Hebius sangzhiensis, Zhou & Sun & Qi & Lu & Lyu & Wang & Li & Ma, 2019

Zhou, Zhengyan, Sun, Zhiyong, Qi, Shuo, Lu, Yuyan, Lyu, Zhitong, Wang, Yingyong, Li, Pipeng & Ma, Jianzhang, 2019, A new species of the genus Hebius (Squamata: Colubridae: Natricinae) from Hunan Province, China, Zootaxa 4674 (1), pp. 68-82 : 68-82

Hebius sangzhiensis sp. nov. Zhou, Qi, Lu, Lyu & Li

Figs. 3–5

Holotype. SYNU 08070350 , adult male, from Sangzhi County, Hunan Province, China, ca. 110°07’ E, 29°47’ N, 1,430 m a.s.l., collected by Zheng-Yan Zhou and Shi-Yang Mi on 28 July 2008, deposited in the Institute of Herpetology , Shenyang Normal University ( SYNU).

Paratype. Two specimens, SYNU 08070349 , adult female, the same information as the holotype; SYS r001397, adult male, from Mt. Tianping , Badagongshan National Nature Reserve , Sangzhi County, Hunan Province, China, ca. 110°05’ E, 29°47’ N, 1,420 m a.s.l., collected by Yu-Long Li on 1 September 2015, deposited in the Museum of Biology , School of Life Sciences, Sun Yat-sen University ( SYS) .

Diagnosis. A species of the genus Hebius , characterized by a combination of the following characters: (1) tail long, approximately 25% of the total length; (2) DSR 19-19-17, vertebral scales enlarged, smooth, 2 nd– 10 th rows distinctly keeled; (3) anterior temporals 2, preocular 1, postoculars 3; (4) ventrals 160–164; (5) internasals narrowed anteriorly; (6) a pair of occipital spots and a pale postparietal streak; (7) a pale brown or beige dorsolateral stripe on the 4 th– 6 th scale rows; (8) ventral scales brick-red at their outer border, with a row of well-defined dark blotches; (9) maxillary teeth 21, gradually enlarged, followed by 2 moderately enlarged posterior teeth, without diastema; (10) nostrils lateral.

Description of the holotype. SVL 421 mm; tail complete, TaL 141 mm, TaL/TL 0.25. Body elongate and thin; head average (4.4% of SVL), distinct from the neck, flat anterior to eye; snout long, 26% of HL, 1.5 times as long as the diameter of the eye, blunt in dorsal view, slightly bulgy in lateral views; nostril lateral, round, piercing in middle of divided nasal; eye large, diameter 2.9 times greater than the distance between its inferior margin and edge of upper lip; pupil round; tail cylindrical, long and tapering.

Dentition. Maxillary teeth 21, gradually enlarged + 2 distinctly enlarged teeth posteriorly, without diastema.

Body scalation. DSR: 19-19-17. Scales not notched at their posterior extremities.

Dorsal scale row reduction formula.

3+4→3 (86) (left)

19 ————————17

3+4→4 (88) (right)

Vertebral scales enlarged, smooth; scales of dorsal rows 2–10 distinctly keeled with a narrow, sharp keel, more distinct on posterior half of body; scales of outer 1 st row smooth or weakly keeled.

161 VEN (+ 2 preventrals); 82 SC, all paired. Cloacal plate divided.

Head scalation. Rostral trapezoidal, wider than high; nasals rectangular, distinctly longer than high, divided into two parts, with a round, lateral nostril in its middle; internasals trapezoidal, barely narrowing anteriorly, about 0.6 times of the posterior width; prefrontals subrectangular, broader than long, reaching to loreal; frontal hexagonal, 1.6 times longer than wide, with apex directed posteriorly, 2.6 times longer than the suture between the prefrontals; parietals in contact for a length of 0.8 times of frontal length; loreal 1/0 (absent on right side), small, rectangular, elongate horizontally, in broad contact with nasal; preocular 1/1; postoculars 3/3, the upper one much larger than two lower ones; supralabials 7/8, SL 1 at left, SL 1–3 at right in contact with nasal, SL 2 at left in contact with loreal, SL 3 and 4 at left, 4 and 5 at right entering orbit, 6 and 7 largest; Tem: 2+1+2 at left, 2+2 at right; infralabials 9/10, first pair in contact behind the mental, IL 1–4 at left, 1–5 at right in contact with anterior chin shields; posterior chin shields longer than anterior ones.

Hemipenes. The retracted hemipenis extending to the 8 th or 9 th subcaudals. Unilobed hemipenis is uniformly covered with small spines. Sulcus unbranched.

Coloration. Body dark slate-gray, with most scales densely speckled with dark grey, minute dots; body ornate with large, diffuse dark brown blotches on DSR 2–4 and 7 and 8 (anterior part of body with DSR 19) or 6–8 (posterior part of body with DSR 17), giving an indistinct vertebral pattern quincuncially arranged; a dorsolateral stripe extending from the neck to the tail, along the anterior part of body (with DSR 19) on upper part of 5 th row and the whole of 6 th row, along the posterior part of body (with DSR 17) on upper part of 4 th row, the whole of 5 th row and on the lower part of 6 th row, conspicuous, pale brown or beige; scales brick-red on the bottom of 1 st DSR; tail as the posterior part of the body, with diffuse dark brown blotches more or less connected, then changing into a diffuse, ill-defined stripe, dorsolateral pale brown or beige stripe progressively vanishing towards the tip of the tail.

Dorsal surface of head dark slate-gray with irregular dark brown stripes, turning into blackish-brown on its posterior part, paler on the snout and sides; paired, pale ivory cream occipital spots, from the 7 th (left) and 8 th (right) SL, bent upwards and distinctly connected with the thin pale brown or beige dorsolateral stripe of the neck; 2 small, faint off-white spots on the parietals and a very faint off-white sagittal line just behind the parietals; lower part of postoculars ivory cream.

Anterior supralabials pale ivory cream and edged with dark brown on their posterior part; 6 th (left) or 7 th (right) SL divided into a lower anterior part ivory cream and an upper posterior part dark brown, and with its posterior lower corner dark brown; 7 th (left) or 8 th (right) SL with its upper edge and lower anterior corner dark brown, and with a large white spot in the middle, prolonged by the occipital spot.

Venter uniformly ivory cream, with the outer part of each scale brick-red as 1 st dorsal rows, becoming blackish-brown on the scale outer tip; each ventral with a well-defined blackish-brown slim spot between the brick-red and ivory parts, these spots become progressively larger backwards and do not connect with each other. Ventral part of tail same as the venter, bordered on each side by a blackish-brown stripe described above; the blackish-brown ventral spots progressively vanish towards the tip of the tail.

Infralabials, chin, throat and ventral part of the neck ivory cream, uniform in their middle, with some dark brown speckling on the outer parts of the throat. The last infralabial with a blackish-brown spot on both sides.

Variation of the paratypes. Two paratypes are generally similar to the male holotype. Variation in scale counts and meristic data are shown in Table 3 .

Body scalation. Dorsal scales small, approximate rhombus, the first rows slightly enlarged, the vertebral row does not differ in size from other median dorsal rows; scales of dorsal rows 3–10 distinctly keeled, except the outer two rows; DSR: 17-17-15. VEN: 160–164; SC: 81, all paired; cloacal plate divided.

Head scalation. Generally as for the holotype; single loreal and preocular, three postoculars, supralabials VI and V contacting eye; supralabials 8/8, infralabials 10/ 11 in the female paratype (SYNU08070349) and 10/ 9 in the male paratype (SYS r001397). Some variability observed in temporal scales, both paratypes are quite different from holotype, 2+1+2/2+1+ 2 in female paratype and 2+2+2/1+2+ 2 in male paratype.

Coloration in life. The pattern is more or less consistent with the holotype, with some variations in dorsal blotch number, and in the width of light dorsolateral stripe.

Body proportions. Relative tail length differs significantly in the female paratype (TaL/TL 0.24) and male paratype (TaL/TL 0.27).

Etymology. The specific epithet sangzhiensis refers to the type locality, Sangzhi County, Hunan Province, China. We suggest the common name as the “Sangzhi Keelback Snake”, and the Chinese formal name as “sâng zhí fù liàn shé ” (ǾDZDzmẘ).

Distribution and natural history notes. Hebius sangzhiensis sp. nov. is currently known only from its type locality. This species is common in Mt. Tianping and it is expected to be found in other forested areas in Hunan Province and neighboring Hubei Province, China ( Fig. 1 ). The holotype and the female paratype were found in a hill stream, where clear water flowed over a substratum of stone and gravel, and both were swimming on the water surface at night (at 20h00 and 22h00, respectively) on 28 July 2008. The male paratype was found in daytime, moving along the stream bank on 1 September 2015.

Comparisons. The new species is distinct to all other known species of the genus Hebius with the following combination of characters:

H. sangzhiensis sp. nov. can be separated from H. annamensis (Bourret) , H. arquus (David & Vogel) , H. atemporalis , H. celebicus (Peters & Doria) , H. chapaensis , H. frenatus (Dunn) , H. groundwateri (Smith) , H. sarasinorus (Boulenger) , H. sarawacensis (Günther) , H. sauteri , H. taronensis (Smith) and H. venningi by having 19 dorsal scale rows at midbody (vs. 15 or 17).

H. andreae (Ziegler & Le) , H. concelarus (Malnate) , H. ishigakiensis (Malnate & Munsterman) and H. optatus having dorsal crossbars, without or having vague longitudinal dorsolateral stripes (vs. conspicuous, pale brown or beige dorsolateral stripe in H. sangzhiensis sp. nov.).

H. sangzhiensis sp. nov. is differentiated from H. bitaeniatus by having more maxillary teeth (23 vs. 19–22 in H. bitaeniatus ). Furthermore, H. bitaeniatus possesses two distinct, continuous dorsolateral yellow stripes with dark edge (vs. two pale brown or beige dorsolateral stripes without dark edge in H. sangzhiensis sp. nov.).

H. sangzhiensis sp. nov. can be separated from H. beddomei (Günther) , H. inas (Laidlaw) , H. kerinciensis (David & Das) , H. monticolus (Jerdon) , H. pealii (Sclater) , H. petersii (Boulenger) , H. sanguineus (Smedley) and H. viperinus (Schenkel) by having more ventral scales (16 0–164 vs. 140–150 in H. beddomei , 143–151 in H. inas , 140 in H. kerinciensis , 136–144 in H. monticolus , 142–144 in H. pealii , 134–150 in H. petersii , 140–155 in H. sanguineus , 101 in H. viperinus ).

H. boulengeri having a distinct white streak on the side of the head and neck (vs. paired, pale occipital spots in H. sangzhiensis sp. nov.); dorsolateral stripes marked with irregular spots (vs. conspicuous dorsolateral stripe without spots in H. sangzhiensis sp. nov.); and having more subcaudals (93–113 vs. 81–82 in H. sangzhiensis sp. nov.).

H. sangzhiensis sp. nov. can be distinguished from H. clerki by having (1) fewer subcaudals (81–82 vs. 85–108 in H. clerki ), (2) more maxillary teeth (23 vs. 18–22 in H. clerki ) and (3) continuous dorsolateral stripes (vs. dorsolateral stripes consisting of a series of pale dots, discontinuous in H. clerki ), (4) the first dorsal scale row smooth (vs. strongly keeled in all dorsal scale rows in H. clerki ), (5) eye diameter 2.72–2.88 times the distance between its inferior margin and upper lip edge (vs. 2.0–2.6 times in H. clerki ), (6) ventral scales brick-red at their outer border, with a row of well-defined dark blotches (vs. outer tips of ventral scales brown or dark greyish-brown, and a few brown spots on outer parts of some ventrals in H. clerki ), (7) 7 th or 8 th supralabials with a large white spot in the middle, which are prolonged by the occipital spot (vs. uniformly dark or with a pale blotch in H. clerki ), (8) paired, pale occipital spots connected with the thin pale brown or beige dorsolateral stripe of the neck, no chevron on the upper part of the neck (vs. a conspicuous, pale chevron started from each side behind the last supralabial and reached the upper surface of the neck in H. clerki ).

H. sangzhiensis sp. nov. differs from H. craspedogaster by (1) its pale brown or beige dorsolateral stripes (vs. contained within the pale dorsolateral stripe is a series of small, black-edged, white spots in H. craspedogaster ), (2) venter with the outer part of each scale brick-red as scales of the 1 st dorsal rows (vs. venter white and yellowish, the dark flank color encroaching upon the outer edges in H. craspedogaster ), and (3) ventral blackish-brown slim spots between the brick-red and ivory parts do not connect with each other (vs. ventral spots almost connect with each other in H. craspedogaster ).

H. deschauenseei (Taylor) has two preoculars and two postoculars each (vs. one preoculars and three postoculars in H. sangzhiensis sp. nov.).

H. sangzhiensis sp. nov. is differentiated from H. flavifrons (Boulenger) and H. nicobariensis (Sclater) by cloacal plate divided (vs. entire in H. flavifrons and H. nicobariensis ).

H. sangzhiensis sp. nov. is differentiated from H. johannis by (1) having lateral nostrils (vs. rather dorsolateral in H. johannis ), (2) the first dorsal scale row smooth (vs. keeled in H. johannis ), and (3) ventral scales brick-red at their outer border (vs. the outer part of ventral scales black brown in H. johannis ).

H. sangzhiensis sp. nov. differs from H. khasiensis by having all-white supralabials (vs. with distinct, rounded blotches on the posterior supralabials in H. khasiensis ), having more ventrals (160–164 vs. 146–155 in H. khasiensis ), and the first dorsal scale row smooth (vs. often distinctly keeled in H. khasiensis ).

H. sangzhiensis sp. nov. is differentiated from H. lacrima and H. leucomystax (David, Bain, Quang Truong, Orlov, Vogel, Ngoc Thanh & Ziegler) by absence of a broad, white, interrupted stripe on the supralabials.

H. metusius possesses a distinct black streak on the side of the head; it starts from the posterior margin of the eye, extends onto the posterior supralabials, connects with dorsolateral dark spots (vs. without black streak on the side of the head in H. sangzhiensis sp. nov.); and venter red (vs. venter ivory cream, with brick-red edge at their outer border in H. sangzhiensis sp. nov.).

H. sangzhiensis sp. nov. can be distinguished from H. miyajimae by having (1) more maxillary teeth (23 vs. 20 in H. miyajimae ), (2) H. sangzhiensis sp. nov. has the first dorsal scale row smooth (vs. keeled in H. miyajimae ), and (3) more ventrals (160–164 vs. 141–152 in H. miyajimae ).

H. sangzhiensis sp. nov. differs from H. modestus by having (1) ventral scales brick-red at their outer border, with a row of well-defined dark blotches (vs. 3 rows of ventral black spots in H. modestus ); (2) fewer maxillary teeth (23 vs. 29 in H. modestus ); and (3) fewer subcaudals (81–82 vs. 115–124 in H. modestus ).

H. sangzhiensis sp. nov. differs from H. octolineatus by having different dorsal stripes (2 pale brown or beige dorsolateral stripes in H. sangzhiensis sp. nov. vs. 8 distinct dorsal stripes which start from the posterior margin of the eye in H. octolineatus ).

H. sangzhiensis sp. nov. differs from H. parallelus (Boulenger) by several characters: (1) more subcaudals (81–82 vs. 63–77 in H. parallelus ), (2) tooth diastema absent (vs. tooth diastema wide in H. parallelus ).

H. sangzhiensis sp. nov. differs from H. popei by several characters: (1) more ventral scales (16 0–164 vs. 131–142 in H. popei ), (2) 7 th or 8 th supralabials with a large white spot in its middle (vs. a large round spot in the middle of SL 9 in H. popei ), and (3) fewer maxillary teeth (23 vs. 24–28 in H. popei ).

H. sangzhiensis sp. nov. differs from H. pryeri (Boulenger) by having less ventral scales (16 0–164 vs. 131–142 in H. pryeri ).

H. sangzhiensis sp. nov. differs from H. vibakari with its higher number of ventrals (160–164 vs. 147–154 in H. vibakari ). Furthermore, H. vibakari has fewer subcaudals (55–66 vs. 81–82 in H. sangzhiensis sp. nov.), and does not have longitudinal dorsolateral stripes.

H. sangzhiensis sp. nov. differs from H. xenura (Wall) by having different dorsal pattern (vs. dorsum with a series of paired reddish-orange, pale brown, yellow or white spots on each side of upper back, and adjacent spots sometimes connected by faint black cross-lines in H. xenura ).

H. sangzhiensis sp. nov. can be differentiated from H. yanbianensis by having ventrals with brick red outer border and dorsal stripes on body (vs. ventral with a large, black, triangular blotchand the dorso-lateral stripe absent in H. yanbianensis ).

In morphology, H. sangzhiensis sp. nov. is similar to H. clerki and H. parallelus . The key morphological differences between the three taxa are given in Table 4 .

Figures

FIGURE 1. Map showing the type locality (indicated by a blue triangle) of Hebius sangzhiensis sp. nov. in Hunan Province, China.

FIGURE 3. General view of the holotype (SYNU 08070350) of Hebius sangzhiensis sp. nov. in life. Photo by Z.Y. Zhou.

FIGURE 4. Dorsal (A) and ventral (B) views of the holotype (SYNU 08070350) of Hebius sangzhiensis sp. nov. in preservative. Photos by S. Qi.

FIGURE 5. Dorsal (A), ventral (B) and lateral (C) views of the head of the holotype (SYNU 08070350) of Hebius sangzhiensis sp. nov. Photos by S. Qi.