Cyrtodactylus thylacodactylus, Murdoch & Grismer & Wood Jr & Neang & Poyarkov & Tri & Nazarov & Aowphol & Pauwels & Nguyen & Grismer, 2019

Murdoch, Matthew L., Grismer, L. Lee, Wood Jr, Perry L., Neang, Thy, Poyarkov, Nikolay A., Tri, Ngo Van, Nazarov, Roman A., Aowphol, Anchalee, Pauwels, Olivier S. G., Nguyen, Hung Ngoc & Grismer, Jesse L., 2019, Six new species of the Cyrtodactylus intermedius complex (Squamata: Gekkonidae) from the Cardamom Mountains and associated highlands of Southeast Asia, Zootaxa 4554 (1), pp. 1-62 : 38-42

Cyrtodactylus thylacodactylus sp. nov.

Phnom Dalai, Pocket-fingered, Bent-toed Gecko

Figs. 16 & 17 , Table 12.

Cyrtodactylus intermedius Daltry and Chheang 2000: 107 ; Neang, Grismer, Chan, Grismer, Wood, and Youmans 2010: 137.

Holotype. Adult male LSUHC 9319 collected on 6 July 2009 by Neang Thy, L. Lee Grismer, Chan Kin Onn, Jesse L. Grismer, Perry L. Wood Jr., and Timothy M. Youmans from Camp 1, Phnom Dalai, Pursat Province, Cambodia (1225’23”N, 10304’07”E, 556 m in elevation).

Paratypes. Juvenile male LSUHC 9318 bears the same collection data as the holotype; adult females LSUHC 9326 , 9336 and juvenile female LSUHC 9325 were collected on 7 July 2009 , by the same collectors at camp 2, Phnom Dalai , Pursat Province, Cambodia (1226’13”N, 10303’21”E, 968 m in elevation). Juvenile female 9349 was collected from camp 2 by the same collectors on 8 July 2009 .

Diagnosis. Adult males reaching 71.5 mm SVL, adult females reaching 74.6 mm SVL; seven supralabials, 8– 10 infralabials; 29–31 paravertebral tubercles; 18–20 longitudinal rows of dorsal tubercles; 36–42 rows of ventral scales; five or six expanded subdigital lamellae proximal to the digital inflection, 10–11 unmodified, distal, subdigital lamellae; 15–18 total subdigital lamellae on fourth toe; enlarged femoral and precloacal continuous; 17– 22 enlarged femoral scales; proximal femoral scales the same size as distal femorals; 7–9 enlarged precloacal scales with pores on each in males; three rows of enlarged post-precloacal scales; 1–3 postcloacal tubercles; deep interdigital pocketing on either side of digit III on forefoot; deep interdigital pocketing present between third and fourth digits of hind feet; dark pigmented blotches absent from top of head; posterior border of nuchal loop rounded; and four or five dark body bands ( Table 12). These characters are scored across all species of the Cyrtodactylus intermedius complex in Table 7.

Description of holotype. Adult male SVL 71.5 mm; head moderate in length (HL/SVL 0.28) and width (HW/ HL 0.67), somewhat flattened (HD/HL 0.40), distinct from neck, and triangular in dorsal profile; lores concave anteriorly, weakly inflated posteriorly, prefrontal region deeply concave, canthus rostralis rounded; snout elongate (ES/HL 0.40), rounded in dorsal profile; eye large (ED/HL 0.22); ear opening elliptical, obliquely orientated, moderate in size (EL/HL 0.12); eye to ear distance greater than diameter of eye; rostral rectangular, partially divided dorsally by linear furrow, bordered posteriorly by large left and right supranasals and single smaller internasal, bordered laterally by first supralabials; external nares bordered anteriorly by rostral, dorsally by large supranasal, posteriorly by two moderately sized postnasals, bordered ventrally by first supralabial; 7(R,L) rectangular supralabials extending to below midpoint of eye, second supralabial slightly larger than first; 9(R,L) infralabials tapering smoothly to below and slightly past termination of enlarged supralabials; scales of rostrum and lores flat to slightly raised, larger than granular scales on top of head and occiput, scales of occiput intermixed with distinct, enlarged tubercles; dorsal superciliaries not elongate or keeled; mental triangular, bordered laterally by first infralabials and posteriorly by large left and right trapezoidal postmentals which contact medially for 50% of their length posterior to mental; one row of enlarged, elongate sublabials extending posteriorly to seventh infralabial; gular and throat scales small, granular, grading posteriorly into slightly larger, flatter, smooth, imbricate, pectoral and ventral scales.

Body relatively short (AG/SVL 0.47) with poorly defined ventrolateral folds; dorsal scales small, granular interspersed with relatively large, conical, semi-regularly arranged, weakly keeled tubercles; tubercles extend from occiput onto base of tail but terminate at regenerated tail; similar sized and spaced tubercles continue onto nape of neck and occiput but diminish in size and distinction on top of head; approximately 20 longitudinal rows of tubercles at midbody between ventrolateral, body folds; 31 paravertebral tubercles; 36 flat, imbricate, ventral scales between ventrolateral body folds, ventral scales much larger than dorsal scales; nine large, pore-bearing, precloacal scales; and no deep precloacal groove or depression.

Forelimbs moderate in stature, relatively short (FL/SVL 0.14); granular scales of forearm larger than those on body, interspersed with moderately sized, conical tubercles; palmar scales rounded, slightly raised; significant inpocketing of interdigit-webbing present on either side of digit III of the fore foot; digits well-developed, inflected at basal, interphalangeal joints; digits slightly more narrow distal to inflections; subdigital lamellae transversely expanded proximal to joint inflections, more granular distal to inflection; claws well-developed, claw base sheathed by a dorsal and ventral scale; hind limbs more robust than forelimbs, moderate in length (TBL/SVL 0.18), covered dorsally in granular scales interspersed with large, conical tubercles and covered anteriorly by flat, slightly larger scales; ventral scales of thigh flat, imbricate, larger than dorsals; subtibial scales flat, imbricate; one row of eight right and 10 left enlarged femoral scales in contact with enlarged precloacal scales, terminating just proximal to knee; femoral pores absent; proximal femoral scales same size as distal femoral scales, form abrupt union with smaller, rounded, ventral scales of posteroventral margin of thigh; plantar scales flat; significant inpocketing of interdigit-webbing present between digits III and IV of the hind foot; digits relatively long well-developed, inflected at basal, interphalangeal joints; 5(R,L) transversely expanded subdigital lamellae on fourth toe proximal to joint inflection extending onto the sole, 11(R,L) unmodified lamellae distal to inflection; and claws welldeveloped, sheathed by a dorsal and ventral scale at base.

Tail 74 mm in length, first 11.8 mm original, last 62.6 mm regenerated, 5.2 mm in width at base, tapering to a point; dorsal scales of original portion of tail flat, square; regenerated portion of tail covered with small, smooth rectangular scales dorsally; median row of transversely expanded subcaudal scales, significantly larger than dorsal caudal scales; caudal tubercles present on original portion; base of tail bearing hemipenal swellings; three postcloacal tubercles on either side of base of hemipenal swellings; and postcloacal scales flat, imbricate.

Coloration in alcohol. Dorsal ground color of head, body, limbs, and tail brown; dark-brown nuchal loop with rounded posterior border extends from posterior margin of one eye to posterior margin of other eye; nuchal loop edged with thin, light, lines; four similarly colored dorsal bands with slightly lightened centers occur between limb insertions, first band terminates at shoulders; second and third bands terminate dorsal to ventrolateral fold; fourth band terminates at anterior margin of hind limb insertions; light edging on body bands with brighter white on tubercles giving edging a slightly spotted appearance; body band/interspace ratio 1.3; additional dark-brown band posterior to hind limbs; regenerated tail a uniform brown color ( Fig 16 ).

Variation. The paratypes closely approach the holotype in preserved coloration ( Fig 16 ). LSUHC 9336 has very light bordering on the body bands with distinct lightening at the center of each body band. LSUHC 9318 has only three complete body bands with two small spots where the fourth would be between the limb insertions. LSUHC has five body bands with the third and the fourth bands coming into contact in the vertebral region. In life specimens have light-colored edging of the dark dorsal bands and the tubercles cream colored. Tubercles bordering dark dorsal bands and on dorsal margin of thigh cream colored ( Fig 17 ). Meristic differences among the type specimens and additional specimens examined are presented in Table 12.

Distribution. Cyrtodactylus thylacodactylus sp. nov. is known only from Phnom Dalai in Samkos Wildlife Sanctuary, Pursat Province, Cambodia.

Etymology. The specific epithet, thylacodactylus , is a Latinized adjective in masculine gender, derived from Greek thylakos meaning “pouch”, and daktylos meaning “digit” in reference to the unique morphology of the new species having deep interdigital pocketing between some of the digits.

Natural history. Neang et al. (2010) report that the type series was collected between 556–968 m in elevation in evergreen hill forest in the vicinity of rocky streams. All specimens were collected at night at the base of trees and on leaves and branches 1–1.5 m above the ground. Lizards were most commonly seen at the higher elevations of Camp 11.

Comparisons. Cyrtodactylus thylacodactylus sp. nov. is a member of the western group and the sister species to the clade comprised of C. intermedius complex incertae sedis 1 and C. cardamomensis sp. nov. from which it is separated by 3.7%–5.0% sequence divergence ( Table 4). The PCA and DAPC plots Cyrtodactylus thylacodactylus sp. nov. as widely separated in morphospace from all other species within the complex ( Figs. 6 , 7 ). Cyrtodactylus thylacodactylus sp. nov. is well-differentiated from all other members of the C. intermedius complex, by having varying combinations of statistically different mean values of supralabial and infralabial scales, paravertebral tubercles, longitudinal rows of tubercles, ventral scales, unmodified, expanded, and total number of subdigital lamellae, enlarged femoral scales, precloacal scales, and postcloacal tubercles ( Table 6). It differs from C. auralensis sp. nov. in lacking dark pigmented blotches on the top of the head. It is separated from C. bokorensis sp. nov. in having a rounded posterior border of the nuchal loop as opposed to it being pointed. Continuous contact between the precloacal and femoral scales differentiates it from C. laangensis sp. nov. and some individuals of C. bokorensis sp. nov. in which contact is variable. It is separated from all other members of the C. intermedius complex, with the exception of C. cardamomensis sp. nov. in having proximal femoral scales approximately the same size as the distal scales as opposed to being less than half the size of the distal scales. It is further distinguished from all other members of the C. intermedius complex in having deep interdigital pocketing between some of the digits of the front and rear feet ( Table 7).

Remarks. Cyrtodactylus thylacodactylus sp. nov. occupies the most isolated position in morphospace within the C. intermedius complex ( Figs. 6 , 7 ). The majority of variation in the data along PC1 and PC2 accounting for body form (i.e., tibia length, head length, head width, eye diameter, eye to snout distance, and ear to eye distance) whereas only one meristic character (number of femoral scales) accounted for notable variation along PC2 ( Table 5). Overall, C. thylacodactylus sp. nov. is significantly smaller ( Table 7) and more robust in body stature, indicated by shorter hind limb and head length ratios to Snout Vent Length, than that of any other species in the complex. Robustness was measured via an ANOVA of the ratios of Head Length (HL) and Tibia Length (TBL) to Snout Vent Length (SVL) yielding a significant mean difference, adjusted P values <0.05.

Figures

FIGURE 6. Principal component analysis (PCA) of the species of the Cyrtodactylus intermedius complex showing ordination along the first two principal components.

FIGURE 7. Discriminant analysis of principal components (DAPC) of the species of the Cyrtodactylus intermedius complex emphasizing between-group variance and minimizing within-group variance based on retention of the first eight components. Circles represent 95% confidence intervals.

FIGURE 16. Type series of Cyrtodactylus thylacodactylus sp. nov. from left to right: holotype LSUHC 9319, paratypes LSUHC 9318, 9325-26, 9336, 9349.

FIGURE 17. Cyrtodactylus thylacodactylus sp. nov. Top: adult male from Phnom Dalai, Pursat province, Cambodia LSUDPC 5079. Bottom: forested boulder strewn stream bed microhabitat from the slopes of Phnom Dalai. All photos by L. Grismer.