Cyrtodactylus ngati, Le & Sitthivong & Tran & Grismer & Nguyen & Le & Ziegler & Luu, 2021

Le, Dzung Trung, Sitthivong, Saly, Tran, Tung Thanh, Grismer, L. Lee, Nguyen, Truong Quang, Le, Minh Duc, Ziegler, Thomas & Luu, Vinh Quang, 2021, First record of the Cyrtodactylus brevipalmatus group (Squamata: Gekkonidae) from Vietnam with description of a new species, Zootaxa 4969 (3), pp. 492-510 : 495-505

Cyrtodactylus ngati sp. nov.

( Figs. 2–3 )

Holotype. HNUE-R00111 (Field number PT.2017.215), adult male, collected on 17 August 2017 by D. T. Le, D. T. Truong, H.Q. Nguyen, N.H. Nguyen, and A.N. Nguyen, in the karst forest near Pa Thom Cave , Pa Xa Lao Village, Pa Thom Commune, Dien Bien District, Dien Bien Province, Vietnam (21°17’N; 102°54’E, 695 m a.s.l.).

Paratypes. IEBR 4829 (Field number PT.2016.07), adult female, VNUF R.2020.12 (Field number PT.2016.06), adult female, collected on 27 August 2016; HNUE-R00112 (Field number PT.2017.187), subadult female, collected on August 2017, the same data as the holotype .

Diagnosis. The new Cyrtodactylus species can be distinguished from remaining congeners by the following combination of morphological characters: maximum SVL 69.3 mm; dorsal pattern consisting of six dark irregular transverse bands between limb insertions; intersupranasal single; dorsal tubercles present on occiput, body, hind limbs and on first half of tail; 17–22 irregular dorsal tubercle rows at midbody; lateral folds clearly defined, with interspersed tubercles; 32–38 ventral scales between ventrolateral folds; 13 precloacal pores separated by a diastema of 5/5 poreless scales from 7/7 femoral pores in enlarged femoral scales; precloacal and femoral pores absent in females; 1–3 postcloacal tubercles on each side; median subcaudal scales not transversely enlarged.

Description of holotype. Adult male, SVL 66.5 mm; body elongate (TrunkL/SVL 0.43); head elongate (HL/ SVL 0.30), relatively wide (HW/HL 0.62), depressed (HH/HL 0.36), distinguished from neck; loreal region concave; snout long (SE/HL 0.37), obtuse anteriorly, longer than diameter of orbit (OD/SE 0.50); scales on snout small, round or oval, granular, bigger than those in frontal and parietal regions; orbit large (OD/HL 0.19), pupils vertical; supraciliaries with spinous scales posteriorly; ear oval-shaped, small (EarL/HL 0.03); rostral wider than high with a straight medial suture, bordered with first supralabial and nostril on each side; supranasals in contact with each other; nostril opening oval, surrounded by supranasal, rostral, first supralabial, and two enlarged postnasals; mental triangular, slightly wider than long (ML/MW 0.68); two enlarged postmentals; 10/9 supralabials; 8/9 infralabials; dorsal scales granular; dorsal tubercles round, conical, present from occipital region to dorsum and half of tail, tubercles in 18 irregular rows at midbody, larger at midbody, each surrounded by nine granular scales; ventrolateral body folds well defined, with interspersed tubercles; ventral scales smooth, round, midventral scales three times larger than the granules on dorsum, 38 longitudinal ventral scale rows at midbody; gular region with homogeneous, small and smooth scales; 168 ventral scales from mental to cloacal slit; precloacal groove absent; enlarged precloacal scales present; 13 contiguous precloacal pores, separated by 5/5 poreless scales and 7/7 femoral pores (FPl+PP+FPr: 7+13+7); enlarged precloacal and femoral scales present.

Fore- and hind limbs moderately slender (ForeL/SVL 0.13, CrusL/SVL 0.16); enlarged tubercles on dorsal surface of forelimbs absent, but covered with slightly enlarged granules; hind limbs with distinctly developed tubercles dorsally; fingers and toes basally webbed; 16/16 lamellae under fourth finger; 12/13 lamellae under fourth toe.

Tail longer than SVL (TaL 74.1 mm); 3/2 postcloacal tubercles; dorsal surface of tail bearing distinct tubercles on anterior one-half of tail; lateral rows of spinose scales present; median subcaudal scales slightly enlarged, flat, smooth.

Coloration in life. Background coloration light yellowish brown, with dark brown dorsal pattern; dorsal surface of head with irregular dark brown blotches; an irregularly shaped dark nuchal loop present, edged in dark brown, butterfly-shaped; six dark transversal bands between limb insertions, somewhat irregularly shaped, somewhat muted in color; tubercles at midbody greyish brown; dorsal surface of limbs with dark spots; dorsal surface of original tail dark grey with light bands, and dark narrow ring within the latter; ventral surface of head, body and limbs cream; subcaudal region dark grey with light bands (see Fig. 2 ).

Sexual dimorphism and variation. The females differ from males by the absence of hemipenial swellings at the tail base as well as femoral and precloacal pores. For further morphological characters of the paratypes see Table 2 and Fig. 4 .

Comparisons. We compared Cyrtodactylus ngati sp. nov. with other congeners from Vietnam and neighboring countries in the mainland Indochina region, including Laos, Cambodia, and Thailand based on examination of specimens (see Appendix) and data from literature ( Luu et al. 2014; Nazarov et al. 2014; Nguyen et al. 2014; Panitvong et al. 2014; Pauwels et al. 2014; Pauwels & Sumontha 2014; Schneider et al. 2014 a,b; Nurngsomsri et al. 2014; Grismer et al. 2015; Luu et al. 2015; Sumontha et al. 2015; Pauwels et al. 2016; Le et al. 2016; Luu et al. 2016a,b,c, 2017; Nguyen et al. 2017; Chuaynkern et al. 2018; Pauwels et al. 2018; Nazarov et al. 2018; Murdoch et al. 2019; Pham et al. 2019; Sitthivong et al. 2019; Schneider et al. 2020; Ostrowski et al. 2020, 2021). The new species can be differentiated from other known species of the genus Cyrtodactylus by morphological characters (see Table 3). Below we compared the new species with the Cyrtodactylus brevipalmatus group data obtained from Smith (1923); Dring (1979); Ulber (1993); Nurngsomsri et al. (2014); and Chuaynkern et al. (2018).

In comparison with the species from the brevipalmatus group, comprising C. interdigitalis Ulber , C. elok Dring , and C. brevipalmatus (Smith) , the new species can be distinguished from C. interdigitalis by its smaller size (maximum SVL 69.3 mm versus 80.0 mm), having fewer precloacal pores (13 versus 14–16), more body bands (6 versus 3), the absence of tubercles on forelimbs (versus present), the presence of dark narrow ring in each light tail band (versus absent), and the presence of slightly enlarged subcaudal scales (versus absent); from C. elok by its smaller size (maximum SVL 69.3 mm versus 83.0 mm), having fewer ventral scales (32–38 versus 52), more body bands (6 versus 3), more precloacal pores in males (13 versus 8), the presence of enlarged femoral scales and femoral pores in males (versus absent), and the presence of slightly enlarged subcaudal scales (versus absent); from C. brevipalmatus by having more femoral pores in males (13 versus 9 or 10), more body bands (6 versus 3), the absence of precloacal pores in females (versus present), and dorsal pattern banded (versus blotched). For more details see Table 4.

Distribution. Cyrtodactylus ngati sp. nov. is currently known only from the type locality in Dien Bien Province, Vietnam ( Fig. 4 ).

Etymology. We name this new species in honor of our colleague, Assoc. Prof. Dr. Ngat Nguyen Le, Hanoi National University of Education, Vietnam, in recognition of his contribution to herpetological research in Vietnam. As common names, we suggest Ngat’s Bent-toed Gecko (English) and Thằn lằn ngón ngật (Vietnamese).

Ecological notes. Specimens were found between 19:00 and 21:00, on limestone cliffs and in rock crevices, approximately 1–2 m above the ground. The surrounding habitat was disturbed evergreen forest of small hardwoods and shrubs on the mountain slope. The humidity was approximately 74–76% and the air temperature ranged from 23 to 26 oC ( Fig. 5 ).

All other members of the Cyrtodactylus brevipalmatus group are arboreal, have prehensile tails carried above their back in a coiled position, and usually are found only on vegetation ( Grismer et al. 2020). This is the first member of the group that apparently lacks a prehensile tail and occurs on karst. Grismer et al. (2020) demonstrated that an arboreal habitat preference was the ancestral condition for the C. brevipalmatus group and these findings represent tthe first record of a potential transition of an arboreal habitat to a karst habitat preference in Cyrtodactylus .

Figures

FIGURE 2. Dorsolateral, dorsal, ventral views and cloacal region of the adult male holotype of Cyrtodactylus ngati sp. nov. (HNUE-R00111) in life. Photos: D.T. Le

FIGURE 3. Dorsal and ventral views of the adult female paratype of Cyrtodactylus ngati sp. nov. (VNUF R.2020.12) in life. Photos: D.T. Le

FIGURE 4. Distribution map of the Cyrtodactylus brevipalmatus species group: square, C. ngati sp. nov.; solid black squares, C. interdigitalis; circles, C. brevipalmatus; solid black circles, C. elok.

FIGURE 5. Macrohabitat (top) and microhabitat (below) of Cyrtodactylus ngati sp. nov. Photo: D.T. Le

Tables

TABLE 2. Measurements (in mm) and morphological characters of the type series of Cyrtodactylus ngati sp. nov. (for other abbreviations see material and methods).

Character	HNUE-R00111 (Holotype)	IEBR 4829 (Paratype)	VNUF R.2020.12 (Paratype)	HNUE-R00112 (Paratype)
Sex	adult male	adult female	adult female	subadult female
SVL	66.5	68.1	69.3	46.6
TaL	74.1	77.9	83.2	54.6
HH	7.4	7.2	6.6	5.1
HL	20.1	20.4	20.7	16.1
HW	12.6	12.0	11.8	8.8
OD	3.8	4.1	3.4	2.6
SE	7.5	7.6	6.9	5.0
EyeEar	5.8	5.5	5.9	4.4
EarL	0.8	0.8	0.7	0.3
TrunkL	28.8	29.8	30.2	19.7
ForeL	9.2	10.0	10.1	6.5
CrusL	10.8	11.1	11.8	7.8
LD4A	5.7	5.4	6.6	3.8
LD4P	6.6	6.4	7.2	4.7
RW	2.8	2.6	2.6	1.7
RH	1.5	1.4	1.5	0.8
MW	2.2	2.1	2.5	1.4
ML	1.5	1.5	1.5	0.9
SL	10/9	10/10	10/8	10/9
IL	8/9	9/9	9/8	9/9
N	3/3	3/3	3/3	3/3
IN	1	1	1	1
PM	2	2	2	2
GP	6	6	6	6
DTR	18	18	17	22
GST	9	9	9	9
V	38	36	35	32
SLB	168	164	178	158
SR	117	112	110	106
FPl+FPr	7+7	0	0	0
PP	13	0	0	0
PAT	3/2	1/2	1/1	1/2
LD4	16/16	16/16	16/17	16/16
LT4	12/13	16/14	17/14	17/14