Dixonius gialaiensis, Luu & Nguyen & Le & Grismer & Ha & Sitthivong & Hoang & Grismer, 2023
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publication ID |
https://dx.doi.org/10.3897/zookeys.1163.101230 |
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publication LSID |
lsid:zoobank.org:pub:9D07C59D-7AF6-4428-BB1A-79D029368CA9 |
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persistent identifier |
https://treatment.plazi.org/id/10BF67E1-8059-47CE-891C-B219BD7AA9C1 |
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taxon LSID |
lsid:zoobank.org:act:10BF67E1-8059-47CE-891C-B219BD7AA9C1 |
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treatment provided by |
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scientific name |
Dixonius gialaiensis |
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sp. nov. |
Dixonius gialaiensis sp. nov.
Fig. 8 Gialai leaf-toed gecko View Figure 8
Material examined.
Holotype. Adult male, VNUF R.2020.22 (Field no. GL02) in Chu Se Mountain Pass , H'Bong Commune , Chu Se District, Gia Lai Province (13°34'44.3"N, 108°13'55.7"E; 330 m a.s.l.), collected by Oanh Van Lo and Khanh Quoc Nguyen on 15 February 2020 GoogleMaps . Paratypes. VNUF R.2020.44 (Field No. GL 04), juvenile male, and VNUF R.2020.33 (Field No. GL 03), adult female; the same data as the holotype GoogleMaps .
Diagnosis.
Dixonius gialaiensis sp. nov. can be separated from all other species of Dixonius by possessing the unique combination of having a maximum SVL of 47.4 mm; 19 longitudinal rows of dorsal tubercles at midbody; 19-21 longitudinal rows of ventrals across the abdomen; 7 or 8 supralabials, sixth in at midorbital position; 6 or 7 infralabials; 7 interorbital scales; 7 or 8 precloacal pores in males, femoral pores lacking; precloacal and femoral pores absent in female; 13-15 lamellae on fourth toe; dorsum olive grey color with more round brown blotches; canthal stripe continues behind orbit to back of head; lips with dark bars; two regularly disposed whitish tubercles along the sides near the flanks to tail tip. These characters are scored across all Dixonius species from Vietnam and Laos in Tables 6 View Table 6 , 7 View Table 7 .
Description of the holotype.
Adult male, SVL 41.2 mm; head moderate in length (HL/SVL 0.28), wide (HW/HL 0.66), depressed (HD/HL 0.44), distinct from neck; prefrontal region concave; canthus rostralis rounded; snout elongate (ES/HL 0.37), rounded in dorsal profile; eye moderate size (ED/HL 0.25); ear opening oval, obliquely oriented, moderate in size; diameter of eye slightly smaller than eye to ear distance (ED/EE 0.88); rostral rectangular, partially divided dorsally by straight rostral groove, bordered posteriorly by large left and right supranasals, bordered laterally by first supralabials; external nares bordered anteriorly by rostral, dorsally by large supranasal, posteriorly by two smaller postnasals, bordered ventrally by first supralabial; 8,7 (R,L) rectangular supralabials extending to below and slightly past posterior margin of eye, sixth in midorbital position; 6,6 (R,L), infralabials tapering smoothly to just below midpoint of eye, decreasing gradually in size; scales of rostrum and lores flat to domed, larger than granular scales on top of head and occiput; scales of occiput intermixed with distinct, small, conical tubercles; superciliaries elongate, largest anteriorly; mental triangular, bordered laterally by first infralabials and posteriorly by large left and right trapezoidal postmentals contacting medially for 60% of their length posterior to mental; gular and throat scales small, granular, grading anteriorly into slightly larger, flatter, smooth, imbricate, pectoral and ventral scales.
Body relatively short (AG/SVL 0.38); dorsal scales small, granular interspersed with larger, conical, regularly arranged, keeled tubercles; tubercles extend from top of head onto posterior haft of tail forming longitudinal rows, terminating at last portion of tail; smaller tubercles extend anteriorly onto nape and occiput, diminishing in size and distinction on top of head; 19 longitudinal rows of tubercles at midbody; 33 paravertebral scales, number of scales in a paravertebral row from first scale posterior to parietal scale to last scale at the level of vent opening; 23 paravertebral scales in a row between limb insertions; 21 flat, imbricate, ventral scales much larger than dorsal scales; 7 enlarge, pore-bearing, precloacal scales in an angular series; and no deep precloacal groove or depression.
Forelimbs moderate in stature, relatively short (FA/SVL 0.15); granular scales of forearm slightly larger than those on body, interspersed with small tubercles; hind limbs more robust than forelimbs, moderate in length (TBL/SVL 0.17), covered dorsally by granular scales interspersed with large, and small conical tubercles; ventral scales of thigh flat, imbricate, larger than dorsals; subtibial scales flat, imbricate; proximal femoral scales smaller than distal femorals; femoral pores absent; digits relatively long with 14 lamellae on fourth toe; and claws well developed.
Tail 108.4 mm in length, 4.5 mm in width at base, tapering to a point; dorsal scales of flat, square with conical, keeled tubercles in anterior part; median row of transversely expanded subcaudal scales, significantly larger than dorsal caudal scales on original portion; base of tail bearing hemipenal swellings; and postcloacal scales flat, imbricate.
Coloration in life
(Fig. 8 View Figure 8 ). Ground color of dorsal head and dorsum grey brown with rounded black-brown blotches, decreasing gradually in size from head to body; canthal stripe continues behind orbit to back of head; dark bars on the lips; uneven light spots running from postorbital along the flanks to tip tail; upper surface of fore- and hindlimbs uniformly light grey with black-brown spots; dorsum of tail covered with some small rounded black-brown blotches; ventral surface beige uniformly as the belly and the throat.
Variation
(Fig. 8 View Figure 8 ). The female paratype (VNUF R.2020.33) generally has more dark brown blotches on head and dorsum, and uniformly black on the new regenerated tail. The dorsum of the of head and body of the juvenile male paratype (VNUF R.2020.44) pale brown with pale-colored blotches on granulose skin arranged along its sides extending from the flanks to the tail tip. Further measurements are summarized in Tables 2 View Table 2 - 4 View Table 4 , Suppl. material 1: table S1.
Distribution.
Dixonius gialaiensis sp. nov. currently is only known from the type locality of Chu Se Mountain Pass, H’Bong Commune, Chu Se District, Gia Lai Province, Central Highlands, Vietnam (Fig. 1 View Figure 1 ).
Natural history.
The specimens were found at night, between 19:45 and 21:00 h, on the ground in an area along the National Highway 25. The surrounding habitat was secondary montane forest with woody trees. The temperature and humidity were approximately 32.6 °C and 57% (Fig. 9 View Figure 9 ).
Etymology.
The new species is named after the type locality of Gia Lai Province, Central Highlands, Vietnam.
Comparisons.
Dixonius gialaiensis sp. nov. is the sister species to D. minhlei (Fig. 2 View Figure 2 ) from which it differs by an uncorrected pairwise sequence divergence of 3.60% (Table 4 View Table 4 ). It is differentiated from it morphologically by having a significantly higher mean number of head length (HL), head width (HW), and axilla to groin length (AG). In addition, it differs from D. minhlei in color pattern (grey-brown dorsum with more round black-brown blotches versus olive gray dorsum with round brownish olive blotches). Statistically significant and discrete categorical differences between Dixonius gialaiensis sp. nov. and all other species and populations are presented in Tables 5 View Table 5 - 7 View Table 7 .
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