Gekko carusadensis, Linkem, Charles W., Siler, Cameron D., Diesmos, Arvin C., Sy, Emerson & Brown, Rafe M., 2010

Linkem, Charles W., Siler, Cameron D., Diesmos, Arvin C., Sy, Emerson & Brown, Rafe M., 2010, A new species of Gekko (Squamata: Gekkonidae) from central Luzon Island, Philippines, Zootaxa 2396, pp. 37-49 : 39-46

Gekko carusadensis sp. nov.

Figs. 2–5

Holotype. PNM 9715 (ACD Field No. 4537; formerly KU 319968), adult male, collected inside a cave in secondary-growth forest (19:30) in Barangay Biak na Bato, Municipality of San Miguel and Doña Remedios Trinidad, Bulacan Province, Luzon Island, Philippines, N 15.1084, E 121.0724, on 17 January, 2009, collected by Arvin C. Diesmos and Charles W. Linkem.

Paratypes. Five males KU 320484, 320485, 319970, PNM 9717–18, two females PNM 9716, KU 319985, and one juvenile KU 319986 collected on karst formations and in cave systems in secondary-growth forest (18:00–21:00), 17–18 January 2009, other data identical to holotype.

Diagnosis. Gekko carusadensis differs from non-Philippine G. kikuchii Oshima, G. shibatai Toda, Sengoku, Hikida & Ota, G. tawaensis Okada , G. vertebralis Toda, Sengoku, Hikida & Ota , and G. v i t t a t u s Houttuyn by the presence of precloacal pores in males; from G. badenii Szczerbak & Nekrasova , G. grossmanni Günther , G. petricolus Taylor , G. russelltraini Van Tri, Bauer, Wood , & Grismer, and G. t a y l o r i Ota & Nabhitabhata by the presence of femoral pores in males; from G. m e l l i Vogt, G. scientiadventura Rösler, Yiegler, Vu, Herrmann & Böhme , G. subpalmatus Günther , and G. t a w a e n s i s by the presence of dorsal tubercles; from G. albofasciolatus Günther , G. nutaphandi Bauer, Sumontha & Pauwels , G. siamensis Grossmann & Ulber , G. smithii Gray , and G. verreauxi Tytler by having a smaller adult SVL (<98 mm vs.> 110 mm); from G. auriverrucosus Zhao & Liu , G. liboensis Zhao & Li , G. japonicus (Schlegel) , G. scabridus Liu & Zhou , G. swinhonis Günther , G. taibaiensis Song, and G. wenxianensis Zhou & Wang by a larger number of digit IV lamellae (18–20 vs. 9 or fewer); from G. c h i n e n s i s Gray, G. hokouensis , and G. yakuensis Matsui & Okada by lacking any interdigital webbing; from G. similignum Smith by the presence of more dorsal tubercle rows and from G. palmatus Boulenger and G. ulikovskii Darevsky & Orlov by the presence of more precloacofemoral pores.

Gekko carusadensis differs from all other species of Philippine Gekko (i.e., G. athymus , G. crombota , G. ernstkelleri , G. gecko , G. gigante , G. mindorensis , G. monarchus , G. palawanensis , G. porosus , G. romblon and G. rossi ) by the following characters (1) moderately large body size (SVL 83.4–97.2 mm for adult males; 79.9–87.5 for females); (2) dorsum gray, with little to no dark gray mottling or transverse bars; (3) moderate number of precloacofemoral pores (46–50) arranged in a continuous, uninterrupted series (pore bearing in males; lacking pores in females); (4) moderate number of mildly conical dorsal body tubercle rows (16–18 midbody; 25–28 paravertebrally).

Gekko carusadensis differs from its phenotypically most similar congener, G. mindorensis , by the presence of fewer precloacofemoral pores (46–50 vs 52–66); by having 18–20 scansors beneath toe IV (vs. 12–14); by having on average fewer midbody tubercle rows (14–17 vs. 16–20); and by G. carusadensis females being larger than G. mindorensis females (79.9–87.5 mm vs. 68.2–70.9). It can be further diagnosed from G. mindorensis by the difference in coloration (light gray with small dark gray mottling versus gray with dark thin transverse bands).

The presence of 46–50 precloacofemoral pores distinguishes Gekko carusadensis from all Philippine congeners, including G. rossi (77–88), G. crombota (58–74), G. p o ro s u s (74–80), G. m o n a rc h u s (31–40), G. mindorensis (52–66), G. ro m b l o n (71–84), G. gigante (52–66), G. ernstkelleri (36–42), G. palawanensis (64– 70), G. athymus (20–24), and G. g e c k o (12–20). A high number of toe IV subdigital scansors (18–20) distinguish G. carusadensis from G. rossi (10–16), G. c ro m b o t a (15–18), G. p o ro s u s (14–16), G. monarchus (13–15), G. mindorensis (12–14), and G. ro m b l o n (12, 13). Moderately large body size in males and females distinguishes Gekko carusadensis from the smaller species G. monarchus (male 56.2–80.7 mm; female 40.6– 69.7 mm), G. mindorensis (male 55–88.2 mm; female 68.2–70.9 mm), and G. palawanensis (male 57.2–65.7 mm; female 44.5–61.8 mm) and from the larger species G. athymus (male 99.2–119.9 mm; female 88.2–117.1 mm), G. g e c k o (male 120.1–166.1 mm; female 119.2–144.1 mm) and female G. p o ro s u s (91–96.7 mm). Gekko carusadensis is further distinguished from Gekko porosus by the absence of a modified distal femoral porebearing patch (vs. present, composed of a short series of 2 or 3 rows of pore-bearing scales). The new species differs from G. crombota ( Brown et al., 2008) by small dark mottling on light gray dorsum (vs. presence of trilobed cream bars) on the body trunk; by fewer (16–18) midbody dorsal tubercle rows (vs. 18–22); and precloacofemorals arranged in a continuous series (vs. 1 or 2 scale separation between preacloacals and femorals; Brown et al., 2008:fig 4B). Finally, dorsal coloration (light gray with small dark gray mottling) distinguishes G. c a r u s a d e n s i s from the highly variable range of patterns exhibited by other Philippine Gekko . These and other differences are summarized in Table 1.

FIGURE. 2. Image of Gekko carusadensis in life.

Description of holotype. Adult male ( PNM 9715, formerly KU 319968; field No. ACD 4537). Snout– vent length 83.4 mm; habitus robust, limbs well-developed, relatively slender, tibia length 15.7% snout–vent length, 77.9% femur length; tail relatively long, 1/2 regenerated; margins of limbs smooth, lacking cutaneous flaps or dermal folds; small cutaneous fold running along ventrolateral margin of trunk.

Head large, characterized by lightly hypertrophied temporal and adductor musculature, as wide as body at widest point; snout flattened, rounded at tip in dorsal and lateral aspect (Fig. 3); head width 70.1% head length, 20.8% snout–vent length; head length 29.7% snout–vent length; snout length 55.7% head width, 39.1% head length; dorsal surfaces of head relatively smooth, with pronounced concave postnasal, prefrontal, interoribital, and parietal depressions; auricular opening large, oval, oriented slightly lateroposteriorly from beneath temporal swellings on either side of head; tympanum very deeply sunk; orbits large, bordered anteriorly by slightly distinct supraorbital crests; eye large, pupil vertical with crenulated margins (Fig. 3); auricular opening 64.3% eye diameter, interocular diameter 16.1% head width.

Rostral large, rectangular, twice as broad as high, with two dorsomedial depressions between raised posterodorsal projections that form the anterolaterally-projecting edge of the nares and anterior suture of the supranasals; nostril surrounded by rostral, the first labial, an enlarged, round, convex supranasal, and two small postnasals; supranasals separated by two large internasals, anterior and posterior, anterior in contact with rostral.

FIGURE. 3. Dorsal, lateral, and ventral view of the holotype ( PNM 9715) of Gekko carusadensis showing scalation and coloration. Scale bar = 5 mm.

FIGURE. 4. Precloacal region of the male holotype ( PNM 9715) of Gekko carusadensis showing the continuous line of precloacofemoral pores and the enlarge scales prior to the pore bearing series. Lower image is of left manus of the holotype showing scansors and palmar scalation. Scale bar = 1mm

Total number of differentiated supralabials 13/13 (L/R; 10/10 to center of eye), bordered dorsally by one row of slightly differentiated snout scales; total number of differentiated infralabials 11/10 (10/9 to center of eye), bordered ventrally by one row of enlarged scales and four rows of only slightly differentiated chin scales; mental triangular; mental and first four infralabials greatly enlarged and wrapping onto ventral surfaces of chin, ≥ twice the size of infralabials 5–11; mental bordered posteriorly by a pair of slender, elongate postmentals; postmentals in medial contact for 3/4 their length, bordered posterolaterally by a secondary pair, less than one half the length of first pair, and a tertiary pair of non-elongate, hexagonal lateral postmentals, ≤ one quarter the length of primary postmentals; postmentals bordered posteriorly by 1 scale row of slightly enlarged, irregular scales; followed immediately by a sharp transition to non-differentiated chin and gular scales; postrictal scales slightly enlarged, 2 or 3 times the size of gular scales; remainder of undifferentiated gular scales very small, round, juxtaposed (Fig. 3).

FIGURE. 5. Part of the type series showing the lack of dorsal coloration pattern in Gekko carusadensis adults. The specimens are (left to right): males PNM 9715, KU 319970, PNM 9718, PNM 9717, female KU 319985, and juvenile KU 319986. Juvenile coloration differs from adults as discussed in the variation section. Female is slightly smaller than males, but shows the same coloration. Scale bar = 1 cm.

Dorsal cephalic scales highly heterogeneous and varied in shape and disposition; scales posterior the nares and loreal region somewhat enlarged, round, oval to subrectangular, and convex; postnasal, prefrontal, and interorbital depressions with noticeably smaller scales; palpebral scales homogeneous, larger than adjacent interorbital region intermixed on posterior half with slightly raised tubercles; undifferentiated temporal region scales granular, flat to irregularly convex, reducing in size posteriorly, interspersed with numerous highly enlarged, protuberant and conical tubercles; nuchal region with small, juxtaposed, flat trunk scales interspersed with enlarged sharply conical body tubercles; pectoral region with enlarged cycloid, imbricate scales, increasing posteriorly through venter, becoming very enlarged and strongly imbricate.

Ornamental occiput scalation includes numerous tubercles on posterolateral portions of head (temporal, supratympanic, and postrictal regions; Fig 3) and a short curved series of 2 enlarged, bluntly conical preorbital scales anterior to a row of slightly enlarged preorbitals (Fig. 3); circumorbitals differentiated into the following distinct regions: (1) 12 minute precircumorbitals, dorsal three with spine-like projections, (2) 8 enlarged, flat, squarish circumoribtals dorsoanterior to orbit, (3) 17 transversely elongated fringe-like spiny ciliaria across dorsoposterior margin of orbit.

Axilla–groin distance 42.8% snout–vent length; undifferentiated dorsal body scales round to irregularly octagonal, convex, nonimbricate, relatively homogeneous; dorsals sharply transition to imbricate ventrals along the ventrolateral adipose fold; dorsals lack interstitial granules but interspersed with 14 irregularly transverse rows (26 paravertebral rows) of slightly enlarged and protuberant dorsal body tubercles; 43 transversely arranged ventrals; scales on dorsal surfaces of limbs larger than dorsals, with interspersed enlarged tubercles extending down limbs, especially concentrated on radioulnar segment of forelimb and the anteriodorsal region of femur and entirety of dorsal tibia/fibia region of hind limb, terminating at the dorsal surfaces of hands and feet; enlarged patches of distinct imbricate scales present on wrist, anterior (prebrachial) surface of upper arm and anterior thigh, on knee, and on distal ventral surface of hind limb, just before attachment of foot; scales on dorsal surfaces of hands and feet similar to dorsal limb scales; ventral body scales flat, cycloid, strongly imbricate, much larger than lateral or dorsal body scales, largest at midventral line and pectoral region; gular scales small and granular, smaller than lateral and dorsal head scales.

Forty-nine dimpled pore-bearing scales (Fig. 4) in a continuous precloacofemoral series each punctured with light orange exudate; precloacofemorals arranged in a wavy, obtuse, inverted "V" and continuing just past mid-thigh; inferred “precloacal” pores 2–3 times the diameter of inferred “femoral” pores (Fig. 4); precloacofemorals preceded by three similarly enlarged but non-dimpled scale rows; precloacals followed by enlarged scales that extend down to the edge of the cloaca, femoral series followed abruptly by small scales which continue around the posterior edge of the hind limb.

Digits moderately expanded and covered on palmar/plantar surfaces by bowed, unnotched, undivided scansors (Fig. 4); no interdigital webbing; scansors of manus: 14, 13, 14, 16, and 16 on right digits I–V respectively; pes: 14, 14, 17, 18, and 16 on right digits I–V respectively; scansors of manus and pes bordered basally (on palmar and plantar surfaces) by 1–4 slightly enlarged scales that form a near-continuous series with enlarged scansors; all but first digit clawed; terminal claw-bearing compressed phalanges, with large recurved claws, not free until beyond dilated portion of digit.

Tail base bordered by a double, greatly enlarged conical postcloacal spur on each side of vent; postcloacal swellings pronounced; hemipenes completely everted; half of tail regenerated; tail depth (not including basal postcloacal swelling) 85.5% tail width; tail slightly depressed, ovoid; dorsal surface with small infrequent tubercles, concentrated along posterior edge of annulations, caudals similar in size to dorsals, but arranged in rows; subcaudals enlarged, plate-like, 2 rows per annulus, widely expanded to cover most of ventral surface; distal portion regenerated; tail with clear autotomy scar and distally regenerated portion, 8 annuli before autotomy scar (37 mm), autotomized portion 48 mm.

Measurements of holotype (in mm). Snout–vent length 83.4; axilla–groin distance 35.7; Tail length 82.5; Tail width 6.9; Tail height 5.9; head length 24.8; head width 17.4; snout length 9.7; eye–narial distance 8.2; interorbital distance 3.7; internarial distance 2.8; eye diameter 5.6; auricular diameter 3.6; tibia length 13.1; femur length 16.8; Toe I length 5.9; Toe IV length 8.4.

Coloration of holotype in preservative. Dorsal ground coloration of head, body, tail and dorsal surfaces of limbs light gray with scattered, irregular, dark gray mottling. The mottling of dark gray is without pattern, slightly increased in concentration around the vertebral, nuchal, scapular, and sacral regions. Dark bands on original portion of tail just prior to autonomy scar

Dorsal and lateral surfaces of head similar to dorsal ground color; supraocular region dark black from eyes; rostral and supralabial regions light gray; infralabials very light gray; infra-auricular region light gray, slightly lighter than medium gray supra-auricular region.

Limbs colored as torso, lacking transverse banding; dorsal surfaces of hands and feet light gray with heavy dark gray mottling; digits medium gray with cream spots; tail medium gray with dark gray bands on distal portion of original tail, no bands for proximal 1/3 of tail; regenerated portion dark gray.

Ventral head, neck, and torso white; ventral surfaces of limbs slightly darker with black flecks; ventral surfaces of digits (scansors) dark gray; palmar and plantar surfaces medium gray; precloacofemoal region white with light orange pores; ventral surfaces of tail medium gray, not banded.

Variation. The type series contains six large adult males with hemipenes everted, two gravid females, and one juvenile.

Dorsal color pattern is similar across the type series (Fig 5). All males exhibit nearly identical coloration, with a lack of distinct pattern; specimens (KU 320484–5) are slightly darker than the other males. A single female ( PNM 9716) has more concentrated dark mottling, but still lacks a distinct pattern. The mottling in the single juvenile (KU 319986) is concentrated into transverse bands starting at the scapular region and continuing down the tail, with 9 bands from head to tail margin. The juvenile banding is assumed to fade and disappear in the adults.

Ventral coloration is more variable than dorsal coloration: ventral body surfaces are white to medium gray; subcaudal coloration is medium to dark gray. Two males (KU 319970, PNM 9717) have dark gray speckling concentrated in the axilla–groin region and two others (KU 320484–5) have diffuse speckling throughout the ventral surface, including the gular region. Females with a lighter ventral color, more similar to the holotype, but not as immaculate.

Etymology. Gekko carusadensis is derived from the word “Carusadus” which refers to a region in Slovenia with extensive Karst topography ( Kranjc, 2001). This region is considered the origin of the term “Karst” ( Kranjc, 1998), the current term for the type of topography in which the new species occurs. Suggested common name, Luzon Karst Gecko .

Distribution. Gekko carusadensis is known only from the type locality (Fig. 1).

Ecology and natural history. We observed the new species to be very common in karst habitat within the Biak na Bato park. Lizards were only found on the karst rock, never on vegetation. They were common within the caves and crevaces that make up the park habitat and could be found on the outside surfaces of the caves at night. Sympatric gekkonid species include Cyrtodactylus philippinicus (Steindachner) , Gekko gecko (Linnaeus) , Gehyra mutilata (Wiegmann) , Hemidactylus frenatus Schlegel , and Hemidactylus platyurus (Schneider) . None of the sympatric species occupied the karst habitat, but were found in abundance in the more disturbed areas of the park near or on buildings. Cyrtodactylus philippinicus could be found on trees near the karst rocks.