Cyrtodactylus thochuensis, Ngo, Van Tri & Grismer, Lee, 2012

Ngo, Van Tri & Grismer, Lee, 2012, A new endemic species of Cyrtodactylus Gray (Squamata: Gekkonidae) from Tho Chu Island, southwestern Vietnam., Zootaxa 3228, pp. 48-60 : 49-56

Cyrtodactylus thochuensis sp. nov.

( Figs. 1–3 )

Holotype. ITBCZ 2300, adult male collected by Ngo Van Tri at 19:25 on 15 August, 2009 on Tho Chu Island, Phu Quoc district, Kien Giang Biosphere Reserve, Kien Giang Province, southwestern Vietnam; 9o18’56’’N 103o28’53’’E, at an elevation of approximately 80 m a.s.l.

Paratypes. ITBCZ 2301–2306 collected by Ngo Van Tri at 20:00, from the same locality and the same date as the holotype. ITBCZ 2205 and 2206 were collected by Ngo Van Tri at 18:46 on 20 July 2008 at the same locality as the holotype.

Common names. English name: Thochu Bent–toed Geckο, vietnamese name “Τhằn lằn chȃn ngόn Τhổ Chu”.

Diagnosis. Adult SVL 80.0–81.8 mm; body relatively robust; limbs and digits short, relatively robust; dorsal pattern consisting of 3–5 irregularly shaped yellowish brown bands between the limbs overlaying a brown background; original tail very long with 12–14 yellowish white bands alternating with dark brown bands; 3–6 intersupranasals in broad contact with supranasals; 3–5 scales bordered posteriorly by the first postmental; 20–26 irregularly aligned rows of strongly keeled dorsal tubercles; 29–34 paravertebral tubercles; 30–40 ventral scales between ventrolateral folds; no precloacal groove; 3–5 precloacal pore-bearing scales in lateral contact with 15–17 enlarged femoral scales; enlarged scales on heel; 13 or 14 distal subdigital lamellae on the first toe; 17–19 distal subdigital lamellae on the fourth toe; and dorsal caudal tubercles extending 32.3% down length of tail. Median subcaudal scales form enlarged transverse plates.

Description of holotype ( Fig. 1A ). Adult male, SVL 83.5 mm; head moderately long (Head/SVL ratio 0.28), relatively narrow (HeadW/HeadL ratio 0.67), depressed (HeadH/HeadL ratio 0.38), distinct from neck; lores and interorbital regions convex; canthus rostralis prominent; frontonasal region concave; snout elongate (Sneye/HeadL ratio 0.36), relatively pointed, longer than eye diameter (OrbD/SnEye ratio 0.64); scales on snout and forehead small, rounded, granular, homogeneous; scales on snout larger than those on occipital region; eye large (OrbD/ HeadL ratio 0.23); pupil vertical with crenellate margins when closed, and round when opened; supraciliaries short, bearing tiny conical spines posteriorly; ear opening oval, small (EarL/HeadL ratio 0.09); eye to ear distance greater than diameter of eye (EyeEar/OrbD ratio 0.19); rostral incompletely divided dorsally by a Y-shaped shallow groove; two enlarged supranasals separated from each other by three intersupranasals and all contacting smaller snout scales posteriorly ( Fig. 2A ); nostril oval, bordered by rostral anteriorly, first supralabial, supranasal dorsally, and two enlarged postnasals posteriorly; orbit separated from supralabials by three or four rows of small scales; mental triangular, wider (3.3 mm) than deep (2.3 mm); one pair of enlarged postmentals in broad contact medially, bordered anterolaterally by first infralabial on each side and second pair of postmentals, followed by five enlarged gular scales ( Fig. 2 B); nine (R), 10 (L) supralabials to midorbital position; enlarged supralabials to angle of jaws 11 (R) 13 (L) infralabials; 20 interorbital scale rows across narrowest point of frontal region; 24 scales between eye and nostril.

Body relatively robust, elongate (TrunkL/SVL ratio 0.40) with ventrolateral folds; gular region bearing relatively homogeneous, smooth scales; dorsal scales granular to conical; regularly distributed strongly keeled tubercles (4–10 times larger than adjacent scales) ( Fig. 2 C), extending from frontal region to base of tail; approximately 25 irregular rows of tubercles at midbody; smallest tubercles on flanks and in the frontal region; 32 paravertebral tubercles; ventral scales much larger than dorsals, smooth, round, subimbricate, largest posteriorly; 30 ventral scale rows at midbody between ventrolateral folds, bearing small, scattered tubercles ( Fig. 2 D); precloacal groove absent; precloacal region bearing more than 40 smooth enlarged scales, bordered anteriorly by three enlarged porebearing scales in an angular series ( Fig. 2 E); several slightly enlarged scales present in anterior region of pore-bearing scales; 16 smooth enlarged femoral scales on both sides contacting enlarged scales of precloacal region; scales on plantar surface and hind limb granular, scattered, keeled dorsal tubercles extending to manus and pes; 9 or 10 enlarged scale rows on each heel.

Forelimbs and hind limbs relatively robust (ForeL/SVL ratio 0.14; CrusL/SVL ratio 0.18); digits relatively short, strongly inflected at basal interphalangeal joints, all bearing slightly curved claws; basal subdigital lamellae nearly as broad as digit, lacking a scansorial surface; lamellae distal to inflection narrow and not including ventral claw sheath, 13–13–16–16–14 distal subdigital lamellae on manus ( Fig. 2 G); 13–15–17–18–19 distal subdigital lamellae on pes ( Fig. 2 H); interdigital webbing present but weakly developed; relative length of fingers IV(6.4)> III(6.0)> V(5.6)> II(5.4)> I(3.8) and of toes: V(8.8)> IV(8.0)> III(7.5)> II(6.3)> I(5.0).

Tail original, long (TailL/SVL ratio 1.57), cylindrical, tapering to the tip and segmented, each segment consisting of 10–12 scale rows dorsally and three median enlarged subcaudal scales; three smooth yellowish white postcloacal tubercles on each side of tail base; tail bearing dorsal tubercles for approximately 32.3% of its length, consisting of nine tubercles in the proximal segments, and reducing to four posteriorly; anterior region of tail bearing eight longitudinal rows of smaller keeled tubercles extending posteriorly from body ( Fig. 2 F); medial row of subcaudals smooth, enlarged, subimbricate ( Fig. 2 H); dorsal caudal scales flat, round, hexagonal, or pentagonal, and juxtaposed.

Coloration in life ( Fig. 1A ). Ground color of body, head, limbs and tail dull yellowish brown; dark irregularly shaped markings on rostrum and top of head; wide dark stripe extending from postnasal region through eye onto occiput and angling posteriorly on the midline of the nape and coming into close approximation with a dark stripe from the opposite side; stripes transform into semi-paired, dark angularly shaped, paravertebral markings extending onto tail to form dark, irregularly shaped markings; larger whitish tubercles on flanks; five dark vertebral spots present; dorsal surface of limbs weakly mottled; ventral surfaces dull, generally immaculate, and lighter than dorsal surfaces; iris brownish gold.

Variation. The dorsal pattern of the paratypes ITBCZ 2304–2306 is more regularly banded than that of the holotype and contains four or five bands that lack dark vertebral spots. The paratype ITBCZ 2206 closely resembles the holotype in color pattern except it has a regenerated tail. Measurements of the type series are presented in Table 1.

Etymology. The specific epithet is derived from Tho Chu Island, the type locality.

Distribution. Extensive surveys conducted by NVT on the smaller nearby islands did not reveal the presence of Cyrtodactylus thochuensis sp. nov. which, at this point, appears to be restricted to Tho Chu Island, Phu Quoc district, Kien Giang Biosphere Reserve, Kien Giang Province, southwestern Vietnam.

Natural history. Most of the specimens were collected at 20:00 hrs on 15 August 2009 among rocky outcroppings along an small intermittent stream. ITBCZ 2205–06 were collected on 20 July 2008 at the same location at approximately 19:30 hrs. ITBCZ 2206 is a gravid female with two eggs. Other lizards observed and collected in the area were Gekko gecko (Linnaeus) , Gehyra mutilata (Wiegmann) , Hemidactylus frenatus (Dumeril & Bibron) , H. platyurus (Schneider) , Eutropis multifasciatus (Kuhl) and Dasia olivacea (Gray) .

Comparison with other species. Cyrtodactylus thochuensis sp. nov. is most similar to Cyrtodactylus condorensis (Smith) , Cyrtodactylus paradoxus (Darevsky & Szczerbak) and C. leegrismeri Chan & Ahmad in having maximum SVLs of 86.3 mm versus 82.9 mm, 84.0 mm, and 92.0 mm, respectively, and having enlarged transverse subcaudal scales. However it differs from C. condorensis by having fewer pore-bearing precloacal pores (3–5 in a chevron versus 4–7 in two juxtaposed rows), more paravertebral tubercles (29–34 versus 25–26), a dorsal pattern of bands with spots present in the middle of each band versus having crossbands, and lastly having continuous precloacal and femoral pore-bearing scales versus these scales being discontinuous. From C. paradoxus it differs in the arrangement of pore-bearing precloacal pores (chevron versus two juxtaposed rows), number of longitudinal rows of dorsal body tubercles (22–26 versus 20–22), and number of paravertebral tubercles (29–34 versus 24–26), and from C. leegrismeri it differs by having a dorsal pattern of bands versus one of symmetrical blotches, a different arrangement of pore-bearing precloacal pores (chevron versus arch), a greater number of longitudinal rows of dorsal body tubercles (20–26 versus 18–19), and a greater number of paravertebral tubercles (29–34 versus 25–29).

These character states are scored across all other species of Asian Cyrtodactylus ( Table 2 ) illustrating the nature of separation of C. thochuensis sp. nov. from the remainder of its congers.

continued.

Data derived from: Darevsky & Szczerbak, 1997; Bauer et al. 2002, 2010; David et al. 2004; Nguyen et al. 2006; Nguyen et al. 2010; Heidrich et al. 2007; Hoang et al. 2007; Nazarov et al. 2008; Rösler et al. 2007, 2008; Ngo et al. 2010; Ngo & Chan, 2010; Ngo, 2011; Geissler et al. 2009; Nguyen et al. 2010; Schneider et al.2011; * n = 8 for tail length of C. cattienensis .Note: “?” unsure.

Figures

FIGURE 1. A: Male holotype of Cyrtodactylus thochuensis sp. nov. (ITBCZ 2300), B: Female of Cyrtodactylus paradoxus.

FIGURE 2. A: Snout scales of Cyrtodactylus thochuensis sp. nov. showing three intersupranasals in broad contact with supranasals. B: Mental scale of C. thochuensis sp. nov. C: Dorsal tuberculation of C. thochuensis sp. nov. D: Ventral scales of C. thochuensis sp. nov. E: Precloacal and femoral region showing a series of several enlarged smooth scales and three precloacal pores in an angular arrangement. F: Dorsum of tail of holotype of C. thochuensis sp. nov. G: Manus of C. thochuensis sp. nov. H: Pes and median enlarged subcaudal scales of Cyrtodactylus thochuensis sp. nov.

FIGURE 3. A: Adult female paratype of Cyrtodactylus thochuensis sp. nov. (ITBCZ 2304). B: Subadult male ITBCZ 2306, showing three irregular dorsal bands. C: Subadult female paratype ITBCZ 2305 of C. thochuensis sp. nov. showing the original tail with many bands. D: Adult female ITBCZ 2206, showing five irregular bands on the dorsum and dark brown markings on the regenerated tail.

Tables

TABLE 2. Comparison of the new species among other Cyrtodactylus from the Indochinese peninsula.

	C.thochuensis sp. nov.	C. angularis	C. buchardi	C. cattienen- sis	C. chauquan- gensis	C. condorensis	C. cryptus
n	9	?	1	21	3	4	4
SVL	57.2–86.3	66.0	33.4	>69.0	90.9–99.3	70.2–82.9	74.0–84.8
TailL	80.3–131.5	80.0	64.2	57.5–62.0	96.9–108.3	86.5–112.0	63.6–88.4
VenS	30–40	34–42	30	28–42	36–38	30–40	47–50
TubR Fem-Pores	20–26 3–5	? 6 pitted	25 Unclear	16–22 6–8	? 6–7	22–24 (n=3) 4–7	19–20 9–11
Fem-Pores	0	0	0	0	0	0	0
EnlfemS	Present	Present	Absent	3–8	Absent	Present	Absent
Subcaudal Scales	Enlarged	Median enlarged	Round	Round	Round	Enlarged	Small
SupL	10–14	10–12	14	8–10	9–10	10–12	8–11
Infra	9–10	10–12	11	8–11	9–11	8–11	6–10
NST4	14–17	15–16	12	14–19	19–23	14–16	20–23