Scincella fansipanensis sp. nov.

(Figs. 3–5)

Holotype. IEBR R.5188, an adult male, collected on 2 May 2022 by S. Okabe from Mt. Fansipan, Hoang Lien Son Range, Lao Cai Province, Vietnam, 22.3269°N, 103.7756°E, at an elevation of 2347 m above sea level (a.s.l.).

Paratypes. IEBR R.5185, 5186, 5189, 5191, 5192, adult females; IEBR R.5187 and 5193, adult males; IEBR R.5190 and 5194, juveniles; collected on 2 and 3 May 2022 by S. Okabe from Mt. Fansipan, Hoang Lien Son Range, Lao Cai Province, Vietnam, at 22.32699°N, 103.77486°E, 2366 m a.s.l. (IEBR R.5185, and 5186); 22.32693°N, 103.77569°E, 2347 m a.s.l. (IEBR R.5187); 22.32636°N, 103.77696°E, 2325 m a.s.l. (IEBR R.5189); 22.32651°N, 103.78013°E, 2298 m a.s.l. (IEBR R.5190); 22.32650°N, 103.77264°E, 2358 m a.s.l. (IEBR R.5191); 22.32636°N, 103.77696°E, 2325 m a.s.l. (IEBR R.5192, and 5193); and 22.32673°N, 103.78083°E, 2282 m a.s.l. (IEBR R.5194).

Diagnosis. Scincella fansipanensis sp. nov. is distinguished from other congeners by a combination of the following morphological characteristics: size medium (SVL up to 59.0 mm; AG up to 36.5 mm); 22 (rarely 24) midbody scale rows, smooth; 60–68 paravertebral scale rows; 58–64 ventral scale rows; prefrontals separated from each other; five (rarely six) supraciliaries; two to six nuchals; ear opening present, tympanum deeply sunk, without lobules; limbs short, toe separated from finger when limbs adpressed; toe IV with 10–12 subdigital lamellae, smooth; and dorsal surface of body with irregularly shaped dark spots.

Description of holotype. Adult male; SVL 51.7 mm; TaL 88.3 mm, tail regenerated; head longer than wide (STL 8.9 mm, HW 6.9 mm); snout round; lower eyelid with an undivided opaque window; body slender; tympanum round, deeply sunk with an oblique edge dorsally; ear opening without lobules. Head scales smooth; rostral visible from above, in contact with frontonasal; frontonasal wider than long; prefrontals separated from each other; no supranasal; no postnasal; four supraoculars; frontal large, narrowing posteriorly, longer than wide, length approximately 1.11 times of its distance from tip of snout, bordered anteriorly by frontonasal and prefrontals, laterally by first two supraoculars, and posteriorly by frontoparietals; a pair of frontoparietals in contact with the second to fourth supraoculars; interparietal narrow posteriorly, longer than wide; parietals in contact posteriorly, behind the interparietal; one pair of prenuchals; three nuchals in left side and four in right. Nostril in center of nasal; nasal in contact with the first supralabials, rostral, frontonasal, and anterior loreal; two loreals; six supraciliaries; two preoculars, lower one contacting first presubocular; two presuboculars, lower one in contact with fourth and fifth supralabials; two postsuboculars; one primary temporal, contact with sixth and seventh supralabials; two secondary temporals, lower secondary temporal overlapping the upper one, contacting seventh supralabials; seven supralabials, fifth below center of the eye; six infralabials; mental wider than long, in contact with the first infralabials; postmental undivided, in contact with first two infralabials; three pairs of chin shields, first pair medially in contact with each other. Dorsal scales smooth, slightly wider than ventral and lateral ones; 22 midbody scale rows; 1/2+4+1/2 scale rows between dark dorsolateral stripes; 68 paravertebral scale rows; 63 ventral scale rows; two enlarged precloacals, outer scales overlapped median ones; tail thick, widened until the tip, small scales around tail base. Limbs relatively short, pentadactyl; toe separated from finger when limbs adpressed along body; eight smooth subdigital lamellae under finger IV, ten under toe IV.

*: regenerated tail.

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Coloration in life. The dorsal surface of head and body brown with irregularly shaped dark spots; dorsolateral stripe narrow, 1+1/2 scales wide, dark, and without paler spots; the upper part of flank dark brown with paler spots, faint in lower edge; the lower part of flank with a mosaic of black and paler spots; the venter yellowish cream.

Variation. Intraspecific variations of Scincella fansipanensis sp. nov. were as follows: none or one pair of prenuchals; two to six nuchals; five or six supraciliaries; six or seven supralabials; 22 or 24 midbody scale rows; 60–68 paravertebral scale rows; 58–64 ventral scales; seven to nine subdigital lamellae on finger IV and 10–12 on toe IV. For the morphological characteristics of the type series, see Table 2–3. The body color before preservation showed little variation, except in the arrangement of the irregularly shaped dark spots, which differed among individuals. One individual (IEBR R.5190) exhibited very few spots.

Distribution. This species is currently known only from Mt. Fansipan, Hoang Lien Son Range in Lao Cai Province, northwestern Vietnam, at high elevations from 2282 to 2366 m a.s.l.

Natural history. Scincella fansipanensis sp. nov. were found under fallen trees (Fig. 1C) in open areas or grassland during the day in May. The skinks appeared to be brumation, as they did not move or attempt to escape when the fallen trees were removed. The air temperature was not recorded at collecting site, however according to Dedov et al. (2020), it is usually approximately 10–12 oC from November to April and the minimum temperature is -3ºC in the area of Hoang Lien National Park. Only two other herpetofaunal species, one individual of the viper Ovophis monticola (Günther) and several individuals of the treefrog Zhangixalus puerensis (He), were found during the survey.

Etymology. The specific name “fansipanensis ” is derived from Mt. Fansipan.As the common name, we suggest Fansipan ground skink (English) and Thằn lằn cổ fansipan (Vietnamese).

Comparisons. Scincella fansipanensis sp. nov. can be distinguished morphologically from other Indochinese and southern Chinese congeners as summarized in Table 4.

In our phylogenetic analysis, Scincella fansipanensis sp. nov. is closely related to S. modesta and S. potanini. It can be distinguished from S. modesta by having a larger SVL (43.5–59.0 mm vs. 31.2–45.7), fewer midbody scale rows (22 or 24 vs. 24–32), and by dorsal color pattern (with irregularly shaped dark spots vs. indistinct lines of black spots). It is distinguished from S. potanini by having fewer midbody scale rows (22 or 24 vs. 25–29), subdigital lamellae on toe IV (10–12 vs. 15–17), and in dorsal color pattern with (irregularly shaped dark spots vs. a median black line).

Scincella fansipanensis sp. nov. differs from S. apraefrontalis, S. modesta, and S. monticola by having a larger SVL (43.5–59.0 mm vs. 36.1, 31.2–45.7, and 31.8–45.4, respectively), and from S. darevskii by having a smaller SVL (43.5–59.0 mm vs. 88.6). Scincella fansipanensis sp. nov. is further distinguished from S. apraefrontalis by the presence of prefrontals (vs. absent), having a larger SVL (43.5–59.0 mm vs. 36.1), more midbody scale rows (22 or 24 vs. 18), paravertebral scale rows (60–68 vs. 52), ventral scale rows (58–64 vs. 50), subdigital lamellae on toe IV (10–12 vs. 8/9), and dorsal scale rows between dorsolateral stripes (1/2+4+1/2 vs. 4). It differs from S. badenensis prefrontals separated from each other (vs. in contact), fewer supralabials (6 or 7 vs. 7 or 8), more nuchals (2–6 vs. 0 or 1 pairs), fewer midbody scale rows (22 or 24 vs. 32–36), ventral scale rows (58–64 vs. 68–74), subdigital lamellae on toe IV (10–12 vs.18–20), toes separated from fingers when limbs adpressed along body (vs. reaching) and in dorsal color pattern (with irregularly shaped dark spots vs. none of dark spot); from S. baraensis, S. darevskii and S. doriae by having fewer midbody scale rows (22 or 24 vs. 30, 28, 26–32, respectively), ventral scale rows (58–64 vs. 64–66, 65, 70–79, respectively) and subdigital lamellae on toe IV (10–12 vs.18–20, 17, 15–18, respectively); from S. barbouri by having fewer midbody scale rows (22 or 24 vs. 26–28), fewer paravertebral scale rows (60–68 vs. 70–79), ventral scale rows (58–64 vs. 70–80), subdigital lamellae on toe IV (10–12 vs. 15–17), and dorsal color pattern (with irregularly shaped dark spots vs. five indistinct lines); from S. devorator by having fewer midbody scale rows (22 or 24 vs. 28–30), subdigital lamellae on toe IV (10–12 vs. 17–19) and dorsal scale rows between dorsolateral stripes (1/2+4+1/2 vs. 1/2+6+1/2); from S. melanosticta by having prefrontals separated from each other (vs. in contact), more nuchals (2–6 vs. none), fewer midbody scale rows (22 or 24 vs. 34–37), subdigital lamellae on toe IV (10–12 vs. 17–22) and dorsal scale rows between dorsolateral stripes (1/2+4+1/2 vs. 8); from S. modesta by having a larger SVL (43.5–59.0 mm vs. 31.2–45.7), fewer midbody scale rows (22 or 24 vs. 24–32), subdigital lamellae on toe IV (10–12 vs. 12–17), dorsal scale rows between dorsolateral stripes (1/2+4+1/2 vs. 6 or 1/2+6+1/2), toes separated from fingers when limbs adpressed along body (vs. reaching) and in dorsal color pattern (with irregularly shaped dark spots vs. indistinct lines of black dots); from S. nigrofasciata by having prefrontals separated from each other (vs. in contact), more nuchals (2–6 vs. 0 or 1 pairs), fewer midbody scale rows (22 or 24 vs. 32–33), paravertebral scale rows (60–68 vs. 69–74), ventral scale rows (58–64 vs. 65–69), subcaudal scales (75 or 83 vs. 111), subdigital lamellae on toe IV (10–12 vs. 15–17), dorsal scale rows between dorsolateral stripes (1/2+4+1/2 vs. 8), and in dorsal color pattern (with irregularly shaped dark spots vs. 5–7 regular discontinuous stripes); from S. ochracea by having prefrontals separated from each other (vs. in contact), fewer midbody scale rows (22 or 24 vs. 30–32), ventral scale rows (58–64 vs. 66–71), subdigital lamellae on toe IV (10–12 vs. 15–19), dorsal scale rows between dorsolateral stripes (1/2+4+1/2 vs. 1/2+6+1/2), and in dorsal color pattern (with irregularly shaped dark spots vs. a dark vertebral stripe); from S. reevesii by having more nuchals (2–6 vs. 0 or 1 pair), fewer midbody scale rows (22 or 24 vs. 28–34), fewer subdigital lamellae on toe IV (10–12 vs. 15–20), and fewer dorsal scale rows between dorsolateral stripes (1/2+4+1/2 vs. 8); from S. rufocaudata by having more nuchals (2–6 vs. none), fewer midbody scale rows (22 or 24 vs. 30–34), subdigital lamellae on toe IV (10–12 vs. 15–20), dorsal scale rows between dorsolateral stripes (1/2+4+1/2 vs. 10), toes separated from fingers when limbs adpressed along body (vs. reaching) and in dorsal color pattern (with irregularly shaped dark spots vs. 1–3 dark brown spots); and from S. rupicola by having prefrontals separated from each other (vs. in contact), more nuchals (2–6 vs. 0 or 1 pairs), fewer midbody scale rows (22 or 24 vs. 33–36), paravertebral scale rows (60–68 vs. 68–73), subcaudal scales (75 or 83 vs. 119), subdigital lamellae on toe IV (10–12 vs. 17–21), dorsal scale rows between dorsolateral stripes (1/2+4+1/2 vs. 8), toe separated from finger when limbs adpressed (vs. reaching), and in dorsal color pattern (with irregularly shaped dark spots vs. dark blotches).