Scincella baraensis, Nguyen & Nguyen & Nguyen & Murphy, 2020

Nguyen, Sang Ngoc, Nguyen, Vu Dang Hoang, Nguyen, Luan Thanh & Murphy, Robert W., 2020, A new skink of the genus Scincella Mittleman, 1950 (Squamata: Scincidae) from southern Vietnam, Zootaxa 4868 (3), pp. 423-434 : 426-430

Scincella baraensis sp. nov.

( Figs. 2 , 3 )

Holotype. ITBCZ 6534 , adult male, collected from Ba Ra Mountain , Binh Phuoc Province, Vietnam; coordinates 11°49’42.0” N, 107°00’30.8” E; elevation 337 m a.s.l. by Sang N. Nguyen and Vu D.H. Nguyen, on 4 June 2018 ( Fig. 2 ).

Paratypes. Two specimens, also collected from Ba Ra Mountain by Sang N. Nguyen and Vu D.H. Nguyen on the same date and coordinates as the holotype: ITBCZ 6535 , adult male ( Fig. 3 A–C) and ITBCZ 6536 , adult female ( Fig. 3D ) .

Diagnosis. Scincella baraensis sp. nov. is distinguished from all of its congeners by a combination of the following morphological characters: relatively small size in adults (SVL up to 49.2 mm); when limbs adpressed toes do not or just reach fingers; 30 smooth midbody scale rows; dorsal scales not enlarged; 66–70 paravertebrals; 64–66 ventral scale rows; 4 supraoculars; prefrontals in broad contact with or separated from one another; 2 loreals; 7 supralabials, the fifth and sixth below the center of the eye; 1 anterior and 2 posterior enlarged temporals; 3 or 3.5 pairs of nuchals; tympanum deeply sunk with weak auricular lobules on anterior margin of ear; 12 or 13 smooth lamellae beneath finger IV and 18–20 beneath toe IV; 2 enlarged precloacals; hemipenis smooth, short, unforked; dorsum with faint black dots.

Description of holotype. Adult male; SVL 46.8 mm; snout short and obtuse; lower eyelid with an undivided transparent disc; body rather compressed; tail longer than snout-vent length, regenerated; limbs pentadactyl, toes just reach to fingers when limbs adpressed.

Head scales smooth; rostral convex, distinctly visible from above, in broad contact with frontonasal, broader than long (1.8 mm width, 0.8 mm height); no supranasals; prefrontals in broad contact with one another (1.1 mm width, 1.1 mm length, in contact 0.4 mm); four supraoculars; a pair of frontoparietals, shorter than frontal; frontal narrowing posteriorly, longer than wide, bordered laterally by first two supraoculars, anteriorly by prefrontals, and posteriorly by frontoparietals; frontoparietals in contact with supraoculars 2–4; parietals in contact posteriorly, behind the interparietal; 3.5 pairs of nuchals, 2.5 anterior pairs three times the size of dorsal scale, the other pair twice as the size of dorsal scale; 7 supralabials on both sides, fifth and sixth below center of the eye, sixth largest; 2 loreals; 2 preoculars, the lower one much larger than the upper one; nostril in center of nasal, in contact with the first supralabial, rostral, anterior loreal, and frontonasal; 8 supraciliaries, first largest; 1 enlarged anterior temporal, in contact with sixth and seventh supralabials; 2 posterior temporals, lower one overlapping upper one; 7 infralabials, first two in contact with postmental, fifth longest; 3 pairs of chin shields, first pair medially in contact with each other; tympanum deeply sunk; ear with weak auricular lobules on the anterior margin.

Dorsal scales smooth, not larger than lateral and ventral scales, eight rows on the back between dorsolateral bands; 30 midbody scale rows; 66 paravertebral scales; ventral scales smooth, in 64 rows; subcaudal scales on the original part of tail not enlarged; 13 smooth lamellae beneath finger IV and 20 beneath toe IV; 2 enlarged precloacal scales, left scale overlapping right one.

Hemipenis. Fully everted hemipenis short, smooth, and unforked; clear sulcus spermaticus starting from base to the single lobe; a prominent longitudinal fold along with the sulcus at the proximal part ( Fig. 2 E–G).

Coloration. In life, overall dorsal coloration dark brown with faint black dots on dorsum; dorsolateral band black with bright spots; lower part of check, body, limbs, and tail yellow to orange; lower part of head and neck white. Free margin of upper add lower eyelids orange to yellow. Eyes with black round pupil and yellow iris. In preservation, color fades; orange and yellow faded to cream or white; overall dorsal and lateral coloration black to dark brown; venter cream.

Variation. Paratype ITBCZ 6535 has supraoculars 3 and 4 incompletely fused on both sides, separated by a suture that is about one third of their width. Supraoculars 1 and 2 incompletely separated from each other on right side . Paratype 6536 with prefrontals separated from each other. Table 3 summarizes variation in size and scalation of the type series.

Field notes. All specimens were collected at night, on the ground among rotting leaves in secondary forest connected with a cashew plantation. However, the skink was observed being active in the daytime and it may be diurnal.

Sexual dimorphism. Males have lower part of cheek, body, limbs, and tail yellow to orange while these parts in female are cream. Fingers and toes not touching in female when limbs adpressed.

Distribution. The new species is currently known only from Ba Ra Mountain, Binh Phuoc Province, southern Vietnam ( Fig. 4 ). Based on the continuous habitat and elevation between Ba Ra Mountain and its vicinity, this skink may also occur in Binh Phuoc and Dak Nong provinces ( Vietnam) and Mondulkiri Province in eastern Cambodia.

Etymology. The specific epithet baraensis is a toponym derived from the Ba Ra Mountain where the new species was discovered. We recommend “Bara ground skink”, “Thằn lằn cổ bà rá”, and “Rắn mối bà rá” as the common English, Vietnamese, and local names of the new species, respectively.

Comparisons. Scincella baraensis sp. nov. differs morphologically from its Asian congeners as follows: from S. apraefrontalis by having more midbody scale rows (30 vs. 18), dorsal scales not enlarged (vs. enlarged—distinct-ly larger than lateral scales [ Smith 1935]), more lamellae beneath toe IV (18–20 vs. 8–9), and presence (vs. absence) of prefrontal ( Nguyen et al. 2010a); from S. badenensis by having fewer midbody scale rows (30 vs. 32–36), more nuchal pairs (3–3.5 vs. 0–1), fewer temporals (1+2 vs. 2+3), and unforked (vs. forked) hemipenis (Nguyen et a. 2019); from S. barbouri (Stejneger) by having more midbody scale rows (30 vs. 26–28), more lamellae beneath toe IV (18–20 vs. 15–17), and presence (vs. absence) of weak auricular lobules ( Stejneger 1925; Ouboter 1986); from S. boettgeri (van Denburgh) by having more lamellae beneath toe IV (18–20 vs. 15–16) and presence (vs. absence) of weak auricular lobules ( van Denburgh 1912; Ouboter 1986); from S. capitanea Ouboter by having more lamellae beneath toe IV (18–20 vs. 15–17) and presence (vs. absence) of weak auricular lobules ( Ouboter 1986); from S. darevskii by having more midbody scale rows (30 vs. 28), more paravertebral scale rows (66–70 vs. 62), and fewer supraoculars (4 vs. 5) ( Nguyen et al. 2010); from S. devorator by having small (vs. enlarged) dorsal scales and presence (vs. absence) of weak auricular lobules ( Darevsky et al. 2004; Nguyen et al. 2011); from S. doriae by having small (vs. enlarged) dorsal scales, more dorsal scale rows on back (8 vs. 6), presence (vs. absence) of weak auricular lobules, and absence (vs. presence) of transversely enlarged subcaudals ( Boulenger 1887; Smith 1935; Taylor 1963; Bourret 2009); from S. formosensis (van Denburgh) by having by having more lamellae beneath toe IV (18–20 vs. 15–17) and presence (vs. absence) of weak auricular lobules ( van Denburgh 1912; Ouboter 1986); from S. huanrenensis Zhao & Huang by having more midbody scale rows (30 vs. 26–28), more lamellae beneath toe IV (18–20 vs. 13–16), and fewer ventral scale rows (64–66 vs. 75–89) ( Zhao & Huang 1982; Chen et al. 2001); from S. macrotis (Steindachner) by having small (vs. enlarged) dorsal scales, presence (vs. absence) of weak auricular lobules, and absence (vs. presence) of transversely enlarged subcaudals ( Smith 1935); from S. melanosticta by having nuchal scales (3 or 3.5 pair vs. 0), fewer midbody scale rows (30 vs. 34–38), and short and unforked (vs. long and deeply forked) hemipenis ( Smith 1935; Taylor 1963; Bourret 2009; Neang et al. 2018); from S. modesta (Gunther) by having small (vs. enlarged) dorsal scales, more lamellae beneath toe IV (18–20 vs. 10–15), and presence (vs. absence) of weak auricular lobules ( Smith 1935); from S. monticola by having more midbody scale rows (30 vs. 22–26), more lamellae beneath toe IV (18–20 vs. 10–13), more paravertebrals and ventrals (66–70 and 64–66 vs. 52–59 and 52–58, respectively), and presence (vs. absence) of weak auricular lobules ( Schmidt 1927; Neang et al. 2018); from S. nigrofasciata Neang, Chan & Poyarkov by having fewer midbody scale rows (30 vs. 32–33), more nuchal scales (3 or 3.5 pair vs. 0 or 1), more lamellae beneath toe IV (18–20 vs. 15–17), short and unforked (vs. long and deeply forked) hemipenis, and fewer enlarged anterior temporal (1 vs. 2) ( Neang et al. 2018); from S. ochracea by having fewer enlarged anterior temporal (1 vs. 2), more lamellae beneath finger IV (12 or 13 vs. 9–11), more dorsal scale rows between dorsolateral lines (8 vs. 6), and absence (vs. presence) of dark vertebral stripe ( Bourret 2009; Pham et al. 2015; Neang et al. 2018); from S. potanini (Gunther) by having more midbody scale rows (30 vs. 27), more lamellae beneath toe IV (18–20 vs. 17), and presence (vs. absence) of weak auricular lobules ( Gunther 1896); from S. przewalskii (Bedriaga) by having fewer midbody scale rows (30 vs. 22–34), more lamellae beneath toe IV (18–20 vs. 17), more supralabials (7 vs. 6), and more dorsal scale rows between dorsolateral lines (8 vs. 6) ( Wang & Zhao 1986); from S. punctatolineata (Boulenger) by having more midbody scale rows (30 vs. 24–26), more lamellae beneath toe IV (18–20 vs. 12–14), and presence (vs. absence) of nuchals ( Smith 1935); from S. rara by having small (vs. enlarged) dorsal scales, more midbody scale rows (30 vs. 24), and a single (vs. double) row of lamellae beneath toes and figures II–IV ( Darevsky & Orlov 1997); from S. reevesii by having more nuchals (3 or 3.5 pairs vs. 0 or 1), presence (vs. absence) of weak auricular lobules, short and unforked (vs. long and deeply forked) hemipenis, and absence (vs. presence) of slightly enlarged transversal subcaudals ( Smith 1935; Bourret 2009; Neang et al. 2018); from S. rufocaudata by having short and unforked (vs. long and deeply forked) hemipenis, fewer midbody scale rows (30 vs. 32–34), and one (vs. two) anterior temporal ( Darevsky & Nguyen 1983; Neang et al. 2018); from S. rupicola by having fewer midbody scale rows (30 vs. 34–36), more nuchals (3 or 3.5 pairs vs. 0 or 1), short and unforked (vs. long and deeply forked) hemipenis, and one (vs. two) anterior temporal ( Smith 1935; Taylor 1963; Neang et al. 2018); from S. schmidti (Barbour) by having more midbody scale rows (30 vs. 26), presence (vs. absence) of weak auricular lobules, and more lamellae beneath toe IV (18–20 vs. 11) ( Barbour 1927); from S. tsinlingensis (Hu & Zhao) by having more lamellae beneath toe IV (18–20 vs. 11–16), presence (vs. absence) of weak auricular lobules, and more dorsal scale rows between dorsolateral bands (8 vs. 6) ( Ouboter 1986; Inger et al. 1990); from S. vandenburghi (Schmidt) by having more midbody scale rows (30 vs. 28) and more lamellae beneath toe IV (18–20 vs. 12) ( Schmidt 1927); and from S. victoriana (Shreve) by having more midbody scale rows (30 vs. 26), more lamellae beneath toe IV (18–20 vs. 15), and smooth (vs. keeled) scales on dorsum and tail ( Ouboter 1986).

Figures

FIGURE 2. Holotype of Scincella baraensis sp. nov., ITBCZ 6534. A, living specimen; B–D, lateral, dorsal and ventral views of head, respectively; E&F, dorsal and ventral views of left hemipenis (not fully everted); G, fully everted hemipenes.

FIGURE 3. Paratypes of Scincella baraensis sp. nov. A–C, ITBCZ 6535 in life (A) and its hemipenes when pressed on tail base (B) and after water injection (C); D, ITBCZ 6536 in life.

FIGURE 4. Map of sampling sites of Scincella in southern Vietnam and Cambodia used in this study. Localities: 1, Kon Chu Rang NR., Gia Lai Prov., Vietnam; 2, Kon Ka Kinh NP., Gia Lai Prov., Vietnam; 3, Keo Seima WS., Mondulkiri Prov., Cambodia; 4, Bidoup—Nui Ba NP., Lam Dong Prov., Vietnam; 5, Ba Ra Mountain, Binh Phuoc Prov., Vietnam; 6, Dinh Mountain, Ba Ria—Vung Tau Prov., Vietnam; 7, Ba Den Mountain, Tay Ninh Prov., Vietnam; 8, Veal Veng Dist., Pursat Prov., Cambodia; 9, Phnom Samkos WS., Pursat Prov., Cambodia; 10, Phnom Kulen Dist., Krong Siem Reap, Cambodia; 11, Kuleaen Dist., Preah Vihear Prov., Cambodia (modified from Nguyen et al. 2019).