Pareas melanops, Liu & Li & Yang & Rao, 2025

Pareas melanops sp. nov.

Figs 3–6 View Figure 3 View Figure 4 View Figure 5 View Figure 6

https://zoobank.org/ A8C5F112-61CF-4A48-A44A-BD64B1EEEC84 Diagnosis. Body size moderate (SVL 352–472 mm in adults), tail moderately long (TL/SVL 0.25–0.29), prefrontal bordering orbit, preoculars 1–2, subocular single, postocular single, subocular and postocular not fused, supralabials 7–8, infralabials seven, infralabial not fused with chin-shield, anterior temporal 1–3, posterior temporals 2–3, one row of vertebral scales slightly enlarged, 1–7 rows of dorsal scales keeled at mid-body, ventral scales 172–176, subcaudals 68–77, maxillary teeth 4–5, dorsal head solid black, dark nuchal band present, two large black spots on each side of head, 62–69 vertical black bars on each side of trunk, 27–33 vertical black bars on each side of tail, iris solid black.

Type Material. HOLOTYPE: KIZ 2024092 View Materials , adult male, collected on 28 August 2024 by Shuo Liu from Mangdi Village, Hepai Township, Gengma County, Lincang City , Yunnan Province, China, 23°29’58”N, 99°18’45”E, 1,940 m elevation GoogleMaps . PARATYPES: KIZ 2024093 View Materials and KIZ 2024095 View Materials , two adult females, collected on 29 August 2024 ; KIZ 2024094 View Materials , adult male, collected on 28 August 2024; and KIZ 2024096 View Materials , juvenile, collected on 27 August 2024, all from the same locality as the holotype GoogleMaps .

Description. Holotype: adult male, SVL = 472 mm, TL 135 = mm, TL/SVL = 0.29, TL/total length 0.22; body elongated; head distinct from neck; snout blunt, projecting beyond lower jaw; body laterally compressed, vertebral ridge feebly developed; rostral approximately as wide as high, nearly invisible from above; nasals undivided; internasals elongated, much wider than long; prefrontals triangular, bordering orbits; frontal shield-shaped, slightly longer than wide; parietals large, longer than wide, median suture slightly longer than frontal; supraoculars longer than wide; loreal 1/1, not bordering orbit; preocular 1/1; subocular 1/1, elongated crescent-shaped; postocular 1/1; anterior temporal 1/1, posterior temporals 2/2; supralabials 7/7, not bordering orbit; infralabials 7/7, anterior-most in contact with its opposite, first four in contact with anterior chin-shield, infralabial not fused with chin-shield; chin-shields three pairs, left one smaller than right one in first pair, left and right ones almost equal size in second and third pairs; ventral scales 172; cloaca plate undivided; subcaudals 71, paired; dorsal scales in 15 rows throughout, one row of vertebral scales slightly enlarged, seven rows of mid-dorsal scales slightly keeled at middle of body; maxillary teeth 4/4.

Coloration of holotype in life. Dorsal surface of head solid black, a large black band on neck, dorsal surface of body and tail brown; lateral surface of head yellow with many dark brown spots, two large black spots on each side of head, one on lower rear region of eye, another above angle of mouth; lateral surface of body and tail brownish yellow, approximately 64 vertical, billowing, black bars on each side of trunk and approximately 33 vertical, billowing, black bars on each side of tail, bars on different sides connected to each other on vertebrals; ventral surface of head light yellow, a few black spots on outer margin of ventral head; ventral surface of body light yellow with a few small black spots; ventral surface of tail yellowish white with many black spots; iris solid black.

Variations. Morphometric and meristic data of the paratypes is similar to that of the holotype except that all paratypes are smaller than the holotype. The two female paratypes ( KIZ 2024093 View Materials and KIZ 2024095 View Materials ) have two preoculars on each side, and the juvenile paratype ( KIZ 2024096 View Materials ) has two preoculars on right side; the loreal borders the orbit in three paratypes ( KIZ 2024093 View Materials , KIZ 2024094 View Materials , and KIZ 2024096 View Materials ); the male paratype ( KIZ 2024094 View Materials ) has 3/2 anterior temporals and 3/3 posterior temporals; and the female paratype ( KIZ 2024095 View Materials ) has five maxillary teeth on left side ( Table 2). Concerning the coloration, the female paratype ( KIZ 2024093 View Materials ) has a darker body while the other paratypes ( KIZ 2024094 View Materials – KIZ 2024096 View Materials ) have paler body than the holotype ( Fig. 4 View Figure 4 ) .

Distribution. This species is currently known only from Gengma County, Lincang City , Yunnan Province, China ( Fig. 5 View Figure 5 ).

Habitat. All specimens of the new species were found on bushes beside a stream at night, surrounded by secondary forests. Four other reptile species were found at the type locality of the new species, namely Lycodon chapaensis (Angel & Bourret, 1933) , Ovophis makazayazaya (Takahashi, 1922) , Pseudoxenodon macrops (Blyth, 1855) , and Trimeresurus sp.

Etymology. The specific epithet “ melanops ” is an adjective in the nominative case derived from the Ancient Greek “ melanos ” for “black” and “ ops ” for “eye”, and is given in reference to the conspicuous uniform black iris coloration of the new species. We recommend “Black-eyed slug-eating snake” for the common English name and “ ” (Pinyin: heī yǎn dùn tóu shé) for the common Chinese name of the new species.

Comparisons. Pareas melanops sp. nov. can be easily distinguished from all other species of the genus except P. andersonii Boulenger, 1888 , P. macularius Theobald, 1868 , P. margaritophorus (Jan, 1866) , P. modestus Theobald, 1868 , P.nigriceps , and P. tigerinus by having solid black iris (vs. iris being yellow, orange, red, or brown). Pareas melanops sp. nov. can be further distinguished from all other species of the genus except P. andersonii , P. dulongjiangensis Liu, Yang, Rao, Guo & Rao, 2023 , P.kaduri Bhosale, Phansalkar, Sawant, Gowande, Patel & Mirza, 2020 , P.macularius , P.margaritophorus , P. modestus , P. niger (Pope, 1928) , P. nigriceps , P. stanleyi (Boulenger, 1914) , P. tigerinus , and P. yunnanensis ( Vogt, 1922) by the solid black dorsal surface of the head (vs. dorsal surface of head being yellow, orange, red, or brown with no or some dark spots) ( Boulenger 1900, 1905, Vogt 1922, Pope 1935, Zhao et al. 1998, Grossmann and Tillack 2003, Guo and Deng 2009, Guo et al. 2011, Loredo et al. 2013, Vogel 2015, You et al. 2015, Hauser 2017, Yang et al. 2019, 2021, Bhosale et al. 2020, Ding et al. 2020, Vogel et al. 2020, 2021, Wang et al. 2020, Le et al. 2021, Liu and Rao 2021, David and Deuti 2022, Poyarkov et al. 2022, Gong et al. 2023, Liu et al. 2023a, 2023b, 2024).

Pareas melanops sp. nov. can also be easily distinguished from P. andersonii View in CoL , P. modestus View in CoL , P. macularius View in CoL , and P. margaritophorus View in CoL by having yellow or brownish yellow body background color (vs. body background color being grey, brownish grey, or black) ( Hauser 2017, Vogel et al. 2020, David and Deuti 2022, Poyarkov et al. 2022).

Pareas melanops sp. nov. can be further distinguished from P. dulongjiangensis View in CoL and P. stanleyi View in CoL by preocular being present (vs. preocular being absent); from P. kaduri View in CoL by 1–5 rows of dorsal scales being keeled at mid-body in females (vs. all dorsal scales being smooth in females) and having fewer maxillary teeth (4–5 vs. 6–7); from P. niger View in CoL by having one subocular and one postocular (vs. subocular and postocular being fused) and fewer maxillary teeth (4–5 vs. 6–8); and from P.yunnanensis View in CoL by having dark nuchal band (vs. not having dark nuchal band), distinct dark spots on each side of head (vs. having no or indistinct spots on each side of head), and more subcaudals (68–77 vs. 59–65) ( Vogt 1922, Pope 1935, Bhosale et al. 2020, Liu et al. 2023a, 2023b).

Pareas melanops sp. nov. is phylogenetically closely related to and resembles P. nigriceps View in CoL and P. tigerinus View in CoL . However, it can be distinguished from the latter two species by having one subocular and one postocular (vs. subocular and postocular being fused into one crescent-shaped scale). In addition, Pareas melanops sp. nov. can be distinguished from P. nigriceps View in CoL by having fewer maxillary teeth (4–5 vs. 6–7) and more vertical black bars on tail (27–33 vs. 18); Pareas melanops sp. nov. can be distinguished from P. tigerinus View in CoL by having more ventral scales (172–176 vs. 160–171), more subcaudals (68–77 vs. 62–64), more vertical black bars on trunk (63–69 vs. 53–61), and more vertical black bars on tail (27–33 vs. 22–24) ( Liu et al. 2023b, Guo and Deng 2009, Yang et al. 2019) ( Table 3).