (10), and digit V (7); toe lengths of left manus – digit IV (2.8)> digit III (2.5)> digit V (2.2)> digit II (2.1)> digit I (1.6); toe lengths of left pes – digit IV (3.4)> digit III (3.2)> digit II (2.7)> digit V (2.3)> digit I (1.6).

TAIL. Original, complete; oval in cross section; long (tail length/snout-vent length: 1.1) with fairly pointed tail tip in dorsal aspect, flat beneath, tapering posteriorly, tail dorsum covered with smooth, flat, somewhat rounded, sub-imbricate scales, larger than those on dorsum, becoming slightly enlarged laterally; subcaudal scales larger, with an undivided median series of enlarged scales.

Variation

Type series of Dravidogecko beddomei sp. nov. is comprised of three adult males (BNHS 2648: holotype; BNHS 2645, BNHS 2646: paratypes), and one adult female (BNHS 2647). In general, agreeing well with the holotype, the intraspecific meristic, morphometric and basic pholidosis variations in paratypes ( Fig. 4 ), are summarized in Table 3 .

Coloration in preservation

After preservation in alcohol for 11 years, overall dorsum uniformly brown, mottled with dark chocolate brown discontinuous longitudinal streaks from the snout to the base of tail. Similar mottling faintly visible on dorsal aspect of limbs. Neck pale brown, with discontinuous longitudinal streaks same as dorsum; single continuous, roughly rectangular, pale brown streak bordered with the dark chocolate brown streaks originates from the narial region, following the contour of the cranium posteriorly and prolonging almost the neck region. Frontal and interorbital region with scattering of smaller dark blotches which are faintly visible. A distinct dark blotch bordering the supraciliary region on either side. Labials slightly paler than the head dorsum with scattering of dark brown splotches. Tail same as like dorsum with brown colour with alternating pale-dark brown longitudinal bands, the first of which is roughly saddle-shaped. Ventral surface of tail is cream colored, with scattered faintly visible mid-brown blotches in the hemipenal region followed by alternating pale-dark bands.

Coloration in life (based on live uncollected specimens)

Dorsum creamy brown with dark brown mottling and longitudinal streaks throughout; dorsal markings distinct in life. Head dorsum brown or ground colour, with three distinctly paler patches bordered with chocolate brown streaks, anterior and posterior to the eye and just above the ear opening, extending till neck. Labials with the dark brown blotches with alternating off-white blotches. Snout mottled with brown spots. A brown discontinuous streak originating at ear opening, delimited with two dark streaks that continue beyond forelimb insertion. Limbs creamy brown, irregularly scattered with dark blotches. Tail original, with distinctly banded pale and dark portions. Iris marbled, golden, suffused with darkbrown venation; pupil vertical, black with crenulated margins.

Suggested common name

Beddome’s Dravidogecko .

Ecology and distribution

Dravidogecko beddomei sp. nov. is a poorly known species that is currently known only from in and around the type localities – Devar Malai, Kakki Dam and Sivagiri Hills. The first two sites are situated ca 20 airline km apart across the Ranni Rivulets of Periyar river, Suttivezhi Vayal (holotype locality) being to the east and Kakki Dam (paratype locality) being to the west of it. The live sightings of the referred material originate from Sivagiri Hills, situated in Tenkasi district, Tamil Nadu, just 20 airline km north of the holotype locality. It is to be noted that all these localities are well within a geographically proximate and ecologically homogenous area and are also comparable in their elevations: 970 m, 1030 m and 1100 m a.s.l. It is likely that D. beddomei also occurs in other nearby areas of Periyar Plateau (in Kerala and Tamil Nadu States). Like other congeners, D. beddomei is nocturnal and rupicolous. The geographically closest species to D. beddomei is D. meghamalaiensis that is distributed ca 50 airline km northeast off this range in the geographically disparate and detached Meghamalai Mountains ( Chaitanya et al. 2019). The new species D. beddomei occurs within a Protected Area – the Periyar Tiger Reserve. But yet the presence of a seasonal pilgrim spot (Sabarimalai) and a Damming site (Kakki) should be causes for its conservation concern.

Figures

Fig. 1. Map of Southern Western Ghats, India, showing the type locality (Devar Malai / Suttivezhi Vayal / Vairavankulam Hills), paratypes’ locality (Kakki Dam) and referred materials’ locality (Sivagiri) – the distribution range of Dravidogecko beddomei sp. nov.

Fig. 3. Dravidogecko beddomei sp. nov., holotype, ♂ (BNHS 2648). A. Dorsal view of entire specimen. B. Ventral view of entire specimen. C. Right side of the head. D. Left side of the head. E. Ventral view of the head. F. Dorsal view of the head. G. Lamellae on digits of left manus. H. Lamellae on digits of left pes. I. Precloacal-femoral pores.

Fig. 4. Dravidogecko beddomei sp. nov., paratypes. A–B. Male (BNHS 2645), dorsal and ventral view. C–D. Male (BNHS 2646), dorsal and ventral view. E–F. Female (BNHS 2647), dorsal and ventral view.

Fig. 5. Live uncollected adult females of Dravidogecko beddomei sp. nov. sighted in Sivagiri Hills.

Fig. 6. Landscape (left) and habitat (right) of Dravidogecko beddomei sp. nov. at the Sivagiri Hill.