Hebius citrinoventer Xu, Yang, Ouyang, Huang & Peng, 2024

Xu, Yu-Hao, Yang, Dian-Cheng, Gong, Yan-An, Ouyang, Kai-Chen, Weng, Shi-Yang, Deng, Jun-Dong, Huang, Song & Peng, Li-Fang, 2024, A new species of the genus Hebius (Squamata, Natricidae) from Yunnan, China, ZooKeys 1206, pp. 255-274 : 255-274

Hebius citrinoventer Xu, Yang, Ouyang, Huang & Peng sp. nov.

Figs 3 , 4 , 5

Material examined.

Holotype. ANU 20230016 (field number: HSR 23030, Figs 3 , 4 ), an adult female, collected by Diancheng Yang and Jundong Deng on July 18, 2023, in Tongbiguan Town , Yingjiang County, Dehong Dai and Jingpo Autonomous Prefecture, Yunnan Province, China (24 ° 36 ′ 30.60 ″ N, 97 ° 39 ′ 27.00 ″ E, 1300 m a. s. l.) . Paratype. QHU 2024005 (field number: LFR 2024007, Fig. 5 ), a subadult male, had been crushed to death on the side of the road, collected by Kaichen Ouyang and Lifang Peng on February 5, 2024, in Tongbiguan Town , Yingjiang County, Dehong Dai and Jingpo Autonomous Prefecture, Yunnan Province, China (24 ° 36 ′ 03.60 ″ N, 97 ° 39 ′ 05.76 ″ E, 1300 m a. s. l.) .

Etymology.

The specific name citrinoventer comprises the Latin words “ citrinus ” (yellowish-orange or orange) and “ venter ” (the belly or underside), based on the pale orange venter of the new species. According to its type locality Yingjiang County, Yunnan Province, China, the name we suggest is Yi ́ ng Jia ̄ ng Fu ̀ Lia ̀ n She ́ (盈江腹链蛇) in Chinese and Yingjiang Keelback Snake in English.

Diagnosis.

Hebius citrinoventer sp. nov. can be distinguished from its congeners by the following set of characters: (1) DSR 19–17 – 17, feebly keeled; (2) ventrals 146–151; (3) nasal complete, nostril in the middle of the nasal; (4) supralabials 9, the fourth to sixth in contact with the eye; (5) infralabials 10–11, the first 5 touching the first pair of chin shields; (6) preoculars 2; (7) postoculars 3; (8) temporals 3, arranged in two rows (1 + 2); (9) maxillary teeth 31, the last 4 slightly enlarged, without diastema; (10) tail comparatively long, TAL / TL ratio 0.334 in male; (11) dorsolateral series of irregular orange or ochre yellow blotches, extending from the neck to the posterior part of the tail; and (12) venter pale orange, tips of ventrals with subrectangular black blotches.

Comparisons.

In many characters, Hebius citrinoventer sp. nov. is similar to H. venningi ( Wall, 1910) and H. taronensis ( Smith, 1940) . However, the new species can be distinguished from H. venningi by (1) 19 DSR on the anterior part of the body (vs. 17), (2) VS 146–151 (vs. 155–172), (3) TEMP 1 + 2 (vs. 1 or 1 + 1); (4) maxillary teeth 31 (vs. 28–30), (5) venter pale orange, tips of ventrals with subrectangular black blotches (vs. venter pink or bright coral red, sometimes yellow). It can be distinguished from H. taronensis by (1) 17 DSR at midbody (vs. 19); (2) VS 146–151 (vs. 158–176); (3) TEMP 1 + 2 (vs. 1 or 1 + 1); (4) SC 113 (vs. 92–104); (5) tail comparatively longer, TAL / TL ratio 0.334 (vs. TAL / TL ratio 0.254 –0.288); and (6) venter pale orange, tips of ventrals with subrectangular black blotches (vs. pale areas of the venter are yellowish-ochre or yellowish-brown). For more detailed information and visual comparisons, please refer to Table 3 and Fig. 6 .

Due to the absence of a dark belly, Hebius citrinoventer sp. nov. can be distinguished from H. annamensis ( Bourret, 1934) , H. chapaensis ( Bourret, 1934) , H. deschauenseei ( Taylor, 1934) , H. nigriventer ( Wall, 1925) , H. igneus David, Vogel, Nguyen, Orlov, Pauwels, Teynie ́ & Ziegler, 2021, and H. youjiangensis Yang, Xu, Wu, Gong, Huang & Huang, 2023 (vs. the dark belly present). Moreover, it can be distinguished from H. deschauenseei and H. igneus by having 17 DSR at midbody (vs. 19); from H. chapaensis and H. nigriventer by having 19 DSR on the anterior part of the body (vs. 17); from H. annamensis by having prefrontals 2 (vs. prefrontal single), VS 146–151 (vs. 158–172), IL 10–11 (vs. up to 10); and from H. youjiangensis by having TEMP 1 + 2 (vs. 1 + 1), PRO 2 (vs. 1), PO 3 (vs. 2), and dorsolateral series of irregular blotches (vs. a continuous stripe on dorsolateral).

By having 17 DSR at midbody, Hebius citrinoventer sp. nov. can be easily distinguished from the other 35 known species in the genus, which have 19 or 15 rows: H. andreae (Ziegler & Le Khac Quyet, 2006) , H. beddomei (Günther, 1864) , H. bitaeniatus ( Wall, 1925) , H. boulengeri ( Gressitt, 1937) , H. celebicus (Peters & Doris, 1878) , H. clerki ( Wall, 1925) , H. concelarus (Malnate, 1963) , H. craspedogaster (Boulenger, 1899) , H. flavifrons (Boulenger, 1887) , H. inas (Laidlaw, 1901) , H. ishigakiensis (Malnate & Munsterman, 1960) , H. johannis (Boulenger, 1908) , H. kerinciensis ( David & Das, 2003) , H. khasiensis (Boulenger, 1890) , H. lacrima Purkayastha & David, 2019 , H. leucomystax (David, Bain, Quang Truong, Orlov, Vogel, Ngoc Thanh & Ziegler, 2007) , H. metusia (Inger, Zhao, Shaffer & Wu, 1990) , H. modestus ( Günther, 1875) , H. miyajimae (Maki, 1931) , H. nicobariensis (Sclater, 1891) , H. octolineatus (Boulenger, 1904) , H. optatus (Hu & Zhao, 1966) , H. parallelus (Boulenger, 1890) , H. petersii (Boulenger, 1893) , H. popei (Schmidt, 1925) , H. pryeri (Boulenger, 1887) , H. sanguineus (Smedley, 1932) , H. sangzhiensis Zhou, Qi, Lu, Lyu & Li, 2019 , H. sarasinorum (Boulenger, 1896) , H. septemlineatus (Schmidt, 1925) , H. terrakarenorum Hauser, Smits & David, 2022 , H. vibakari (Boie, 1826) , H. viperinus (Schenkel, 1901) , H. weixiensis Hou, Yuan, Wei, Zhao, Liu, Wu, Shen, Chen, Guo & Che, 2021 and H. yanbianensis Liu, Zhong, Wang, Liu & Guo, 2018 .

Compared with the other seven congeners that have 17 DSR at the midbody, Hebius citrinoventer sp. nov. can be distinguished from H. arquus ( David & Vogel, 2010) , H. atemporalis ( Bourret, 1934) , H. frenatus (Dunn, 1923) , H. sarwacensis (Günther, 1872) , H. sauteri (Boulenger, 1909) , and H. maximus (Malnate, 1962) by the 19–17 – 17 DSR counts (vs. 17–17 – 15 in H. arquus and H. frenatus ; and 17–17 – 17 in H. atemporalis , H. sarwacensis H. sauteri and H. maximus ), from H. groundwateri (Smith, 1922) by the divided cloacal plate (vs. CP entire). Furthermore, this new species differs from H. arquus by having a single loreal (vs. the absence of loreal). It differs from H. atemporalis , H. frenatus and H. sarwacensis in terms of SL, namely (9 vs. 6 in H. atemporalis , 5–8 in H. sauteri , and 8 in H. frenatus and H. sarwacensis ).

Description of holotype.

An adult female specimen with SVL 583 mm and incomplete tail (TAL 198 + mm). Body slightly stout and cylindrical; head flattened anteriorly, distinct from the neck, HL 26.1 mm, HW 15.6 mm. Nostril: lateral, round, piercing in the middle of the nasal. Eye large, ED 3.5 mm, pupil round.

Body scalation: DSR 19–17 – 17, feebly keeled, including the outermost DSR on both sides, not notched at the posterior extremity. VEN 144 (+ 2 preventrals); SC 80 +, all paired; CP divided.

DSR reduction:

3 + 4 → 3 (79–80) (right)

19 ——————————— 17

3 + 4 → 3 (78–79) (left)

Dentition: Maxillary teeth 31, gradually enlarged, the last four slightly enlarged, without diastema between last four and anterior teeth.

Head scalation: Rostral pentagonal, wider than high, visible from above; nasal entire, subpentagonal, about twice as wide as high; internasals 2, trapezoidal, in broad contact with each other, narrowing anteriorly; prefrontals 2, pentagonal, wider than long, in contact with loreal; frontal narrow, pentagonal, longer than wide, shield-like, slightly concave in the middle on both sides; SPO 1 on each side, hexagonal, much longer than wide; LOR 1 / 1, subrectangular, wider than long; PRO 2 / 2, upper one larger than lower one; PO 3 / 3; SL 9 / 9, the first 2 in contact with nasal, the 2 nd to 4 th in contact with the loreal, 4 th to 6 th entering orbit, the 7 th and 8 th largest; TEMP 3 / 3, arranged in two rows (1 + 2), the anterior temporal long and trapezoidal; chin shields in 2 pairs, the posterior pair longer than anterior one and separated by several small scales; IL 11 / 11, first pair in contact behind the mental, 1 st to 5 th touching the first pair of chin shields, the 5 th and 7 th largest.

Coloration of the fresh specimen: Dorsal surface of the head is olive-brown and scattered with pale-brown vermiculate stripes or irregular blotches. A pale, irregular yellow-ochre oblique streak is directed upward on both sides of the head, extending from the temporal region to the nape. The upper half of the 1 st to 8 th SL is olive-brown, the lower half is pale brown, and the 9 th is completely olive-brown. Ventral surface of head creamy yellow, the edges of partial scales have irregular black-gray patches.

Body olive-brown, darker on the top than on the sides. A faint, yellow-ochre or rusted dorsolateral stripe extends from the neck to the end of the tail, on the upper part of the 5 th to the lower part of the 7 th scale rows in the anterior part of the body, and the upper part of the 4 th to 6 th in the middle and posterior parts of the body, accompanied by a series of conspicuous, pale orange or ochre yellow irregular blotches, about two scales in diameter. The orange or ochre yellow blotches are not symmetrically distributed on both sides of the body but are arranged in a staggered manner, that is, the blotch on the left side of the body corresponds to the area between the two blotches on the right side of the body, and vice versa. Above and below the orange blotch, there is a slightly smaller, dull blackish-brown irregular blotch. The blackish-brown blotches above are arranged in a staggered pattern in the middle of the body, forming a checkered pattern with the background color.

Ventral anterior pale orange, darker toward the rear, and scattered with a few small black spots. The outermost edge of the ventral is black. Outer one-sixth of the ventrals with subrectangular black blotches on each side, producing an irregular, continuous ventrolateral stripe, which merges with the dark ventral edge in the posterior part of the body. The ventral surface of the tail is uniform pale orange with black-brown edge; a thin, brown-black stripe extends on the ventral part of the tail, formed by the inner margins of the SC, extending from the 1 st SC to the end of the tail.

Coloration in preservation: In preservation, the background color of the dorsal body changed to brownish-black, and the checkered pattern on dorsal surface has disappeared or faded. An indistinct pale-brown dorsolateral stripe extends from the neck to the end of the tail and is accompanied by a series of ochre yellow, irregular blotches. Head brownish-black, upper half of the 1 st to 8 th supralabials brownish-black, lower half gray white, the 9 th completely brownish-black. The infralabials mainly black-gray, the left half of the 5 th to 11 th pale gray, and the right half very dark gray. Ventral surface of the head cream, the edges of the partial scales had irregular very dark gray patches. The ventral surface of the body cream anteriorly, darker toward the rear, and the posterior part is light creamy yellow. In addition, the rest of the color pattern is similar to that seen in life.

Variation.

The paratype has a similar coloration in preservation as the holotype, but the subcaudals are almost completely black, with only the inner margins being creamy yellow. In scalation features, there is the following variation: the paratype has fewer infralabials (10 vs. 11) and more ventrals (151 vs. 146). The measurements and scalation features of the series (N = 2) are listed in Table 4 .

Distribution and habitat.

Hebius citrinoventer sp. nov. is currently only known from Yingjiang County, Dehong Dai and Jingpo Autonomous Prefecture, Yunnan Province, China: Tongbiguan Town (1300 m a. s. l.) (Fig. 7 ). The holotype ( ANU 20230016) was found drowned in a fish-catching cage placed by local residents in a wide stream at approximately 7: 00 am, and we presume that it may have fallen into the trap the preceding night while attempting to catch fish in the cage. The paratype ( QHU 2024005) was found road-killed on the side of the road next to a stream after a light rain between 21: 00 and 22: 00. Both specimens were found in a well-preserved monsoon forest habitat.

Figures

Figure 3. Fresh specimen of the holotype (ANU 20230016) of Hebius citrinoventer sp. nov.: dorsal (A), and ventral views (B). Photos by Kai-Chen Ouyang. Scale bars are not shown.

Figure 4. Preserved specimen of the holotype (ANU 20230016) of Hebius citrinoventer sp. nov. Photos by Yu-Hao Xu. Scale bars: 10 mm.

Figure 5. Preserved specimen of the paratype (QHU 2024005) of Hebius citrinoventer sp. nov. Photos by Yu-Hao Xu. Scale bars: 5 mm.

Figure 6. Comparisons of the lateral head (A), dorsal head (B), dorsal overview (C), and ventral overview (D) among the holotypes of H. citrinoventer sp. nov. (ANU 20230016; A 1 – D 1), H. venningi (BMNH 1946.1. 21.86; A 2 – D 2), and H. taronensis (BMNH 1946.1. 13.55; A 3 – D 3). Photos of H. venningi and H. taronensis were obtained from David et al. (2021), remaining photos by Yu-Hao Xu. Scale bars are not shown.

Figure 7. Habitat of Hebius citrinoventer sp. nov., Tongbiguan Town, Yingjiang County, Yunnan Province. Photos by Kai-Chen Ouyang.