Cyrtodactylus denticulatus, Chomdej & Suwannapoom & Pradit & Phupanbai & Grismer, 2023

Chomdej, Siriwadee, Suwannapoom, Chatmongkon, Pradit, Waranee, Phupanbai, Apichaya & Grismer, L. Lee, 2023, A new species of the Cyrtodactylus brevipalmatus group (Squamata, Gekkonidae) from Tak Province, northwestern Thailand, ZooKeys 1164, pp. 63-88 : 63

Cyrtodactylus denticulatus sp. nov.

Figs 4 , 5 , 6 Suggested common name: Spiny-tailed bent-toed gecko Suggested Thai common name: ต ุ๊กกายฟันเลื่อย Tuk Kay Fhun Leuy

Cyrtodactylus sp. 10: Chomdej et al. 2021: 11; Grismer et al. 2021: 725, 2022a: 247, 2022b: 111; 2023: 95.

Type material.

Holotype. Adult male AUP-00680 collected on 8 March 2019 by Parinya Pawangkhanant and Chatmongkon Suwannapoom from a bamboo forest near a rocky stream at the Chao Doi waterfall, Mae Meoi, Tha Song Yang District, Tak Province, Thailand at 17°30.000'N, 98°03.000'E (DDM) and 610 m a.s.l.

Diagnosis.

Cyrtodactylus denticulatus sp. nov. is tentatively separated (see below) from all other species of the Cyrtodactylus brevipalmatus group by the combination of having nine supralabials, nine infralabials, 20 paravertebral tubercles, 19 rows of longitudinally arranged tubercles, 42 transverse rows of ventrals, 158 longitudinal rows of ventrals, nine expanded subdigital lamellae on the fourth finger, 11 unexpanded subdigital lamellae on the fourth toe, 19 total subdigital lamellae on the fourth toe; nine expanded subdigital lamellae on the fourth finger, ten unexpanded subdigital lamellae on the fourth finger, 19 total subdigital lamellae on the fourth finger; 16 total number of enlarged femoral scales, 20 total number of femoral pores in the male specimen; 13 precloacal pores in the male specimen; 16 enlarged precloacals; enlarged femorals and enlarged precloacals not continuous; proximal femorals smaller than distal femorals; tubercles on forelimbs and flanks nearly same size as those on body; ventrolateral body fold weakly denticulate; spinose paravertebral rows; row of large dorsolateral caudal tubercles; wide ventrolateral caudal fringes; ventrolateral caudal fringes composed scales of different size; small longitudinal ventrolateral subcaudal ridges; tail square in cross-section; no slightly enlarged unpaired medial subcaudals; subcaudals not posteromedially furrowed; SVL 69.5 mm; three dark transverse body bands (Tables 2 - 4 ).

Description of holotype

(Figs 5 , 6 ). Adult male SVL 69.5 mm; head moderate in length (HL/SVL 0.27), width (HW/HL 0.68), depth (HD/HL 0.38), distinct from neck, triangular in dorsal profile; lores slightly concave anteriorly, weakly inflated posteriorly; prefrontal region weakly concave; canthus rostralis rounded; snout elongate (ES/HL 0.42), rounded in dorsal profile; eye large (ED/HL 0.21); ear opening obliquely elliptical, small; eye to ear distance greater than diameter of eye; rostral rectangular, divided by a dorsal furrow, bordered posteriorly by large left and right supranasals and one smaller azygous internasal, bordered laterally by first supralabials; external nares bordered anteriorly by rostral, dorsally by large supranasal, posteriorly by two unequally sized smaller postnasals, bordered ventrally by first supralabial; 9R/9L rectangular supralabials, second through seventh supralabials nearly same size as first, then tapering below eye; 9R/9L infralabials tapering smoothly to just below and slightly past posterior margin of eye; scales of rostrum and lores flat to slightly domed, larger than granular scales on top of head and occiput; scales of occiput intermixed with distinct, small tubercles; superciliaries subrectangular, largest anterodorsally; mental triangular, bordered laterally by first infralabials and posteriorly by large left and right trapezoidal postmentals contacting medially for 50% of their length posterior to mental; one row of enlarged, square to rectangular sublabials extending posteriorly to first (L) and fourth (R) infralabial; gular and throat scales small, granular, grading posteriorly into slightly larger, flatter, smooth, imbricate, pectoral, and ventral scales.

Body relatively short (AG/SVL 0.46) with well-defined denticulate ventrolateral folds; dorsal scales small, granular interspersed with larger, conical, semi-regularly arranged, weakly keeled tubercles; tubercles extend from occipital region onto base of tail and slightly beyond as paravertebral rows; smaller tubercles extend anteriorly onto nape and occiput, diminishing in size anteriorly; approximately 19 longitudinal rows of tubercles at midbody; approximately 20 paravertebral tubercles; small tubercles on flanks; 42 longitudinal rows of flat, imbricate, ventral scales much larger than dorsal scales; 158 transverse rows of ventral scales; 13 large, pore-bearing, precloacal scales; no deep precloacal groove or depression; and three rows of enlarged post-precloacal scales on midline.

Forelimbs moderate in stature, relatively short (HumL/SVL 0.13; ForL/SVL 14.7); granular scales of forearm larger than those on body, interspersed with slightly larger tubercles; palmar scales rounded, slightly raised, subimbricate; digits well-developed, relatively short, inflected at basal interphalangeal joints; digits narrower distal to inflections; subdigital lamellae wide, transversely expanded proximal to joint inflections, narrower lamellae distal to inflections; claws well-developed, claw base sheathed by a dorsal and ventral scale; 9R/9L expanded and 11R/11L unexpanded lamellae beneath the fourth finger; hind limbs longer and thicker than forelimbs, moderate in length (FemL/SVL 18.4; TibL/SVL 0.09), covered dorsally by granular scales interspersed with moderately sized, conical tubercles dorsally and posteriorly and anteriorly by flat, larger, subimbricate scales; ventral scales of thigh flat, imbricate, larger than dorsals; subtibial scales flat, imbricate; one row of 8R/8L enlarged pore-bearing femoral scales not continuous with enlarged pore-bearing precloacal scales, terminating distally at knee; proximal femoral scales smaller than distal femorals, the former forming an abrupt union with much smaller, rounded, ventral scales of posteroventral margin of thigh; plantar scales raised, subimbricate; digits relatively long, well-developed, inflected at basal interphalangeal joints; 9R/9L wide, transversely expanded subdigital lamellae on fourth toe proximal to joint inflection extending onto sole, and 11R/11L unexpanded lamellae beneath the fourth toe distal to joint inflection; and claws well-developed, claw base sheathed by a dorsal and ventral scale.

Posterior one-fifth of tail regenerated, 83.0 mm long (TL/SVL 1.19), 6.5 mm in width at base, tapering to a point; nearly square in cross-section; dorsal scales flat, intermixed with large tubercles forming spinose paravertebral rows; row of large dorsolateral caudal tubercles; large, posteriorly directed, spinose tubercles forming wide ventrolateral caudal fringe; much larger scales of ventrolateral fringe occur at regular intervals; medial subcaudals slightly enlarged, no enlarged single medial subcaudal longitudinal row; subcaudals, larger than dorsal caudals; small longitudinal ventrolateral subcaudal ridges; base of tail bearing hemipenal swellings; 3R/3L conical postcloacal tubercles at base of hemipenal swellings; and postcloacal scales flat, imbricate.

Coloration in life

(Fig. 4 ). Ground color of the head body, limbs, and tail tan; diffuse darker mottling on the top of the head; wide, cream-colored postorbital stripe extends across the occipital region from one eye to the other; faint whitish canthal markings; dark-brown, nuchal band bearing two posteriorly directed projections; paired dark-brown paravertebral blotches between forelimb insertions; three wide, dark brown, irregularly shaped and deeply emarginated body bands edged in slightly darker brown between the limb insertions; band interspaces bearing irregularly shaped scattered dark-brown markings; limbs generally unicolor tan; digits darkly banded; six wide pale-brown caudal bands separated by six paler colored bands; bands do not encircle tail; ventral surfaces of body and limbs beige, generally immaculate, subcaudal region generally darker; iris orange-gold in color bearing black vermiculations.

Distribution.

Cyrtodactylus denticulatus sp. nov. represents the northwestern-most species of the Cyrtodactylus brevipalmatus group. At present, it is known only from the type locality at Chao Doi waterfall, Tha Song Yang District, Tak Province, western Thailand (Fig. 1 ).

Etymology.

The specific epithet Cyrtodactylus denticulatus is given as a noun in apposition, meaning “denticulate” or with small teeth, a reference to bearing small tooth-like dorsolateral and ventrolateral caudal tubercles and denticulate ventrolateral body folds.

Comparisons of categorical data

(Tables 2 - 4 ). Cyrtodactylus denticulatus sp. nov. can be separated from all other species of the Cyrtodactylus brevipalmatus group by having denticulate ventrolateral body folds and small ventrolateral subcaudal ridges. These characters were not observed in any other individuals of the Cyrtodactylus brevipalmatus group (n = 51). The presence or absence of the following characters showed no intrapopulational variation. Cyrtodactylus denticulatus sp. nov. can be separated from C. brevipalmatus , C. cf. ngati 1, C. cf. ngati 2, C. fluvicavus , C. interdigitalis , C. ngati 3, C. rukhadeva , and C. sp. 13 by have large as opposed to small dorsolateral caudal tubercles and a ventrolateral caudal fringe. It differs from C. cf. ngati 1, C. cf. ngati 2, C. interdigitalis , C. ngati 3, C. rivularis , C. rukhadeva , C. sp. 11, and C. sp. 13 by having ventrolateral heterogeneous ventrolateral caudal fringe scales. It differs from all species except C. kochangensis , C. rivularis , C. rukhadeva , C. sp. 11, and C. thongphaphumensis by having a square cross-section of the tail. It differs from all species except C. brevipalmatus , C. cf. ngati 1, C. cf. ngati 2, C. fluvicavus , C. ngati , C. ngati 3, C. thongphaphumensis and C. uthaiensis in having slightly enlarged medial subcaudal scales. Cyrtodactylus denticulatus sp. nov. can be differentiated from C. interdigitalis , C. rivularis , and C. rukhadeva by lacking an enlarged longitudinal row of medial subcaudals. From C. interdigitalis and C. uthaiensis it differs by lacking intermittently enlarged, medially furrowed, and posteriorly emarginate medial subcaudals. Being that this species is known from only one specimen we acknowledge that some of the meristic differences in Tables 2 - 4 may eventually prove not be diagnostic with the addition of more specimens just as other meristic characters may prove to be statistically diagnosable. Until then, we refrain from including metric characters in the diagnosis. Potential diagnostic meristic characters are highlighted (Tables 2 - 4 ).

Natural history.

The holotype was collected at night between 19.00-23.00 hours in a bamboo forest near a rocky stream. The lizard was found on a bamboo branch 4 m above a large granite boulder (Fig. 7 ). The habitat was composed of large Bamboo ( Dendrocalamus copelandii ) Myrtaceae ( Syzygium sp.) and dipterocarp trees ( Anisoptera costata ) (Fig. 5 ). We speculate C. denticulatus sp. nov. is an arboreal specialist that generally resides in the upper canopy similar to C. brevipalmatus and C. elok (Grismer 2011). At the type locality, C. denticulatus sp. nov. was recorded in sympatry with Cyrtodactylus sp. 1 ( Chomdej et al. 2021), Trimeresurus guoi , Ansonia inthanon , Rhacophorus rhodopus , and Theloderma albopunctatum .

Figures

Figure 1. Distribution of the species of the Cyrtodactylus brevipalmatus group and the localities of the specimens used in this analysis. Stars denote type localities and white circles represent the localities of unsampled populations photographed in social media.

Figure 4. Photograph of the living holotype of Cyrtodactylus denticulatus sp. nov. AUP- 00680 from the Chao Doi waterfall, Mae Meoi, Tha Song Yang District, Tak Province, Thailand.

Figure 5. Head of the holotype of Cyrtodactylus denticulatus sp. nov. AUP- 00680 from the Chao Doi waterfall, Mae Meoi, Tha Song Yang District, Tak Province, Thailand A ventral view B dorsal view C right lateral view.

Figure 6. Holotype of Cyrtodactylus denticulatus sp. nov. AUP- 00680 from the Chao Doi waterfall, Mae Meoi, Tha Song Yang District, Tak Province, Thailand A ventral view of the cloacal and femoral regions B ventral view of the left hand C ventral view of the left foot D dorsal view of the anterior section of the tail E ventral view of the tail showing the ventrolateral subcaudal ridge.

Figure 7. Habitat of Cyrtodactylus denticulatus sp. nov. AUP- 00680 from the Chao Doi waterfall, Mae Meoi, Tha Song Yang District, Tak Province, Thailand.