Cyrtodactylus tripuraensis, Agarwal & Mahony & Giri & Chaitanya & Bauer, 2018

Agarwal, Ishan, Mahony, Stephen, Giri, Varad B., Chaitanya, R. & Bauer, Aaron M., 2018, Two new species of bent toed geckos, Cyrtodactylus Gray, 1827 (Squamata: Gekkonidae) from Northeast India with comments on name-bearing types from the region, Zootaxa 4420 (3), pp. 334-356 : 348-353

Cyrtodactylus tripuraensis sp. nov.

Figs. 6B , 7–9

Holotype. BNHS 2244 , adult male, from Chobimura (23.55039°N 91.62054°E; ca. 36 m asl.), Gomati district , Tripura state, India, collected by A. Datta-Roy, T. Khichi, NPI Das and I. Agarwal, 10 November 2010.

Paratypes. All from Tripura state, India, same collectors as holotype: BNHS 2230 , adult female, from Rowa Wildlife Sanctuary (24.29062°N 92.16496°E; ca. 56 m asl.), North Tripura district, 0 2 October 2010 ; BNHS 2236– 2238, BNHS 2242, and BNHS 2243, five adult males, BNHS 2239–2241, three adult females, Sepahijala Wildlife Sanctuary (23.65906°N 91.33167°E; ca. 29 m asl.), Sepahijala district , 06–08 November 2010; BNHS 2245 , adult male, Gumti (23.42661°N 91.81937°E; ca. 40 m asl.), Gomati district , 11 November 2010.

Etymology. The species epithet is a toponym for Tripura, the Indian state in which all currently known populations are found.

Suggested common name. Tripura bent-toed gecko.

Diagnosis and comparison against regional congeners. A moderate sized Cyrtodactylus , snout-vent length to 70.7 mm; body and limbs relatively slender, digits short; one pair of enlarged postmental scales in broad contact behind mental; 19–21 rows of circular tubercles at mid-dorsum, bluntly conical and weakly keeled throughout; 44– 54 paravertebral tubercles; 35–43 mid-body ventral scale rows; no precloacal groove; males with 29–37 precloacofemoral pores in a single series, females with 19–29 pitted/pored scales. Four to nine basal and 11–16 apical subdigital lamellae beneath Digit IV of pes with one or two intervening rows of non-lamellar granular scales between basal and distal lamellae series. Subcaudals larger than dorsal tail scales, not in an enlarged median series (on original tail). Dorsal pattern of 7–10 paired transversely arranged dark spots that may be irregular and broken up, occasionally alternating with lighter spots. Original tail with 11–13 alternating dark and light bands, last few light bands almost white.

Cyrtodactylus tripuraensis sp. nov. differs from the following species by the presence of a continuous series of precloacofemoral pores (vs. precloacal pores separated from femoral pores by a diastema of multiple poreless scales): C. annandalei , Cyrtodactylus bhupathyi sp. nov., C. fasciolatum , C. gubernatoris , C. russelli , and C. slowinskii . The large number of precloacofemoral pores on males of the new species (29–37) separates it from C. brevidactylus (8 PcP), C. cayuensis (6–9 PcP), Cyrtodactylus himalayicus comb. nov. (10 PcP), C. khasiensis (10– 12 PcP), C. mandalayensis (8 PcP + single enlarged pore-bearing scale at the posterior apex of PcP), C. markuscombaii (7 PcP), C. martinstolli (0–8 PcP), and C. wakeorum (12 PcP). Cyrtodactylus tripuraensis sp. nov. differs from C. tamaiensis by having slightly fewer precloacofemoral pores (29–37 vs. 40), male body size (SVL 55.4–65.0 mm vs. 90.0 mm), longer trunk (TrL/SVL mean 0.49, range 0.46–0.52 vs. 0.41) and dorsal pattern (8–10 irregular paired dark spots vs. irregular dark and light reticulations), and from C. gansi in the absence of a precloacal groove (vs. presence of precloacal groove on males). Cyrtodactylus tripuraensis sp. nov. is most similar to C. ayeyarwadyensis from which it differs by a slightly higher number of precloacofemoral pores on males (29– 37 vs. 10–28), the presence of pores in females (vs. absence of pores), and fewer dorsal tubercle rows (19–21 vs. 22–24). Cyrtodactylus tripuraensis sp. nov. differs from C. ayeyarwadyensis sensu lato ( Mahony et al. 2009a) by the presence of precloacofemoral pores on females (vs. absence of pores).

Description of holotype. Holotype in generally good condition, except minor folds on skin of abdomen, slightly protruding tongue, constriction anterior to hindlimb insertions (from tying previously attached specimen tag), all artefacts of preservation; tail tip removed for molecular tissue sampling ( Fig. 7A ). Adult male, snout to vent length 63.7 mm. Head moderately long (HL/SVL ratio 0.27), slightly wide (HW/HL ratio 0.62), somewhat depressed (HH/HW ratio 0.58), distinct from neck; loreal region slightly inflated, interorbital area flat, canthus rostralis not prominent; snout moderately short (SE/HL ratio 0.40), almost twice as long as OD (OD/SE ratio 0.56); scales on forehead homogenous, small, rounded, granular; those on canthus rostralis and snout are homogenous, slightly larger than those on forehead, roughly hexagonal, juxtaposed; distinctively larger than those on interorbital region and occipital region; scales on interorbital and occipital region homogenous, granular, those on occipital region smallest ( Figure 8A ). Eye small (OD/HL ratio 0.23); pupil vertical with crenulated margins; supraciliaries small, slightly mucronate, decreasing in size towards posterior edge of orbit, last three or four more strongly mucronate; ear opening oval, obliquely oriented, large (EL/HL ratio 0.09); eye to ear distance slightly more than eye diameter (OD/EE ratio 0.72). Rostral wider (2.7 mm) than deep (1.8 mm), divided dorsally by weakly developed rostral groove; single large supranasal on either side, separated by eight smaller scales arranged in three rows completely filling space formed by dorsal bifurcation of rostral; rostral in contact with SL I, nasals, supranasals, and three scales separating supranasals; nostrils semicircular, laterally oriented, posterior half covered by nasal pad, each in broad contact with rostral and also surrounded by supranasal, SL I, and three to four postnasals; three to four scale rows separate orbits from supralabials; mental wider (2.5 mm) than long (1.8 mm), triangular, two well developed postmentals on either side, inner pair much larger (maximum length 2.0 mm) than outer pair and broadly in contact with each other (forming 1.0 mm long suture) behind mental, outer postmental pair 0.8 mm long, separated from each other by inner postmental pair; inner postmentals bordered by mental, IL I, outer postmental and six gular scales; outer postmental bordered by inner postmental, IL I and II, and three gular scales on either side ( Figure 8C ); supralabials 10 (7) (right)–12 (9) (left), bordered by two rows of large, flat, slightly elongated scales; nine infralabials on each side, bordered by one row of chinshields, largest anteriorly; interorbital scale rows across narrowest point of frontal bone ~25. Body moderately slender, relatively short (TrL/ SVL ratio 0.52) with weak ventrolateral folds; dorsal scales heterogeneous, mostly rounded granular, intermixed with irregularly arranged small (2–4 times granule size) circular tubercles, bluntly conical and weakly keeled throughout, becoming more conical and strongly keeled posteriorly towards tail, tubercles extend from frontal region to proximal portion of tail; tubercles on nape considerably smaller than those of dorsum and those of tail completely flat and elongate ( Figures 7A, 7C ); tubercles in approximately 21 non-linear longitudinal rows at midbody; 46 tubercles in paravertebral row from occiput to mid-sacrum; ventral scales much larger than dorsal scales, smooth, cycloid, imbricate to subimbricate, 37 mid-body ventral scale rows; posterior most row under thighs, and those bordering pored scales posteriorly and medially, enlarged; gular region with smaller granular scales, grading into large, flat and juxtaposed scales anterolaterally, those posterior to chinshields largest. Twenty-nine precloacofemoral pores in a continuous series, most prominent near precloacal region; no precloacal groove; a patch of enlarged scales border pored scales posteriorly and medially; prominent hemipenal bulge. Tail base original, remaining portion regenerated, rounded, without distinct median furrow, tail tip removed. Dorsal scales on original portion of tail granular, gradually becoming flatter and subimbricate posteriorly, intermixed with six to eight slightly enlarged, flat tubercles; ventral scales larger than dorsal scales, subimbricate; no median row of enlarged subcaudals; regenerated portion covered with uniform, small, flat subimbricate scales throughout; three enlarged postcloacal tubercles at base of tail on each side. Fore and hindlimbs relatively slender; forearm (FL/SVL ratio 0.14) and crus (CL/SVL ratio 0.16) relatively short; digits relatively short, strongly inflected at each joint, all bearing robust, recurved claws; subdigital lamellae widened beneath basal phalanx; basal lamellae series on Digits I-V: 4-4-4-5-3 (right manus) and 4-4-5-7-5 (right pes); apical lamellae series (intervening rows of non-lamellar granular scales between basal and distal lamellae series in parentheses) on Digits I-V: 7(1)-9(0)-10(0)-9(1)-8(1) (right manus) and 7(2)-8(2)-10(1)-11(1)-11(1) (right pes); interdigital webbing absent on manus, rudimentary between Digits I–V of pes; relative length of digits (measurements in mm in parentheses): I (3.5) <V (4.1) <II (4.2) <III (5.2) <IV (5.4) (right manus) and I (4.0) <II (5.3) <V (5.7) <III (6.2) <IV (6.3) (right pes); palmar and plantar scales smooth, rounded; scales on forelimb heterogeneous, dorsal aspect of proximal forelimb with granular scales, without tubercles, those on forearm granular with scattered, slightly enlarged tubercles, ventral portion covered mostly with smaller granular scales; scales on hindlimbs heterogeneous, dorsal part of thigh and shank are similar to those on dorsum, with granular scales, intermixed with scattered, enlarged, slightly conical, feebly keeled tubercles, more dense on shank than thigh, anterior portion of thigh and ventral aspect of hindlimb with enlarged, smooth, imbricate scales.`

Colouration in preservative. Ground colour mottled brown, dorsum with six darker irregular paired blotches from hindlimb insertion to nape, one each on occipital region and tail base. Head and limbs slightly rufous, heavily mottled with darker markings. Venter off-white with darker abdomen (artefact of preservation). Colour of regenerated tail similar to dorsum, with dark speckling ( Fig. 7 ).

Colouration in life. Ground colouration in life mottled brown with darker brown-black transverse markings, head with indistinct markings. Pupil outlined by bronze, remaining iris dull greenish-gold ( Fig. 6B ).

Variation. Relative size and shape of dark blotches on the back variable, sometimes very broken up ( Fig. 9 ). There are six males and four females in the type series, with 29–37 PcFPs on males and 19–29 pitted scales on females. The largest specimen is 70.7 mm SVL (BNHS 2230). The number of mid-body ventral scale rows ranges from 35–43, the number of dorsal tubercle rows from 19–21, supralabials from 9–12, infralabials 8–10, and the number of postcloacal spurs from 2–4 (Table 3).

Molecular Data. Cyrtodactylus tripuraensis sp. nov. is more than 12% divergent from C. gubernatoris , C. khasiensis and Cyrtodactylus bhupathyi sp. nov., with a minimum divergence of 7.3/ 9.8% (ND2/ cyt b) from its closest sampled sister taxon, C. ayeyarwadyensis ( Table 4). Animals from Sepahijala (BNHS 2236, 2238) and Gumti (BNHS 2245) are less than 1% divergent from each other, and are 4.6–5.0% divergent from BNHS 2230 from Rowa, North Tripura (ND2 data). Agarwal et al. (2014) referred to this species as Cyrtodactylus sp. Tripura.

Distribution and Natural History. This is one of the few widely distributed Cyrtodactylus species in the Indo-Burma region ( Agarwal et al. 2014), found across the lowlands of Tripura. These geckos were always collected <1.5 m from the ground and mainly from muddy road cuts in secondary and degraded moist deciduous forest; the individual from Rowa was on the trunk of a coppiced tree and one from Gumti was found under a rock in a hill forest approximately 10 m from the road. Considering this species’ habitat preference and the proximity of populations to the Tripura state border (e.g., at Sepahijala), C. tripuraensis sp. nov. should be found in neighbouring regions of eastern and southeastern Bangladesh, and southern Assam (e.g., Karimganj district) in India. This species, though widely distributed, was not observed by us in the same abundance as other Cyrtodactylus species found in more rocky habitats in other parts of Northeast India (including a high elevation habitat in Tripura). Cyrtodactylus tripuraensis and C. ayeyarwadyensis are the only Cyrtodactylus in India and Myanmar with wide distributions that have been confirmed by genetic data ( Agarwal et al. 2014), and these two species both live in lowland habitats at elevations below 300 m asl.

Remarks. Southeastern Bangladesh populations referred to as Cyrtodactylus sp. ( Mahony & Reza 2008; Mahony et al. 2009b) were later considered to represent Cyrtodactylus ayeyarwadyensis based on overall morphological similarity ( Mahony et al. 2009a). The northern most Bangladesh population, from Kaptaimukh Beat, is located ca. 100 km south of Gumti Wildlife Sanctuary in the same continuous north–south running valley. These Bangladesh populations therefore require further molecular confirmation of taxonomic affinity in light of the morphologically similar new species, Cyrtodactylus tripuraensis sp. nov. described here.

Figures

FIGURE 6. Cyrtodactylus bhupathyi sp. nov. in life (female holotype BNHS 2255; A), Cyrtodactylus tripuraensis sp. nov. in life (paratype BNHS 2236; B).

FIGURE 7. Dorsal view (A), ventral view (B) and details of dorsal pholidosis (C) of Cyrtodactylus tripuraensis sp. nov. (male holotype, BNHS 2244). Scale bars 10 mm.

FIGURE 8. Head of Cyrtodactylus tripuraensis sp. nov. (male holotype, BNHS 2244), dorsal (A), lateral (B) and ventral (C) view. Scale bars 10 mm.

FIGURE 9. Cyrtodactylus tripuraensis sp. nov. in life, paratypes: female BNHS 2230 (A), male BNHS 2243 (B), male BNHS 2238 (C), female BNHS 2240 (D), male BNHS 2236 (E).