Dixonius fulbrighti, Luu & Grismer & Hoang & Murdoch & Grismer, 2023
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publication ID |
https://dx.doi.org/10.3897/evolsyst.7.105850 |
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publication LSID |
lsid:zoobank.org:pub:E54BFCD3-E0CB-4984-AC62-2E0DC3072F21 |
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persistent identifier |
https://treatment.plazi.org/id/F9F5907A-1B5D-4985-B6FE-8B4092947C56 |
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taxon LSID |
lsid:zoobank.org:act:F9F5907A-1B5D-4985-B6FE-8B4092947C56 |
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treatment provided by |
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scientific name |
Dixonius fulbrighti |
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sp. nov. |
Dixonius fulbrighti sp. nov.
Fulbright Leaf-toed Gecko, Fig. 8 View Figure 8
Type material.
Holotype. Adult male, VNUF R.2022.81 (Field no. GL22.01) in Grong Village, Ia Krieng Commune, Duc Co District, Gia Lai Province (13°44'25.6"N, 107°43'39.5"E; 372 m a.s.l.), collected by Vinh Quang Luu, Tron Thanh Tran, Siu Biu, Ksor Lang on 8 July 2022.
Paratypes. VNUF R.2022.82 (Field GL22.02), adult female, VNUF R.2020.83 (Field No. GL22.03), juvenile female, VNUF R.2020.84 (Field No. GL22.04), juvenile female; bear the same data as the holotype.
Diagnosis.
Dixonius fulbrighti sp. nov. can be separated from all other species of Dixonius by possessing the unique combination of having a maximum SVL of 46.0 mm; 16-20 longitudinal rows of dorsal tubercles at midbody; 22-24 longitudinal rows of ventrals across the abdomen; seven-nine supralabials, sixth in at midorbital position; five-seven infralabials; eight or nine interorbital scales; seven precloacal pores in the adult male, femoral pores lacking; seven precloacal-pitted scales, femoral pores absent in adult female; 13-15 lamellae on fourth toe; dorsal ground color grey-brown with the presence of thick, irregular-shaped, black brown blotches from head to body; canthal stripe extending from the nostrils continuing behind orbit to back of head; dark bars on the lips absent; two rows of regularly disposed whitish tubercles along the flanks to originale portion of tail. These characters are scored across all Dixonius species from Vietnam and Laos in Tables 6 View Table 6 and 7 View Table 7 .
Description of the holotype.
Adult male, SVL 46.0 mm; head moderate in length (HL/SVL 0.30), wide (HW/HL 0.57), depressed (HD/HL 0.42), distinct from neck; prefrontal region concave; canthus rostralis rounded; snout elongate (ES/HL 0.35), rounded in dorsal profile; eye moderate size (ED/HL 0.16); ear opening oval, obliquely oriented, moderate in size; diameter of eye smaller than eye to ear distance (ED/EE 0.59); 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; 8,8 (R,L) rectangular supralabials extending to below and slightly past posterior margin of eye, sixth in midorbital position; 6,7 (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 two postmentals (large right trapezoidal shape and left irregular shape) 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 0.44); dorsal scales small, granular interspersed with larger, conical, regularly arranged, keeled tubercles; tubercles extend from top of head onto posterior half of original tail forming longitudinal rows, terminating at last portion of orginale tail; smaller tubercles extend anteriorly onto nape and occiput, diminishing in size and distinction on top of head; 18 longitudinal rows of tubercles at midbody; 32 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; 22 paravertebral scales in a row between limb insertions; 24 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 0.12); 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 0.15), 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.
Regenerated tail 46.4 mm in length, 5.4 mm in width at base, tapering to a point; dorsal scales of tail flat, oval 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 ) Dorsal ground color of grey-brown with thick, irregular-shaped, black to brown blotches extending from head to the body; canthal stripe extending from behind the nostrils conitinuing behind orbit to back of head; dark bars on lips; uneven light-colored spots running from postorbital region along the flanks to the base of tail; dorsal surface of fore- and hind limbs uniformly light-grey with dark-brown spots; dorsum of orginal tail covered with some small black to brown blotches; all ventral surfaces uniformly beige.
Variation.
(Fig. 8 View Figure 8 ) The female paratypes (VNUF R.2022.82-84) are generally uniformly brown dorsally with uneven light-colored spots running from the postorbital region along the flanks to the tail tip; dorsum of posterior part of tail grey with narrowed light-colored bands. Additional measurements are in Tables 2 View Table 2 , 3 View Table 3 , 8 View Table 8 .
Distribution.
Dixonius gialaiensis sp. nov. is currently known only from the type locality of in Grong Village, Ia Krieeng Commune, Duc Co District, Gia Lai Province, Central Highlands, Vietnam (Fig. 1 View Figure 1 ).
Natural history.
The specimens were found on the forest floor, during the evening between 1900 hrs and 2000 hrs. The surrounding habitat consisted of secondary forest with Narra Padauk ( Pterocarpus macrocarpus ) trees as the dominant species and shrub trees on the forest floor (Fig. 9 View Figure 9 ). Currently, the area is managed by the local commune, but it is not part of any protected area system. Therefore, further investigation on the population status is needed to suggest appropriate conservation measures.
Etymology.
The new species is named after Mr. J. William Fulbright, the founder of the Fulbright Program which has provided opportunities for thousands of students, scholars, and professionals from around the world to study, teach, and conduct research in the United States and other countries in order to promote a greater understanding and cooperation between nations.
Comparisons.
Dixonius fulbrighti sp. nov. is the sister species to a clade containing D. gialaiensis and D. minhlei (Fig. 2 View Figure 2 ). It differs from the former by an uncorrected pairwise sequence divergence of 3.12% (Table 4 View Table 4 ) and significantly normalized morphometric characters, including a significantly lower mean head length (HL) (1.03 vs. 1.07, p = 0.021), head width (HW) (0.81 vs. 0.89, p = 0.001), head depth (HD) (0.54 vs. 0.73, p = <0.001), eye diameter (ED) (0.33 vs. 0.47, p = <0.001), and tibia length (TBL) (0.75 vs. 0.83, p = <0.006). In addition, it differs from D. gialaiensis in dorsal color pattern of head and body (thick, irregular-shaped, back brown blotches versus disseminated round black brown blotches). It differs from the latter by 3.6% genetic difference (Table 4 View Table 4 ). Additionally, the new species can be distinguished from D. minhlei by having a significantly higher mean number of head length (HL) (1.03 vs. 0.86, p = 0.000), a significantly lower mean number of body width (BW) (0.85 vs. 0.97, p = <0.001), head depth (HD) (0.54 vs. 0.67, p = <0.001), eye diameter (ED) (0.33 vs. 0.45, p = <0.001), eye nostril distance (EN) (0.45 vs. 0.55, p = <0.001), eye snout distance (ES) (0.55 vs. 0.68, p = <0.001), forearm length (FA) (0.66 vs. 0.80, p = <0.001), tibia length (TBL) (0.75 vs. 0.86, p = <0.001), and axilla to groin length (AG) (1.18 vs. 1.33, p = <0.001). Additionally, the new species differs from D. minhlei by the presence of two regularly disposed whitish tubercles on each side of body (absent in D. minhlei ). Statistically significant differences among D. fulbrighti sp. nov. and all other species and populations are presented in Tables 5 View Table 5 - 7 View Table 7 .
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