Hemiphyllodactylus houaphanensis, Luu & Hoang & Ha & Grismer & Murdoch & Sitthivong & Phimpasone & Grismer, 2024

Luu, Vinh Quang, Hoang, Tuoi Thi, Ha, Hong Bich, Grismer, Jesse L., Murdoch, Matthew, Sitthivong, Saly, Phimpasone, Vilay & Grismer, L. Lee, 2024, Integrative taxonomy reveals two new species of karst-dwelling Hemiphyllodactylus Bleeker, 1860 (Squamata: Gekkonidae) from the border region of Laos and Vietnam, Zootaxa 5486 (1), pp. 71-108 : 97-101

Hemiphyllodactylus houaphanensis sp. nov.

Houaphan Slender Gecko ( Fig. 7 ).

Holotype. Adult male VNUF R.2020.16 (Field no. HP 16) collected on 27 March 2020 at 1945 hrs by Vilay Phimpasone, Saly Sitthivong, and Lo Van Oanh at the Sa Kok Village , Hiem District, Houaphan Province, Laos (20°10'01.3"N 103°10'36.7"E; 644 m in elevation).

Paratypes. Adult female VNUF R. 2020.17 (Field no. HP 17) and juvenile male NUOL R.2020.20 (Field no. HP 20) bear the same collection data as the holotype .

Diagnosis. Hemiphyllodactylus houaphanensis sp. nov. can be separated from all other species of Hemiphyllodactylus by possessing the unique combination of having a maximum SVL of 45.6 mm; eight or nine chin scales; enlarged postmentals; two circumnasal scales; one or two intersupranasals (=postrostrals);11or 12supralabials; 8–11 infralabials; 18–23 longitudinally arranged dorsal; 10–13 ventral scales; three or four subdigital lamellae on the first finger; four subdigital lamellae on the first finger; 20–25 continuous, pore - bearing, femoroprecloacal scales (pitted scales in the female); no plate - like subcaudal scales; a dark postorbital stripe extending to at least base of neck; postorbital and dorsolateral light - colored spots present on trunk; dark, dorsolateral or ventrolateral stripes present on trunk; dark zig - zag of paravertebral markings on trunk variable; light - colored postsacral marking variably bearing anteriorly projecting arms; and caecum and gonads unpigmented. These characters are scored across all Hemiphyllodactylus species in Table 5 and from all other species of Hemiphyllodactylus from southern China, Vietnam and Laos (clade 6 in Agung et al., (2021)).

Description of holotype. Adult male, SVL 39.5 mm; head triangular in dorsal profile, depressed, distinct from neck; lores flat; rostrum moderate in length (SnEye/SVL 0.10); prefrontal region weakly concave; canthus rostralis smoothly rounded, barely discernible; snout moderate, rounded in dorsal profile; eye large; ear opening elliptical, small; eye to ear distance greater than diameter of eye; rostral rectangular, wider than high, partially divided dorsally by straight rostral groove, bordered posteriorly by large supra - nasals; two intersupranasals (=postnasals); external nares bordered anteriorly by rostral, dorsally by supranasal, posteriorly by two postnasals, ventrally by first supralabial; 12 (R, L) rectangular supralabials; 11 (R, L) rectangular infralabials; scales of rostrum, lores, top of head, and occiput small, granular, those of rostrum largest and slightly raised; dorsal superciliaries flat, mostly square, subimbricate, largest anteriorly; mental triangular, bordered laterally by first infralabials, posteriorly by two enlarged postmentals; each postmental in contact with first infralabial; nine chin scales; gular scales small, subimbricate, grading posteriorly into slightly larger, subimbricate throat. Body somewhat elongate (Trunk/SVL 0.49), dorsoventrally compressed; dorsal scales small, granular, 18 dorsal scales at midbody contained within one eye diameter; ventral scales flat, subimbricate much larger than dorsal scales, 11 ventral scales contained within one eye diameter; precloacal scales slightly larger than abdominal scales; pore - bearing precloacal scales continuous with pore - bearing femoral scales, totaling 25 pore - bearing femoroprecloacal scales; single enlarged tubercle on anterior margin of hemipenial swelling; 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 and U – shaped, lamellae proximal to these transversely expanded; distal lamellar formula of digits II–V 3 - 4 - 4 - 4 (left); 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 flat, juxtaposed scales dorsally and larger, flat subimbricate scales ventrally; plantar scales low, flat, subimbricate; all digits except digit I well - developed; digit I vestigial, clawless; distal subdigital lamellae of digits II–V undivided, angular and U - shaped, lamellae proximal to these transversely expanded; distal lamellar formula of digits II–V 4 - 4 - 4 - 4 (left); 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; caudal scales not occurring in whorls; dorsal caudal scales of original tail larger than dorsal body scales, flat, subcycloid, subimbricate; subcaudals slightly larger than dorsal caudals, not plate - like. Raw morphological data are presented in Table 8 .

Coloration in life ( Fig. 7 ). Ground color of top of head, body, and limbs, gray and densely mottled with darker markings; top of head overlain with dark, semi - reticulate pattern; dark stripe extends from the external nares, through eye to just posterior of forelimb insertion on the body; dark paravertebral markings with diffuse white spots extend from nape to base of tail transforming into a distinct, black, post - sacral band; cream post - sacral marking immediately posterior to black post - sacral band; bearing light - colored, anteriorly projecting arms; dorsolateral region of trunk faintly mottled with diffuse speckling; limbs bearing irregularly shaped, diffuse, dark markings; original portion of tail bearing six light bands, V-shaped posteriorly; gular region cream with darker lateral areas and faint stippling in scales; pigmentation density increases posteriorly with abdomen being generally gray; ground color of dorsal caudal region brownish gray, bearing six light bands not encircling tail; median subcaudal region faintly yellowish orange, regenerated portion of tail dark markings.

Variation ( Fig. 7 ). The color patterns of the paratypes generally match that of the holotype. The dark, dorsal pattern of VNUF R.2020.17 is not as bold as that of the holotype. Light bands on dorsal surface of the tail of VNUF R.2020.17 are wider, irregular, and encircle the tail posteriorly. Variation in scale counts and morphomeric data are presented in Table 8 .

Distribution. Hemiphyllodactylus houaphanensis sp. nov. is only known from Sa Kok Village, Hiem District, Houaphan Province, Laos ( Fig. 1 ).

Natural History. Hemiphyllodactylus houaphanensis sp. nov. is an upland species and all individuals from Sa Kok Village were found at night between 1900 hrs and 2030 hrs on karstic outcrops in undisturbed forest ( Fig. 8 ) 0.5–1.5 m from the ground. Relative temperatures ranged from 21.7–25.5 oC; humidity ranged from 44–47%.

Etymology. The specific epithet is a toponym referring to the type locality of Houaphan Province, Laos.

Comparisons. Hemiphyllodactylus houaphanensis sp. nov. is the sister species to a lineage containing the remaining species in clade 6 ( Agung et al., 2022) with uncorrected pairwise sequence divergences of 16.9% from H. zugi , 17.1% from H. lungcuensis ( Luu et al., 2023) and to 21.1% from H. kiziriani ( Table 2 ). H. houaphanensis sp. nov. differs significantly from H. zugi in mean values of Trunk (1.25 vs. 1.33, p = <0.001) and SnEye (0.58 vs. 0.64, p = <0.001); and from H. lungcuensis in mean values of Trunk (1.25 vs. 1.31, p = <0.001), NarEye (0.44 vs. 0.50, p = 0.011), EyeD (0.41 vs. 0.31, p = <0.001), CN (2.00 vs. 2.86, p = <0.002), VS (11.33 vs. 8.14, p = 0.031), DS (19.67 vs. 14.57, p = <0.009), and SL1F (3.67 vs. 3.86, p = <0.009). Statistically significant differences between Hemiphyllodactylus houaphanensis sp. nov. and all other species in clade 6 are presented in Tables 5 & 6 .

Figures

FIGURE 1. Type localities of the species of Hemiphyllodactylus of clade 6 (Agung et al., 2022).

FIGURE 7. Dorsal views of Hemiphyllodactylus houaphanensis sp. nov. from Sa Kok Village, Hiem District, Houaphan Province, Laos. A: adult male holotype (VNUF R.2020.16) and B: adult female paratype (VNUF R.2020.17). Photos: Vilay Phimpasone.

FIGURE 8. Habitat of Hemiphyllodactylus houaphanensis sp. nov. at the Sa Kok Village, Hiem District, Houaphan Province, Laos. Photo: Vilay Phimpasone.