Cyrtodactylus ngopensis, Bohra & Zonunsanga & Das & Purkayastha & Biakzuala & Lalremsanga, 2022

Bohra, Sanath Chandra, Zonunsanga, Hmar Tlawmte, Das, Madhurima, Purkayastha, Jayaditya, Biakzuala, Lal & Lalremsanga, Hmar Tlawmte, 2022, Morphological and molecular phylogenetic data reveal another new species of bent-toed gecko (Cyrtodactylus Gray: Squamata: Gekkonidae) from Mizoram, India, Journal of Natural History 56 (41 - 44), pp. 1585-1608 : 1593-1601

Cyrtodactylus ngopensis sp. nov.

Holotype

Adult male ( MZMU2553 ; GenBank accession no. OM912605 ), from Tuikhur veng, Chawngbawla section, Ngopa (23.884098°N, 93.211943°E; 1138 m asl), Champhai District, Mizoram, Northeast India, collected by Johny M.S. Dawngkima, Rochanhlua and H.T. Zonunsanga on 16 September 2021 at ca. 8p.m.

Paratypes

One adult male ( MZMU2555 ) and one adult female ( MZMU2552 ) from NEC road, Khuangchera section, Ngopa (23.886567°N, 93.212244°E; 1171 m asl), Champhai District , Mizoram, Northeast India, collected by Rochanhlua and Johny M.S. Dawngkima on 17 September 2021 at ca. 7p.m. ; one adult female ( MZMU2554 ; GenBank Accession No. OM912605 ) from Taitesena section, Ngopa (23.884992°N, 93.212629°E; 1169 m asl), Champhai district, Mizoram, Northeast India, collected by H.T. Zonunsanga, Lal Biakzuala and H.T. Lalremsanga on 18 September 2021 at ca. 9p.m. ; one adult female ( MZMU2556 ) from Taitesena section, Ngopa (23.884614°N, 93.212311°E; 1,160 m asl), Champhai district, Mizoram, Northeast India, collected by Johny M.S. Dawngkima, on 19 September 2021 at ca. 9.30 p.m. ; two adult females ( MZMU2557 and MZMU2558 ) from Taitesena section, Ngopa (23.884234°N, 93.212704°E; 1152 m asl), Champhai district, Mizoram, Northeast India, collected by H.T. Lalremsanga and Lal Biakzuala on 20 September 2021 at ca. 6p.m. (Appendix B).

Etymology

The species epithet is derived from the township of Ngopa in Champhai district of Mizoram State, from which the type specimens were collected.

Suggested common name

Ngopa bent-toed gecko.

Description of holotype

Holotype in generally good preservation condition. Adult male, SVL 62.6 mm. Head less than one-third of SVL (HL/SVL 0.28), longer than broad (HW/HL 0.59), distinct from neck and somewhat depressed (HD/HW 0.63); interorbital area flat, canthus rostralis broadly rounded; loreal region inflated with granular scales; snout less than half of the head length (SO/HL 0.38); scales on the canthus rostralis, snout and forehead are homogeneous; scales from the interorbital region of the head to the nape are slightly smaller than those of the forehead, somewhat blunt and juxtaposed; scales on the interorbital and occipital regions somewhat homogeneous in size, having very few indistinct tubercles; eye approximately one-quarter of the head length (OD/HL 0.23); vertical pupil with crenulate margins; supraciliaries moderate in size, blunt and somewhat oval and circular, those present in the mid-portion (above the orbit) largest and more prominent; ear opening oval, obliquely orientated, small (EL/HL 0.11); orbit to ear distance is less than the eye diameter (OE/OD 0.78); rostral wider than long (RL/RW 0.56), partially and dorsally divided by a poorly developed rostral groove; single enlarged supranasal on either side, separated by three small granular internasals, slightly larger than the scales on the snout; rostral in contact with the first supralabials, nasals, two supranasals and three internasals; nostrils semicircular, openings laterally orientated, posterior half covered by the nasal pad, each nasal is in broad contact with the rostral and surrounded by the supranasal, first supralabial, and four small postnasals; a single row of small granular scales separates the orbit from the supralabials; mental wider than long (MML/MW 0.85), triangular; two well-developed postmentals on either side; the inner pair of postmentals more than 1.5 times the size of the outer pair (PMIIL/PMIL 0.63), bordered by the mental, infralabial I, the outer postmental and four gular scales; outer postmentals bordered by inner postmental, infralabials I and II, and three to four gular scales on either side; 10 supralabials on each side, bordered by a row of medium to large-sized scales, somewhat flat and elongated; nine infralabials on each side, a row of enlarged gular scales (largest anteriorly) ventrally bordering infralabials II to IV; gular region with small granular scales throughout except for a few scale rows bordering the mental, postmentals and infralabials which are larger, flat and juxtaposed.

Body moderately slender, trunk length approximately half of the snout to vent length (TRL/SVL 0.51); dorsal scales are mostly heterogeneous, small rounded granule-like scales intermixed with irregularly arranged, bluntly conical and feebly keeled enlarged tubercles (3–4 times the size of granular scales) becoming slightly smaller and more conical towards the flanks, the largest on the mid-dorsum; tubercles extending posteriorly from the occipital region to the second segment of the tail and smaller on the nape than on the dorsum; 20 mid-dorsal tubercle rows throughout the dorsum; 36 paravertebral tubercles between the level of the axilla and the level of the groin; ventrolateral folds are poorly developed, not denticulate but with a single row of continuous, projected smooth tubercles; ventral scales smooth, cycloid, imbricate to subimbricate, much larger than dorsals and slightly smaller in size under thighs; 33 mid-ventral scale rows; six distinct precloacal pores in a continuous series; a single row of four slightly enlarged scales (median scale being the largest) between the precloacal pores and the vent; three postcloacal tubercles on the left side and two on the right side of the tail base. Forearm (FL/SVL 0.14) and tibia (CL/SVL 0.18) short; digits narrow, without a scansorial pad, strongly inflected at each joint, all bearing robust, recurved claws; sub-digital lamellae transversely widened beneath the basal phalanx; basal lamellae 4-4-4-5-4 on the right manus, 4-5-5-6-5 on the right pes; distal lamellae (intervening rows of nonlamellar granular scales between the basal and distal lamellae series in parentheses): 6(1)-7(2)- 8(1)-7(2)-6(2) on the right manus, 6(1)-7(2)-8(2)-8(3)-8(1) on the right pes; interdigital webbing absent from both the manus and pes; relative length of digits I <II <V<III <IV on the right manus, I <II <V <III <IV on the right pes; scales on the palms and soles are smooth, weakly raised, subimbricate; scales on the fore limbs are heterogeneous in size, comprising flat, imbricate to subimbricate scales on the upper arms, while those on forearms are heterogeneous in size, ventral portion covered with heterogeneously sized imbricate scales; scales on the hind limbs are heterogeneous in size, dorsal surfaces of the thighs and shanks have slightly enlarged scales, intermixed with scattered, enlarged, conical, feebly keeled tubercles; anterior portion of thighs and ventral aspect of hind limbs have slightly enlarged, smooth, imbricate scales.

Tail regenerated from the sixth tail segment, oval in cross section, dorsoventrally depressed; dorsal tubercles on the tail base (tail portion containing the hemipenes) are enlarged, flat and pointed; a few enlarged, flat and distinctly keeled, tubercles randomly scattered near the first segment of the tail, remaining dorsal caudal scales smooth, flat, heterogeneous in size and shape; subcaudal scales smooth, imbricate and heterogeneous in size, forming a mid-ventral series of granular scales; no enlarged transverse or paired row of subcaudals ( Figures 4 and 5 (a)).

Colouration in preservative

The colour is pale in comparison to the live specimen. The dark spots on the dorsum have partially darkened ( Figure 4 ).

Colouration in life

Dorsum and dorsal surface of head primarily greyish brown in colour; nape has a distinct chevron which is divided at the middle; nine pairs of indistinct dark brown blotches on the dorsum, with those on the anterior half forming a reticulating pattern. A distinct postorbital stripe present that runs over the ear opening. Fore limbs and hind limbs have indistinct whitish or cream-coloured blotches intermixed with dark brown blotches. Tail (regenerated from the sixth segment) has alternating dark brown and transverse white bands. Ventral surface is off-white in colour ( Figure 5 (a)).

Diagnosis

Cyrtodactylus ngopensis sp. nov. is a moderate-sized gecko (adult SVL 62.6–68.6 mm); 10– 11 supralabials; 9–11 infralabials; dorsal tubercles rounded, conical to weakly keeled and in 19–20 longitudinal rows; 32–36 paravertebral tubercles between the level of axilla and groin; 32–39 mid-ventral scale rows across the ventral region; 6 precloacal pores in males and 0–6 precloacal pits in females; 14–18 subdigital lamellae under toe IV; no single row of transversely enlarged subcaudal scales; somewhat indistinct but quantifiable pattern of alternating dark brown blotches on the dorsum of the body.

Variation

Refer to Table 2 for meristic, morphometric and basic pholidosis variation within the type series of C. ngopensis sp. nov. The type series of C. ngopensis sp. nov. includes two adult male (MZMU 2553 and MZMU 2555) and five adult female specimens (MZMU 2552, MZMU 2554, MZMU 2556, MZMU 2557 and MZMU 2558). All the female specimens except MZMU 2558 have visible pitted scales in their precloacal region.

Comparisons

Here, C. ngopensis sp. nov. was compared with all known members of the genus Cyrtodactylus within the khasiensis clade, which also includes species ( C. cayuensis , C. martinstollii , C. markuscombaii , C. himalayicus , C. tamaiensis ) that have yet to be assigned to any clade because of the absence of molecular data.

Morphologically, C. ngopensis sp. nov. can be differentiated from its congeners by the possession of the following diagnostic characters: a smaller maximum adult size, SVL 68.6 mm (vs C. lungleiensis max. 75.1 mm; C. bengkhuaiai max. 72.5 mm; C. bapme 77.0 mm max; C. kazirangaensis min. 80.0 mm; C. arunachalensis max. 81.7 mm; C. ayeyarwadyensis max. 78.0 mm; C. khasiensis max. 81.1 mm; C. mombergi max. 74 mm; C. martinstolli max. 82.0 mm; C. tamaiensis max. 90.0 mm; C. cayuensis max. 79.78 mm; C. urbanus max. 74.0 mm; C. jaintiaensis min. 96.2 mm; C. montanus max. 78.2 mm; C. nagalandensis min. 72.0 mm; C. brevidactylus max. 88 mm; C. markuscombaii max. 72.0 mm; C. chrysopylos max. 83.8 mm; C. aunglini max. 81.6 mm); presence of a nonoverlapping number of precloacal pores in males, 6 PcP (vs 7–8 PcP in C. aaronbaueri ; 12 PcP in C. namtiram ; 11–18 PcP in C. agarwali ; 10–28 PcFP in C. ayeyarwadyensis ; 10 PcP in C. himalayicus ; 11–12 PcP in C. jaintiaensis ; 34–38 PcFP in C. karsticola ; 26–39 PcFP in C. guwahatiensis ; 10–11 PcP in C. kaziranagensis ; 10–12 PcP in C. khasiensis ; 7 PcP in C. markuscombaii ; 8–10 PcP in C. montanus ; 14 PcP in C. septentrionalis ; 40 PcFP in C. tamaiensis ; 29–37 PcFP in C. tripuraensis ; 9–12 PcP in C. urbanus ; 3–5 PcP in C. lungleiensis ; 9–11 PcP in C. mombergi ; 8–9 PcP in C. brevidactylus ; 8–13 PcP in C. chrysopylos ; 12–13 PcP in C. aunglini ; 16–29 PcFP in C. gansi ; 7 PcP in C. siahaensis ; 11– 15 PcP in C. exercitus ); 0–6 precloacal pits in females (vs no visible pitted scales in females of C. bengkhuai , 0–13 precloacal pits in C. bapme ); 19–20 rows of feebly keeled, conical dorsal tubercles throughout the dorsum (vs 22–28 rows in C. aaronbaueri ; ca. 21 rows in C. namtiram ; 21–25 rows in C. agarwali ; 24–26 rows in C. arunachalensis ; 22–24 rows in C. ayeyarwadyensis and C. siahaensis ; 22–26 rows in C. bengkhuai ; 18 rows in C. cayuensis and C. mandalayensis ; 21–24 rows in C. karsticola , C. guwahatiensis , C. urbanus , C. exercitus and C. bapme ; 22–23 rows in C. kazirangaensis ; 14–15 rows in C. markuscombaii ; 21–23 rows in C. montanus ; 16–18 rows in C. nagalandensis ; 23–24 rows in C. septentrionalis ; 21 rows in C. tamaiensis ; 24–28 rows in C. lungleiensis ; 23–27 rows in C. mombergi ; 27–30 rows in C. brevidactylus ; 21–26 rows in C. aunglini ); presence of 32–36 rows of paravertebral tubercles between the level of axilla and level of groin (vs 36–39 rows in C. aaronbaueri and C. siahaensis ; 38–42 rows in C. septentrionalis ; 37–43 rows in C. montanus ; 36–38 rows in C. kazirangaensis ); 32–39 rows of mid-ventral scales across the venter (vs 40–42 rows in C. jaintiaensis ; 57 rows in C. myaleiktaung ; 39–55 rows in C. chrysopylos ; 47–49 rows in C. aunglini ); 14–18 subdigital lamellae beneath fourth toe (vs 19–23 subdigital lamellae in C. aunglini and C. chrysopylos ; 13 in C. martinstolli ; 19 in C. markuscombaii ; 19–22 in C. khasiensis and C. mombergi ; 10 in C. himalayicus and C. gansi ).

Again, a larger maximum adult size separates Cyrtodactylus ngopensis sp. nov. (SVL 68.6 mm) from C. namtiram (65.8 mm, N = 1); C. himalayicus (SVL 64.5 mm max.), C. mandalayensis (SVL 61.7 mm max.), C. myaleiktaung (SVL 59.0 mm max.), C. gansi (SVL 62.3 mm max.) and C. siahaensis (SVL 63.9 mm max.). Furthermore, a single row of slightly enlarged scales below pored scales (median scale being the largest) separates C. ngopensis sp. nov. from C. arunachalensis , which has three to four rows of slightly enlarged scales below pored scales. Additionally, the presence of indistinct dark dorsal spots on the dorsum differentiates C. ngopensis sp. nov. from C. tripuraensis (vs presence of dark brown blotches on the dorsum usually bordered posteriorly by white punctations in the latter) as well as from C. khasiensis , C. martinstolii and C. cayuensis by the presence of uniform granular subcaudals (vs presence of a median series of enlarged paired subcaudals in the latter three species).

Distribution and natural history

We have collected the new species so far from only the type locality in Ngopa town, one of the townships in Champhai district of the south-eastern part of Mizoram. The approximate aerial distances between type localities of the new species and of C. aaronbaueri ( Purkayastha et al. 2020) is ca. 50 km westward (from this point onwards, the directions are given from the perspective of this study’s type location towards the type locations of the other species); C. bengkhuaiai ( Purkayastha et al. 2020) is ca 73 km south-westward; C. lungleiensis ( Lalremsanga et al. 2022) is ca. 119 km south-westward; and C. siahaensis ( Purkayastha et al. 2022) is ca. 156 km southward.

All the specimens of C. ngopensis sp. nov. were collected during night time between ca. 7p. m. and 9: 30p. m. The microhabitat of the holotype is a crevice between a length of dried rotten wood and a sand wall ( Figure 6 (a)) near a public spring water, whilst the paratypes were collected from clefts in a retaining wall ( Figure 6 (b)) and stacked boulders ( Figure 6 (c)). All the specimens were collected from anthropogenic areas fringed with secondary forest in the peripheral part of the town. Climatic conditions in the area varied between 10 and 20°C during winter and 15 to 30°C during summer; the annual rainfall is 2037.6 mm ( Guhathakurta et al. 2020). The location falls under montane subtropical forest as per the classification by Singh et al. (2002), and the vegetations around the area comprises tree species such as Bauhinia variegata , Callicarpa arborea , Castanopsis echinocarpa , Erythrina stricta, Lithocarpus polystachyus, Litsea monopetala, Mangifera indica, Melocanna baccifera, Macaranga sp., Phyllanthus acidus , Schima wallichii, Toxicodendron succedaneum and Rhus chinensis ; and shrub and herb species such as Ageratum conyzoides , Bidens pilosa, Chrysopogon aciculatus, Conyza stricta, Imperata cylindrica, Laggera pterodonta, Microlepia strigosa, Mikania micrantha, Saccharum arundinaceum, Saccharum longisetosum, Sida acuta and Triumfetta bogotensis .

Figures

Figure 4. The holotype of Cyrtodactylus ngopensis sp. nov. (MZMU2553): (a) dorsal view; (b) ventral view; (c) details of dorsal pholidosis; (d) dorsal view of head; (e) lateral view of head; (f) ventral view of head.

Figure 5. Live specimens of Cyrtodactylus ngopensis sp. nov.: (a) holotype, MZMU2553; (b) paratype, MZMU2552; (c) paratype, MZMU2554; (d) paratype, MZMU2555; (e) paratype, MZMU2556; (f) uncollected individual.

Figure 6. Habitats of Cyrtodactylus ngopensis sp. nov. from Ngopa, Mizoram, Northeast India: (a) collection site of the holotype at Tuikhur veng, Chawngbawla section, Ngopa; (b) collection site of paratypes at NEC road, Khuangchera section, Ngopa; (c) collection site of paratypes at Taitesena section, Ngopa.