Acanthosaura cuongi, Ngo & Le & Nguyen & Nguyen & Nguyen & Phan & Nguyen & Ziegler & Do, 2025

Ngo, Hai Ngoc, Le, Linh Tu Hoang, Nguyen, Tao Thien, Nguyen, Tuan Minh, Nguyen, Ngan Thi, Phan, Tien Quang, Nguyen, Truong Quang, Ziegler, Thomas & Do, Dang Trong, 2025, A new species of Acanthosaura Gray, 1831 (Reptilia: Agamidae) from the Truong Son Mountain Range, Vietnam, European Journal of Taxonomy 976, pp. 108-132 : 118-128

Acanthosaura cuongi sp. nov.

urn:lsid:zoobank.org:act:FDB2D34D-A091-4BB2-8456-A5E43E28BCAA

Figs 1–8 ; Tables 3–4 ; Supp. file 1

Diagnosis

Moderately-sized agamid lizard (SVL 79.40–87.06 mm in males, 85.69–104.61 mm in females); head triangular, relatively long (HL/SVL 0.27–0.31, HW/SVL 0.18–0.21), tail relatively long (TaL/SVL 1.44–1.51 in males and 1.09–1.38 in females), postorbital and occipital spines present; gular pouch undeveloped; 8–10 scales between nasals; four scales bordering mental scale; 10–13 supralabials; 10–13 infralabials; 5–7 scales bordering rostral scale; nuchal crest composed of 7–9 spines relatively high and one spine short; dorsal crest present, undeveloped; double rows of vertebral scales followed the dorsal crest; nuchal and dorsal crests continuous, filled with small spine scales; lateral scales small, intermixed with large, keeled scales, keels directed backward and back-upward; number of subdigital lamellae 14–17 on fourth finger and 19–23 on fourth toe ( Table 3 ); black nuchal collar present; dorsum with black bands; a black patch extending from eye posteriorly to the anterior edge of tympanum.

Etymology

The specific epithet is dedicated to the Vietnamese herpetologist Dr Cuong The Pham, Institute of Ecology and Biological Resources (IEBR), Hanoi, in recognition of his support for field surveys in Khanh Hoa and Phu Yen provinces and his great contributions to herpetological research in Vietnam.

Type material

Holotype

VIETNAM • ♂ adult; Phu Yen Province, Tay Hoa District; 312 m a.s.l.; 22 May 2023; H.N. Ngo leg.; IEBR R.5250 (PY.2023.127).

Paratypes

VIETNAM • 3 ♂♂ adult; same locality as for holotype; Apr. 2022; N.N. Hai, D.T. Do and T.Q. Phan leg.; IEBR R.5259, 5260, 5261 (DTD.2, 375, 429) • 4 ♀♀ adult; same locality as for holotype; May 2022; same collectors as for preceding; IEBR R.5255, 5257, 5256, 5262 (PY.2023.120, 128, 130, 131) • 4 ♀♀ adult; Khanh Hoa Province, Van Ninh District; 120–387 m a.s.l.; 27 May 2023; same collectors as for preceding; IEBR R.5251, 5258, 5252, 5253 (KH.2023.50, 51, 52, 61) . Coordinates were recorded for each specimen and can be shared upon request to the authors to avoid abuse.

Description

Adult male ( Figs 3–4 )

Snout-vent length 87.06 mm; tail complete, 129.74 mm in length (TaL/SVL 1.49); head triangular in dorsal view, 26.47 mm in length (HL/SVL 0.3), 17.37 mm in width (HW/HL 0.66), 14.6 mm in height (HH/HL 0.55); snout moderately long (SL 7.77 mm, SL/HL 0.38); loreal region steeply sloping anteriorly; a row of 10/11 large scales along canthus-rostralis edge, forming a large projecting shelf extending above eye, terminated by a notch anterior to postorbital spine; rostral moderate in size, 2.5 times as wide as high, rectangular, bordered laterally by first supralabial and posteriorly by seven smaller scales; nostril round, surrounded by prenasal anteriorly, two postnasals posteriorly, three subnasals and two supranasals; nasals separated from each other by 10 scales; orbit large (orbit/HL 0.34); interorbital, prefrontal and frontal scales slightly keeled, smaller than scales below orbit; postorbital spine broken at both sides; a single row of 5/6 large, keeled scales extending from suborbital below posterior margin of eye to above tympanic margin, increasing in size posteriorly; a spine prominent above tympanic margin; occipital spine short, on lateral margin of nape, surrounded by a rosette of four small lanceolate scales; tympanum exposed, round, nearly one half that of orbit (TD/EYE 0.47), surrounded by tiny keeled scales; supralabials 12/11, rectangular, scales in center of series largest, slightly decreasing in size posteriorly; infralabials 11/11, rectangular, similar in size; gular scales sharply keeled and spinose with a larger midventral row; mental pentagonal, edged by four postmental scales including two infralabials; narrow dewlap present; nuchal crest composed of eight medium elongated, dagger-like scales, decreasing in size posteriorly, bordered on each side by two rows of large, flat, keeled, triangular scales; nuchal crest followed by pseudo-diastema (4.35 mm) at base of nape with four low continuous spines; dorsal crest composed of three single and four of two rows of slightly low dagger-like spines; followed by vertebral crest, composed of two rows of enlarged, keeled, pointed scales, arranged as a zipper line, ending at base of tail.

Body slightly robust, triangular in cross-section; dorsal scales small, intermixed with large, keeled scales arranged in transverse rows; flanks covered by small scales, randomly intermixed with small, keeled scales, projecting posteriorly; scales in pectoral region and abdomen larger than those on dorsum, keeled, spinose, arranged in semi-transverse rows; ventral scales keeled, larger in size posteriorly; limbs relatively long, dorsal surface of fore and hind limb with keeled scales, larger than ventral scales; five digits on manus; subdigital scales keeled, subdigital lamellae 15/15 on the fourth finger; five digits on pes; subdigital scales keeled, subdigital lamellae 20/20 on the fourth finger; tail covered by small keeled scales, directed posteriorly.

Coloration of live holotype

Dorsal surface of head brown-green with a short transverse band light-green between orbital regions; occipital surface light-green; a black patch extending from behind the eye backward and slightly upward to anterior margin of tympanum; upper and lower lips green; lateral side of neck grey-white in most parts; nuchal crest spines pastel-orange (third, fifth and sixth spines) and green (remaining spines); iris yellowbrown; tongue blueish gray; dorsal surface of body light-green with seven brownish blackblured stripes, oriented obliquely forward from both sides of the vertebral region and one on shoulder; dorsal surface of limbs light-green, light spots on elbows and knees present; gular region and ventral side yellow-white in most parts; ventral sides of limbs yellow-green in the upper half part and white in the remaining part; black and light-green rings on tail, the rings become indistinct on posterior part of tail ( Fig. 3 ).

Coloration of holotype in preservative

In preservative, the light-green on the dorsal surface of the body, dorsal and ventral surface of limbs and rings on tail faded to dark gray but the pattern remained unchanged ( Fig. 4 ).

Variations

Morphometric and meristic data for the type series are provided in Supp. file 1. The dorsal ground color of the body varies with green, orange-yellow, light to purplish gray, and deep-brown; paratype IEBR R.5258 lacks patches on the back; paratype IEBR R.5256 has brown upper and lower lips and the nuchal crest is grayish black, green and yellow ( Figs 5–6 ).

Sexual size dimorphism

The observed sexual dimorphism in size of A. cuongi sp. nov., is that of a female-biased pattern: SVL of females (98.1 ± 6.0 mm, 85.69–104.61 mm, n = 8) is significantly longer than that of males (83.19 ± 4.2 mm, 79.4–87.06 mm, n = 4) (Supp. file 1).

Distribution

Acanthosaura cuongi sp. nov. is currently known from two sites: Van Ninh District of Khanh Hoa Province and Tay Hoa District of Phu Yen Province, with findings recorded from nearby the coastline, south-central Vietnam ( Fig. 7 ).

Natural history

Lizards were collected at elevations ranging from 120 to 387 m a.s.l. in evergreen forests, belonging to the southeast Truong Son Mountain Range of Phu Yen and Khanh Hoa provinces ( Fig. 8 ). Lizards were observed during night surveys, clinging to, and sleeping in shrubs, thin trunks of small trees, beneath dense forest canopy. The height of occupied perches ranged from 0.1–1.8 m above the ground. The new species occurs in sympatry with A. murphyi in the aforementioned provinces.

Comparisons

Acanthosaura cuongi sp. nov. differs from A. armata (Gray, 1827) , A. aurantiacrista Trivalairat et al., 2020 , A. capra , A. cardamomensis , A. crucigera Boulenger, 1885 , A. meridiona Trivalairat et al., 2022 , A. murphyi , A. nataliae , A. phuketensis Pauwels et al., 2015 and A. tongbiguanensis Liu & Rao, 2019 by having a shorter body length (max snout-vent length: 104.61 vs 138 mm, 130 mm, 137.9 mm, 149 mm, 127 mm, 118.1 mm, 127.3 mm, 158 mm, 123.5 mm, 115.6 mm, respectively), shorter postorbital spines (0.4–1.49 vs 4.9–12 mm, 5.5–19.1 mm, 5.2–10.2 mm, 3.2–12.7 mm, 1.9–7.8 mm, 3.4–7 mm, 5.6–11.8 mm, 7.7–17.8 mm, 4.6–11.8 mm, 3.6–6.3 mm, respectively), shorter nuchal crest spines (1.63–2.66 mm vs 5.5–11.2 mm, 5.5–21.6 mm, 4.2–14.7 mm, 3.8–17.4 mm, 3.2–8.9 mm, 2.6–6.9 mm, 7–14.9 mm, 8.5–23.8 mm, 4.1–12.2 mm, 4–6.7 mm, respectively), shorter dorsal crest spines (0.6– 1.14 vs 4.9–11.3 mm, 2.4–8.7 mm, 3.5–6.8 mm, 2–14.2 mm, 2–5.5 mm, 1.4–3.9 mm, 2.6–10.5 mm, 6–17.7 mm, 2.3–8.3 mm, 2.4–4.2 mm, respectively), and the absence of a diastema between nuchal and dorsal crests (vs presence) (Supp. file 2).

Acanthosaura cuongi sp. nov. differs from A. bintangensis Wood et al., 2009 and A. titiwangsaensis Wood et al., 2009 by having a shorter body length (max snout-vent length: 104.61 vs 142 mm, 118.4 mm, respectively), fewer subdigital lamellae on the fourth finger (14–17 vs 23, 20–21, respectively) and on the fourth toe (19–23 vs 26–28, 23–27, respectively), fewer canthus rostralis scales (9–11 vs 14–15, 14–15, respectively), and the presence of light knee spot (vs absence) (Supp. file 2).

Acanthosaura cuongi sp. nov. differs from A. brachypoda by having a relatively longer postorbital spine (0.4–1.9 vs 3.2 mm), shorter nuchal crest spines (1.63–2.66 vs 4.7 mm), fewer ventral scales (51–60 vs 63), fewer subdigital lamellae on the fourth finger (14–17 vs 18) and on the fourth toe (19–23 vs 24), and the absence of a diastema between nuchal and dorsal crests (vs presence) (Supp. file 2).

Acanthosaura cuongi sp. nov. differs from A. coronata by having a longer body length (max snout-vent length: 104.61 vs 86.1 mm) and head length (23.34–31.1 vs 14.4–16.3 mm), the presence of dorsal crest spines, more subdigital lamellae on the fourth toe, fewer canthus rostralis scales (9–11 vs 12–15), fewer scales bordering the rostral scale (5–7 vs 9), and fewer scales between the nasal and the rostral (1 vs 3–4) (Supp. file 2).

Acanthosaura cuongi sp. nov. differs from A. lepidogaster by having a shorter orbit diameter (orbit/HL: 0.27–0.38 vs 0.4–0.57), shorter snout length (SL/HL: 0.29–0.39 vs 0.42–0.66), fewer subdigital lamellae on the fourth finger (14–17 vs 17–19), the absence of the diastema between nuchal and dorsal crests (vs presence), black patch extending from behind the eye backward and slightly upward to the anterior edge of tympanum (vs upward to through occipital spine to reach anterior edge of black nuchal collar) (Supp. file 2). Acanthosaura cuongi sp. nov. differs from A. liui Liu et al., 2020 by having a shorter nuchal crest spines (1.63–2.66 vs 2.2–7.1 mm), a shorter dorsal crest spines (0.6–1.14 vs 2.7–3.7 mm), more nuchal crest scales (7–9 (1) vs 5–7), shorter occipital spine (1.24–2.54 vs 3.6–4.8 mm), fewer canthus rostralis scales (9–11 vs 12), fewer scales bordering the rostral scale (5–7 vs 8–9), fewer scales bordering the mental (4 vs 5–6), the absence of a diastema between nuchal and dorsal crests (vs presence) (Supp. file 2).

Acanthosaura cuongi sp. nov. differs from A. longicaudata Liu et al., 2022 by having more nuchal scales (7–9 (1) vs 6–7), fewer subdigital lamellae on the fourth finger (14–17 vs 17–19) and on the fourth toe (19–23 vs 22–25), fewer canthus rostralis scales (9–11 vs 11–13), fewer scales between the nasal and the rostral scales (1 vs 1–3), a black patch extending from behind the eye backward and slightly upward to the anterior edge of tympanum (vs upward to through occipital spine to reach anterior edge of black nuchal collar) (Supp. file 2).

Acanthosaura cuongi sp. nov. differs from A. phongdienensis by having a longer body length (79.4– 104.61 vs 58.5–77.4 mm), a longer head (23.34–31.1 vs 18.6–23.8 mm), a broader head (15.94–19.6 vs 13.1–15.9 mm), a shorter orbit diameter (orbit/HL: 0.27–0.38 vs 0.4–0.57), two rows of slightly low dagger-like vertebral spines (vs single row, black eye patch extending backward and slightly upward to the anterior edge of the tympanum vs upward to through occipital spine to reach anterior edge of black nuchal collar) (Supp. file 2).

Acanthosaura cuongi sp. nov. differs from A. prasina by having a longer body length (79.4–104.61 vs 79.8–88.4 mm), a longer head (23.34–31.1 vs 20.7–22.4 mm), fewer ventral scales (51–60 vs 59–63), fewer subdigital lamellae on the fourth toe (19–23 vs 23–26), more canthus rostralis scales (9–11 vs 5–6), scales of nuchal crest and vertebral scales light orange (vs white), and lips green (vs white) (Supp. file 2).

Acanthosaura cuongi sp. nov. differs from A. rubrilabris Liu et al., 2022 by having shorter nuchal crest spines (1.63–2.66 vs 1.9–7.0 mm), more nuchal scales (7–9 (1) vs 3–6), fewer canthus rostralis scales (9– 11 vs 11–14), and the absence of a bright red pattern on upper and lower lips (vs presence) (Supp. file 2).

Figures

Fig. 1. Bayesian – Maximum Likelihood tree based on partial COI gene sequences of specimens used in this study. Values at each node indicate Bayesian Posterior Probabilities and Ultrafast Bootstrap Values from Maximum Likelihood analysis respectively (BI/ML).

Fig. 2. Bayesian – Maximum Likelihood tree based on Cytb gene sequences of specimens used in this study. Values at each node indicate Bayesian Posterior Probabilities and Ultrafast Bootstrap Values from Maximum Likelihood analysis respectively (BI/ML).

Fig. 3. Live male holotype of Acanthosaura cuongi sp. nov. (IEBR R.5250). A. Dorsolateral view. B. Dorsal view. C. Cloacal region. D. Head, lateral view. E. Head, dorsal view. F. Head, ventral view.

Fig. 4. Dorsolateral (above) and ventral (below) views of the male holotype of Acanthosaura cuongi sp. nov. (IEBR R.5250) in preservative.

Fig. 5. Dorsolateral (above), dorsal (middle) and ventral (below) views of male paratype IEBR R.5259 (left) and female paratype IEBR R.5255 (right) of Acanthosaura cuongi sp. nov. in preservative.

Fig. 6. Color variations of live paratypes of Acanthosaura cuongi sp. nov.

Fig. 7. Distribution of Acanthosaura cuongi sp. nov. in Vietnam (violet circles).

Fig. 8. Forest habitat of Acanthosaura cuongi sp. nov in Phu Yen Province, Vietnam.