Hemiphyllodactylus nahangensis, Do & Pham & Phan & Le & Ziegler & Nguyen, 2020

Do, Quyen Hanh, Pham, Cuong The, Phan, Tien Quang, Le, Minh Duc, Ziegler, Thomas & Nguyen, Truong Quang, 2020, A new species of Hemiphyllodactylus (Squamata: Gekkonidae) from Tuyen Quang Province, Vietnam, Zootaxa 4821 (3), pp. 511-532 : 515-517

Hemiphyllodactylus nahangensis sp. nov.

( Figs. 3 , 4 )

Holotype. IEBR 4741 (Field number TQ.2018.140), adult male, collected on 20 June 2018 by C. T. Pham, A.M. Luong, T. Q. Phan and H. T. Ninh from the limestone karst area near Trung Phin Village (20 o 30.215’N, 105 o 23.402’E, at an elevation of 915 m a.s.l.), Sinh Long Commune, Na Hang District, Tuyen Quang Province, northern Vietnam.

Paratypes. Two specimens collected from the same site as the holotype: IEBR 4742 (Field number TQ.2018.141), adult male, collected on 20 June 2018 and IEBR 4743 (Field number TQ.2018.96), adult female, collected on 18 June 2018, by C. T. Pham, A.M. Luong, T. Q. Phan and H. T. Ninh .

Diagnosis. The new species from northern Vietnam differs from the remaining congeners of the genus Hemiphyllodactylus by a combination of the following characters: a bisexual taxon; SVL of adults 41.4–43.6 mm; dorsal scale rows 18–23; ventral scale rows 9–13; chin scales bordering mental and first infralabial, distinctly enlarged; digital lamellae formula 3-4-5-4 (forefoot) and 4-5-5-5 (hindfoot); 22–24 pore-bearing femoral and precloacal scales, in a continuous row, absent in females; cloacal spur single in both sexes; dark lateral head stripe indistinct; postsacral mark cream and bearing anteriorly projecting arms.

Description of holotype. Adult male; size small (SVL 43.6 mm); tail length (TaL 37.4 mm); body elongate (TrunkL 21.3 mm); head longer than wide (HeadL 10.7 mm, HeadW 7.4 mm), not markedly depressed (HeadD/ HeadL 0.34), distinct from neck; eye large, pupils vertical (EyeD 2.5 mm); ear oval shaped, small (EarD 0.69 mm); nare–eye length (NarEye 3.1 mm), snout-eye length (SnEye 3.8 mm), internarial distance (SnW 1.3 mm). Proportions: Trunk/SVL 0.44, HeadL/SVL 0.24, HeadW/SVL 0.17, HeadW/HeadL 0.69, HeadD/HeadL 0.34, SnEye/HeadL 0.36, NarEye/HeadL 0.29, EyeD/HeadL 0.24, EyeD/SnEye 0.67, EyeEar/EyeD 1.39, SnW/HeadL 0.12, EyeD/NarEye 0.82, SnW/HeadW 0.18.

Scalation: Rostral very large, wider than high, with a shallow suture, bordered posteriorly by large supranasals; supralabials 11/11, gradually decreased in size towards angle of jaw; nare in contact with rostral anteriorly, first supralabial ventrally, supranasal dorsally and three nasals posteriorly on each side; supranasals separated from each other by four small granular internasals; snout flat; pupil vertical, upper eyelid with small supraciliaries; ear oval-shaped, approximately 27% of the eye diameter, not bordered by enlarged scales; infralabials 10/9; mental triangular, slightly wider than rostral, bordered by the first infralabial on each side and posteriorly by two enlarged postmentals; eight chin scales touching internal edge of infralabials and mental between the juncture of the second and third infralabials on each side of the head, anterior pair enlarged; gular scales small, subimbricate; throat and pectoral scales which grade into slightly larger, subimbricate; dorsal scales small, granular, in 22 rows at midbody (contained within one eye diameter); ventrolateral folds absent; enlarged turbercles absent; ventral scales flat, subcircular, larger than dorsal scales, in 9 rows at midbody on venter (contained within one eye diameter); femoral pores and precloacal pores in continuous series, 24 in total; cloacal spur single; dorsal surface of fore and hindlimbs covered with granular scales; terminal two phalanges free, claws absent on first finger and on first toe, present on second to fifth digit of fore and hindfoot; pads of digits II–V each with large triangular lamella, digital formula 3-4-5-4 (forefoot) and 4-5-5-5 (hindfoot); lamellae three on first fingers, three on first toes; caudal scales flat, not forming distinct caudal segments.

Coloration in life: Ground color of dorsum, head and limbs grey with indistinct black markings; dark lateral head stripe indistinct; light postorbital stripe extending to anterior margin of forearm; ventral surface cream with dark mottling; dorsum with indistinct dark pattern, upper zone of flank with light spots and indistinct dark longitudinal markings; postsacral mark cream in U-shape and bearing anteriorly projecting arms; original tail with some dark spots, edged by light grey and cream markings.

Coloration in preservative: Color became darker, dark pattern disappeared on dorsum, head and dorsal surface of limbs. Tail pattern did not change noticeably in preservation.

Sexual dimorphism and variation. Measurements and scalation characters of the paratypes are given in Table 2. The female differs from the males in the absence of hemipenial swellings at the tail base. The scale counts vary among the type series: scales between supranasals 4–6; supralabials 10–12; infralabials 9–11; chin scales 8 or 9; dorsal scale rows 18–23; ventral scale rows 9–13. The males have 22–24 femoral and precloacal pores (versus absent in female). Ground color on upper surface of head, body, and tail is also different among individuals, varying from whitish grey to brownish grey with yellowish marks.

Distribution. Hemiphyllodactylus nahangensis sp. nov. is currently known only from the type locality in Na Hang District, Tuyen Quang Province, northern Vietnam ( Fig.1 ).

Etymology. Specific epithet nahangensis is a toponym in reference to the type locality of the species. For the common names we suggest Nahang Slender Gecko (English) and Thạch sùng dẹp na hang (Vietnamese).

Natural history. The new species is associated with residential habitat. Type specimens were collected between 20:00 and 22:00 h, one individual was collected on the wooden wall of a house in Trung Phin Village, two individuals were collected on a branch of a peach tree near the house, approximately 2.5–3.5 m above the ground. The surrounding habitat of Trung Phin village was disturbed evergreen karst forest of medium, small hardwood and shrub trees. Air temperature ranged from 25ºC to 31ºC and relative humidity was 63–87%.

Comparisons: We compared the new species from northern Vietnam with all other members of the genus Hemiphyllodactylus from Vietnam, Laos, and China based on examination of specimens (see Appendix) and data obtained from the literature ( Boulenger 1903; Barbour 1924; Smith 1935; Taylor 1963; Zhou et al. 1981 with English translation of Ota 1996; Bourret 2009; Zug 2010; Grismer et al. 2013, 2014a,b, 2015, 2018a,b, 2020; Nguyen et al. 2013, 2014, 2020; Ngo et al. 2014; Guo et al. 2015; Cobos et al. 2016; Yan et al. 2016; Sukprasert et al. 2018; Sung et al. 2018; Eliades et al. 2019; Agarwal et al. 2019, 2020). For comparisons with other species of Hemiphyllodactylus see Table 3.

Hemiphyllodactylus nahangensis sp. nov. differs from H. banaensis Ngo, Grismer, Pham & Wood by having a smaller size (maximum SVL 43.6 mm versus 51 mm in H. banaensis ), fewer subdigital lamellae 3 (1FingLm) and 3 (1ToeLm) (versus 5 and 5, respectively, in H. banaensis ), and more precloacal and femoral pores in males (22–24 versus 18–21 in H. banaensis ); from H. bonkowskii by having more chin scales (8–9 versus 5–7 in H. bonkowskii ), fewer dorsal scale rows (18–23 versus 24–27 in H. bonkowskii ), fewer subdigital lamellae 3 (1FingLm) and 3 (1ToeLm) (versus 5 and 4–5, respectively, in H. bonkowskii ), digital lamellae formula 3-4-5-4 (forefoot) and 4-5-5- 5 (hindfoot) (versus 3-4-4-4 and 4-5-5-4, respectively, in H. bonkowskii ), and more precloacal and femoral pores in males (22–24 versus 19 in H. bonkowskii ); from H. dushanensis by having a smaller size (maximum SVL 43.6 mm versus 50.6 mm in H. dushanensis ), more dorsal scale rows (18–23 versus 11–15 in H. dushanensis ), fewer subdigital lamellae 3 (1FingLm) and 3 (1ToeLm) (versus 4–5 and 5–6, respectively, in H. dushanensis ), and the presence of anteriorly projecting arms on postsacral (versus absent in H. dushanensis ); from H. hongkongensis by having more chin scales (8–9 versus 5–6 in H. hongkongensis ), more dorsal scale rows (18–23 versus 12–15 in H. hongkongensis ), fewer subdigital lamellae 3 (1ToeLm) (versus 5 in H. hongkongensis ), digital lamellae formula 3-4-5-4 (forefoot) and 4-5-5-5 (hindfoot) (versus 3-4-4-4/3-3-4-4 and 3-4-4-4/4-4-5-4/4-4-5-5, respectively, in H. hongkongensis ); from H. huishuiensis Yan, Lin, Guo, Li & Zhou by having more scales between supranasals (4–6 versus 2–3 in H. huishuiensis ), more dorsal scale rows (18–23 versus 13–15 in H. huishuiensis ), more ventral scale rows (9–13 versus 7–9 in H. huishuiensis ), and more precloacal and femoral pores in males (22–24 versus 18–20 in H. huishuiensis ); from H. indosobrinus Eliades, Phimmachak, Sivongxay, Siler & Stuart by having more scales between supranasals (4–6 versus 3 in H. indosobrinus ), fewer supralabials (10–12 versus 15 in H. indosobrinus ), fewer dorsal scale rows (18–23 versus 30 in H. indosobrinus ), fewer subdigital lamellae 3 (1FingLm) and 3 (1ToeLm) (versus 4 and 5, respectively, in H. indosobrinus ), and more precloacal and femoral pores in males (22–24 versus 18 in H. indosobrinus ); from H. kiziriani by having more scales between supranasals (4–6 versus 2–3 in H. kiziriani ), fewer subdigital lamellae 3 (1FingLm) and 3 (1ToeLm) (versus 5 and 5, respectively, in H. kiziriani ), digital lamellae formula 3454 (forefoot) and 4-5-5-5 (hindfoot) (versus 3-4-4-4 and 4-4(5)-4(5)-4, respectively, in H. kiziriani ), and more precloacal and femoral pores in males (22–24 versus 10–13 in H. kiziriani ); from H. ngocsonensis by having more scales between supranasals (4–6 versus 3 in H. ngocsonensis ), fewer subdigital lamellae 3 (1FingLm) and 3 (1ToeLm) (versus 4–5 and 5–6, respectively, in H. ngocsonensis ), digital lamellae formula 3454 (forefoot) and 4555 (hindfoot) (versus 3-4-4-4 and 4-5-5-4, respectively, in H. ngocsonensis ), and more precloacal and femoral pores in males (22–24 versus 20 in H. ngocsonensis ); from H. serpispecus by having more scales between supranasals (4–6 versus 2 in H. serpispecus ), fewer dorsal scale rows (18–23 versus 26 in H. serpispecus ), fewer subdigital lamellae 3 (1FingLm) and 3 (1ToeLm) (versus 4 and 4, respectively, in H. serpispecus ), digital lamellae formula 3-4-5-4 (forefoot) and 4-5-5-5 (hindfoot) (versus 3-4-4-4 and 3-4-4-5, respectively, in H. serpispecus ), and more precloacal and femoral pores in males (22–24 versus 11 in H. serpispecus ); from H. zugi Nguyen, Lehmann, Le, Duong, Bonkowski & Ziegler by having fewer ventral scales (9–13 versus 14–16 in H. zugi ), fewer subdigital lamellae 3 (1FingLm) and 3 (1ToeLm) (versus 4–5 and 4–5, respectively, in H. zugi ), digital lamellae formula 3-4-5-4 (forefoot) (versus 3-4-4- 4 in H. zugi ), and more precloacal and femoral pores in males (22–24 versus 18–21 in H. zugi ).

Figures

FIGURE 1. Type locality of Hemiphyllodactylus nahangensis sp. nov. in Tuyen Quang Province (1), northern Vietnam.

FIGURE 3. The male holotype of Hemiphyllodactylus nahangensis sp. nov. (IEBR 4741): A) Dorsal view in life, B) Ventral view in life, C) Precloacal region with precloacal and femoral pores in a continuous series, D) Subdigital view of right hand, and E) Subdigital view of right foot. Photos: C.T. Pham, Q.H. Do. Scale bar = 1 mm.

FIGURE 4. Hemiphyllodactylus nahangensis sp. nov. in life: A) male paratype (IEBR 4742) and B) female paratype (IEBR 4743). Photos: C.T. Pham.