Pareas (Eberhardtia) tigerinus, Liu & Zhang & Poyarkov & Hou & Rao & Nguyen & Vogel, 2023

Liu, Shuo, Zhang, Dongru, Poyarkov, Nikolay A., Hou, Mian, Wu, Li, Rao, Dingqi, Nguyen, Tan Van & Vogel, Gernot, 2023, Resurrection of Pareas yunnanensis (Vogt, 1922) with description of a new species of Pareas from Yunnan Province, China (Squamata, Pareidae), European Journal of Taxonomy 860 (1), pp. 1-26 : 14-21

Pareas (Eberhardtia) tigerinus sp. nov.

urn:lsid:zoobank.org:act:6538EBDF-DB82-47C7-8EB1-9E9BD178B414

Figs 5–7 ; Tables 5–6

Diagnosis

This species differs from Pareas nigriceps by having a relatively shorter tail, more infralabials, fewer ventral scales, fewer subcaudals, and fewer maxillary teeth; itdiffers from P. kaduri Bhosale, Phansalkar, Sawant, Gowande, Patel & Mirza, 2020 by having relatively smaller body size, keeled mid-dorsal scales in females, fewer temporals, and fewer maxillary teeth.

Single preocular; postocular fused with subocular; loreal not bordering orbit; prefrontal bordering orbit; infralabials not fused with chin-shields; three chin-shield pairs, the first pair triangular, the second pair and the third pair elongate; dorsal scales in 15 rows throughout; vertebral scales enlarged; scales not keeled on the anterior part of the body, 3–5 rows of mid-dorsal scales keeled on the middle part of the body, 5–9 rows of mid-dorsal scales keeled on the posterior part of the body; seven supralabials; eight infralabials; precloacal plate undivided; ventral scales 160–171; subcaudals 62–64, paired. Dorsal surface of head solid black or reddish-brown; dark nuchal band present; vertical dark bars on trunk and tail distinct; iris brownish-black or reddish-brown.

Etymology

The species epithet “ tigerinus ” is attributed to this species due to the similarity of the species colour pattern to the prominent lateral stripes in tigers. We propose “Tiger slug-eating snake” for the common English name and “ẋọ钝±蛇” (Hǔ Wén Dùn Tóu Shé) for the common Chinese name.

Type material

Holotype CHINA • ♀ adult; Yunnan Province, Xishuangbanna Prefecture, Menghai County, Xiding Township ; 21°49ʹ54″ N, 100°7′21″ E; elev. 1920 m; 21 Jul. 2021; S. Liu leg.; KIZ 20210705 .

Paratypes CHINA • 1 ♂ adult; same collection data as for preceding; 20 Jul. 2021; KIZ 20210703 • 1 ♀ adult; same collection data as for preceding; 20 Jul. 2021; KIZ 20210704 .

Description of holotype

Adult female, SVL 434 mm, TL 109 mm, TL/SVL 0.25, TL/total length 0.20; body elongated; head distinct from neck; snout wide and blunt, projecting beyond lower jaw; body slightly compressed laterally, vertebral ridge developed. Rostral approximately as wide as high, slightly visible from above; nasals undivided; internasals wider than long; prefrontals pentagonal, bordering orbits; frontal hexagonal, longer than wide; parietals large, much longer than wide, median suture longer than frontal; single loreal, not entering orbit; single preocular; one supraocular, longer than wide; subocular and postocular fused into one thin elongated crescent-shaped scale; one anterior temporal and two posterior temporals on each side; seven supralabials on each side, not touching orbit; eight infralabials on each side, anteriormost in contact with its opposite between mental and anterior chin-shields; infralabials not fused with chin-shield; three chin-shield pairs, the first pair triangular, the second pair and the third pair elongate, the first pair slightly larger than other two; ventral scales 169; precloacal plate undivided; subcaudals 62, paired; dorsal scales in 15 rows throughout, vertebral scales enlarged, scales not keeled at anterior of body, five rows of mid-dorsal scales keeled at middle of body, seven rows of mid-dorsal scales keeled at posterior of body.

Coloration of holotype in life

Dorsal surface of head solid black; occipitalia yellow; dorsal surface of body yellow, a large black band on neck and not connect with the black patch on top of head; sides of head yellow; two black spots on the left side of head, one on the lower rear part of eye and one on the angle of mouth; three black spots on the right side of head, two on the lower rear part of eye and a large elongate one on the angle of mouth; ventral surface of head light yellow, a few black spots on the outer margins of the third chin-shield and the first preventral; approximately 59 vertical, slightly billowing dark bars on trunk and approximately 22 vertical, slightly billowing dark bars on tail; belly and ventral surface of tail pale yellow with sparse small black spots; iris brownish black, pupil black.

Colouration of holotype in preservative

The dorsal surface of the head and body became darker in alcohol; the belly and ventral surface of head and tail faded to yellowish-white; the iris changed to greyish-black and the pupil changed to white.

Variation

The male paratype KIZ 20210703 has a slightly darker body colour, a smaller SVL, an incomplete tail, fewer ventral scales, fewer vertical dark bars on trunk, two large black spots on each side of head, no black spots on ventral side of head, and nine rows of mid-dorsal scales keeled on the posterior part of the body. The female paratype KIZ 20210704 has a much paler body colour: the dorsal surface of head, nuchal band, vertical bars on trunk and tail, and iris are reddish-brown; and there is only one reddishbrown spot at the angle of mouth on each side of head, only one posterior temporal on each side, no spots on ventral side of head, three rows of mid-dorsal scales keeled on the middle part of the body, and five rows of mid-dorsal scales keeled on the posterior part of the body.

Natural history notes

The specimens were found in the forest ( Fig. 7D ) at night perching on bushes growing along a small stream at elevation 1920 m a.s.l. Other species of amphibians and reptiles observed at the type locality of the new species include Diploderma menghaiense Liu, Hou, Wang, Ananjeva & Rao, 2020 ; Pareas xuelinensis , and Raorchestes hillisi Jiang, Ren, Guo, Wang & Li, 2020 . The sympatric occurrence of the new species with congeneric P. xuelinensis is remarkable, since both are members of the P. hamptoni species group. Pareas xuelinensis is usually smaller than Pareas tigerinus sp. nov. in body size, however, P. xuelinensis is more dominant than Pareas tigerinus in the population size at the type locality of the new species. Relatively, P. xuelinensis is more arboreal and Pareas tigerinus is more terrestrial through our brief observation, but the specific feeding habits of these two species are currently unknown.

Distribution

The new species is currently known only from its type locality in Xiding Township, Menghai County, Xishuangbanna Prefecture, Yunnan Province, China ( Fig. 8 ). This new species likely occurs in Myanmar and northwestern Laos.

Phylogenetic position

Pareas tigerinus sp. nov. belongs to the subgenus Eberhardtia and is a member of the P. hamptoni species group. Phylogenetically, it is reconstructed as a sister species of P. nigriceps (see Fig. 1 ).

Comparison

Pareas tigerinus sp. nov. can be distinguished from P. andersonii (Boulenger, 1888) , P. modestus Theobald, 1868 , P. macularius Theobald, 1868 , and P. margaritophorus (Jan, 1866) by its yellow body background colour (vs body background colours of grey, dark grey, brownish grey, or completely black).

Pareas tigerinus sp. nov. can be distinguished from P. abros Poyarkov, Nguyen, Vogel & Orlov, 2022 , P. atayal You, Poyarkov & Lin, 2015 , P. berdmorei Theobald, 1868 , P. carinatus Wagler, 1830 , P.formosensis (Van Denburgh, 1909) , P.iwasakii (Maki, 1937) , P. komaii (Maki, 1931) , P. kuznetsovorum Poyarkov, Yushchenko & Nguyen, 2022 , P. nuchalis ( Boulenger, 1900) , and P. temporalis Le, Tran, Hoang & Stuart, 2021 by subocular and postocular fused into one thin elongated crescent-shaped scale (vs subocular and postocular not fused).

Pareas tigerinus sp. nov. can be distinguished from P. boulengeri (Angel, 1920) and P. monticola (Cantor, 1839) by 3–5 rows of mid-dorsal scales keeled at middle of the body, 5–9 rows of mid-dorsal scales keeled on the posterior part of the body (vs all dorsal scales smooth), and having fewer ventral scales (160–171 vs 176–199).

Pareas tigerinus sp. nov. can be distinguished from P. chinensis by one row of vertebral scales enlarged (vs vertebral scales not enlarged or three rows of vertebral scales enlarged), having fewer temporals (1+1 or 1+2 vs 2+3 or 2+4), and fewer subcaudals (62–64 vs 69–76).

Pareas tigerinus sp. nov. can be distinguished from P. geminatus by having fewer subcaudals (62–64 vs 73–91) and relatively shorter tail (TL/SVL 0.25–0.26 vs 0.27–0.35).

Pareas tigerinus sp. nov. can be distinguished from P. hamptoni by having one preocular (vs two preoculars), fewer ventral scales (160–171 vs 195–202), fewer subcaudals (62–64 vs 96), relatively shorter tail (TL/SVL 0.25–0.26 vs 0.37), and infralabials not fused with the chin-shield (vs fourth or fifth infralabial fused with second chin-shield).

Pareas tigerinus sp. nov. can be distinguished from P. kaduri by having relatively smaller body size (SVL 392–434 vs 455–550), 3–5 rows of mid-dorsal scales keeled on the middle part of the body, 5–7 rows of mid-dorsal scales keeled on the posterior part of the body in females (vs all dorsal scales smooth in females), fewer temporals (1+1 or 1+2 vs 2+3), and fewer maxillary teeth (4 or 5 vs 6 or 7).

Pareas tigerinus sp. nov. can be distinguished from P. niger (Pope, 1928) by yellow colouration of dorsum with dark crossbars (vs solid black marking on dorsum), ventral surface of tail with no or sparse spots (vs ventral surface of tail with dense black spots or ventral surface of tail completely black), and having fewer maxillary teeth (4 or 5 vs 6–8).

Pareas tigerinus sp. nov. can be distinguished from P. stanleyi (Boulenger, 1914) , P. victorianus Vogel, Nguyen & Poyarkov, 2021 , and P. vindumi Vogel, 2015 by preocular present (vs preocular absent), loreal not entering the orbit (vs loreal entering orbit).

Pareas tigerinus sp. nov. can be distinguished from P. xuelinensis by having enlarged vertebral scales (vs vertebral scales not enlarged), infralabials not fused with chin-shield (vs fourth or fifth infralabial fused with second chin-shield), having fewer ventral scales (160–171 vs 182–188), fewer subcaudals (62–64 vs 87–93), and relatively shorter tail (TL/SVL 0.25–0.26 vs 0.33–0.34).

Pareas tigerinus sp. nov. can be distinguished from P. yunnanensis by no black stripes on the neck (vs two wide black stripes pass from parietals to the vertical black bars on the neck), having dark nuchal band (vs dark nuchal band absent), having distinct dark spots on each side of the head (vs no or indistinct spots on each side of head), and iris brownish black or reddish brown (vs iris brownish yellow or brownish orange).

Pareas tigerinus sp. nov. is superficially most similar to P. nigriceps in morphology characteristic and coloration. However, the new species can be distinguished from P. nigriceps ( Table 6 ) by having a relatively shorter tail (TL/SVL 0.25–0.26 vs 0.32), eight infralabials (vs seven infralabials), fewer ventral scales (160–171 vs 175), fewer subcaudals (62–64 vs 76), and fewer maxillary teeth (4 or 5 vs 6 or 7).

Figures

Fig. 5. Pareas tigerinus sp. nov., type specimens in preservative. A. Dorsal views. B. Ventral views. Photos by S. Liu.

Fig. 6. Pareas tigerinus sp. nov. in preservative, head. A–C. Holotype, ♀ (KIZ 20210705). A. Dorsal view. B. Lateral view. C. Ventral view. D–F. Paratype, ♂ (KIZ 20210703). D. Dorsal view. E. Lateral view. F. Ventral view. Photos by S. Liu.

Fig. 7. Pareas tigerinus sp. nov. in life.A. Holotype, ♀ (KIZ 20210705). B. Paratype, ♂ (KIZ 20210703) C. Paratype, ♀ (KIZ 20210704). D. Habitat at the type locality. Photos by S. Liu.

Fig. 8. Map showing the type locality of Pareas yunnanensis (Vogt, 1922) (black star), the type locality of P. geminatus Ding, Chen, Suwannapoom, Nguyen, Poyarkov & Vogel, 2020 (black square), the type locality of P. xuelinensis Liu & Rao, 2021 (black circle), the type locality of P. nigriceps Guo & Deng, 2009 (black diamond), and the type locality of P. tigerinus sp. nov. (black triangle).

Fig. 1. Bayesian phylogeny tree of Pareas Wagler, 1830 inferred from cyt b sequences. Node numbers before slashes indicate BPP (values below 0.90 are not shown) and numbers after slashes indicate UFB (values below 90 are not shown).