Cyrtodactylus borgattaorum, Tran & Lam & Nguyen & Nguyen & Nguyen & Smith & Nguyen & Grismer, 2024

Tran, Thinh Gia, Lam, Ngon Quang, Nguyen, Truong Minh Nhat, Nguyen, Nga Thi, Nguyen, Thao Thi Phuong, Smith, Jacob, Nguyen, Vu Dang Hoang & Grismer, Lee, 2024, A new granite cave dwelling endemic species of the Cyrtodactylus intermedius group (Squamata: Gekkonidae) from Hon Son Island, Kien Giang Province, Vietnam, Zootaxa 5541 (4), pp. 485-512 : 497-509

Cyrtodactylus borgattaorum sp. nov.

Figs. 5 , 6 , Tables 8 , 9 .

Holotype. ITBCZ 11078 , subadult male collected by Nguyen Dang Hoang Vu on Hon Son Island , Kien Hai District, Kien Giang Province, southwestern Vietnam (9.81253° N, 104.62040° E) on 13 January 2024, at approximately 25 m a.s.l..

Paratypes. ITBCZ 11066 , subadult male collected by Nguyen Dang Hoang Vu on the same island as the holotype (9.81363° N, 104.62281° E) on 15 January 2024, at approximately 12 m a.s.l..

Diagnosis ( Table 8 ). Cyrtodactylus borgattaorum sp. nov. is separated from all congeners by having the combination of 12 supralabials; 10 or 11 infralabials; 22 or 23 small, rounded, smooth, paravertebral tubercles; 12 rows of small, rounded, smooth, longitudinally arranged body tubercles; 35 or 39 ventrals; 8 or 10 expanded subdigital lamellae, 12 or 13 unexpanded subdigital lamellae, and 21 or 22 total subdigital lamellae on the fourth toe; 21 or 22 enlarged femorals; 8 or 9 enlarged precloacals; 8 or 9 precloacal pores in males; three rows of enlarged post-precloacals; 3/3 postcloacal tubercles; enlarged femorals and enlarged precloacals not continuous; proximal femorals nearly same size of distal femorals; body tubercles smooth, greatly reduced; no pocketing between digits on the hands and feet; subdigital toe lamellae expanded nearly beyond body of digit; two dark-colored pigmented blotches on top of head; four dark-colored dorsal bands lacking lightened centers, thinner than light-colored interspaces between bands, bordered by prominent white tubercles; no dark body markings in light-colored interspaces; limbs with white tubercles; and six dark-colored and light-colored caudal bands.

Description of holotype ( Figs. 5 , 6 ; Table 8 , 9 ). Subadult male SVL 65.84 mm, TaiL 83.35 mm.

Head. Head distinct from neck, elongate (HL/SVL 0.28), depressed (HD/HL 0.41), longer than width (HW/HL 0.66), and triangular shaped in dorsal view; lores concave anteriorly, moderately concave on prefrontal region, weakly inflated posteriorly, canthus rostralis rounded; snout elongate (SN/HL 0.46), rounded in dorsal view; eye large (ED/HL 0.25), pupils vertical; ear opening below the dark nuchal loop, obliquely directed and oval, small in size (EL/HL 0.07), eye to ear distance shorter than eye to nostril distance (EE/EN 0.83); rostral rectangular with a medial suture, bordered by 1/1 supranasal and single internasal posteriorly, 1 st /1 st supralabial laterally; external nares bordered by rostral anteriorly, 1/1 supranasal dorsally, 2/2 postnasals posteriorly, 1 st /1 st supralabial ventrally; supralabials 12/12; scales of rostrum and lores flat to slightly raised, larger than granular scales on top of head and occiput; infralabials 11/11; scales on the top of occiput intermixed with distinct, enlarged tubercles; mental triangular, bordered by 1 st /1 st infralabial laterally, 1/1 trapezoidal postmentals posteriorly; postmentals two pairs, enlarged, first pairs in contact with each other; gular and throat scales small, granular, larger laterally near infralabials, slightly larger posteriorly, flatter, smooth, imbricate, pectoral and ventral scales.

Body. Body relatively long (AG/SVL 0.40) with well-defined ventrolateral folds; dorsal scales small, granular, interspersed with small, smooth, rounded, semi-regularly arranged tubercles extending from anterior edge of nuchal loop onto base of tail but no farther;12 longitudinal rows of tubercles at midbody; approximately 22 paravertebral tubercles; 39 flat, imbricate, ventral scales much larger than dorsal scales; 9 enlarged precloacal scales, and bearing pits; no deep precloacal groove or depression; and three rows of large post-precloacal scales on midline.

Limbs. Forelimbs thin, relatively long (FL/SVL 0.17); lacking tubercles, granular scales of forelimbs slightly larger than those on body; palmar scales rounded, slightly raised; digits well-developed, inflected at basal interphalangeal joints, slightly narrower distal to inflections; subdigital lamellae transversely expanded, those proximal to joint inflections much wider than those distal to inflections; claws well-developed, sheathed by a dorsal and ventral scale; hind limbs thin, wider than forelimbs, long (TBL/SVL=0.20), covered dorsally by granular scales interspersed with enlarged tubercles same sized as on dorsum; ventral scales of thighs flat, imbricate, larger than dorsals; subtibial scales large, flat, imbricate; one row of 11/11 enlarged femoral scales terminating distally before knee, not continuous with enlarged precloacal scales; proximal femorals much smaller than distal femorals, the posteroventral margin of thigh covered with smaller, rounded scales; femoral pores absent; plantar scales flat; digits well-developed, inflected at basal interphalangeal joints; basal subdigital lamellae well expanded transversely, expanding nearly beyond body of digits, claws well-developed, sheathed by a dorsal and ventral scale at base; and 10/10 wide proximal subdigital lamellae on fourth toe, 12/12 more narrow lamellae distal to joint inflection, 22 total subdigital lamellae.

Tail. Tail length longer than snout-vent length (TL/SVL 1.27), 83.35 mm, 6.18 mm wide at base, tapering to a point; caudal scales small, square, in transverse rows on dorsal side; subcaudal region bearing large, transverse scales; body tubercles not extending beyond the posterior edge of hemipenal region; 3/3 conical postcloacal tubercles at left and right side of base of hemipenal region; and postcloacal scales flat, imbricate.

Coloration ( Fig. 6 ). In life, light-brown color of top of head, limbs, and dorsum; top of head dark-with two dark-brown blotches on parietal region; dark brown nuchal loop extends from posterior margin of one orbit to posterior margin of other orbit with white tubercles extending from the posterior margin of one orbit across the nape to the posterior margin of the opposing orbit; four dark brown bands edged with lightened centers, and white tubercles terminating above the ventrolateral folds extending from shoulders to pelvis; dark brown body bands thinner than light brown interspaces; limbs brown, with white tubercles; 6 wide, dark-brown caudal bands wider than 5 light-colored caudal bands and the last light-colored caudal band the largest; all caudal bands immaculate, caudal bands encircle the tail; iris gold, bearing thin, dark-brown reticulations; ventral surfaces of gular region, limbs and body dull-white with small, dark spots on each ventral scales. In preservative the color became faint, but the pattern had no change.

Variation. The second specimen resembles the coloration and pattern of the holotype. Meristic differences of the second specimen examined are presented in Table 8 .

Etymology. We name the new species in honor of the Borgatta family, and in particular Drs. Edgar and Marie Borgatta. Both made significant contributions to the fields of sociology and gemology. Their spirit of generosity and passion for discovery and knowledge have and will continue to inspire future generations. We recommend “Borgatta’s Bent-toed Gecko” and “Thằn lằn Chân Ngón Bo-ga-ta” as the English and Vietnamese common names of the new species, respectively. Edgar and Marie Borgatta were the grandparents of coauthor Jacob Smith’s wife, Emilia Borgatta Smith.

Comparisons ( Table 9 ). C. borgattaorum sp. nov. differs from C. auralensis by having a higher number of supralabials (12 vs. 8–9), a lower number of paravertebral tubercles (22 or 23 vs. 29–32), fewer longitudinal rows of tubercles (12 vs.17–18), lower total number of enlarged femoral scales (21 or 22 vs. up to 28), fewer dark caudal bands (6 vs. 9–10), fewer light caudal bands (6 vs. 10–11), having body tubercles greatly reduced (vs. not greatly reduced), having femoral and precloacal scales not continuous (vs. continuous), having proximal femorals nearly the same size as the distal femorals (vs. <1/2 size of distal femorals); C. borgattaorum sp. nov. differs from C. bokorensis by having a higher number of supralabials (12 vs. 8), a lower number of paravertebral tubercles (22 or 23 vs. 30–33), fewer longitudinal rows of tubercles (12 vs.18–20), a lower number of ventral scales (35 or 39 vs. 42–48), a higher number of subdigital lamellae on the 4 th toe (21 or 22 vs. 18–20), a lower number of enlarged femoral scales (21 or 22 vs. 27–30), fewer dark caudal bands (6 vs. 11–12), fewer light caudal bands (6 vs. 10–12), having body tubercles greatly reduced (vs. not greatly reduced), having proximal femorals nearly the same size as the distal femorals (vs. <1/2 the size of the distal femorals); C. borgattaorum sp. nov. differs from C. cardamomensis by having a higher number of supralabials (12 vs. 7–8), a lower number of paravertebral tubercles (22 or 23 vs. 29–34), fewer longitudinal rows of tubercles (12 vs.17–21), a higher total of subdigital lamellae on the 4 th toe (21 or 22 vs. 17–19), a lower number of enlarged femoral scales (21 or 22 vs. 23–28), fewer dark caudal bands (6 vs. 10–11), fewer light caudal bands (6 vs. 10–12), having body tubercles greatly reduced (vs. not greatly reduced), having femoral and precloacal scales not continuous (vs. continuous), having dark pigmented blotches on top of the head (vs. absence); C. borgattaorum sp. nov. differs from C. disjunctus by having a lower number of paravertebral tubercles (22 or 23 vs. 41), a higher number of ventral scales (up to 39 vs. 36), more subdigital lamellae on the 4 th toe (21 or 22 vs. 17), a lower number of enlarged precloacal scales (8 or 9 vs. 10), more post-precloacal scale rows (three vs. one), having dark pigmented blotches on top of the head (vs. absence), fewer dark and white caudal bands (6 vs. 11), having proximal femorals nearly the same size as the distal femorals (vs. <1/2 the size of the distal femorals), dark dorsal bands bordered by prominently colored white tubercles (vs. absent), the presence of white tubercles on hind limbs (vs. absence); C. borgattaorum sp. nov. differs from C. intermedius by having a higher number of supralabials (12 vs. 8), fewer paravertebral tubercles (22 or 23 vs. 29–31), fewer longitudinal rows of tubercles (12 vs. 18–20), a higher total of subdigital lamellae on 4 th toe (21 or 22 vs. 19–20), a lower number of enlarged femoral scales (21 or 22 vs. 22–25), having body tubercles greatly reduced (vs. not greatly reduced), having femoral and precloacal scales not continuous (vs. continuous), having dark pigmented blotches on top of the head (vs. absence); C. borgattaorum sp. nov. differs from C. hontreensis by having more longitudinal rows of tubercles (12 vs. 7 in C. hontreensis ), a lower number of ventral scales (35 or 39 vs. 40–42), more subdigital lamellae on 4 th toe (21 or 22 vs. 17–19), a higher number of enlarged femoral scales (21 or 22 vs. 4–9), more body bands (4 vs. 3), having dark pigmented blotches on top of the head (vs. absence), the presence white caudal bands (vs. absence); C. borgattaorum sp. nov. differs from C. kohrongensis by having a higher number of supralabials (12 vs. 8–10), a lower number of paravertebral tubercles (22 or 23 vs. 25–33), fewer longitudinal rows of tubercles (12 vs. 16–20), fewer dark caudal bands (6 vs. 8–11), fewer light caudal bands (6 vs. 9–11), having body tubercles greatly reduced (vs. not greatly reduced), having proximal femorals nearly same size as the distal femorals (vs. <1/2 the size of the distal femorals), having dark pigmented blotches on top of the head (vs. absence); C. borgattaorum sp. nov. differs from C. kulenensis by having a higher number of supralabials (12 vs. 8–11), a lower number of paravertebral tubercles (22 or 23 vs. 33–38), fewer longitudinal rows of tubercles (12 vs. 17–19), having femoral and precloacal scales not continuous (vs. continuous), having proximal femorals nearly the same size as the distal femorals (vs. <1/2 the size of the distal femorals), having dark pigmented blotches on top of the head (vs. absence); C. borgattaorum sp. nov. differs from C. laangensis by having a higher number of supralabials (12 vs. 7–9), a lower number of paravertebral tubercles (22 or 23 vs. 29–32), fewer longitudinal rows of tubercles (12 vs. 17–18), a higher total of subdigital lamellae on the 4 th toe (21 or 22 vs. 18–20), a higher number of enlarged femoral scales (21 or 22 vs. 0–16), fewer dark caudal bands (6 vs. 10–12), fewer light caudal bands (6 vs. 10–12), having body tubercles greatly reduced (vs. not greatly reduced), having proximal femorals nearly the same size as the distal femorals (vs. <1/2 the size of distal femorals); C. borgattaorum sp. nov. differs from C. septimontium by having a higher number of supralabials (12 vs. 8–10), a lower number of paravertebral tubercles (22 or 23 vs. 23–30), fewer longitudinal rows of tubercles (12 vs. 16–20), a lower number of ventral scales (35–39 vs. up to 46), a higher total of subdigital lamellae on the 4 th toe (21 or 22 vs. 17–20), a lower number of enlarged femoral scales (21 or 22 vs. 24–33), more postcloacal tubercles (3 vs. 2), fewer dark caudal bands (6 vs. 10–11), fewer light caudal bands (6 vs. 9–11), having body tubercles greatly reduced (vs. not greatly reduced), having femoral and precloacal scales not continuous (vs. continuous), having proximal femorals nearly the same size as the distal femorals (vs. <1/2 the size of distal femorals), having dark pigmented blotches on top of the head (vs. absence); C. borgattaorum sp. nov. differs from C. thylacodactylus by having a higher number of supralabials (12 vs. 7), a lower number of paravertebral tubercles (22 or 23 vs. 29–31), fewer longitudinal rows of tubercles (12 vs. 18–20), a higher total of subdigital lamellae on 4 th toe (21 or 22 vs. 15–18), fewer dark caudal bands (6 vs. 10–12), fewer light caudal bands (6 vs. 10–12), having body tubercles greatly reduced (vs. not greatly reduced), having femoral and precloacal scales not continuous (vs. continuous), lacking pocketing between the digits of the hind feet (vs. presence), having dark pigmented blotches on top of the head (vs. absence).

C. borgattaorum sp. nov. is most closely related to C. phuquocensis in morphological characters but the new species can be distinguished from C. phuquocensis by having fewer paravertebral tubercles (22 or 23 vs. 25–31), fewer longitudinal rows of tubercles (12 vs. 16–19), a lower number of ventral scales (35–39 vs. up to 43), more subdigital lamellae on the 4 th toe (21 or 22 vs. 15–19), a lower total number of enlarged femoral scales (21 or 22 vs. up to 30), fewer dark caudal bands (6 vs. 10–12), fewer light caudal bands (6 vs. 10–12), having body tubercles greatly reduced vs. not greatly reduced, having femoral and precloacal scales not continuous (vs. continuous), having proximal femorals nearly the same size as the distal femorals (vs. <1/2 the size of the distal femorals), one small intersupranasal (vs. two intersupranasals of equal size), and its significantly different (p =0.012) morphospatial position in the meristic-morphometric PCA.

Natural history

Five specimens of C. borgattaorum sp. nov. were observed over the two days of searching. All five were observed on 14 January in or near boulder cave environments around the northwest of the island—the same environment and area as the specimen photographed and described in Grismer & Smith (2023). These caves are located just a few meters above sea level, and approximately 50–80 meters inland from the beach ( Fig. 7 ). It was not possible to photograph any of the new specimens in situ due to the risk of the animals escaping into the narrow caves. Both collected specimens were first observed within boulder caves ( Fig. 7 ). The first was collected during the day on 14 January, deep within a cave approximately 20 meters below the surface. The second was collected at night, near the entrance of a second cave. Three additional specimens of the Cyrtodactylus were observed by the team (but not photographed or collected), including one specimen found deep within a cave (10–20 m), one specimen found inside near the cave entrance, and a final specimen on the surface in a partially vegetated boulder field directly above a cave tunnel. The latter three observations were all made at night. In total, the C. borgattaorum sp. nov. was observed at four different cave sites, including the one mentioned in Grismer & Smith (2023). All four caves had C. condorensis near their entrances and C. eisenmanae were observed deeper within the caves. Cyrtodactylus condorensis leaves the caves to hunt on the surface at night, but C. eisenmanae and C. borgattaorum sp. nov. were only seen within the caves or close to their entrances/tunnels—even at night.

We suggested the taxonomic change of Polypedates cf. megacephalus Hallowell according to Yuan et al. (2021) and added the following seven species to the checklist of herpetofauna on Hon Son Island of Grismer & Smith (2023) ( Table 10 , Fig. 8 ). All species were photographed in situ except the Cyrtodactylus and the Oligodon cinereus (Günther) , which were both photographed on the island immediately after collection. The first insular record of Oligodon cinereus (from Hon Son) will be described in a separate paper (Tran et al. 2024) being prepared for publication.

A single Dasia olivacea ( Fig. 8C ) Gray was observed and photographed during the day, at approximately 1100 hrs. on 13 January 2024. The species was ascending the trunk of a coconut palm on the central road bisecting the island.

A single Eutropis multifasciata (Kuhl) ( Fig. 8B ) was observed in leaf litter during the day on 13 January 2024 along the road on the northern side of the island.

Several ground skinks of the genus Lipinia cf. trivittata Poyarkov et al. (2019) ( Fig. 8A ) were observed during the day on 13 January 2024 on boulders near the edge of a forested area on the northern side of the island.

Two Ahaetulla prasina (Boie) ( Fig. 8G ) were observed in secondary forest on the western ridge of the island on 13 January 2024 at night, at approximately 200 meters above sea level. One was gray and the second was yellow.

A single Chrysopelea ornata (Shaw) ( Fig. 8E ) was observed dead on the road along the north side of the island on 13 January 2024. The specimen was completely desiccated but could still be identified.

A single Xenopeltis unicolor Reinwardt ( Fig. 8D ) was observed crossing the central road that bisects the island at approximately 02:00 hrs. on 15 January 2024.

A pair of Pareas sp. ( Fig. 8F ) were observed and photographed at night, at approximately 10:00 hrs. on 13 January 2024. The species were sleeping on the tree branch in degraded secondary forest on the island.

Three Polypedates cf. megacephalus Hallowell were observed in a water cistern. A fourth specimen was collected by our team in degraded secondary forest on the island. We suggest these are the same species recorded as Polypedates cf. mutus (Smith) in Grismer & Smith, 2023 and Polypedates cf. leucomystax (Gravenhorst) in Grismer et al., 2008.

Conservation status. Cyrtodactylus borgattaorum sp. nov. is only known from two specimens collected from one locality on Hon Son Island, Kien Giang Province, Vietnam. The snake Trimeresurus honsonensis (Grismer, Ngo & Grismer) and the gecko Cyrtodactylus eisenmanae Ngo are the other insular endemics. Specific threats to C. borgattaorum sp. nov. require further investigation, but the new species is adapted to small granite cave microhabitats in an already degraded forest on a small island. Tourism development on the island is expanding and may pose a threat to this species as resorts, rock quarries, and other infrastructure encroach on the forest and boulder fields ( Fig. 7 ). Though the population status of C. borgattaorum sp. nov. requires further study, as an inhabitant of an isolated island undergoing rapid change, this new species is likely imperiled.

It appears that C. borgattaorum sp. nov. is a site-specific insular endemic with a narrow habitat preference as it has only been recorded from granite boulder cave habitats ( Fig. 7 ). Given the available information, we suggest that Cyrtodactylus borgattaorum sp. nov. be considered an Endangered (B1ab(iii) and B2ab(iii), EN) species following IUCN Red List categories including: B1-EOO and B2-AOO with number of locations ≤ 5 and a decline in quality of habitat according to the IUCN Red List Categories and Criteria: Version 3.1 ( IUCN, 2012). Additional surveys at other boulder fields and cave areas on Hon Son Island are necessary to elucidate further details of the biology of the new species.

Figures

FIGURE 5. Photo of the holotype Cyrtodactylus borgattaorum sp. nov. ITBCZ 11078 from Hon Son Island, Kien Giang Province, Vietnam. A. Dorsal view. B. Ventral view of femoral and precloacal regions. C. Ventral view of the right hand. D. Ventral view of the right foot. E. Lateral view of head. F. Dorsal view of head. G. Ventral view of the gular region.

FIGURE 6. A. Photo of the holotype (ITBCZ 11078) in life on Hon Son Island, Kien Giang Province, Vietnam. B. Photo of the paratype in life on Hon Son (ITBCZ 11066).

FIGURE 7. A. Topography of Hon Son Island. B. Habitat of Cyrtodactylus borgattaorum sp. nov. on Hon Son Island, Kien Giang Province, southern Vietnam. The base map of Vietnam was sourced from CIAT-CSI SRTM website (http://srtm.csi.cgiar. org).

FIGURE 8. Photographs of new herpetological records for Hon Son Island. A. Lipinia cf. trivittata. B. Eutropis multifasciata. C. Dasia olivacea. D. Xenopeltis unicolor. E. Chrysopelea ornata dead on the road. F. Pareas sp. G. Ahaetulla prasina yellow morph. H. Ahaetulla prasina gray morph.