Cyrtodactylus amphipetraeus, Chomdej & Suwannapoom & Pawangkhanant & Pradit & Nazarov & Grismer & Poyarkov, 2020

Chomdej, Siriwadee, Suwannapoom, Chatmongkon, Pawangkhanant, Parinya, Pradit, Waranee, Nazarov, Roman A., Grismer, L. Lee & Poyarkov, Nikolay A., 2020, A new species Cyrtodactytlus Gray (Squamata: Gekkonidae) from western Thailand and the phylogenetic placement of C. inthanon and C. doisuthep, Zootaxa 4838 (2), pp. 179-209 : 189-198

Cyrtodactylus amphipetraeus sp. nov.

Tak Bent-toed Gecko

( Figs. 5 , 6 )

Holotype. Adult male AUP-00696 was collected on August 3, 2019, at 21:00 hrs by S. Chomdej, C. Suwannapoom and P. Pawangkhanant from limestone rocks at the entrance to the Tham Sri Fah Cave , Mae Sot District, Tak Province, Thailand (16.602162°N, 98.712481°E WGS; 710 m in elevation).

Paratypes. Nine specimens, including the paratypes AUP-00688–90 (three adult males), and AUP-00691–93 and AUP-0097 (four adult females) bear the same collecting data as the holotype; AUP-00698, an adult male, was collected on August 3, 2019, at 20:00 hrs by S. Chomdej, C. Suwannapoom and P. Pawangkhanant from granite rocks near the Tha Ra Rak waterfall, Mae Sot District , Tak Province, Thailand (16.569339° N, 98.694566° E WGS; 610 m in elevation); ZMMU R-16626 (field No. NAP-06637) was collected on November 13, 2016, at 20:00 hrs by N.A. Poyarkov and P. Pawangkhanant from granite rocks near the Tha Ra Rak waterfall, Mae Sot District, Tak Province, Thailand (16.569339° N, 98.694566° E WGS; 610 m in elevation) .

Diagnosis. Cyrtodactylus amphipetraeus sp. nov. differs from all species in the C. sinyineensis group by having the combination of nine supralabials; seven infralabials; 34–38 paravertebral tubercles; 17–20 longitudinal rows of dorsal tubercles; 28–30 ventral scales ventral scales; seven expanded subdigital lamellae on the fourth toe; 11 or 12 unmodified subdigital lamellae on the fourth toe; 18 or 19 total subdigital lamellae on the fourth toe; 27–34 enlarged femoral scales; a total of 10–12 pore-bearing femoral scales in males; 8–11 enlarged precloacal scales; 7–9 pore-bearing precloacal scales in males; three rows of enlarged post-precloacal scales; approximately 4–7 broken to hour glass shaped dorsal body bands; 10–12 light-colored caudal bands (n=2); 11–13 dark-colored caudal bands (n=2); raised and strongly keeled dorsal tubercles that extend beyond base of tail; enlarged femoral and precloacal scales nearly the same size and continuous; pore-bearing femoral and precloacal scales not continuous; medial subcaudals two to three times wider than long and extending onto lateral side of tail; iris green; nuchal loop lacking an anterior azygous notch, and bearing a jagged posterior border; dorsal bands bearing paravertebral elements, generally equal in width than interspaces, bearing lightened centers, edged with white tubercles; dark markings in dorsal interspaces; light caudal bands in adults bearing dark-colored markings; light-colored caudal bands not encircling tail; and mature regenerated tail not spotted ( Table 5).

Description of holotype. Adult male SVL 81.3 mm ( Fig. 5 ); head moderate in length (HL/SVL 0.30), wide (HW/HL 0.69), flat (HD/HL 0.47), distinct from neck, triangular in dorsal profile; lores inflated, prefrontal region concave, canthus rostralis rounded; snout elongate (ES/HL 0.39), rounded in dorsal profile, broad in lateral profile; eye large (ED/HL 0.25); ear opening oval (EL/HL 0.10); eye to ear distance greater than diameter of eye; rostral rectangular, partially divided dorsally, bordered posteriorly by supranasals and one internasal, laterally by first supralabials; external nares bordered anteriorly by rostral, dorsally by supranasals, posteriorly by smaller postnasals, and ventrally by first supralabials; 9(R,L) rectangular supralabials extending to below midpoint of eye; 7(R,L) infralabials tapering posteriorly to commissure of jaw; scales of rostrum and lores slightly raised, larger than granular scales on top of head and occiput; scales on top of head and occiput intermixed with small tubercles; dorsal superciliaries weakly pointed and directed posteriorly; 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 chinshields, outermost row bordering first five infralabials; gular and throat scales granular, grading posteriorly into larger, subimbricate pectoral and ventral scales.

Body relatively short (AG/SVL 0.42) with well-defined ventrolateral folds; dorsal scales small, raised and interspersed with large, raised, semi-regularly arranged, strongly keeled tubercles; tubercles extend from top of head onto base of tail just beyond the postcloacal swelling; tubercles on nape smaller than those on body; 35 paravertebral tubercles; approximately 18 longitudinal rows of dorsal tubercles; 28 flat, subimbricate, ventral scales larger than dorsal scales; 11 enlarged precloacal scales; eight pore-bearing precloacal scales separated on the midline by one poreless scale; three rows of large, post-precloacal scales; and no deep precloacal groove or depression.

Forelimbs moderate in stature, relatively short (FL/SVL 0.17); slightly raised, juxtaposed scales of forearm larger than those on body, intermixed with large tubercles; palmar scales slightly raised, juxtaposed; digits welldeveloped, relatively long, inflected at basal, interphalangeal joints; digits narrow distal to inflections; widened proximal subdigital lamellae do extend onto palm; slight webbing at base of digit; claws well-developed, sheathed by a dorsal and ventral scale at base; hind limbs more robust than forelimbs, moderate in length (TBL/SVL 0.15), covered dorsally by small, raised, juxtaposed scales intermixed with large pointed tubercles and bearing flat, slightly larger imbricate scales anteriorly; ventral femoral scales flat, imbricate, much larger than dorsals; one row of 13/14 (R,L) enlarged femoral scales and enlarged precloacal scales continuous; enlarged femoral scales nearly equal in size; small, postfemoral scales form an abrupt union with larger, flat ventral scales on posteroventral margin of thigh; six (R,L) pore-bearing femoral scales not continuous with pore-bearing precloacal scales; subtibial scales flat, imbricate; plantar scales raised; digits relatively long, well-developed, inflected at basal, interphalangeal joints; seven (R,L) transversely expanded subdigital lamellae on fourth toe proximal to joint inflection that do not extend onto sole, 11 (R,L) unmodified subdigital lamellae distal to inflection; and claws well-developed, base of claw sheathed by a dorsal and ventral scale.

Tail complete, original, gracile in proportions, 115.1 mm in length, 9.9 mm in width at base, tapering to a point, TL/SVL (1.42); dorsal scales of tail flat, forming indistinct whorls; median row of transversely expanded subcaudal scales three times as wide as long, extending onto lateral subcaudal region; three enlarged postcloacal tubercles at base of tail on hemipenal swellings; and postcloacal scales large, flat.

Color pattern ( Fig. 5 , Fig. 6A ). Dorsal ground color of head, body, limbs, and tail yellowish-brown; top of head and rostrum nearly unicolor, bearing areas of slightly darker, diffuse irregularly shaped markings; nuchal loop jagged posteriorly, divided medially, bearing two posterior projections; triangular occipital band composed of three dark oval-shaped blotches; approximately five dark hour glass shaped body bands with paravertebral elements bearing lightened centers and edged with whitish tubercles extend from the shoulder to the presacral region; lighter colored interspaces between bands bear darker markings; whitish tubercles scattered on flanks; sacral and postsacral bands continue onto the tail to form 13 black caudal bands that are wider than the 12 light-colored caudal bands; light-colored caudal bands bear dark markings and do not encircle tail; limbs bear distinct, dark-colored irregularly shaped markings; gular scales bearing only two or three black stipples; black stippling in throat, pectoral region, and anterior portion of belly more dense; anterior one-half of subcaudal region light-colored, posterior one-half bearing faint whitish mottling.

Variation. The dorsal color pattern in the type series is highly variable. The body bands are often so irregularly shaped it is difficult to accurately assess how many there are. Paratypes AUP-00688, AUP-00692–93, and AUP- 00698 have well-defined generally oval-shaped paravertebral components to their dorsal bands that are separated on the midline of the body ( Fig. 6B,E ). Whereas the banding pattern of the holotype and paratypes AUP-00689–91, 00697–98 are generally more irregularly shaped ( Fig. 6 ). Paratypes AUP-00689, 00691–93, 00698 and ZMMU R-16626 have partially regenerated tails ( Fig. 6 ). Additional variation in meristic and mensural characters are presented in Table 6 .

Distribution. Cyrtodactylus amphipetraeus sp. nov. is known only from the type locality at Tham Sri Fah Cave, Mae Sot District, environs of Mae Sot, Tak Province, western Thailand; and Tha Ra Rak Waterfall located approximately 4 km to the southwest from the cave ( Fig. 1 ).

Etymology. The specific epithet amphipetraeus is a Latinized adjective in nominative singular, derived from Greek amphi or ἀμφί (meaning of both kinds) and petra or πέτρα (for rock). The species name is given in reference to the remarkable natural history of this species which inhabits both limestone and granite rocks. The recommended vernacular name in English is Tak Bent-toed Gecko; in Thai is Tuk kai tak.

Natural history. The type locality—Tham Sri Fah Cave (or Blue Cave), is located in Mae Sot District of Tak Province, and represents a karstic cave on the northern slope of a small limestone hill with a Buddhist temple at the entrance ( Fig. 7 ). The hill runs northeast to southwest reaching 730 m in elevation and is covered with sparse secondary vegetation and is approximately 500 m in length and approximately 20 m in its widest central point. Hill slopes are jagged, bearing numerous karstic alcoves, deep cracks and crevices, creating suitable microhabitat for Cyrtodatcylus. This small limestone area is surrounded by agricultural landscapes. At the type locality several specimens were seen at night after 20:00 hrs on the cave walls near the entrance and on rocks near cracks and holes in karst. The species is quite weary and would rapidly retreat into crevices and holes when disturbed by light. Approximately 4 km to the southwest from the Tham Sri Fah Cave is the Tha Ra Rak waterfall, formed by ca. 3–5 m wide river flowing within highly disturbed secondary evergreen forest. The valley of this river is covered with large granite boulders, where the new species was observed at night sitting on granite rocks or hiding among them. Only few specimens were spotted and just two of them collected. Remarkably, specimens recorded on granite rocks had distinctive dorsal pattern forming a more blotched ( Fig. 6B,E ) rather than banded ( Fig. 6A ) appearance. Cyrtodactylus amphipetraeus sp. nov. is expected to occur in several nearby limestone hills within the Mae Sot District. Reproductive biology, diet and predators of the new species remain unknown.

data unavailable.

Comparisons. Cyrtodactylus amphipetraeus sp. nov. (n=10) differs from various combinations of all other species except C. naungkayaingensis in clade 2 of the C. sinyineensis group in having statistically different mean values across 1–5 of the nine scale characters. These differences are summarized in Tables 4 and 5 and visualized in Figure 4 and do not need to be written out here. Cyrtodactylus amphipetraeus sp. nov. is not the sister species of C. naungkayaingensis ( Fig. 2 ) and differs from it by a 7.0% uncorrected pairwise sequence divergence. As noted above, the jagged dorsal bands of C. naungkayaingensis are not wider than the interspaces whereas the broken to hour glass-shaped dorsal bands of C. amphipetraeus sp. nov. are wider than the interspaces and it has a maximum SVL of 93.4 mm and a green iris whereas C. naungkayaingensis has a maximum SVL 66.9 mm and a reddish iris. Additional differences between C. amphipetraeus sp. nov., C. doisuthep , and the species of clade 1 are listed in Table 5.

Figures

FIGURE 1. Distribution of the species of the Cyrtodactylus sinyineensis group in Thailand and Myanmar.

FIGURE 2. BEAST maximum clade credibility tree of the Cyrtodactylus sinyineensis group based on ND2 and its flanking tRNAs.

FIGURE 4. Boxplot comparisons of discrete meristic characters among the species of clade 2 of the Cyrtodactylus sinyinensis group. Light blue circle is the mean and the black horizontal bars is the median. Asterisks denote species bearing statistically significant mean differences from C. amphipetraeus sp. nov.

FIGURE 5. Holotype of adult male Cyrtodactylus amphipetraeus sp. nov. (AUP-00696). A. Dorsal view of body showing nuchal loop, dorsal band, and caudal patterns (in preservative). B. Lateral view of head showing greenish coloration of iris. C. Gular region showing mental, postmental, and chin scales arrangement. D. Dorsal view of top of head. E. Precloacal and femoral region showing scale sizes and pore arrangements, and plantar view of feet showing subdigital lamellae morphology. Photos by C. Suwannapoom.

FIGURE 6. Variation in dorsal pattern in Cyrtodactylus amphiptraeus sp. nov. in life. A. Adult holotype male (AUP-00696) from Tham Sri Fah Cave, Pop Pra District, Tak Province, Thailand. B. Adult paratype male (AUP-00698) from Tha Ra Rak waterfall, Pop Pra District, Tak Province, Thailand. C. General view of the adult paratype female (ZMMU R-16626) from Tha Ra Rak waterfall, Pop Pra District, Tak Province, Thailand. D. Close-up of the head of the same specimen showing green iris. E. Adult male (not collected) hiding in crevice near Tha Ra Rak waterfall, Pop Pra District, Tak Province, Thailand. F. Juvenile specimen (not collected) from Tha Ra Rak waterfall, Pop Pra District, Tak Province, Thailand. Photos by C. Suwannapoom (A–B), N.A. Poyarkov (C–D), and P. Pawangkhanant (E–F).

FIGURE 7. Karstic habitat of Cyrtodactylus amphipetraeus sp. nov. at the type locality of Tha Pha Pum, Tham Sri Fah Cave, Tak Province, Thailand.