Cyrtodactylus kimberleyensis, Bauer, Aaron M. & Doughty, Paul, 2012

Bauer, Aaron M. & Doughty, Paul, 2012, A new bent-toed gecko (Squamata: Gekkonidae: Cyrtodactylus) from the Kimberley region, Western Australia, Zootaxa 3187, pp. 32-42 : 34-38

Cyrtodactylus kimberleyensis sp. nov.

Kimberley Bent-toed Gecko Figs. 2–5

Holotype. WAM R164144, gravid adult female ( Fig. 2 ); Australia, Western Australia, Kimberley region, East Montalivet Island (14º16’S, 125º18’E), collected with a funnel trap in a vine thicket by R. Browne-Cooper, 26 April 2007.

Diagnosis. A small sized Cyrtodactylus (female gravid at SVL of 45 mm); body slender; limbs and digits relatively long, slender; partly regenerated tail longer than SVL; one pair of greatly enlarged postmental scales in contact with one another behind mental, a smaller pair of enlarged chin shields (second postmentals) lateral to these; small, mostly keeled tubercles in 16–18 longitudinal rows on dorsum; 36 scales across mid-venter between lowest rows of flank tubercles; ventrolateral folds weakly developed and atuberculate; six broad basal lamellae and nine narrow distal lamellae beneath digit IV of pes; dorsal and basal portion of tail only with flattened and keeled tubercles. Color pattern of small diffuse light and dark spots or blotches, no dark transverse bands or large dark blotches.

Description of holotype. Adult female. SVL 45.1 mm; TailL 53.3 mm (terminal 5.3 mm regenerated); mass in life 2.5 g. Head moderately long (HeadL/SVL ratio 0.29), narrow (HeadW/HeadL = 0.58), somewhat depressed (HeadH/HeadL = 0.34), distinct from neck. Loreal region weakly inflated, canthus rostralis not prominent. Snout elongate (SnEye/HeadL = 0.42), somewhat accuminate; longer than eye diameter (OrbD/SnEye = 0.58); scales on snout small, oval, conical with apex directed posteriorly, mostly homogeneous, distinctly larger than those on crown, interorbital and occipital regions. Eye moderately large (OrbD/HeadL = 0.24); pupil vertical with crenelated margins; supraciliaries short, lacking spines or projections. Ear opening horizontally elliptical (right ear opening partly occluded by fold of skin), large (EarL/HeadL = 0.10); eye to ear distance much greater than diameter of eyes (EyeEar/OrbD = 1.42). Rostral much wider (1.9 mm) than deep (1.0 mm), rostral crease about 2/3 height of rostral. Two slightly enlarged, rhomboidal supranasals separated by a single, smaller, pentagonal internasal. Rostral in contact with first supralabials, nostrils, internasal and supranasals. Nostrils oval, slightly posterolaterallydirected, each surrounded by supranasal, rostral, first supralabial and two postnasals ( Fig. 3 A). Two to three rows of small scales separate orbit from supralabials. Mental triangular with very acute posteriorly-oriented apex separating anterior 2/3 of postmentals, narrower (1.8 mm) than deep (2.2 mm). A single pair of enlarged postmentals in contact behind mental, each bordered anteromedially by mental, anterolaterally by first infralabial, posterolaterally by an enlarged lateral chinshield (or second postmental), and posteriorly by one or two enlarged granules ( Fig. 3 B). Supralabials to midorbital position 7 (right) to 8 (left); enlarged supralabials to angle of jaws 9 (left) to 10 (right). Infralabials 9 (right) to 10 (left). Interorbital scale rows across narrowest point of frontal bone 11; 33 scales between left and right supraciliary rows.

Body slender, elongate (TrunkL/SVL = 0.42) lacking well defined ventrolateral folds, although small discrete folds clearly present in life. Dorsal scales largely homogeneous, conical with slightly posteriorly-oriented apices; somewhat irregularly distributed tubercles (2–6 times size of adjacent scales), each wider than long, extending from shoulder region on to tail base, smallest on flanks, largest over sacrum, smaller tubercles on postocular region, crown, occiput, and nape; most dorsal tubercles bearing a keel, those on flanks conical, often lacking a distinct keel, those on posterior trunk and sacral region most prominent; tubercles in 16–18 rows at midbody, typically separated from one another by 1–3 dorsal granules ( Fig. 2 ). Ventral scales larger than dorsals, smooth, oval to subtriangular and subimbricate, largest on posterior abdomen and in precloacal region. Midbody scale rows across belly to lowest rows of tubercles ~36. Gular region with homogeneous, smooth, juxtaposed granular scales.

No precloacal or femoral pores. No precloacal groove. Anteroventral scales of thigh much larger than posteroventral and posterior, but lacking a distinct single row of enlarged femoral scales. Two slightly enlarged, smooth postcloacal spurs, anterior larger than posterior.

Scales on palm and sole smooth, rounded to oval, flattened to slightly domed. Scalation on dorsal surfaces of limbs similar to body dorsum with enlarged, conical, usually keeled tubercles interspersed among smaller scales (except for proximal portion of forearm, which lacks tubercles); tubercles separated from one another by 1–2 small scales, or in direct contact with one another. Fore and hindlimbs moderately short, slender (ForeaL/SVL = 0.12; CrusL/SVL = 0.14). Digits long, slender, inflected at interphalangeal joints, especially antepenultimate joint of longer digits, all bearing robust, slightly recurved claws. Basal subdigital lamellae broad, squarish to rectangular with rounded corners, distalmost generally largest, without scansorial surfaces (1-3-4-5-3 left manus, 1-4-4-5-3 right manus; 2-4-5-6-5 left and right pes); narrow lamellae distal to digital inflection and not including ventral claw sheath: 6-5(tip missing)-8-7-7 (left manus), 6-7-8-8-7 (right manus), 6-7-9-9-9 (left pes), 7-7-9-9-7 (right pes) ( Fig. 4 ); very weakly developed interdigital webbing between digits (except IV and V). Relative length of digits: IV>III>II>V>I (manus); V~IV~III>II>I (pes). Mostly original tail, long, slightly depressed, gently tapering to pointed tip; longer than SVL (TailL/SVL = 1.18).

Scales of tail dorsum squarish, flat, juxtaposed to weakly imbricate, arranged in distinct segments of 8–9 scale rows basally, decreasing to 7, then 6 scale rows distally. Pygal segments bearing 6 strongly keeled tubercles, each 5–6 times the size of adjacent scales and separated from each other by 1–2 scales, in a transverse row; next three tail segments with four tubercles, followed by a single segment with two enlarged, flattened, keeled scales in position of tubercles, but on left side only; no tubercles more distally. Subcaudals approximately 1.5 times size of dorsal caudals, squarish proximally, becoming rounded to oval distally. No enlarged median subcaudal plates.

Measurements (in mm): SVL 45.1, ForeaL 5.6, CrusL 6.1, TailL 53.3, TailW 3.5, TrunkL 19.1, HeadL 13.0, HeadW 7.5, HeadH 4.4, OrbD 3.2, EyeEar 4.5, SnEye 5.5, NarEye 3.5, Interorb 4.5, EarL 1.3, Internar 1.2.

Coloration in ethanol: Dorsum light brown mottled with small darker blotches and tubercles. A series of small rounded white blotches on lower flanks, neck and lower part of side of head. Two dark blotches on occiput and a broken, heart-shaped marking on the crown. A broad bold dark brown streak from posterior midpoint of orbit to above ear, confluent with a narrower incomplete stripe continuing on to shoulder. A pair of dark brown canthal streaks and several dark stray marks on other areas of head.

Rostral mostly medium brown. Labials mostly brown with some scales bearing white patches. Limbs similar to dorsum, light brown with darker mottling and distinct white blotches. Digits with alternating light and dark markings. Soles and palms pale grayish brown. Tail light brown with a pair of paravertebral dark brown stripes proximally breaking into paired dashes at approximately midpoint of tail. Distal 70% of tail with alternating white to cream and mid-brown markings. Regenerated tail tip without regular pattern.

Venter beige with cream to whitish spots under throat and posterior border of thighs. Underside of tail uniform brown with white speckling along entire length.

Color in life (based on live photograph of holotytpe, Fig. 5 ): Similar to that in preservative, pale areas of body with a pale grayish to grayish-pink suffusion, and pale spots on flanks and limbs more evident than in preserved specimen. Pale coloration of tail base pale yellowish-cream to straw. Iris silvery with dark reticulations.

Etymology. The specific epithet refers to the Kimberley region of northern Western Australia.

Distribution, reproduction and habitat. The only known specimen of C. kimberleyensis sp. nov. is from East Montalivet Island ( Fig. 1 ), although it is possible the taxon occurs on the Kimberley mainland as well. The holotype is a gravid female containing a single egg measuring 9.4 mm x 5.3 mm. Like most gekkotans Cyrtodactylus spp. typically produce two eggs per clutch. Single egg clutches are uncommon in the Gekkonidae ( Marquet et al. 1990) , but do occur, chiefly in miniaturized lineages. If a single egg clutch is normal for C. kimberleyensis sp. nov. it would be the first member of its genus known to do so. The specimen was collected in late April, very late in the tropical wet season, and it is possible the female had produced other clutches earlier in the season, as occurs in many other tropical geckos ( Inger & Greenberg 1966). The holotype was collected from a vine thicket on a lateritic slope (R. Browne-Cooper, pers. comm.; Fig. 6 ). Other reptiles also occurring on the island are the gekkotan lizards Heteronotia binoei (Gray) and Delma borea Kluge , the skinks Carlia johnstonei Storr , C. triacantha (Mitchell) , Ctenotus inornatus (Gray) , Eremiascincus isolepis (Boulenger) , Lerista walkeri (Boulenger) , and the elapid snake Parasuta nigriceps (Günther) .

Comparisons with other species. The diagnosis of Cyrtodactylus spp. known only from female specimens is generally quite difficult because the presence/absence, number, and distribution of precloacal and femoral pores in males are useful and convenient characters that often distinguish species from one another ( Bauer 2003). However, the very small size C. kimberleyensis sp. nov. (confirmed as an adult because the sole known specimen is gravid) easily separates it from the majority of its congeners. Most gekkotans show little sexual dimorphism in overall body length, with slightly larger females in approximately two-thirds of species investigated ( Fitch 1981). In only two species of Cyrtodactylus are size and maturity data known for large samples ( C. malayanus (de Rooij), n= 131 males, 162 females; C. pubisulcus Inger , n= 56 males, 62 females; Inger & Greenberg 1966). In both species females were slightly larger on average and attained somewhat greater maximum sizes than males. A review of recent descriptions of new Cyrtodactylus based on samples containing both males and females suggests no intrageneric directionality of sexual dimorphism in SVL, and no clear examples of strong size asymmetry between genders. In C. pubisulcus the minimum size at which females were gravid was 89.6% of maximum SVL and in C. malayanus it was 83.1%. ( Inger & Greenberg 1966). Most studies of size at maturity in geckos suggest that females reach maturity at 73–82% of maximum size ( Parker 1972; Vitt 1986; How et al. 1986; Selcer 1986; Okada et al. 2002) although there are some genera in which sexual maturity may be reached at smaller relative sizes (e.g., Ptenopus Gray, Hibbitts et al. 2005 ; Homonota Gray, Ibargüengoytía & Casalins 2007 ). These values may, however, be influenced by the criteria used to determine maturity. For example, in Homopholis wahlbergii Smith females had muscular oviducts at <50% of maximum size, but fully developed eggs were only found in females>71.4% of maximum size ( Whiting et al. 2007).

Based on data from other geckos one may thus conservatively estimate that the holotype of C. kimberleyensis sp. nov. is at least 70% of the maximum size the species might attain. Of named species summarized by Rösler and Glaw (2008), only the following species had maximum SVLs of less than 65 mm, the maximum size of C. kimberleyensis sp. nov. so predicted: C. consobrinoides (Annandale) , C. feae (Boulenger, C. annandalei Bauer , C. gansi Bauer , and C. wakeorum Bauer—all from Myanmar, C. agamensis (Bleeker) from Sumatra, C. buchardi David et al. from Laos, C. gubernatoris (Annandale) from the eastern Himalayas, C. laevigatus Darevsky from Komodo and Flores, C. malcolmsmithi (Constable) from northern India, and several species in the subgenus Geckoella occurring in peninsular India and Sri Lanka. Cyrtodactylus jellesmae (Boulenger) from Sulawesi was reported to have a maximum SVL of 63 mm by Rösler & Glaw (2008) but adults are now known to reach at least 75 mm SVL (Linkem et al. 2008). All descriptions published since the summary of Rösler and Glaw (2008) were consulted and the only additional taxon with a mature SVL of less than 65 mm subsequently described is C. mandalayensis Mahony. However , this description was based on a single, apparently immature specimen of 61.7 mm SVL, implying a maximum adult size of> 75–85 mm SVL. The new species may be distinguished from Geckoella spp. by its longer toes, more depressed habitus, tail longer than SVL, and tubercular dorsum. By the absence of enlarged caudal midventral plates it may be distinguished from C. annandalei and from this species and C. agamensis in having fewer ventral scales across midbody (36 versus 43 and 67, respectively) [Note: The ventral scale count in C. kimberleyensis sp. nov., which lacks ventrolateral folds, was made between the lowest rows of lateral tubercles and is thus not strictly comparable to counts of species with folds. However, as tubercles are never present ventral to such folds, and the ventralmost tubercles are often several scale rows above the folds, the ventral count in the new species may be assumed to be equal to or greater than (but not less than) corresponding inter-fold counts. Inter-fold scale counts of greater magnitude than the inter-tubercle count of the new species may thus be conservatively regarded as putatively diagnostic]. It differs from C. malcolmsmithi in having small caudal tubercles restricted to the proximal portion of the tail (versus prominent tubercles along the entire tail), from C. buchardi , C. annandalei and C. consobrinoides , C. gansi and C. wakeorum in lacking a banded dorsal pattern and from the last two of these, as well as C. buchardi , in having a lower number of dorsal tubercle rows (16–18 versus 20–25 [24 in C. wakeorum , 25 in C. buchardi ]). It is distinguished from C. feae and C. gubernatoris in having a weakly defined ventrolateral fold (versus a well-defined row of enlarged tubercles separating flank and venter) and further from the former species in lacking a reticulate pattern on the head and from the latter in lacking irregular blackish transverse markings on the dorsum. Cyrtodactylus kimberleyensis sp. nov. is the same size as C. laevigatus and C. l. uniformis Auffenberg from Flores but differs from these in its more regularly arranged dorsal tubercles (16–18 discrete longitudinal rows versus scattered or irregularly arranged tubercles) and in having at most a single transverse row of granules separating the proximal and distal series of subdigital lamellae (versus multiple such rows; see Darevsky 1964, Fig. 4 ; Auffenberg 1980, Fig. 14E). It also differs from these species in dorsal pattern (light and dark blotches versus short, sometimes interrupted transverse bars in the nominate form and mostly patternless in C. l. uniformis).

Figures

FIGURE 1. Map of the Kimberley region, Western Australia, showing East Montalivet Island (arrow), the type locality of Cyrtodactylus kimberleyensis sp. nov. was collected.

FIGURE 2. Adult female holotype of Cyrtodactylus kimberleyensis sp. nov. (WAM R 164144). Scale bar = 10 mm.

FIGURE 3. Head of Cyrtodactylus kimberleyensis sp. nov. A) oblique view of right side of face showing circumnarial and labial scales; B) ventral view of chin and throat showing mental and post-mental scales.

FIGURE 4. Ventral view of right pes of Cyrtodactylus kimberleyensis sp. nov. showing disposition of the subdigital lamellae. Roman numerals indicate digit numbers. Scale bar = 2 mm.

FIGURE 5. Photo in life of the holotype of Cyrtodactylus kimberleyensis sp. nov. (WAM R 164144). Photo—R. Browne-Cooper.

FIGURE 6. Vine thicket habitat of Cyrtodactylus kimberleyensis sp. nov. on East Montalivet Island, Western Australia. Photo — M. Bamford.