Hemiphyllodactylus kyaiktiyoensis Grismer & Wood & Quah & Thura & Oaks & Lin 2020, sp. nov.

Hemiphyllodactylus kyaiktiyoensis sp. nov. Kyaiktiyo Mountain Slender Gecko

(Figs. 7, 9)

Holotype. Adult female (LSUHC 14032) collected on 4 November 2018 at 1900 hrs by Evan S. H. Quah, L. Lee Grismer, Perry L. Wood Jr., Myint Kyaw Thura, Jamie R. Oaks, and Aung Lin along a trail leading down the northwest facing flank of the mountain from the Golden Rock Pagoda, Mon State, Myanmar (17.47840°N 97.10042°E WGS; 1057 m in elevation).

Paratypes. Female paratypes (LSUHC 14030–31, 14033–34) bear the same collection data as the holotype.

Diagnosis. Hemiphyllodactylus kyaiktiyoensis sp. nov. can be separated from all other species of Hemiphyllodactylus by possessing the unique combination of having a maximum SVL of 43.4 mm; 8–10 chin scales; enlarged postmentals; five circumnasal scales; 3–5 intersupranasals (=postrostrals); 7–10 supralabials; eight or nine infralabials; 12–16 longitudinally arranged dorsal scales at midbody contained within one eye diameter and eight or nine ventral scales; four subdigital lamellae on the first finger and four or five on first toe; no plate-like subcaudal scales; adult females not yellow; a dark postorbital stripe extending to at least base of neck; dorsolateral light-colored spots on trunk; no dark, dorsolateral stripe on trunk; faint, dark, ventrolateral stripe on trunk; no dark-colored pattern on trunk; wide, light-brown, nearly unicolor, vertebral region on trunk; beige, postsacral marking bearing anteriorly projecting arms; and caecum and gonads unpigmented. These characters are scored across all Burmese species in Tables 3 and 6 and from all other species of Hemiphyllodactylus from southern China and western Thailand (clades 3 and 4 in Grismer et al. [2017: Table 3]).

Description of holotype Adult female SVL 43.4 mm; head triangular in dorsal profile, depressed, distinct from neck; lores flat; rostrum moderate in length (SN/SVL 0.11); prefrontal region weakly concave; canthus rostralis smoothly rounded, barely discernable; snout moderate, rounded in dorsal profile; eye large; ear opening elliptical, small; eye to ear distance greater than diameter of eye; rostral wider than high, bordered posteriorly by large supranasals; three equally sized intersupranasals (=postnasals); external nares bordered anteriorly by rostral, dorsally by supranasal, posteriorly by two postnasals, ventrally by first supralabial (=circumnasals); nine (R, L) rectangular supralabials tapering to below posterior margin of eye; 8 (R, L) rectangular infralabials tapering to below posterior margin of eye; scales of rostrum, lores, top of head, and occiput small, granular, those of rostrum largest, slightly raised; dorsal superciliaries flat, mostly square, subimbricate, largest anteriorly; mental triangular, bordered laterally by first infralabials and posteriorly by two rectangular postmentals; each postmental in contact with first infralabial and bordered laterally by slightly smaller sublabial; 10 chin scales; gular scales small, subimbricate, grading posteriorly into slightly larger, subimbricate throat and even larger pectoral scales which grade into slightly larger, subimbricate ventrals.

Body somewhat elongate (AG/SVL 0.54), dorsoventrally compressed; ventrolateral folds absent; dorsal scales small, granular, 13 dorsal scales at midbody contained within one eye diameter; ventral scales flat, subimbricate much larger than dorsal scales, eight ventral scales contained within one eye diameter; precloacal scales larger than abdominal scales; no pore-bearing femoroprecloacal scales; single enlarged tubercle on lateral margin of tail base; forelimbs short, robust in stature, covered with flat, subimbricate scales dorsally and ventrally; palmar scales flat, subimbricate; all digits except digit I well-developed; digit I vestigial, clawless; distal subdigital lamellae of digits II–V undivided, angular, U-shaped, lamellae proximal to these transversely expanded; distal lamellar formula of digits II–V 3-3-4-3 (R, L); four transversely expanded lamellae on digit I; claws on digits II–V well developed, unsheathed; distal portions of digits strongly curved, terminal joint free, arising from central portion of lamellar pad; hind limbs short, more robust than forelimbs, covered with raised, juxtaposed scales dorsally and by larger, flat, subimbricate scales anteriorly and ventrally; plantar scales slightly raised, subimbricate; all digits except digit I well-developed; digit I vestigial, clawless; distal subdigital lamellae of digits II–V undivided, angular, and Ushaped, lamellae proximal to these transversely expanded; distal lamellar formula of digits II–V 3-4-4-4 (R, L); five transversely expanded lamellae on digit I; claws on digits II–V well-developed, unsheathed; distal portions of digits strongly curved, terminal joint free, arising from central portion of lamellar pad; caudal scales occurring in whorls; dorsal caudal scales of original tail larger than dorsal body scales, flat, subcycloid, subimbricate; ventrolateral caudals enlarged, weakly flared giving a fringe-like appearance punctuated every five or six scales by even larger, raised scales; subcaudals flat slightly larger than dorsal caudals, not plate-like; posterior one-half of tail regenerated; dorsal caudals of regenerated portion smaller, more irregular in shape; other caudal scales generally same shape as those in original tail. Morphometric data are presented in Table 9.

Coloration in life (Fig. 7). All Hemiphyllodactylus are capable of considerable change in the intensity and boldness of their coloration and pattern. The description below is of that when the holotype was photographed the morning after capture, approximately 12 hours after the time of collection when in its light-phase. Ground color of top of head, body, limbs, and tail dull-yellow or straw; top of head overlain with a dense dark-brown mottling giving top of head a brownish appearance; brown, semi-reticulate pattern on top of head; broad, dark, diffuse pre- and postorbital stripe extends from external nares, through eye to forelimb, preorbital portion very faint; wide, nearly immaculate, light-brown stripe with crenulated margins extends from nape to base of tail, nearly covering entire dorsum; invaginations of crenulated margins contain a diffuse, light-colored spot that collectively appear as regularly spaced, dorsolateral spots along trunk; faint, dark, ventrolateral stripe on trunk; immaculate, beige, postsacral marking bears light-colored, anteriorly projecting arms; flanks faintly mottled with diffuse brown speckling; limbs bearing irregularly shaped, diffuse, brown bands and markings; base of toes bearing a faintly orange spot; gular region mottled with brown and faint stippling in scales; pigmentation density in scales decreases posteriorly with the abdomen being generally beige with faint stippling; original portion of tail bearing four faint, irregularly shaped, brown bands and heavily mottled interspaces; enlarged scales of ventrolateral fringe highlighted in white; subcaudal region densely stippled; regenerated portion of tail brownish with faint, dark markings.

Variation (Figs. 7, 9). The color pattern of the paratypes (LSUHC 14030–31, 14033–34) generally match that of the holotype. The dark, dorsal patterns of LSUHC 14031 and 14033 are slightly bolder. LSUHC 14030 has a more lightly colored dorsal pattern overall and the dorsolateral trunk spots are more obvious. Variation in scales counts, mensural data, and additional minor aspects in coloration are presented in Table 9.

Distribution. Hemiphyllodactylus kyaiktiyoensis sp. nov. is known only from the type locality on Kyaiktiyo Mountain in Mon State, Myanmar but is expected to occur in other, nearby upland areas (Fig. 1).

Natural History. All individuals of the type series were found on the brick wall of a house at night beneath a neon light approximately 2.5 meters above the ground in disturbed hill forest (Fig. 10). No other geckos were found on the wall but Hemidactylus garnotii, Hemidactylus brookii, Gehyra mutilata, and Cyrtodactylus aequalis were abundant on all other nearby vegetation and human-made structures. Specimens LSUHC 14032–34 were gravid with two eggs indicating the month of November falls within the reproductive season of this species. Although no males were found, we cannot determine if this species is parthenogenetic or not.

Etymology. The specific epithet is a toponym referring to the type locality of Kyaiktiyo Mountain, Mon State, Myanmar.

Comparisons. The molecular analyses indicate that Hemiphyllodactylus kyaiktiyoensis sp. nov. is a genetically distinct member of the south lineage and is the sister species to H. pinlaungensis sp. nov. (Fig. 1) from which it bears an uncorrected pairwise sequence divergence of 9.5% (Table 10). Hemiphyllodactylus kyaiktiyoensis sp. nov. differs significantly from H. pinlaungensis sp. nov. in having a lower mean value of CS (9.2 vs 11.2, p = 0.014) and a lower adjusted mean value of SN (1.242 vs 1.363) p = 0.018, respectively; Table 6, Fig. 3). It differs further from H. pinlaungensis sp. nov. by having a significantly different centroid position based on the factor loadings of the PC1–3 (p = 0.002; Fig. 3). This latter metric can not be considered a diagnostic character but serves as a measure of the quantitative difference between these two species in multivariate space. Its differences from H. zwegabinensis sp. nov. are listed above in the comparisons section for that species.