A new skink of the genus Subdoluseps Freitas, Datta-Roy, Karanth, Grismer & Siler, 2019 (Squamata: Scincidae) from southern Vietnam Author Le, Manh Van 0000-0002-7401-4830 University of Science and Education, University of Danang, 459 Ton Duc Thang St., Lien Chieu District, Danang City, Vietnam. leemanh 94 @ gmail. com; https: // orcid. org / 0000 - 0002 - 7401 - 4830 leemanh94@gmail.com Author Nguyen, Vu Dang Hoang Institute of Tropical Biology, Vietnam Academy of Science and Technology, 85 Tran Quoc Toan St., Dist. 3, Ho Chi Minh City, Vietnam. Author Phan, Hoa Thi 0000-0002-7401-4830 University of Science and Education, University of Danang, 459 Ton Duc Thang St., Lien Chieu District, Danang City, Vietnam. leemanh 94 @ gmail. com; https: // orcid. org / 0000 - 0002 - 7401 - 4830 & hoaphansdh @ gmail. com; https: // orcid. org / 0000 - 0003 - 2884 - 3299 leemanh94@gmail.com Author Rujirawan, Attapol 0000-0001-9179-6910 Department of Zoology, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Chatuchak, Bangkok, Thailand. fsciapr @ ku. ac. th; https: // orcid. org / 0000 - 0001 - 9179 - 6910 fsciapr@ku.ac.th Author Aowphol, Anchalee 0000-0001-9179-6910 Department of Zoology, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Chatuchak, Bangkok, Thailand. fsciapr @ ku. ac. th; https: // orcid. org / 0000 - 0001 - 9179 - 6910 & fsciacl @ ku. ac. th; https: // orcid. org / 0000 - 0001 - 9504 - 4601 fsciapr@ku.ac.th Author Vo, Thi-Dieu-Hien Faculty of Environmental and Food Engineering, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam. Author Murphy, Robert W. 0000-0001-8555-2338 Centre for Biodiversity and Conservation Biology, Royal Ontario Museum, 100 Queen’s Park, Toronto, Canada M 5 S 2 C 6. bob. murphy @ utoronto. ca; https: // orcid. org / 0000 - 0001 - 8555 - 2338 bob.murphy@utoronto.ca Author Nguyen, Sang Ngoc Institute of Tropical Biology, Vietnam Academy of Science and Technology, 85 Tran Quoc Toan St., Dist. 3, Ho Chi Minh City, Vietnam. & Faculty of Environmental and Food Engineering, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam. text Zootaxa 2021 2021-04-09 4952 2 257 274 journal article 7331 10.11646/zootaxa.4952.2.3 a0c3d86a-90d9-461e-b9db-e24143d6d581 1175-5326 4674021 4318A013-961A-4B00-811C-7C71112492A4 Subdoluseps vietnamensis sp. nov. ( Figs. 3 & 4 ) Holotype . ITBCZ 5842 , adult male, collected from Ho Tram Area , Xuyen Moc District , Ba Ria-Vung Tau Province , Vietnam ; coordinates 10°29’38.2” N , 107°27’40.0” E ; elevation 11 m asl by Sang N. Nguyen and Vu D.H. Nguyen , on 21 March 2017 ( Fig. 3 ). FIGURE 3. Holotype of Subdoluseps vietnamensis sp. nov. , ITBCZ 5842. A, general view, in life (photo by Sang N. Nguyen); B&C, line drawing of lateral and dorsal views of head (drawn by Manh V. Le). Paratypes . Two adult males ITBCZ 5843 and 5844, and one adult female ITBCZ 5856 collected by Sang N. Nguyen and Vu D.H. Nguyen from the same site as the holotype ; two adult males, ITBCZ 7038 and 7046, collected by Manh V . Le on 04 June 2020 at Ho Tram Area , Xuyen Moc District , Vietnam , coordinates 10°28’59.8” N , 107°26’03.6” E , elevation 10 m asl ; two adult females ITCBZ 7056 and 7059, and one juvenile ITBCZ 7070 , collected by Manh V . Le on 04 June 2020 at La Gi Town , Binh Thuan Province , Vietnam , coordinates 10°42’38.8’’ N , 107°42’10.8” E , elevation 62 m asl ( Fig. 4 ) . FIGURE 4. Paratypes of Subdoluseps vietnamensis sp. nov. in life. A, ITBCZ 5843, adult female (photo by Sang N. Nguyen); B, ITBCZ 7038, adult male; C, ITBCZ 7046, adult male; D, ITBCZ 7056, adult female; E, ITBCZ 7059, adult female; F, ITBCZ 7070, juvenile (photos by Manh V. Le). Diagnosis . Subdoluseps vietnamensis sp. nov. is distinguished from its congeners by a combination of the following morphological characters: medium size in adults (SVL up to 48.7 mm ); tail length approximately equal to SVL; 27–30 smooth midbody scale rows; dorsal scales not enlarged; 55–57 paravertebral scales; 34–37 axilla-groin scales; 55–62 ventral scale rows; 64–74 subcaudal scales; four supraoculars; frontoparietal single; prefrontals not in contact with one another; two loreal scales; seven supralabials, the fifth below the center of the eye; one anterior and two posterior enlarged temporal scales; ear opening with two lobules on the anterior margin; 9 or 10 smooth subdigital lamellae beneath finger III and 12–15 beneath toe IV; six enlarged precloacal scales; and four distinct black stripes on dorsum. Description of holotype . Adult male, SVL 46.5 mm ; snout short and obtuse; lower eyelid scaly; body rather robust; tail regenerated. Head scales smooth; rostral convex, distinctly visible from above, broader than long (2.0 mm width, 1.0 mm height); a pair of supranasals forming short median suture, touching nasals and anterior loreals laterally, width equal to length ( 0.7 mm ); prefrontals small, quadrangular, widely separated from each other, each touching both loreals; four supraoculars; frontal truncate anteriorly, longer than its distance from tip of snout, shorter than its distance from nuchal (2.0 mm vs. 3.2 mm ), longer than wide ( 1.8 mm width, 2.6 mm length), touching two anterior supraoculars; frontoparietal single, much larger than interparietal, wider than long (3.0 mm width, 1.9 mm length), touching three supraoculars; parietals in contact posteriorly behind the interparietal; interparietal longer than wide ( 1.1 mm width, 1.6 mm length), with parietal eye visible posterior to center; a pair of nuchals; seven supralabials on both sides, fifth below center of the eye, first larger than the three following, sixth largest; two loreals, anterior ( 0.6 mm length, 0.6 mm height) slightly higher, the posterior ( 0.9 mm length, 0.5 mm height) longer; nasal divided, in contact with the first supralabial, rostral, anterior loreal, and supranasal; nostril in center of nasal; eight supraciliaries, first largest; one enlarged anterior temporal in contact with the sixth and the seventh supralabial; two posterior temporals, lower one smaller and overlapping the upper one, the lower temporal in contact with seventh supralabials; six infralabials, first two in contact with postmental; two pairs of chin shields, first pair medially in contact with each other; ear-opening moderately small, the anterior border with two lobules. Body elongate (AGD/SVL = 0.56); dorsal scales smooth, not larger than lateral and ventral scales, with eight longitudinal rows on the back; 28 midbody scale rows; 71 paravertebral scales; 35 axilla-groin scales; ventral scales smooth, in 55 rows; limbs short (FLL/SVL = 0.18, HLL/SVL = 0.25), pentadactyl, widely separated by ten scales when adpressed; 3, 6, 9, 9, and 7 smooth lamellae beneath fingers I–V, respectively; 4, 7, 13, 13, and 9 smooth lamellae beneath toes I–V, respectively; six enlarged precloacal scales, the two middle ones slightly larger than the others; size of median subcaudal series on the original part of the tail equal to those of its adjacent rows. Coloration. In life, overall dorsal coloration reddish brown with two dorsolateral bright lines on anterior part of dorsum; each dorsal scale of four central rows with a black spot forming four distinct longitudinal lines on dorsum; ear and surrounding area orange; sides dark brown to black intermixed with white, brown and yellow spots; chest and belly yellow ( Fig. 3 ). In preservation, color fades but the four longitudinal dorsal lines remain distinct; orange and yellow faded to cream or white; overall dorsal and lateral coloration black to dark brown with bright spots on lateral sides; venter cream. Variation in paratypes (n = 8). Most morphological characters of paratypes agree with those of the holotype . The following main characters vary: (1) midbody scale rows: vary from 27 to 30; (2) paravertebral and ventral scale rows: range from 55 to 57 and from 55 to 62, respectively; (3) axilla-groin scales: range from 34 to 37; (4) and nuchals: range from one to three scales. Table 3 summarizes variation in size and scalation of the type series. FIGURE 5. Habitats of Subdoluseps vietnamensis sp. nov. from southern Vietnam. A&B, earleaf acacia plantation and dipterocarp forest on the sandy soil in Ho Tram area, Xuyen Moc District, Ba Ria-Vung Tau Province, respectively; C, rubber plantation in La Gi Town, Binh Thuan Province (Photos by Manh V. Le). TABLE 3. Measurements (in mm) and scalation of the types series of Subdoluseps vietnamensis sp. nov . See Material and Methods for abbreviations.

Holotype	Paratypes	Mean ±SD
Morphological character	ITBCZ 5842	ITBCZ 5843	ITBCZ 5844	ITBCZ 5856	ITBCZ 7038	ITBCZ 7046	ITBCZ 7056	ITBCZ 7059	ITBCZ 7070	Min-Max
Sex	Male	Female	Male	Male	Male	Male	Female	Female	Juvenile
SVL	46.5	46.8	48.2	46.9	44.2	47.5	44.0	48.7	31.9
46.8 ±1.7
TL	-	-	-	-	49.3	52.1	43.4	48.3	38.8
48.8 ±3.6
TL/SVL	-	-	-	-	1.12	1.10	0.99	0.99	-
1.04±0.07
AGD	26.1	26.3	26.2	24.4	24.9	26.8	25.5	28.6	18.1
26.1±1.3
HL	8.7	8.4	9.4	9.0	8.2	8.7	7.9	7.7	6.0
8.6±0.6
HW	6.8	6.2	6.4	6.7	6.1	6.2	5.5	5.6	4.1
6.2±0.5
HD	4.9	5.2	5.3	5.3	4.9	4.7	4.0	4.1	3.1
4.9±0.5
ED	1.8	1.8	1.9	1.6	1.5	1.8	1.6	1.5	1.5
1.7±0.2
END	2.3	2.3	2.5	2.2	2.2	1.9	2.0	1.9	1.5
2.2±0.2
SNL	3.7	3.7	4.0	2.8	3.6	3.3	3.4	3.2	2.5
3.5±0.4
IND	1.7	1.7	2.0	1.8	1.6	1.7	1.7	1.7	1.4
1.7±0.1
FLL	8.2	7.9	8.1	7.9	8.1	7.5	7.4	7.6	6.3
7.9±0.3
HLL	11.6	10.6	13.0	11.1	12.5	12.2	11.4	11.8	8.8
11.7±0.8
MBSR	28	30	30	30	29	30	28	28	27	27–30

...Continued on the next page TABLE 3. (Continued)

Holotype	Paratypes	Mean ±SD
Morphological character	ITBCZ 5842	ITBCZ 5843	ITBCZ 5844	ITBCZ 5856	ITBCZ 7038	ITBCZ 7046	ITBCZ 7056	ITBCZ 7059	ITBCZ 7070	Min-Max
PVSR	55	57	56	56	57	56	56	55	57	55–57
AGSR	35	37	34	35	37	36	36	36	37	34–37
Ventral scales	55	62	55	56	57	56	56	56	59	55–62
F3lam	9	10	10	9	9	10	9 (left)	9	9	9–10
T4lam	13	14 (left)	14	14	13	13	13	12	15	12–15
SCa	-	-	-	-	72	74	68	64	73	64–74
CP	6	6	6	6	6	6	6	6	6	6
SO	4	4	4	4	4	4	4	4	4	4
Temp	1+2	1+2	1+2	1+2	1+2	1+2	1+2	1+2	1+2	1+2
SC	8	8	8	9	8	8	9	8	8	8–9
LO	2	2	2	2	2	2	2	2	2	2
SL	7	7	7	7	7	7	7	7	7	7
IFL	6	6	6	6	6	6	6	6	6	6
NU	2	2	2	2	3	2	2	3	1	1–3

TABLE 4. Morphological data of Subdoluseps frontoparietale from Thailand in comparison with S. vietnamensis sp. nov. . Data on holotype and paratypes of S. frontoparietale were taken from Taylor (1962) . Additional specimens were collected from Mittraphap Subdistrict, Muak Lek District, Saraburi Province, Thailand, coordinates 14°38’04.9” N, 101°08’45.4” E, elevation 190 m a.s.l., see Material and Methods for abbreviations.

Subdoluseps frontoparietale			S. vietnamensis sp. nov.
Morphological character
Holotype	Paratypes	Additional specimens		Mean±SD	Mean±SD
1694	33341	333342	333391	333392	333393	ZMKU R705	ZMKU R706	ZMKU R707	min-max	min-max
SVL	38.0	33.0	35.0	41.0	41.0	36.0	35.7	43.3	25.9	37.0±3.6	46.8±1.7
TL	47.0	38.0	41.5	55.0	-	42.0	48.1	54.6	-	47.0±6.6	48.8±3.6
TL/SVL	1.24	1.15	1.19	1.34	-	1.17	1.35	1.26	-	1.24±0.08	1.04±0.07
AGD	-	-	-	-	-	-	19.8	24.1	13.7	22.0±3.0	26.1±1.3
FLL	8.0	6.0	7.0	8.0	8.2	8.0	8.0	10.0	6.5	8.0±0.9	7.9±0.3
HLL	10.3	7.5	9.5	12.0	11.2	11.0	10.7	11.9	8.4	10.9±1.5	11.7±0.8
MBSR	28	30	30	28	28	30	30	29	30	28–30	27–30
PVSR	56	59	60	57	59	60	61	58	61	56–61	55–57
AGSR	-	-	-	-	-	-	41	42	39	39–42	34–37
Ventral scales	-	-	-	-	-	-	58	61	67	58–67	55–62
SCa	78	-	-	-	-	-	80	78	-	78–80	64–74
F3lam	10	-	-	-	-	-	10	9	10	9–10	9–10
T4lam	13	-	-	-	-	-	15	13	13	13–15	12–15
CP	6	-	-	-	-	-	6	5	6	5–6	6
SO	4	-	-	-	-	-	4	4	4	4	4

...Continued on the next page TABLE 4. (Contined)

Subdoluseps frontoparietale			S. vietnamensis sp. nov.
Morphological character	Holotype	Paratypes	Additional specimens		Mean±SD	Mean±SD
1694	33341	333342	333391	333392	333393	ZMKU R705	ZMKU R706	ZMKU R707	min-max	min-max
Temp	-	-	-	-	-	-	1+2	1+2	1+2	1+2	1+2
SC	7	-	-	-	-	-	8	8	8	7–8	8–9
LO	2	-	-	-	-	-	2	2	2	2	2
SL	7	-	-	-	-	-	7	7	7	7	7
IFL	6	-	-	-	-	-	6	6	6	6	6
NU	2	-	-	-	-	-	2	2	2	2	1–3
FP	single	single	single	single	single	single	single	single	single	single	single
Bright dorsolateral band from eye to tail base	present	present	present	present	present	present	present	present	present	present	absent
Number of distinct black stripes on dorsum	6	6	6	6	6	6	6	6	6	6	4

Field notes. All specimens were collected during the daytime, on sandy ground among rotting leaves in Earleaf acacia ( Acacia auriculiformis A.Cunn. ex Benth.) plantation, secondary dipterocarp forest, and rubber plantation in lowland coastal areas ( Fig. 5 ). The holotype and paratypes ITBCZ 5843 & 5844 were collected at 15:42, air temperature 30.3 oC , relative humidity 70.2 %; ITCBZ 7038 was collected at 13:30, air temperature 33 oC , relative humidity 75 %; ITBCZ 7046 was collected at 8:54, air temperature 30 oC , relative humidity 80 %; ITBCZ 7056 , 7059 & 7070 were collected at 12:10, air temperature 32 oC , relative humidity 65%. To avoid capture, this species can dive into and stay under loose sand . Sexual dimorphism. Adult males mainly differ from adult females in body coloration in life and shape of tail base. Males have yellow color on chest and belly (vs. white, cream or yellowish color in females), orange around the ear (vs. dark brown in females), and distinct bright spots on lateral side (vs. pure dark brown or with small bright dots in females). Ventral side of tail base is slightly swollen in males and flat in females ( Figs. 3 , 4A–E ). Juvenile has bright golden color on the dorsum with four clear dorsal longitudinal stripes ( Fig. 4F ). Distribution. The new species is currently known only from (1) Ho Tram, Xuyen Moc District, Ba Ria-Vung Tau Province and (2) La Gi Town, Binh Thuan Province , southern Vietnam ( Fig. 1 ). Etymology. The new skink is named after the nation of Vietnam . We recommend “ Vietnam Agile Skink” and “Thằn lằn chân ngắn việt nam” as the common English and Vietnamese names of the new species, respectively. Comparisons. Subdoluseps vietnamensis sp. nov. differs morphologically from other species of the Lygosoma s.l. in Asia as follows: For Subdoluseps , S. vietnamensis sp. nov. differs from S. herberti , S. malayana , S. purthi , and S. samajaya by having a single frontoparietal scale (vs. paired) ( Grismer 2019 ; Karin et al. 2018 ; Sharma 1977 ; Smith 1916 ). In addition, it differs from S. herberti by having a smaller adult size (maximum SVL = 48.7 mm vs. 54.0 mm), presence (vs. absence) of nuchal scales (1–3 vs. 0), and smooth dorsal scales (vs. dorsal with 5 strong keels) ( Smith 1916 ); from S. malayana by having a smaller adult size (maximum SVL = 48.7 mm vs. 65.4 mm ), more supralabials (7 vs. 6) with the fifth below the center of the eye (vs. the fourth below the center of the eye), smooth dorsal scales (vs. dorsal with 3–5 strong keels) ( Grismer et al. 2019 ); from S. purthi by having a smaller adult size (maximum SVL = 48.7 mm vs. 67.0 mm), fewer midbody scale rows (27–30 vs. 32–34), and more paravertebral scale rows (55–57 vs. 50) ( Sharma 1977 ); from S. samajaya by having a smaller adult size (maximum SVL = 48.7 mm vs. 70.1 mm ), fewer paravertebral scale rows (55–57 vs. 60 or 61), and smooth dorsal scales (vs. dorsal with 5 strong keels) ( Karin et al. 2018 ). Subdoluseps vietnamensis sp. nov . is phenotypically most similar to S. bowringii and S. frontoparietale but can be distinguished from both based on a combination of characters. The new species differs from S. bowringii by having a single frontoparietal scale (vs. paired) ( Geissler et al. 2011 ; Smith 1935 ; this study), tail length approximately equal to SVL (vs. tail longer than SVL) (mean TL/SVL = 1.04 vs. 1.27 [ Smith 1935 ; this study]), and fewer subcaudal scales (64–74 vs. 76–81) (this study); from S. frontoparietale by having a tail length approximately equal to SVL (mean TL/SVL = 1.04 vs. tail longer than SVL, mean TL/SVL = 1.24 [ Taylor 1962 ; this study, Table 4 ]), fewer subcaudal scales (64–74 vs. 78–80) [ Taylor 1962 ; this study]), fewer axilla-groin scales (34–37 vs. 39–42) (this study), four distinct longitudinal black stripes on dorsum (vs. six distinct black stripes) ( Taylor 1962 ; this study), and absence (vs. presence) of bright dorsolateral band extending from eye to tail base ( Taylor 1962 ; this study, Fig. 6 ). From genus Lygosoma s.s. , Subdoluseps vietnamensis sp. nov. differs from L. isodactylum , L. siamensis , L. tabonorum , and L. quadrupes (Linnaeus) by having supranasals in contact with each other (vs. not in contact) ( Geissler et al. 2011 , Heitz et al . 2016 , Siler et al. 2018 ) and from L. corpulentum by having smaller adult size (maximum SVL = 48.7 mm vs. 170.0 mm), frontoparietal scale single (vs. paired), and fewer midbody scale rows (27–30 vs. 36–40) ( Smith 1921 ; Geissler et al. 2011 ). For the genus Riopa , Subdoluseps vietnamensis sp. nov. differs from R. albopunctata , R. anguinua , R. goaensis , R. guentheri , R. popae Shreve , and R. punctata (Gmelin) by having frontoparietal scales single (vs. paired) ( Geissler et al. 2012 ; Sharma 1976 ; Smith 1935 ); from R. lineata and R. lineolata by having fewer paravertebral scale rows (55–57 vs. 104–110 in R. lineata [ Smith 1935 ] and 78–93 in R. lineolata [ Siler et al. 2018 ]); and from R. vosmaeri by having hind-limb with 5 (vs. 4) toes (Gray 1939; Seetharamaraju et al. 2009 ). For remaining Asian species of the Lygosoma s.l. that were not confirmed by Freitas et al . (2019) , Subdoluseps vietnamensis sp. nov. differs from L. boehmei Ziegler, Schmitz, Heidrich, Vu & Nguyen , L. opisthorhodum Werner , L. singha (Taylor) , and L. veunsaiensis Geissler, Hartmann & Neang by having frontoparietal scale single (vs. paired) ( Geissler et al . 2012 ; Werner 1910 ; Ziegler et al. 2007 ); from L. angeli (Smith) by having a smaller adult size (maximum SVL = 48.7 mm vs. 100.0 mm) and fewer paravertebral scale rows (55–57 vs. 107–115) ( Smith 1937 ; Geissler et al. 2011 ); from L. haroldyoungi (Taylor) by having a smaller adult size (maximum SVL = 48.7 mm vs. 136.0 mm), fewer paravertebral scale rows (55–57 vs. 141–145), and fewer midbody scale rows (27–30 vs. 38–42) [ Taylor 1962 ; Geissler et al. 2011 ]; from L. kinabatanganensis Grismer, Quah, Duzulkafly & Yambun by having a smaller adult size (maximum SVL = 48.7 mm vs. 141.0 mm), fewer paravertebral scale rows (55–57 vs. 98), and fewer midbody scale rows (27–30 vs. 42) ( Grismer et al . 2018 ); from L. koratense Smith by having a smaller adult size (maximum SVL = 48.7 mm vs. 105.0 mm) and fewer midbody scale rows (27–30 vs. 32–34) [ Smith 1935 ]; and from L. bampfyldei Bartlett , L. peninsulare Grismer, Quah, Duzulkafly & Yambun , and L. schneideri Werner by having fewer paravertebral scale rows (55–57 vs. 81–85 in L. bampfyldei [ Grismer et al . 2018 ], 87 in L. peninsulare [ Grismer et al . 2018 ], and 95 in L. schneideri [ Grismer et al . 2018 ]).