Scincella auranticaudata, Nguyen & Nguyen & Le & Nguyen & Phan & Vo & Murphy & Che, 2025

Scincella auranticaudata sp. nov.

urn:lsid:zoobank.org:act:2EBCDACA-55AA-4222-86CD-B492EAA4D4BB

Figs 1–2 View Fig View Fig , 4–5 View Fig View Fig ; Table 1–3 View Table 1 View Table 2 View Table 3

Diagnosis

Scincella auranticaudata sp. nov. is distinguished from all of its congeners by a combination of the following morphological characters: medium size in adults (SVL up to 62.1 mm); 34–36 smooth midbody scale rows; dorsal scales not enlarged, ½+8+½ rows on back; 67–74 paravertebrals; 65–69 ventral scale rows; 4 supraoculars; prefrontals separated from or just in contact with one another; 2 loreals; 7 supralabials, fifth below center of eye; 2 anterior and 2 posterior enlarged temporals; 1 pairs of nuchals; tympanum deeply sunk and oval; 10–13 smooth lamellae beneath finger IV and 17–20 beneath toe IV; 2 enlarged precloacals; hemipenis smooth, forked near the base with two long symmetrical lobes; dorsum with a vertebral line formed by large black spots.

Etymology

The specific epithet ‘ auranticaudata ’ is a Latin compound word derived from ‘ aurantiacus ’ (meaning ‘orange-colored’) and ‘ caudatus ’ (meaning ‘tail’), referring to the orange coloration on the tail of the new species. We recommend ‘Orange-tailed Ground Skink’, ‘Thằn lằn cổ đuôi cam’, and ‘Rắn mối đuôi cam’ as the common English, Vietnamese, and local names of the new species, respectively.

Type material

Holotype VIETNAM • ♂, adult; Binh Thuan Province, Ta Kou Mountain ; 10°49′30″ N, 107°53′46″ E; 286 m a.s.l.; 3 Jun. 2020; Sang N. Nguyen and Vu D.H. Nguyen leg.; GenBank: PV022551 ; ITBCZ 7700 ; ITBCZ. GoogleMaps

Paratypes VIETNAM • 1 ♀, gravid; Binh Thuan Province, Ta Kou Mountain ; 10°48′53″ N, 107°53′43″ E; 520 m a.s.l.; 2 Jun. 2020; Sang N. Nguyen leg.; GenBank: PV022548 ; ITBCZ 6527 ; ITBCZ GoogleMaps • 1 ♂, adult; Binh Thuan Province, Ta Kou Mountain ; 10°48′52″ N, 107°53′42″ E; 504 m a.s.l; 30 May 2020; Sang N. Nguyen and Vu D.H. Nguyen leg.; GenBank: PV022549 ; ITBCZ 7620 ; ITBCZ GoogleMaps • 1 ♀, gravid; Binh Thuan Province, Ta Kou Mountain ; 10°48′52″ N, 107°53′42″ E; 504 m a.s.l; 30 May 2020; Sang N. Nguyen and Vu D.H. Nguyen leg.; GenBank: PV022550 ; ITBCZ 7623 ; ITBCZ GoogleMaps .

Description (holotype, ♂, adult)

MEASUREMENTS. SVL 62.1 mm; snout short and obtuse; lower eyelid with an undivided transparent disc; body rather robust; tail longer than snout–vent length (TaL = 85.3 mm; TaL/ SVL = 1.37); limbs pentadactyl, toes reach to fingers when limbs adpressed.

Head scales smooth; rostral convex, distinctly visible from above, in broad contact with frontonasal; no supranasals; prefrontals well separated from one another; four supraoculars; frontal narrowing posteriorly, longer than wide (3.8 mm vs 2.2 mm), longer than its distance from snout (2.5 mm), bordered laterally by first two supraoculars, anteriorly by prefrontals and frontonasal, and posteriorly by frontoparietals; pair of frontoparietals, in contact with supraoculars 2–4; parietals in contact posteriorly, behind the interparietal; 1 pair of nuchals, twice as size of dorsal scale; 7 supralabials on both sides, fifth below center of eye, sixth largest; 2 loreals, anterior one smaller than posterior one; 2 preoculars, lower one much larger than upper one; nostril in center of nasal, which in contact with rostral, two first supralabials, anterior loreal, and frontonasal; 9 supraciliaries, first largest; 2 enlarged anterior temporals, lower one larger than and overlapping upper one, in contact with sixth and seventh supralabials; 2 posterior temporals, lower one smaller than and overlapping upper one; 7 infralabials on right side and 6 on left side, first two in contact with postmental; 3 pairs of chin shields, first pair medially in contact with each other, second pair separated by a small scale; tympanum deeply sunk and oval.

Dorsal scales smooth, not larger than lateral and ventral scales, ½+8+½ rows on the back between dorsolateral bands; 36 midbody scale rows; 74 paravertebral scales; ventral scales smooth, in 68 rows; 86 subcaudal scales; 13 smooth lamellae beneath finger IV and 19 beneath toe IV; 2 enlarged precloacal scales, left scale overlapping right one.

Fully everted hemipenis smooth, forked near base, forming two long lobes with regular transversal shallow grooves on body of each lobe; clear sulcus spermaticus starting from base and divided into two lobes prior to forked position ( Fig. 4 View Fig ).

In life, anterior part of dorsum and upper head red to bright brown, posterior part of dorsum dark brown, with vertebral enlarged black spots extending from back to tail base; interrupted dorsolateral band with black spots, starting from shoulder to tail base; lateral side of neck and chest red; tail orange; lower part of head, body, and limbs pink; lower part of tail pink to yellowish; eyes with black round pupil and visible yellowish iris. In preservation, color fades but pattern remained with black vertebral and dorsolateral interrupted bands; red, orange, and yellow faded to cream or white; overall dorsal and lateral coloration bright brown; venter cream.

Variation

Paratype ITBCZ 7620 has prefrontals just in contact with each other and nuchals three times the size of dorsal scale. Other slight variations in size and scalation of the type series were summarized in Table 3 View Table 3 .

Sexual dimorphism

Males are bigger than females (SVL 60.0–62.1 vs 48.9–51.6 mm). Lower side of tail base in males is more or less swollen whereas this area in females is flat.

Field notes

All specimens were collected at night, on the ground among rotting leaves in evergreen forest on a mountain slope. Paratype ITBCZ 6527 was collected during a light rain. The orange tail of the new species was also observed in nature in March 2018, July 2019, and January 2020. Other skink recorded sympatrically with the new species was Sphenomorphus cf. yersini Nguyen, Nguyen, Nguyen, Orlov & Murphy, 2018 .

Distribution

The new species is currently known only from Ta Kou Mountain, Binh Thuan Province, southern Vietnam ( Fig. 1 View Fig ).

Comparisons

Scincella auranticaudata sp. nov. differs morphologically from its congeners in regions of Indochina and China as follows: from S. apraefrontalis by having more midbody scale rows (34–36 vs 18), dorsal scales not enlarged (vs enlarged), more lamellae beneath toe IV (17–20 vs 8–9), more paravertebrals and ventrals (67–74 and 65–69 vs 52 and 50, respectively), and presence (vs absence) of prefrontal ( Nguyen et al. 2010b); from S. badenensis ( Fig. 5A View Fig ) by having hemipenis forked near the base, forming two long smooth lobes (vs forked near the tip with two short lobes and small papilla at the end of each lobe), tail orange (vs dark brown), and males with vertebral black spots on dorsum (vs pure dorsum in males) ( Nguyen et al. 2019); from S. baraensis by having more midbody scale rows (34–36 vs 30), fewer nuchal scales (1 vs 3 or 3.5 pairs), more enlarged anterior temporal (2 vs 1), absence (vs presence) of weak auricular lobules, and hemipenis with two long lobes (vs a short lobe) ( Nguyen et al. 2020); from S. barbouri by having more midbody scale rows (34–36 vs 26–28), fewer nuchal scales (1 vs 4 or 5 pairs), and absence (vs presence) of distinctly enlarged dorsal scales ( Stejneger 1925; Ouboter 1986); from S. darevskii by having more midbody scale rows (34–36 vs 28), more paravertebral scale rows (67–74 vs 62), fewer supraoculars (4 vs 5), more enlarged anterior temporal (2 vs 1), absence (vs presence) of weak auricular lobules, and more longitudinal dorsal scale rows on back (½+8+½ vs 6) ( Nguyen et al. 2010c); from S. devorator by having more midbody scale rows (34–36 vs 28–30), fewer nuchal scales (1 vs 3 pairs), absence (vs presence) of distinctly enlarged dorsal scales ( Darevsky et al. 2004; Nguyen et al. 2011); from S. doriae by having more midbody scale rows (34–36 vs 26–32), fewer nuchal scales (1 vs 3 or 4 pairs), absence (vs presence) of distinctly enlarged dorsal scales, and more longitudinal dorsal scale rows on back (½+8+½ vs 6) ( Boulenger 1887; Smith 1935; Taylor 1963; Bourret 2009); from S. fansipanensis by having more midbody scale rows (34–36 vs 22, rarely 24), more lamellae beneath toe IV (17–20 vs 10–12), fewer nuchal scales (1 vs 3 pairs), more supraciliaries (8 or 9 vs 5, rare 6), and limbs in touch (vs separated) when adpressed ( Okabe et al. 2024); from Scincella honbaensis sp. nov. by having more midbody scale rows (34–36 vs 28), fewer ventral scale rows (65–69 vs 74), fewer nuchal scales (1 vs 3 pairs), and more longitudinal dorsal scale rows on back (½+8+½ vs 6); from S. huanrenensis by having more midbody scale rows (34–36 vs 26–28), more lamellae beneath toe IV (17–20 vs 13–16), fewer ventral scale rows (65–69 vs 75–89), and more longitudinal dorsal scale rows on back (½+8+½ vs 6) ( Zhao & Huang 1982; Chen et al. 2001); from S. melanosticta by having a shorter relative tail (TaL/SVL = 1.23–1.38 vs 1.50–1.75), more nuchal scales (1 pair vs 0), more enlarged anterior temporal (2 vs 1), fewer longitudinal dorsal scale rows on back (½+8+½ vs 10), and dorsum with large vertebral black spots (vs numerous black dots on both sides of midline) ( Boulenger 1887; Smith 1935; Taylor 1963; Bourret 2009); from S. modesta by having small (vs enlarged) dorsal scales, more midbody scale rows (34–36 vs 26–30), and more longitudinal dorsal scale rows on back (½+8+½ vs 6 or 7) ( Smith 1935; Chen et al. 2001); from S. monticola by having more midbody scale rows (34–36 vs 22–26), more lamellae beneath toe IV (17–20 vs 10–13), fewer nuchal scales (1 vs 3 or 4 pairs); more paravertebrals and ventrals (67–74 and 65–69 vs 52–59 and 52–58, respectively), and more enlarged anterior temporal (2 vs 1) ( Schmidt 1927; Neang et al. 2018); from S. nigrofasciata Neang, Chan & Poyarkov, 2018 ( Fig. 5C View Fig ) by having a shorter relative tail (TaL/SVL = 1.23–1.38 vs 1.56–1.94 [in the original description of S. nigrofasciata , TaL/SVL ratio of subadult CBC02841 shown in table 1 is 1.56, not 1.27; female CBC02840 shown in figure 4a probably has a regenerated tail and is excluded herein]), interrupted (vs continuous) dorsolateral band, and dorsum with a vertebral black spots (vs 5–7 dark stripes) (Neang et al. 2018); from S. ochracea by having more midbody scale rows (34–36 vs 30– 32), fewer nuchal scales (1 vs 3 pairs), more longitudinal dorsal scale rows on back (½+8+½ vs 6), and absence (vs presence) of weak auricular lobules ( Bourret 2009; Pham et al. 2015; Neang et al. 2018); from S. ouboteri by having more midbody scale rows (34–36 vs 30–32), fewer nuchal scales (1 vs 2–4 pairs), more longitudinal dorsal scale rows on back (½+8+½ vs 6), and absence (vs presence) of weak auricular lobules ( Pham et al. 2024); from S. potanini by having more midbody scale rows (34–36 vs 27), fewer nuchal scales (1 vs 3 pairs), and limbs in touch (vs separated) when adpressed ( Günther 1896; Ouboter 1986); from S. przewalskii by having small (vs enlarged) dorsal scales, fewer nuchal scales (1 vs 4 pairs), more supralabials (7 vs 6), and more longitudinal dorsal scale rows on back (½+8+½ vs 6) ( Bedriaga 1912; Wang & Zhao 1986); from S. punctatolineata by having more midbody scale rows (34–36 vs 24–26), more lamellae beneath toe IV (17–20 vs 12–14), more longitudinal dorsal scale rows on back (½+8+½ vs 6), and limbs in touch (vs separated) when adpressed ( Smith 1935); from S. rara by having more midbody scale rows (34–36 vs 24), fewer nuchal scales (1 vs 3 pairs), more paravertebrals (67–74 vs 53), and a single (vs double) row of lamellae beneath toes and figures II–IV ( Darevsky & Orlov 1997); from S. reevesii by having more midbody scale rows (34–36 vs 28–32), more longitudinal dorsal scale rows on back (½+8+½ vs 8), a shorter relative tail (TaL/SVL = 1.23–1.38 vs 1.5–2.0), and dorsum with large vertebral black spots (vs small black spots) ( Smith 1935; Bourret 2009); from S. rufocaudata ( Fig. 5B View Fig ) by having fewer longitudinal dorsal scale rows on back (½+8+½ vs 10), presence (vs absence) of nuchal scales, dorsum with large vertebral black spots (vs small black spots), dorsolateral band on flank interrupted (vs continuous), and absence (vs presence) of a distinct black stripe extending from loreal to temporal area ( Darevsky & Nguyen 1983; Neang et al. 2018); from S. rupicola ( Fig. 5D View Fig ) by having a shorter relative tail (TaL/SVL = 1.23–1.38 vs 1.70–1.71), fewer subcaudals (82–88 vs 119), absence (vs presence) of paired black spots on dorsal side of neck, and absence (vs presence) of a black band behind the eye ( Smith 1916, 1935; Taylor 1963); from S. schmidti by having a shorter relative tail (TaL/SVL = 1.23–1.38 vs 1.90), limbs in touch (vs separated) when adpressed, more midbody scale rows (34–36 vs 26), and more lamellae beneath toe IV (17–20 vs 11) ( Barbour 1927); from S. truongi by having more midbody scale rows (34–36 vs 28), more lamellae beneath toe IV (17–20 vs 13–15), fewer nuchal scales (1 vs 3 pairs), and more longitudinal dorsal scale rows on back (½+8+½ vs 6) ( Pham et al. 2025); from S. tsinlingensis by having more midbody scale rows (34–36 vs 26–30), fewer nuchal scales (1 vs 2–5 pairs), and more longitudinal dorsal scale rows on back (½+8+½ vs ½+4+½) ( Ouboter 1986; Inger et al. 1990); from S. victoriana by having more midbody scale rows (34–36 vs 26), fewer nuchal scales (1 vs 3 pairs), and smooth (vs keeled) scales on dorsum and tail ( Ouboter 1986); and from S. wangyuezhaoi by having more midbody scale rows (34–36 vs 27–30), absence (vs presence) of enlarged dorsal scales, fewer nuchal scales (1 vs 2–4 pairs), and more longitudinal dorsal scale rows on back (½+8+½ vs 6) ( Jia et al. 2023).