Dixonius dulayaphitakorum, Sumontha & Pauwels, 2020
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publication ID |
https://doi.org/10.11646/zootaxa.4852.2.2 |
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publication LSID |
lsid:zoobank.org:pub:BCA602DD-86E7-4BDA-95E7-0A32AA424E1B |
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DOI |
https://doi.org/10.5281/zenodo.17794738 |
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persistent identifier |
https://treatment.plazi.org/id/03B787A4-9546-162B-90E8-C8A55AA1F2C4 |
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treatment provided by |
Plazi |
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scientific name |
Dixonius dulayaphitakorum |
| status |
sp. nov. |
Dixonius dulayaphitakorum sp. nov.
( Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )
Holotype. AUP-02002 (field nr MS 626); adult male collected by Montri Sumontha on 20 February 2015 in the garden of the Ranong Marine Fisheries Research and Development Station, Ban Ring Subdistrict , Ranong city, Muang District, Ranong Province, peninsular Thailand.
Paratypes. (4) PSUZC-R 729 (field no. MS 621) and PSUZC-R 730 (field no. MS 622), adult males. AUP-02003 (field no. MS 623) and PSUZC-R 731 (field no. MS 706), adult females. All paratypes with the same locality, collector and collecting date as the holotype, except PSUZC-R 731 (field no. MS 706), collected at the same site but in December 2016 .
Diagnosis. Dixonius dulayaphitakorum sp. nov. can be distinguished from all other congeneric species by its maximal known SVL of 47.8 mm, 22 longitudinal rows of dorsal tubercles; 33 to 35 paravertebral scales; 22 longitudinal rows of ventrals across the abdomen; six or seven precloacal pores in males, no pores in females; no distinct canthal stripe; and a spotted dorsal pattern.
Description of holotype. Adult male ( Figures 1–2 View FIGURE 1 View FIGURE 2 ). SVL 46.2 mm. Head relatively long (HL/SVL ratio 0.30), wide (HW/HL ratio 0.66), not markedly depressed (HD/HL ratio 0.37), distinct from neck. Lores and interorbital region weakly inflated. Canthus rostralis relatively prominent. Snout moderately short (SnOrb/HL ratio 0.34), rounded, longer than orbit diameter (OrbD/SnOrb ratio 0.69). Scales on snout and forehead small, hexagonal to rounded, flattened, with smooth or slightly rugose surface. Scales on snout larger than those on occipital region. Eye of moderate size (OrbD/HL ratio 0.24). Pupil vertical with crenelated margins. Supraciliaries short, without spines. Ear opening rounded, moderate (EarL/HL ratio 0.09); orbit to ear distance greater than orbit diameter. Rostral about twice wider than high. Two enlarged supranasals in contact, separated posteriorly by a small scale. Rostral in contact with supralabial I on each side, nostrils and both supranasals. Nostrils round, each surrounded by supranasal, rostral, supralabial I and two postnasals. Mental triangular, about as long as deep. Two pairs of enlarged postmentals, anteriormost approximately three times larger than posterior. Each anterior postmental bordered anteriorly by mental, medially by the other anterior postmental, anterolaterally by infralabial I, posterolaterally by the second postmental; the pair collectively bordered posteromedially by a row of five throat scales. Supralabials to mid-orbital position 6/6; enlarged supralabials to angle of jaws 8/8. Infralabials 7/7. Interorbital scales 10.
Body slender, elongate (TrunkL/SVL ratio 0.43), without ventrolateral folds. Dorsal scales heterogeneous, small, irregular, flattened to conical, distributed among large, strongly keeled tubercles arranged in 22 more-or-less regular longitudinal rows at midbody. Flanks covered with irregular, smooth to slightly conical scales. Gular region with relatively homogeneous, granular scales. Ventral scales smooth, imbricate, their free margin rounded. Ventrals increasing in size from throat to chest to abdomen, somewhat smaller in precloacal region. Midbody scale rows across belly to lowest rows of tubercles 22. Seven precloacal pores in a continuous series. Pore-bearing scales not enlarged relative to adjacent scale rows. Scales in the row immediately posterior to the pore-bearing row about two times the size of other scales in precloacal region. No femoral pores or enlarged femoral scales.
Fore- and hind limbs short, slender (FAL/SVL ratio 0.10; TibL/SVL ratio 0.17). Digits slender, dilated distally, all bearing robust, slightly recurved claws. Basal subdigital lamellae narrow, without scansorial surfaces (8-9-11-11- 10 right manus; 6-9-13-14-11 right pes); setae-bearing lamellae restricted to enlarged, distal, ‘‘leaf-like’’ scansors. Scales on palm and sole small, smooth, rounded to oval. Interdigital webbing absent. Relative length of digits: III>IV>II>V>I (manus), IV>III>V>II>I (pes). Tail original; total length of tail 56.6 mm. Tail original, slender, tapering to tip, longer than snout-vent length (TailL/SVL ratio 1.23). Supracaudals markedly keeled in the anterior portion of the tail. Ventral tail scales enlarged into transverse plates.
Coloration in life. Dorsal surface of head brown with poorly contrasting, irregular dark brown spots. No distinct canthal stripe. The supralabials are white with each a brown spot. The background color of the neck and dorsum is brown, with irregular dark brown spots, similarly to the head, and two regularly disposed whitish tubercles on each side. Each flank shows four regularly aligned whitish tubercles, pursuing the series on the neck. The upper part of the tail shows the same background color as the dorsum and head, with irregular brown marks, and eight regularly arranged, poorly defined, whitish bands, the tail ending with a whitish tail tip. The upper surface of the legs is light brown with irregular small dark brown spots. Ventral surfaces of head, body, members and tail whitish, with gray palms and soles. In preservative the colors strongly fade and become less contrasted ( Figure 2 View FIGURE 2 ).
Variation. In addition to the type-series, two adult individuals, including a gravid female, were measured but not preserved. Main morphometric and meristic characters of the type-series and these two specimens are provided in Table 1 View TABLE 1 . Morphology and coloration characters of the paratypes and additional specimens agree in most respects with the holotype. The ratio TaiL/SVL among four males (all with an original tail) varies between 1.17 and 1.23; in the only female paratype with an original tail the ratio is 1.12, indicating that females might have a relatively shorter tail. There are four of five regularly aligned pairs of white tubercles on dorsum between limb insertions. The dorsal pattern does not seem to be sexually dimorphic ( Figures 1 View FIGURE 1 , 3–4 View FIGURE 3 View FIGURE 4 ). Hatchling individuals have chocolate brown dorsal surfaces, with four or five beige tubercles on each flank, and beige, regularly arranged, interrupted rings on tail ( Figure 4B View FIGURE 4 ).
Distribution and natural history. Dixonius dulayaphitakorum sp. nov. is currently known only from its typelocality in Muang District, Ranong Province ( Figure 6 View FIGURE 6 ). It is probably more widely distributed in the district and possibly in the neighboring Chumphon Province. It is a nocturnal ground-dweller, probably originally living in forest, and currently surviving in highly disturbed environments. By day it hides under tiles and wood debris ( Figure 5 View FIGURE 5 ). Amphibian and reptile species we found in the immediate surroundings included Duttaphrynus melanostictus (Schneider) (Bufonidae) , Hoplobatrachus rugulosus (Wiegmann) , Fejervarya limnocharis (Gravenhorst) , Occidozyga lima (Gravenhorst) (Dicroglossidae) , Kaloula pulchra Gray , Microhyla mukhlesuri Hasan, Islam, Kuramoto, Kurabayashi & Sumida and M. heymonsi Vogt (Microhylidae) , Hylarana erythraea (Schlegel) (Ranidae) , Polypedates leucomystax (Gravenhorst) (Rhacophoridae) , Calotes versicolor (Daudin) , Draco maculatus (Gray) and D. taeniopterus Günther (Agamidae) , Gekko gecko (Linnaeus) , Gehyra mutilata (Wiegmann) , Hemidactylus frenatus Duméril & Bibron , H. platyurus (Schneider) and H. murrayi Gleadow , Hemiphyllodactylus typus Bleeker (Gekkonidae) , Eutropis multifasciata (Kuhl) , Lygosoma bowringii (Günther) , Sphenomorphus maculatus (Blyth) (Scincidae) , Chrysopelea ornata (Shaw) and C. paradisi Boie , Coelognathus radiatus (Boie) , Gonyosoma oxycephalum (Boie), Ptyas korros (Schlegel) (Colubridae) , Cylindrophis cf. ruffus (Laurenti) (Cylindrophiidae) , Naja kaouthia Lesson (Elapidae) , Homalopsis semizonata Blyth (Homalopsidae) , Rhabdophis subminiatus (Schlegel) , Xenochrophis trianguligerus (Boie) (Natricidae) , Indotyphlops braminus (Daudin) (Typhlopidae) and Xenopeltis unicolor Reinwardt (Xenopeltidae) .
Etymology. The specific epithet is a mark of friendship honoring Mr. Santisak and Mrs. Boonneam Dulayaphitak for their support to the herpetological field work of the first author, and who often drew his attention on interesting specimens. We suggest the following common names: Djing-djok din Ranong (Thai), Ranong leaf-toed gecko (English) , Dixonius de Ranong (French), Ranong-Blattfingergecko (German).
Comparison to other species. Dixonius dulayaphitakorum sp. nov. is distinguished from D. aaronbaueri from southeastern Vietnam based on its larger size (SVL 47.8 vs. 38.6 mm), higher Ven number (22 vs. 18–19), much higher DTR number (22 vs. 11), much lower PV number (33–35 vs. 45–50), lower PV’ number (20–25 vs. 29–32), higher PrePo number (6 or 7 vs. 5), poorly marked canthal stripe, and dorsal pattern (Sp vs. U). It can be differentiated from the western Thai Dixonius hangseesom by its much higher DTR number (22 vs. 12–14), lower IL number (6 or 7 vs. 8), poorly marked canthal stripe, and dorsal pattern (Sp vs. Ba or Bl). It differs from the Thai peninsular endemic Dixonius kaweesaki by its larger size (SVL 47.8 vs. 41.6 mm), lower Ven number (22 vs. 24), much higher DTR number (22 vs. 13 or 14), higher InterOrb number (9 or 10 vs. 6 or 7), lower SL number (8 vs. 10 or 11), lower SLMOrb (6 vs. 7 or 8), lower PrePo number (6 or 7 vs. 9–11), its poorly marked canthal stripe, and its dorsal pattern (Sp vs. St). From Dixonius lao it differs by its smaller size (SVL 47.8 vs. 55.4 mm), lower Ven number (22 vs. 23 or 24), lower PV number (33–35 vs. 40–43), lower SLMOrb (6 vs. 7 or 8), lower PrePo number (6 or 7 vs. 8), and dorsal pattern (Sp vs. U). It can be distinguished from the central Thai Dixonius melanostictus by its much higher DTR (22 vs. 10 or 11), lower SL number (8 vs. 9), lower SLMOrb number (6 vs. 7), lower PrePo number (6 or 7 vs. 9), poorly marked canthal stripe, and dorsal pattern (Sp vs. St). From the southern Vietnamese Dixonius minhlei it can be separated based on its much higher DTR number (22 vs. 14 or 15), lower PV number (33–35 vs. 38–44), and poorly marked canthal stripe. From the Thai peninsular endemic Dixonius pawangkhananti , it differs by its much higher Ven number (22 vs. 16), much higher DTR number (22 vs. 16), higher PV number (33–35 vs. 30–32), higher InterOrb number (9–10 vs. 7), poorly marked canthal stripe, and dorsal pattern (Sp vs. Ba or Bl). It can be separated from Dixonius siamensis by its much smaller size (SVL 47.8 vs. 57 mm) and its much higher DTR number (22 vs. 10–14). Phyllodactylus burmanicus Annandale, 1905 , currently regarded as a subjective junior synonym of D. siamensis , has its type-locality in Tavoy, i.e., in what is now known as Dawei, in southern Myanmar, at about 450 km north of Ranong. It differs from Dixonius dulayaphitakorum sp. nov. by its smaller size (SVL 35 vs. 47.8 mm), lower SL number (6 vs. 8), lower SubLT4 number (8 or 9 vs. 12–15) and the male dorsal pattern (Sp vs. Ba). From the southern Vietnamese Dixonius taoi , Dixonius dulayaphitakorum sp. nov. can be distinguished by its much higher DTR number (22 vs. 11 or 12), weakly marked canthal stripe, and dorsal pattern (Sp vs. Bl). And from Dixonius vietnamensis it differs by its higher Ven number (22 vs. 15–21), higher DTR number (22 vs. 13–17), lower PV number (33–35 vs. 36), higher SL number (8 vs. 7), and poorly marked canthal stripe.
TABLE 1. Meristic and morphometric (in mm) data for the type series and two unvouchered specimens of Dixonius du- layaphitakorum sp. nov. Paired meristic characters are given left/right.
| Holotype, AUP-02002 | Paratype PSUZC-R 729 | Paratype PSUZC-R 730 | Paratype AUP-02003 | Paratype PSUZC-R 731 | Unvouchered specimen 1 | Unvouchered specimen 2 | |
|---|---|---|---|---|---|---|---|
| Sex | Male | Male | Male | Female | Female | Male | Female (gravid) |
| SVL | 46.2 | 39.6 | 37.6 | 40.1 | 46.0 | 47.8 | 46.5 |
| TailL | 56.6 | 46.9 | 43.9 | 44.8 | >29.5 | 57.5 | >20.3 |
| TrunkL | 20.0 | 18.8 | 15.5 | 17.5 | 21.7 | 22.2 | 22.0 |
| TailW | 4.5 | 4.5 | 4.5 | 4.2 | 5.0 | 4.7 | 3.2 |
| BW | 9.6 | 9.9 | 9.0 | 10.1 | 10.6 | 9.2 | 8.4 |
| HL | 14.0 | 12.3 | 12.2 | 12.0 | 13.5 | 14.8 | 13.7 |
| HW | 9.3 | 8.0 | 7.9 | 7.8 | 8.6 | 8.9 | 7.8 |
| HD | 5.2 | 4.3 | 4.6 | 4.5 | 6.0 | 5.7 | 5.0 |
| EarL | 1.3 | 1.0 | 1.0 | 1.2 | 1.3 | 1.0 | 0.9 |
| TibL | 7.9 | 6.5 | 6.2 | 6.4 | 7.6 | 8.0 | 7.0 |
| FAL | 4.6 | 4.6 | 4.4 | 4.5 | 5.6 | 6.8 | 6.0 |
| OrbD | 3.3 | 2.8 | 2.7 | 2.5 | 3.0 | 3.3 | 2.9 |
| NosOrb | 3.7 | 3.2 | 3.1 | 3.2 | 3.8 | 4.1 | 3.8 |
| SnOrb | 4.8 | 4.4 | 4.3 | 4.1 | 4.8 | 5.6 | 4.8 |
| OrbEar | 3.9 | 3.3 | 3.1 | 3.3 | 4.1 | 4.3 | 3.9 |
| InterN | 2.1 | 1.7 | 1.6 | 1.7 | 2.0 | 2.1 | 2.0 |
| InterOrb | 2.2 | 1.9 | 1.7 | 1.9 | 2.3 | 2.4 | NA |
| Ven | 22 | 22 | 22 | 22 | 22 | 22 | 22 |
| DTR | 22 | 22 | 22 | 22 | 22 | 22 | 22 |
| PV | 35 | 34 | 33 | 34 | 34 | NA | NA |
| PV’ | 22 | 25 | 20 | 24 | 24 | NA | NA |
| SubLT4 | 14/13 | 14/13 | 14/14 | 15/15 | 12/12 | NA | NA |
| InterOrb | 10 | 9 | 10 | 10 | 9 | NA | NA |
| ICS | 30 | 30 | 30 | 33 | 31 | NA | NA |
| SL | 8/8 | 8/8 | 8/8 | 8/8 | 8/8 | 8/8 | 8/8 |
| IL | 7/7 | 7/6 | 7/7 | 7/7 | 7/7 | 7/7 | 7/7 |
| SLMOrb | 6/6 | 6/6 | 6/6 | 6/6 | 6/6 | 6/6 | 6/6 |
| PrePo | 7 | 6 | 6 | 0 | 0 | 6 | 0 |
| FemPo | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
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