Hemiphyllodactylus cattien Yushchenko & Grismer & Bragin & Dac & Poyarkov 2023, sp. nov

Hemiphyllodactylus cattien sp. nov. Cat Tien Slender Gecko Figs. 3 & 4, Table 2 ZooBank registration: urn:lsid:zoobank.org:act: 4B7A2B89-BB4C-4F22-B0CC-F4E07B354327 Holotype. Adult female (VRTC NAP-10586; formerly ZMMU Re-17039) collected along the trail to Lake Bau Sau, Nam Cat Tien sector, Cat Tien National Park, Dong Nai Province, southern Vietnam (GPS data 11.4458° N, 107.3864° E WGS; 140 m a.s.l.) on 14 February 2021 at 18:00 h by P.V. Yushchenko and N.A. Poyarkov. Diagnosis. Hemiphyllodactylus cattien sp. nov. can putatively be distinguished from all other congeners by possessing the unique combination of having a maximum SVL of 35.1 mm; trunk slightly elongate and gracile (AG/ SVL 0.52); seven chin scales; enlarged postmentals; five circumnasal scales; three intersupranasals (= postrostrals); nine supralabials; nine infralabials; 20 longitudinal rows of dorsal scales and 11 longitudinal rows of ventral scales at midbody contained within one eye diameter; 4444 digital formulas on hands and 5555 formulas on feet; five subdigital lamellae on the first finger; six subdigital lamellae on the first toe; 19 perforated precloacal scales that extend part-way onto the proximal femoral region; one cloacal spur on each side; no platelike subcaudal scales; a weak dark-colored postorbital stripe extending to at base of neck; no dorsolateral light-colored spots or dark-clored dorsolateral stripe on trunk; no dark-colored ventrolateral stripe on trunk; no dark-clored paravertebral markings on trunk; no light-colored postsacral marking bearing anteriorly projecting arms; and caecum and gonads darkly pigmented. Description of holotype (Table 2). Adult female SVL 35.1 mm (Fig. 4a); head moderate, (HL/SVL 0.24, HW/ SVL 0.16) triangular in dorsal profile (Fig. 4c), depressed, distinct from neck; lores flat to slightly convex; rostrum moderate in length (NE/HL 0.32); prefrontal region weakly concave; canthus rostralis smoothly rounded, barely discernable; snout moderate (NE/HL 0.32), rounded in dorsal profile; eye large (ED/HL 0.26); ear opening elliptical, small (Fig. 4b); eye-ear distance greater than diameter of eye; rostral wider than high, bordered posteriorly by large supranasals (Fig. 4c); 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; nine (R,L) rectangular infralabials not tapering to below posterior margin of eye; scales of rostrum, lores, top of head, and occiput small, raised, those of rostrum largest; dorsal superciliaries flat, mostly square, subimbricate, largest anteriorly; mental triangular, bordered laterally by first infralabials and posteriorly by two postmentals (Fig. 4d); postmentals in contact with first infralabial and bordered laterally by a slightly smaller chin shield; five lateral chin shields; gular scales small, subimbricate, grading posteriorly into slightly larger, subimbricate throat and even larger pectoral scales which grade into slightly larger, subimbricate ventrals. Body moderate in stature, trunk not noticeably elongate (AG/SVL 0.52), dorsoventrally compressed; ventrolateral folds absent; dorsal scales small, granular, 20 dorsal scales at midbody contained within one eye diameter; ventral scales flat, subimbricate, larger than dorsal scales, 11 ventral scales contained within one eye diameter; precloacal scales larger than abdominal scales; 19 perforated, slightly enlarged femoroprecloacal scales in an angular series, scale at apex has a pit; single enlarged tubercle (spur) on lateral margin of tail base (Fig. 4e); forelimbs short, robust in stature, covered with flat, subimbricate scales dorsally and ventrally; palmar scales slightly raised, subimbricate; all digits except digit I well developed; digit I vestigial, clawless; distal subdigital lamellae of digits II–V divided, angular and U-shaped, lamellae proximal to these transversely expanded; distal lamellar formula of digits II–V 4444 (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; hind limbs short, more robust than forelimbs, covered with slightly 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 divided, angular and U-shaped, lamellae proximal to these transversely expanded; distal lamellar formula of digits II–V 5555 (R,L); six 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; tail regenerated, 13.7 mm in length. Raw morphometric data (in mm) are TL 13.7 (regenerated), AG 18.4 HL 8.3, HW 5.9, SN 4.0, NE 2.7, ED 2.2, and SW 1.3. Coloration in life. Dorsal ground color of head and body nearly unicolor wheat-gray with dark-brown and white stippling (Fig. 3); dark-colored, diffuse stripe, bordered dorsally by a white band, extends from rostral scale to forelimb insertion (Fig. 3); another dark-colored U-shaped stripe can be distinguished below the eye; dark-colored, diffuse markings on the head, limbs and trunk are almost indistinguishable in color; sacral region with two pairs of more or less distinct light-colored spots; gular, pectoral and abdominal regions beige with dark stippling; stippling dense on underside of limbs; the regenerated tail is totally dark-gray bearing scattered black and white scales (Fig. 3). Coloration after six months in preservative is much the same but not nearly as distinct and the overall coloration has become dark-grey (Fig. 4). Distribution and Natural history. Hemiphyllodactylus cattien sp. nov. is known only from the type locality in Cat Tien National Park (NP), Dong Nai Province, southern Vietnam (Fig. 1). The holotype was collected at sundown (18:00 h) ca. 1.5 m above the ground on the trunk of a tree, in primary dipterocarp forest along the trail to Bau Sau Lake (Fig. 5). Two specimens were recorded sitting close to one another (ca. 10 cm) on the tree trunk; they tried to escape our presence by ascending the tree and only a single specimen was collected. Despite numerous subsequent attempts to collect additional specimens of the new species and intensive surveys along the Bau Sau Lake trail by P.V. Yushchenko and A.M. Bragin from 2021–2023, no other individuals were recorded. The occurrence of Hemiphyllodactylus cattien sp. nov. in other parts of the Cat Tien NP is expected, including the Cat Loc and Tay Cat Tien sectors covering the lowland and hilly areas of the adjacent parts of Lam Dong and Binh Phuoc provinces of southern Vietnam. Etymology. The name of the new species is a noun in apposition and is therefore invariable; the species name is given in reference to its type locality, the Cat Tien National Park in Dong Nai Province of southern Vietnam. We recommend the names “Cat Tien Slender Gecko” and “Thạch sùng dẹp Cát Tiên” as common names of the new species in English and Vietnamese, respectively. nov cattien sp. dalatensis arakuensis banaensis bonkowskii aurantiacus flaviventris maximum SVL35.145.93937.9514839.2Chin scales77–108–11 10–14 6–75–77–10Postmentals distinctly enlarged (1) or not (0);11 0 0 11/Circumnasal scales5,5 3 /2–4 3 3 5Intersupranasals32–32–33–6 4–11 2–43Supralabials910–119–1210–139–128–109–12Infralabials99–109–128–129–118–118–11Dorsals20 16 13–16 11–17 17–20 24–27 16–18 Ventrals11 8–9 7–9 8–129–12 13–15 8–101st finger lamellae5 3–4 4 or 53,45551st toe lamellae6 3–4 5 or 64,554–55Digits 2–5 finger lamellae44444555/4565 2222 2222 3(4)4(5)4(5)434444444Digits 2–5 toe lamellae55555666/5665 2(3)333 2232(3) 455545544555Continuous femoral/precloacal pores19 (perf)23–2512//1416–2518–2119Precloacal and femoral pore series separate (1) or continuous (0);00 1 1 00/Cloacals on each side1/1 2–3 2–3 1–3111 or 2Subcaudals enlarged, plate–like (1) or not (0)0000000Dark postorbital stripe present (1) or absent (0)1111111Light postocular or trunk spots (1) or absent (0)0 1 0 1 1 1 1 Dark dorsolateral stripe present (1) or not (000 1 0 1 0/Dark dorsal transverse blotches (1) or not (0)00/ 1 1 0/Longitudinal series of white (1) or yellow or red (0) dorsal spots000 1 0 1 0Postsacral mark lacking anteriorly projecting arms (1) or arms present (0)1 0 1 0 0 1 0 Gonads and cecum pigmented (1) or not (0)/01100/ ......continued on the next page Comparisons. Morphologically, Hemiphyllodactylus cattien sp. nov. differs from its close relative H. indosobrinus by having fewer dorsal scales (20 versus 30), supralabials (nine versus 15), infralabials (nine versus 13), and a narrower head (HW/SVL = 0.16 versus 0.18). It differs from its close relative H. flaviventris by having more dorsal scales (20 versus 16—18), 19 perforated femoroprecloacal scales in the female versus nine precloacal pores in male, and more elongate trunk (AG/SVL = 0.52 versus 0.47—0.50) and a narrower (HW/SVL = 0.15 versus 0.17—0.18) and shorter head (HL/SVL = 0.24 versus 0.26—0.27). See Table 2 for potential diagnostic characters separating H. cattien sp. nov. from all other species from Vietnam and South Asian species within clade 5. We are well-aware that additional samples of the new species coupled with statistical analyses of the characters may indicate that some of these putatively diagnostic differences may prove not to be diagnostic but that the same probability exists that other diagnostic differences may be revealed.