Dixonius kaweesaki Sumontha, Chomngam, Phanamphon, Pawangkhanant, Viriyapanon, Thanaprayotsak & Pauwels, 2017, sp. nov.
Creators: name: Sumontha, Montri
name: Chomngam, Nirut
name: Phanamphon, Eakarit
name: Pawangkhanant, Parinya
name: Viriyapanon, Chutinton
name: Thanaprayotsak, Wanlada
name: Pauwels, Olivier S. G.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Gekkonidae
Dixonius
Dixonius kaweesaki

description: Dixonius kaweesaki sp. nov.
(Figs 1–6)
Holotype. THNHM 25607 (field no. MS 566); adult male from Khao Daeng, Kui Buri District, Prachuap Khiri Khan Province, peninsular Thailand; collected by K. Keeratikiat on 20 June 2014.
Paratypes. PSUZC 718 (field no. MS 568), adult male; PSUZC 719 (field no. MS 567), adult female; ZMKU Rep-000319 (field no. MS 570), subadult female; all same locality, collecting date and collector as holotype.
Diagnosis. Dixonius kaweesaki sp. nov. can be distinguished from all other congeneric species by its combination of a maximal SVL of 41.6 mm; 12 or 13 longitudinal rows of dorsal tubercles; 24 longitudinal rows of ventrals across the abdomen; a continuous series of 9-11 precloacal pores in males, no pores in females; and two bold dark stripes from the snout to the base of the tail separated by a contrasting light vertebral stripe.
Description of holotype. Adult male. SVL 41.6 mm. Head relatively long (HeadL/SVL ratio 0.31), wide (HeadW/HeadL ratio 0.62), not markedly depressed (HeadH/HeadL ratio 0.44), distinct from slender neck. Lores and interorbital region weakly inflated, canthus rostralis relatively prominent. Snout moderately short (SnOrb/ HeadL ratio 0.35), rounded, longer than orbit diameter (OrbD/SnOrb ratio 0.84); scales on snout and forehead small, hexagonal to rounded, flattened, with smooth or slightly rugose surface, some conical; scales on snout larger than those on occipital region. Eye moderately large (OrbD/HeadL ratio 0.29); pupil vertical with crenelated margins; supraciliaries short, without spines. Ear opening oval, obliquely oriented, moderate (EarL/HeadL ratio 0.05); orbit to ear distance subequal to orbit diameter. Rostral about twice wider than high, two enlarged supranasals in broad contact; 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, as wide as deep; two pairs of enlarged postmentals, anteriormost approximately three times larger than posterior; each anterior postmental bordered anteriorly by mental, medially by other anterior postmental, anterolaterally by 1st and 2nd infralabials; the pair collectively bordered posteromedially by a row of four throat scales. Supralabials to midorbital position 8/7; enlarged supralabials to angle of jaws 10/10. Infralabials 8/8. Interorbital scales 6. Body slender, elongate (AG/SVL ratio 0.42), without ventrolateral folds. Dorsal scales heterogeneous, small, irregular, flattened to conical scales distributed among large, strongly keeled subimbricate tubercles arranged in 12 or 13 more-or-less regular longitudinal rows at midbody; flanks covered with irregular smooth scales. Ventral scales smooth, imbricate; free margins rounded; increasing in size from throat to chest to abdomen, somewhat smaller in precloacal region; midbody scale rows across belly to lowest rows of tubercles, 24; gular region with relatively homogeneous, granular scales. Eleven precloacal pores in a continuous series; pore-bearing scales not enlarged relative to adjacent scale rows; scales in row immediately posterior to pore-bearing row 2 to 3 times size of other scales of cloacal region. No femoral pores or enlarged femoral scales.
Fore- and hind limbs short, slender (ForeaL/SVL ratio 0.13; TibiaL/SVL ratio 0.18). Digits slender, dilated distally, all bearing robust, slightly recurved claws. Basal subdigital lamellae narrow, without scansorial surfaces (6-9-11-11-10 manus, 7-13-16-15 -14 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). Total length of tail 29.2 mm, last 17.3 mm regenerated. Tail slender, tapering to tip, shorter than snout-vent length (TailL/SVL ratio 0.70); whorls of keeled scales on dorsum of basal portion of tail, lateral and distal scales lacking well-developed keels; ventral tail scales enlarged into transverse plates both in the original and regenerated portions, although much shorter in the regenerated part.
Coloration in life. Dorsal surface of head gray. Behind the nostril a black canthal stripe runs through the eye, joins the upper part of the flanks and extends along the body to the first fifth of the tail where it progressively fades out posteriorly. These two black stripes are bordered on their upper side by a contrasting whitish vertebral stripe which runs all along the dorsum from the nape to the beginning of the tail. On their lower sides, the two black stripes progressively turn into grey, then light gray and eventually become uniformly whitish as the belly and the throat. The upper surface of limbs, hands and feet is uniformly light gray. The vertebral whitish stripe is prolonged anteriorly by two thin stripes running through the temporal area above the postorbital black stripe and above the eye where the supraciliaries are whitish. Supralabials are grey with thin white vertical bars. The dorsal surface of the original part of the tail is light orange, with regularly arranged darker and lighter thin bands. In preservative the colors fade out, and are replaced by nuances of light brown and beige (compare live individuals of Figures 4–6 with the preserved holotype on Figure 1).
Variation. The morphometric and meristic characters of the type series are provided in Table 1. Morphological and coloration characters of the paratypes agree in most respects with the holotype. Two of the paratypes, both females, have an original and complete tail, with a TailL/SVL ratio of 1.55 (PSUZC 719) and 1.36 (ZMKU Rep- 000319), respectively. Precloacal pores are absent in females. Subdigital lamellae of paratype PSUZC 718 6-8-10- 10-8 (manus) and 7-12-16-15-13 (pes), of paratype PSUZC 719 7-8-10-10-7 (manus) and 7-12-16-15-13 (pes). Colors in life are bolder and more contrasted in young individuals than in adults (compare Fig. 6 with Figs 4 and 5).
Distribution and natural history. Dixonius kaweesaki sp. nov. is currently known only from its type locality Khao Daeng in Kui Buri District (Figure 7). The limestone reliefs on which it was found are an extension of the Khao Sam Roi Yot massif, itself a subrange of the Tenasserim Hills. We suspect that the species occurs at other localities within the massif, probably on all limestone hills of the Khao Sam Roi Yot National Park. The species is locally common, nocturnal, and lives in dry microhabitat on limestone boulders (Figure 8), from 5 m to 300 m a.s.l. It was found to be most active between 0 100 and 0 400 hrs, especially after rainfall. We observed it in syntopy with Cnemaspis siamensis (Smith), Cyrtodactylus samroiyot Pauwels & Sumontha, 2014, Dixonius siamensis, Gehyra fehlmanni (Taylor), G. lacerata (Taylor) and G. mutilata (Wiegmann), Gekko gecko (Linnaeus) (Gekkonidae), Ahaetulla nasuta Bonnaterre, Dendrelaphis subocularis (Boulenger), Lycodon capucinus (Boie) (Colubridae), Indotyphlops braminus (Daudin) (Typhlopidae) and Trimeresurus sp. (Viperidae). Additional geographically close populations of Dixonius siamensis are documented north and south of the type locality of Dixonius kaweesaki sp. nov., in Phetchaburi and Prachuap Khiri Khan provinces (Chan-ard et al. 1999; Pauwels and Chan-ard 2006; Pauwels et al. 2009; Figure 10; Appendix).
Etymology. The specific epithet honors the Thai naturalist Kaweesak (Toi) Keeratikiat from Bangkok, in recognition to his help in our herpetological field surveys, and who collected the type series. We suggest the following common names: Djing-djok din Sam Roi Yot (Thai), Sam Roi Yot leaf-toed gecko (English), Dixonius de Sam RoÏ Yot (French), Samroiyot Blattfingergecko (German).
Comparisons to other species. Based on its color pattern, Dixonius kaweesaki sp. nov. can be readily distinguished from all other recognized Dixonius species. The absence of dorsal spots, ocellae and transversal bands readily diagnoses it from D. hangseesom, D. minhlei, D. siamensis (Figure 10; see also individuals from Chaiyaphum, Chon Buri, Loei, Prachuap Khiri Khan, Sisaket and Udon Thani provinces illustrated by Manthey & Grossmann 1997, Chan-ard et al. 1999 and Taylor 1963), D. taoi and D. vietnamensis. The presence of a lateral wide dark stripe on the upper flanks distinguishes it from D. aaronbaueri (absence of stripes, bands or any pattern on dorsum), D. hangseesom (no dark dorsal stripe; see Figure 11), D. melanostictus (lateral wide dark stripe on the lower flanks, not on the upper flanks; see Figure 9 and individuals from Nakhon Ratchasima and Saraburi provinces illustrated by Taylor 1963 and Chan-ard et al. 1999), D. minhlei (no dark dorsal stripe), D. siamensis (no dark dorsal stripe), D. taoi (no dark dorsal stripe) and D. vietnamensis (no dark dorsal stripe). The presence of a vertebral stripe abruptly lighter than the upper flank background color is unique to Dixonius kaweesaki sp. nov. This latter contrast is most marked in young individuals where the vertebral stripe is white and the upper flank color is black. The drawings presented in the original description of Phyllodactylus paviei (Mocquard, 1904) from ‘‘Vatana (Siam)’’and in a complement to the description of Phyllodactylus burmanicus Annandale, 1905a (Annandale 1905b) from ‘‘Tavoy’’, both currently regarded as junior subjective synonyms of D. siamensis (Bauer et al. 2004), show a blotched dorsal pattern without dark stripes; they also both lack a dark canthal stripe.
Besides its unique color pattern Dixonius kaweesaki sp. nov. can be also easily distinguished from all other Dixonius by its combination of meristic and morphometric characters. It indeed differs from D. aaronbaueri by its slightly larger size (maximum SVL 41.6 vs. 38.6 mm), its higher SL number (10 or 11 vs. 8 or 9), distinctly higher Ven number (24 vs. 18 or 19), slightly higher DorTubR number (12 or 13 vs. 11) and its sensibly higher number of precloacal pores in males (9–11 vs. 5). From D. hangseesom it differs by its higher SL number (10 or 11 vs. 8), distinctly lower Interorb number (6 or 7 vs. 10), its higher SubLT4 (15 vs. 13) and its higher number of precloacal pores in males (9–11 vs. 6–8). It can be separated from D. melanostictus by its smaller maximum SVL (41.6 vs. 50 mm), its higher SL number (10 or 11 vs. 9), its higher Ven number (24 vs. 22), and slightly higher DorTubR number (12 or 13 vs. 10 or 11). From D. minhlei it differs by its slightly smaller size (maximum SVL 41.6 vs. 47.5 mm), its higher SL number (10 or 11 vs. 7–9), lower DorTubR number (12 or 13 vs. 14 or 15), higher Ven number (24 vs. 20–23), and its higher number of precloacal pores in males (9–11 vs. 7 or 8). From D. siamensis it differs by its much smaller size (maximum SVL 41.6 vs. 57 mm), higher SL number (10 or 11 vs. 7 or 8), and higher number of precloacal pores in males (9–11 vs. 6 or 7). It is distinguished from D. taoi by its higher SL number (10 or 11 vs. 7 or 8), higher Ven number (24 vs. 21–23), higher SubLT4 (15 vs. 12–14) and higher number of precloacal pores in males (9–11 vs. 5 or 6). From D. vietnamensis it differs by its higher SL number (10 or 11 vs. 7), higher Ven number (24 vs. 20), generally lower DorTubR number (12 or 13 vs. 13–17) and higher SubLT4 (15 vs. 13). Phyllodactylus burmanicus shows 6 SL, 6 IL, 8 or 9 SubLT4, 7 precloacal pores and a maximum known SVL of 35 mm (Annandale 1905a – b). Phyllodactylus paviei shows 8 SL, 6 precloacal pores and a maximum known SVL of 46 mm (Mocquard 1904).
description: Published as part of Sumontha, Montri, Chomngam, Nirut, Phanamphon, Eakarit, Pawangkhanant, Parinya, Viriyapanon, Chutinton, Thanaprayotsak, Wanlada & Pauwels, Olivier S. G., 2017, A new limestone-dwelling leaf-toed gecko (Gekkonidae: Dixonius) from Khao Sam Roi Yot massif, peninsular Thailand, pp. 556-568 in Zootaxa 4247 (5) on pages 557-562, DOI: 10.11646/zootaxa.4247.5.2, http://zenodo.org/record/439160