Scincella truongi Pham, Ziegler, Pham, Hoang, Ngo & Le, 2025, sp. nov.

Scincella truongi sp. nov. Figs 3, 4 Material examined. Holotype. • IEBR R.6329 (Field number PAT. 133) (Figs 3, 4 A, B, 5 A – D), adult female, collected on 3 April 2013 by A. V. Pham and D. A. Nguyen in evergreen forest near Ta Co Village (20°59'13.6"N, 103°37'19.4"E, at an elevation of 1660 m a. s. l.), Sop Cop Commune, within Sop Cop Nature Reserve, Sop Cop District, Son La Province, Vietnam. Paratypes. • IEBR R.6330 (Field number PAT. 129), adult male; HUS.2024.01 (PAT. 130) (Fig. 6), adult female; HUS.2024.02 (PAT. 131), adult female; HUS.2024.03 (PAT 134) (Fig. 7); and adult female, HUS.2024.04 (PAT. 164), adult female, bear the same data as the holotype. Diagnosis. The new species can be distinguished from other species of Scincella by a combination of the following characteristics: size medium (SVL up to 594 mm); primary temporals two; external ear opening without lobules; loreals two; supralabials seven or eight; infralabials six or seven; nuchals in three pairs; midbody scales in 28 rows; dorsal scales smooth, in six rows across the back; paravertebral scales 60–67, not widened; ventral scales in 60–70 rows; ten smooth lamellae beneath finger IV and 13–15 beneath toe IV; toes not reaching to fingers when limbs adpressed along body; dorsal surface of body and tail bronze brown with few black spots, a dark stripe running from nostril to eye and extending from posterior corner of eye along upper part of flank to the middle of the tail. Description of holotype. Size medium (SVL 54.86 mm), tail regenerated (TaL 35 mm); head longer than wide (HL 9.1 mm, HW 6.57 mm, SVL / HL 6.02); snout obtuse, round anteriorly; rostral wider than high, distinctly visible from above; supranasals absent; frontonasal wider than long, in contact with rostral, nasals, anterior loreals, and frontal; prefrontals not in contact with each other; frontal narrowing posteriorly, approximately 1.8 times longer than the distance to the tip of snout, in contact with prefrontals, first and second supraoculars, and frontoparietals; frontoparietals in contact with each other anteriorly, bordered by frontal, three supraoculars, parietals, and interparietal; interparietal lozenge-shaped, transparent spot posteriorly absent; parietals in contact posteriorly, posterolateral border surrounded by three scales on each side; nuchal scales in three pairs; nostril in center of nasal, in contact with rostral, frontonasal, loreal, first supralabial; loreals two, anterior loreal higher but narrower than posterior one; preocular one; presuboculars two, in contact with lower preocular, third and fourth supralabials; supraciliaries seven; supraoculars four, the first longest, the second widest, fourth supraocular followed by a small postsupraocular; postoculars three, anterior one in contact with seventh supraciliary, postsupraocular, and upper postsubocular; postsuboculars two, lower one in contact with sixth supralabial; primary temporals two, lower one in contact with sixth and seventh supralabials; secondary temporals two, upper very large, in contact with posterolateral, border of parietal, overlapped by lower one; lower eyelid with an undivided opaque window (central disc), separated from supralabials by two rows of granular scales; supralabials seven, fifth below the eye; external ear opening present, anterior margin with indistinct lobules, tympanum deeply sunk; mental wider than long, round anteriorly, in contact with anterior infralabials and postmental; infralabials seven, first small; postmental undivided, in contact with mental, first and anterior portion of second infralabials on each side, and first pair of chinshields; chinshields in three pairs, first pair in contact with each other medially, second pair separated from each other by a gular scale, and third pair separated from each other by three scales; midbody scales in 28 rows; dorsal scales smooth, in six rows across the back; paravertebral scales 67, not widened; ventral scales smooth, in 68 rows; precloacals four, inner scales overlapping outer ones, central two enlarged, left one overlapped by right one; tail thick at base, medial subcaudals widened vertical length of tail. Limbs relatively developed (SVL / FlL 4.28, SVL / HlL 3.0), pentadactyl, dorsal surface of digits covered by two scale rows on basal and by a single row on terminal phalanges; subdigital lamellae keeled, in one row under the digits, ten under fourth finger and 15 under fourth toe; toe and finger separated when adpressed along body, adpressed forelimb reaching to eye (Table 3). Coloration in life. Dorsal surface of body and tail bronze brown with black spots; a dark stripe running from nostril to eye and extending from posterior margin of eye along upper part of flank and tail middle; lateral side of the head and flank with a few white spots; chin, throat and venter cream, outer edge of ventral scales dark grey; underside of fore and hind limbs lightly brown; ventral surface of tail greyish cream (Figs 3, 6, 7). Variation. IEBR R. 6330 has 7 / 8 supralabials; infralabials 6 / 6 in paratype (HUS.2024.04); paravertebral scales 60 in IEBR R. 6330, 65 in HUS.2024.01 and HUS.2024.03, 63 in HUS.2024.02, 66 in HUS.2024.04; ventrals in transverse rows 60 in IEBR R. 6330, 64 in HUS.2024.01 and HUS.2024.04, 70 in HUS.2024.02, 65 in HUS.2024.03; lamellae on toe IV 14 in IEBR R. 6330, 64 in HUS.2024.01 and HUS.2024.02, 15 in HUS.2024.04, 13 in HUS.2024.03. Distribution. Scincella truongi sp. nov. is currently known only from the type locality in Son La Province, Vietnam (Fig. 1). Natural history. Specimens were found on the ground in leaf litter of evergreen forest during the daytime between 8: 00 and 16: 00. The surrounding habitat was evergreen forest with large, medium, and small hardwoods mixed with shrubs. Air temperatures at the sites ranged from 26.0–34.0 ° C and relative humidity was 50–70 %. Other reptile species encountered at the sites included Acanthosaura lepidogaster (Cuvier), Sphenomorphus indicus (Gray), and Pareas hamptoni (Boulenger). Etymology. We name the new species in honor of Prof. Dr. Truong Quang Nguyen from the Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, in recognition of his great contributions to the herpetofaunal exploration of the Indochina region. We recommend “ Truong’s Smooth Skink ” as the common English name and “ Th ằn l ằn c ổ trư ờng ” as the common name in Vietnamese for the new species. Comparisons. We compared the new species with other known taxa in the genus Scincella from Asia based on examination of specimens and data obtained from the literature. Morphologically, the new species resembles Scincella ochracea and S. ouboteri two other species known from northwestern Vietnam. However, they are distinguished from S. ochracea by having a larger size in the new species (males with maximum SVL 49.0 mm, n = 1 vs 45.4 mm, n = 7 and females with maximum SVL 59.4 mm, n = 4 vs 51.0 mm, n = 8), external ear opening without lobules (vs present), prefrontal in separate (vs contact), fewer midbody scale rows (28 vs 30–32), fewer lamellae beneath toe IV (13–15 vs 15–17), and different dorsal color pattern (dorsum with black spots vs with a dark discontinuous stripe) and from S. ouboteri by having fewer midbody scale rows (28 vs 30–32), fewer lamellae beneath toe IV (13–15 vs 18–20), toes separating fingers when limbs adpressed along body (vs overlap), and different dorsal color pattern (dorsum with black spots vs with two silver grey stripes, wide dark stripes) (Table 3). Scincella truongi sp. nov. has two primary temporals and thus differs from the following species in the genus Scincella: S. apraefrontalis, S. baraensis, S. darevskii, S. devorator, S. melanosticta, S. monticola, S. punctatolineata, and S. rara, which have only one primary temporal. The new species has toes not reaching fingers when limbs being adpressed along body, which differs from the following species, where toes and fingers do overlap: S. baraensis, S. badenensis, S. dunan, S. formosensis, S. macrotis, S. melanosticta, S. reevesii, and S. rupicola. In addition, the new species has the external ear opening without lobules and thus differs from the following taxa (external ear opening with lobules): S. boettgeri, S. darevskii, S. ouboteri, and S. reevesii. The new species differs from S. apraefrontalis by having more midbody scale rows (28 vs 18), more paravertebral scales (60–67 vs 52), more ventral scales (60–70 vs 50), dorsal scales not enlarged (vs distinctly enlarged), more lamellae beneath toe IV (13–15 vs 8 or 9), and the presence of prefrontal (vs absent); from S. baraensis by having fewer dorsal scale rows on back (6 vs 8), fewer midbody scale rows (28 vs 30), and fewer lamellae beneath toe IV (13–15 vs 18–20); from S. badenensis by having more nuchal pairs (3 vs 0–1), fewer midbody scale rows (28 vs 32–36), and fewer lamellae beneath toe IV (13–15 vs 18–20); from S. barbouri by having fewer paravertebral scale (60–67 vs 70–79) and fewer nuchal pairs (3 vs 4 or 5), and more supraciliaries (7 or 8 vs 5 or 6); from S. boettgeri by having more nuchal pairs (3 vs 2); from S. capitanea by having fewer midbody scale rows (28 vs 30–32) and smaller body size (49.0– 59.4 mm vs 78.5 mm); from S. darevskii by having fewer lamellae beneath toe IV (13–15 vs 17) and fewer supraoculars (4 vs 5); from S. devorator by having fewer lamellae beneath toe IV (13–15 vs 17–19) and different dorsal color pattern (dorsum with black spots vs with two silver grey stripes, wide dark stripes); from S. doriae by having fewer nuchal pairs (3 vs 4 or 5) and fewer midbody scale rows (28 vs 30–32); from S. dunan by having prefrontal in separate (vs contact) and and different dorsal color pattern (dorsum with a few black spots vs with many black spots); from S. huanrenensis by having fewer ventral scales (60–70 vs 75–89); from S. liangshanensis by having different dorsal color pattern (dorsal surface br