Opisthotropis hungtai, Wang & Lyu & Zeng & Lin & Yang & Nguyen & Le & Ziegler & Wang, 2020

Wang, Jian, Lyu, Zhi-Tong, Zeng, Zhao-Chi, Lin, Chao-Yu, Yang, Jian-Huan, Nguyen, Truong Quang, Le, Minh D., Ziegler, Thomas & Wang, Ying-Yong, 2020, Re-examination of the Chinese record of Opisthotropis maculosa (Squamata, Natricidae), resulting in the first national record of O. haihaensis and description of a new species, ZooKeys 913, pp. 141-159 : 141

Opisthotropis hungtai sp. nov. Figures 4 , 5B , 6

Chresonymy.

Opisthotropis maculosa Stuart & Chuaynkern, 2007: Yang et al. (2011) (part); Wang et al. (2017a), Ren et al. (2019).

Holotype.

SYS r000946, adult male, collected by Jian Zhao on 2 September 2014 from Heishiding Nature Reserve [exact coordinates not provided owing to threat from collection for the pet trade, same as paratypes], Fengkai County, Zhaoqing City, Guangdong Province, 300 m a.s.l., P.R. China.

Paratypes (N = 7).

Adult female SYS r001350 collected by Zhi-Tong Lyu on 15 August 2015, adult female SYS r000720 collected by Ying-Yong Wang on 28 June 2012, and adult female SYS r001525 collected by Zhi-Tong Lyu and Ying-Yong Wang on 1 July 2016, from the same locality as the holotype. Adult male KFBG 2002.01 collected by Zhi Xiao on 2 July 2002, adult male SYS r002017 collected by Jian Wang on 14 June 2018, and adult male SYS a001515 collected by Jian Wang on 8 July 2017, all from Dawuling Forestry Station, Xinyi City, Maoming City, Guangdong Province, ca 1150 m a.s.l., P.R. China. Adult male SYS a000538, collected by Qing Du and Runlin Li on 14 July 2009 from Mt. Wuhuang, Pubei County, Qinzhou City, Guangxi Zhuang Autonomous Region, ca 360 m a.s.l., P.R. China.

Etymology.

The species name " hungtai " refers to Professor Hung-Ta Chang (=Hong-Da Zhang, 张宏达), an outstanding botanist, who established the Tropical and Subtropical Forest Ecosystem Experimental Center in Heishiding Nature Reserve, promoting the development of ecological research in southern China. We suggest the English common name Hung-Ta Chang’s mountain Keelback and the Chinese name Zhang Shi Hou Leng She (张氏后棱蛇).

Diagnosis.

Opisthotropis hungtai sp. nov. is characterized by the following combination of characters: (1) TL 464.3-501.2 mm in adult males, 393.2-511 mm in females, (2) tail moderate, TaL/TL 0.20-0.26 in males, 0.19-0.22 in females, (3) internasal not in contact with loreal, prefrontal not touching supraocular, frontal touching preocular, (4) one preocular, one or two postocular(s), (5) temporals 1+1, (6) supralabials seven, the fourth and fifth in contact with eye; (6) maxillary teeth 16-18, (7) anterior pair of chin shields longer than or equal to posterior pair; (8) ventrals 170-189 (+ 2 preventrals) in males, 168-175 (+ 2 preventrals) in females, (9) subcaudals 76-98 in males, 69-84 in females, (9) nasal cleft pointing to the second supralabial, (10) body scale in 15-15-15 rows, (11) body scales smooth, tail scales smooth or indistinctly keeled, (12) chin shields yellow with brownish black mottling, and (13) body and tail dorsum dark, each with a light spot per scale.

Comparisons.

Opisthotropis hungtai sp. nov. is compared with O. maculosa and O. haihaensis , which share a very similar appearance. Measurements, scalation and body proportions of O. haihaensis and Opisthotropis hungtai sp. nov. are listed in Table 3 .

Opisthotropis hungtai sp. nov. differs from O. maculosa by prefrontal not touching supraocular (vs. prefrontal touching supraocular in O. maculosa ), by frontal touching preocular (vs. frontal not touching preocular in O. maculosa ), by fourth and fifth supralabials in contact with eye (vs. fourth supralabial in contact with eye in O. maculosa ), by anterior pair of chin shields longer than or equal to posterior pair (vs. anterior pair of chin shields shorter than posterior pair in O. maculosa ), by a higher number of subcaudals, 76-98 in males (vs. 67 in the single male holotype of O. maculosa ), and by chin shields yellow with brownish black mottling (vs. immaculate in O. maculosa ).

Opisthotropis hungtai sp. nov. differs from O. haihaensis by having seven supralabials, the second last one significantly enlarged, narrow and long, significantly wider than high (vs. eight supralabials, the second last one slightly enlarged, slightly wider than high in O. haihaensis ) (Fig. 5 ), and MT 16-18 (vs. MT 22-24 in O. haihaensis ).

Description of holotype.

Body cylindrical, slender, round to oval in cross section; TL 501.2 mm (SVL 401.6 mm, TaL 99.6 mm); tail thin and pointed, TaL 20% of TL; head small, indistinct from neck; right upper maxilla with 16 subequal teeth or sockets, teeth small, curved, without diastema; rostral nearly flattened, small, slightly less than twice as broad as deep, barely visible from above; two internasals, crescent-shaped, in contact with each other medially behind the rostral, not in contact with loreal, posteriorly in contact with prefrontal; a single prefrontal, in contact with loreal and preocular laterally, with frontal posteriorly, not in contact with supraocular; a single frontal, hexagonal, in contact with supraocular laterally, with two parietals posteriorly; parietals large, in contact with each other medially; nasal directed dorsally, polygonal, in contact with first and second supralabials ventrally, with loreal and prefrontal posteriorly, with internasal dorsally, with rostral anteriorly; nostril horizontally oval, in the upper part of nasal; a short vertical cleft below the nostril and dividing nasal into anterior and posterior parts, pointing to middle of upper edge of second supralabial; a single loreal, trapezoid, not entering the orbit, in contact with second and third supralabials laterally; a single supraocular, much longer than wide, obliquely set; a single preocular, higher than wide, in contact with frontal; a single postocular; a single anterior temporal, significantly elongate, in broad contact with the elongated sixth supralabial; a single posterior temporal, pentagonal; supralabials 7/7, the sixth one significantly elongate, the last one much shorter than the adjacent preceding supralabial; fourth and fifth supralabials entering orbit; infralabials 7/7, the first one in contact with its fellow behind the mental; two pairs of chin shields; anterior chin shields larger, in contact with each other medially, and in contact with the first four infralabials on both sides; posterior chin shields smaller, in contact with each other; dorsal scales in 15-15-15 rows; dorsal scales of body smooth throughout; dorsal scales of tail weakly keeled; ventrals 170; cloacal plate divided; subcaudals 76, paired.

Coloration of holotype in life.

Eye black; scales on dorsal surface of head glossy dark brown with scattered yellow flecking; chin shields yellow with brownish black mottling at each margin; body and tail glossy dark brown with single yellow spot on each scale, yellow spots becoming larger on sides of body; ventrals yellow with brownish black lateral margins and few scattered brown flecks; subcaudals yellow with brownish black anterior and lateral margins.

Coloration of holotype in preservative.

Ground color of upper head and body surface dark brown (Fig. 4B ), that of venter yellowish-beige. Dorsal scales each with light yellow blotch in the center. Dorsal blotches almost equal in size. Blotches becoming wider towards body sides; largest at outermost dorsal scale row, where the light blotches stretch towards the posterior scale end. Dorsal tail scales likewise with light central blotches. Dorsal head surface in part with indistinct light mottling that becomes more obvious on temporals. All supralabials with a light blotch. Infralabials, chin shields and smaller throat scales anterior to ventrals light yellow with brown mottling/blotches per scale. Belly with few, scattered dark flecks. Outermost edges of light ventrals brown. Ground color of subcaudals light yellow with black anterior and lateral margins.

Variations.

Measurements, body proportions and scale counts are listed in Table 3 . All paratype specimens are very similar to the holotype in appearance (Fig. 6 ) except: more maxillary teeth, ventrals and subcaudals, and relatively longer tail length in specimens KFBG 2002.01, SYS r001515, 2017 from Dawuling Forestry Station and SYS r000538 from Mt. Wuhuang; in the three female specimens from the same locality (Heishiding Nature Reserve) as the holotype, there are 17 maxillary teeth (vs. 16 maxillary teeth) and fewer subcaudals, 56 (broken tail) in SYS r000720, 69 in SYS r001350, 70 in SYS r001525 (vs. 76 in the male holotype).

Distribution and habits.

Opisthotropis hungtai sp. nov. is currently known from Heishiding Nature Reserve (ca 300 m a.s.l.) and Dawuling Forestry Station (ca 900 m a.s.l.) in western Guangdong, and Mt. Wuhuang (ca 500 m a.s.l.) in southeastern Guangxi.

The specimen from Mt. Wuhuang was collected in a rocky stream. Besides, specimens from Heishiding Nature Reserve were found in pelitic gutterways along the dirt path, and specimens from Dawuling Forestry Station were collected in a pelitic stream. The collection sites were all surrounded by well-preserved, dense deciduous forest.

Figures

Figure 4. Morphological features of the adult male holotype SYS r 00946 of Opisthotropis hungtai sp. nov. A Habitus view in life B habitus view in preservative C close-up of mid-dorsal body D-E close-up of head scales. Photos by Jian Zhao and Jian Wang.

Figure 5. Comparisons of head scalation of Opisthotropis haihaensis and Opisthotropis hungtai sp. nov. Line illustration by Zhi-Tong Lyu.

Figure 6. Morphological features of the adult female paratypes of Opisthotropis hungtai sp. nov. from Dawuling Forestry Station, Guangdong, China. A, B Habitus view and close-up of mid-dorsal body of SYS r 001515 C-E habitus view and close-up of head scales of SYS r 002017. Photos by Jian Wang.