Cyrtodactylus laangensis, 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 : 42-46

Cyrtodactylus laangensis sp. nov.

Phnom Laang Bent-toed Gecko

Figs. 18 & 19 , Table 13.

Holotype. Adult male LSUHC 8773 collected on 15 December 2007 by Neang Thy, L. Lee Grismer, and Jeremy Holden from Phnom Laang, Kampot Province, Cambodia (10 42’13’’N, 104 20’57’’ E).

Paratypes. Adult males LSUHC 8771–72 , adult females LSUHC 8770 , 8774 , and T 4653 bear the same collection data as the holotype .

Diagnosis. Adult males reaching 76.9 mm SVL, adult females reaching 82.2 mm SVL; 7–9 supralabials, 10 or 11 infralabials; 29–32 paravertebral tubercles; 17 or 18 longitudinal rows of dorsal tubercles; 37–40 rows of ventral scales; seven expanded subdigital lamellae proximal to the digital inflection, 11–13 unmodified, distal, subdigital lamellae; 18–20 total subdigital lamellae on fourth toe; enlarged femoral scales either absent or separated from precloacal scales by a diastema of smaller scales; when present 13–16 enlarged femoral scales with proximal enlarged femoral scales less than half the size of distal femoral scales; 7–9 enlarged precloacal scales with pores on each in males; two or three rows of enlarged post-precloacal scales; 2–4 postcloacal tubercles; no interdigital pocketing; dark pigmented blotches on top of head present or absent; posterior border of nuchal loop rounded; and four dark body bands ( Table 13). These characters are scored across all species of the Cyrtodactylus intermedius complex in Table 7.

Description of holotype. Adult male SVL 76.9 mm; head moderate in length (HL/SVL 0.28) and width (HW/ HL 0.66), somewhat flattened (HD/HL 0.40), distinct from neck, and triangular in dorsal profile; lores concave anteriorly, weakly inflated posteriorly, prefrontal region moderately concave, canthus rostralis rounded; snout elongate (ES/HL 0.39), rounded in dorsal profile; eye large (ED/HL 0.25); ear opening elliptical, obliquely oriented, moderate in size (EL/HL 0.08); eye to ear distance greater than diameter of eye; rostral rectangular, partially divided dorsally by linear furrow, bordered posteriorly by moderately sized left and right supranasals and two internasals, bordered laterally by first supralabials; external nares bordered anteriorly by rostral, dorsally by large supranasal, posteriorly by four moderately sized postnasals, bordered ventrally by first supralabial; 9(R,L) rectangular supralabials extending to below midpoint of eye, second supralabial slightly larger than first; 10(R,L) infralabials tapering smoothly to below and slightly past the 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 slightly 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 to caudal constriction and onto tail where they occur in transverse rows separated by seven or eight small, flat scales; caudal tubercles largest dorsally, weak laterally, and absent ventrally; approximately 17 longitudinal rows of tubercles at midbody between ventrolateral body folds; 32 paravertebral tubercles; 40 flat, imbricate, ventral scales between ventrolateral body folds much larger than dorsal scales; eight large, pore-bearing, precloacal scales; and no deep precloacal groove or depression.

Forelimbs moderate in stature, relatively short (FL/SVL 0.17); granular scales of forearm larger than those on body, interspersed with moderately sized, conical tubercles; palmar scales rounded, slightly raised; interdigital pocketing absent; 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 0.20), covered dorsally by granular scales interspersed with large, conical tubercles and anteriorly by flat, slightly larger scales; ventral scales of thigh flat, rounded, larger than dorsals, decrease smoothly in size towards the posteroventral margin of thigh; subtibial scales flat, imbricate; enlarged femoral scales absent; plantar scales flat; interdigital pocketing absent; digits relatively long, well-developed, inflected at basal, interphalangeal joints; 7(R,L) transversely expanded subdigital lamellae on fourth toe proximal to joint inflection that extend onto the sole, 13(R,L) unmodified lamellae distal to inflection; 20 total subdigital lamellae; and claws well-developed, sheathed by a dorsal and ventral scale at base.

Tail original, 116 mm in length, 6.4 mm in width at base, tapering to a point; dorsal scales small, square, in transverse rows; tail segmented with 6 or 7 transverse scale rows per segment; posterior margin of segments bordered by four large, flat tubercles dorsally extending anterior one-third of tail; subcaudal region bearing large, transverse scales for anterior one-half of tail, second half bearing smaller, irregularly shaped scales; base of tail bearing hemipenal swellings; four postcloacal tubercles on either side of hemipenal swellings; and postcloacal scales smooth, flat, imbricate.

Coloration in alcohol. Dorsal ground color of head, body, limbs, and tail light-brown; 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; faint, light, edging on body bands; body band/interspace ratio 0.90; one brown postsacral band posterior to hind limbs; original tail begins with dark bands with light interspaces but fades to a uniform light-brown color ( Fig 18 ).

Variation. The paratypes closely approach the holotype in preserved coloration ( Fig. 18 ). Color in life shows dark pigmented blotches on top of head ringed by light tubercles and lightened centers in the dark body bands and dark blotches within the light intersperses as well as light and dark reticulations on limbs. Caudal interspaces begin light-tan and change to a much brighter white near the tip ( Fig 19 ).

Distribution. Cyrtodactylus laangensis sp. nov. is known only from Phnom Laang, an isolated karst formation located in Kampot province, Cambodia.

Natural history. The type locality, Phnom Laang, is a small, isolated karst hill rising precipitously from the flat lowlands of the eastern Mekong Delta region. The base of the hill is surrounded by highly disturbed scrub vegetation but the hill itself bears typical ultramafic vegetation on its cliff-faces. The west face of Phnom Laang opens up into a large open cave-like chamber that extends to near the center of the formation. The floor of the chamber is covered with large, eroded karst boulders and rocks and its walls bear several large cracks and alcoves, all of which provide appropriate microhabitat for karst-dwelling Cyrtodactylus (e.g. Grismer et al. 2016, 2017b, 2018a, b). At the base of the formation on the west side is a subterranean pond with clear water. The type series was collected at night and all specimens were found on and amongst the karst microhabitat. Some were found crawling on both large boulders and small rocks and others were found as high as 5 m above the ground on the chamber walls.

Etymology. The specific epithet, laangensis , is an adjective in reference to type locality of the karst formation Phnom Laang to which it is presumably endemic.

Comparisons. Cyrtodactylus laangensis sp. nov. is a member of the eastern group and the sister species to Cyrtodactylus bokorensis sp. nov. from the Bokor Plateau, Kampot Province, Cambodia from which it is separated by 3.9% sequence divergence ( Table 4). The PCA and DAPC analyses indicate that Cyrtodactylus laangensis sp. nov. is very isolated in morphospace from all other species within the complex ( Fig. 6 , 7 ). Cyrtodactylus laangensis 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, ventral scales, expanded, and total number of subdigital lamellae, enlarged femoral scales, precloacal scales, and postcloacal tubercles ( Table 6). It differs from C. bokorensis by having a rounded posterior border of the nuchal loop as opposed to a pointed border. It is differentiated from all other members of the C. intermedius complex in having a diastema between the enlarged femoral scales and the precloacal scales, with the exception of C. bokorensis for which contact is variable. It is further differentiated from C. cardamomensis and C. thylacodactylus in that the proximal most scales of its short femoral scale row are less than half the size of the distal scales. It is further differentiated from C. thylacodactylus in lacking interdigital pocketing ( Table 7).

Parallel evolution of karst-association in Cyrtodactylus . Karst habitats are proving to be an extremely important habitat for a growing number of endemic and microendemic species of amphibians and reptiles ( Grismer et al. 2016, 2017b, 2018a, b). Of all herpetofauna associated with these habitats, Cyrtodactylus has the greatest diversity and shows a number of body form adaptations for this lifestyle. Cyrtodactylus laangensis sp. nov. is another example of a site-specific karst-adapted endemic species. Cyrtodactylus laangensis sp. nov has traits noted in other karst-associated Cyrtodactylus such as a decrease in enlarged femoral scale size and count as well elongate hind limbs, this was measured via an ANOVA of the ratio of Tibia Length (TBL) to Snout Vent Length (SVL) which yielded a significant mean difference, adjusted P values <0.05, for all other members of the C. intermedius complex with the exception of C. septimontium sp. nov. Grismer & Grismer (2017b) demonstrated that these differences are functionally adaptive for locomoting on rocky surfaces in various planes of orientation. Despite being separated by only 25km from its sister species, C. bokorensis sp. nov., the two species have an uncorrected sequence divergence of 3.9% and the morphological and morphometric differences between the two species are larger than between species having greater sequence divergence ( Table 4, Fig. 5 ).

Figures

FIGURE 5. Tree: maximum likelihood topology illustrating the relationships of the Cyrtodactylus intermedius complex. Black circles represent nodes supported by BPP and UBS values of 95% and 95, respectively. Gray circles denote nodes supported only by BPP 95% or above. Map: distribution of the species of the Cyrtodactylus intermedius complex from the Cardamom Mountains and uplands of Thailand, Cambodia, and Vietnam. Localities of new species represented by circles, localities of known species represented by triangles, type locality of C. intermedius represented by a star, and locations of specimens included in genetic analyses but are considered incertae sedis represented by squares.

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 18. Type series of Cyrtodactylus laangensis sp. nov. from left to right: holotype LSUHC 8773, paratypes LSUHC 8770-72, 8774, T 4653.

FIGURE 19. Cyrtodactylus laangensis sp. nov. adult male T 4653 from Phnom Laang, Kampot province, Cambodia. LSUDPC 4016 (photo by L. Grismer).