Pareas dabieshanensis Zhang, Pan & Zhang, 2025

Zhang, Cai-wen, Xu, Shi-hang, Luo, Tao, Liu, Chong, Yu, Lei, Zhou, Jiang, Pan, Tao & Zhang, Bao-wei, 2025, Taxonomic and distributional revision of Pareas boulengeri (Reptilia, Squamata, Pareidae), including two new species from eastern and central China, Zoosystematics and Evolution 101 (4), pp. 1621-1638 : 1621-1638

Pareas dabieshanensis Zhang, Pan & Zhang sp. nov.

Pareas boulengeri ( Chen et al. 2006; Pan et al. 2014). Chresonymy.

Type materials.

Holotype: • An adult male (Fig. 4 , AHU 2024042601 ) was collected from the Tianma National Nature Reserve (31.2250°N, 115.6831°E; elevation 807 m a. s. l.) in Jinzhai County, Luan City, Anhui Province, China, by Tao Pan and Wen-gang Li on April 26, 2024.

Paratypes: • One adult male specimen ( AHU 2014100801 ) was collected from the Yaoluoping National Nature Reserve in Yuexi County, Anqing City, Anhui Province, China, by Tao Pan on October 08, 2014 . • One adult male specimen ( AHU 2021050201 ) was collected from the Taiyang Township in Huoshan County, Luan City, Anhui Province, China, by Caiwen Zhang on May 02, 2021 .

Etymology.

Pareas dabieshanensis sp. nov. refers to the distribution of the new species in the Dabie Mountains. We recommend designating this new species Dabie Mountains Slug-eating Snake and 大别山钝头蛇 (Dà Bié Shān Dùn Tóu Shé).

Diagnosis.

Pareas dabieshanensis sp. nov. is distinguished from its congeners by several morphological characteristics (Table 2 ): (1) medium body size (TL 443–517 mm, n = 3 males); (2) yellow – brown body featuring numerous irregular black horizontal stripes; (3) the length of the suture between the internasals is subequal to that between the prefrontals, with the prefrontal bordering the orbit; (4) the frontal is subhexagonal to diamond-shaped, with its lateral sides converging posteriorly; (5) the anterior pair of chin shields is longer than broad; the loreal scale partially borders the orbit; (6) the prefrontal contacts the eye, and there are two subocular scales; (7) 7–8 supralabials and 9 infralabial scales; (8) 15-15 - 15 rows of dorsal scales, with mid-dorsal scales smooth, and the vertebral scale row is not enlarged; (9) 184–187 ventral scales and 68–74 subcaudals, divided, with a single cloacal plate; (10) prefrontal and postfrontal bones do not exhibit contact, asymmetric teeth number in maxilla, palatine, pterygoid, and dentary bones (MX 5 / 5, PAL 3 / 3, PT 10–11 / 9 – 11, DT 16–18 / 20); (11) dorsal surface of the head exhibits a dense arrangement of small, black spots; three distinct black vertical stripes on the lateral aspect of the head, which do not converge; the central horizontal stripe, posterior to the supraorbital scales, extends posteriorly toward the neck; additionally, a horizontal stripe posterior to the eyes terminates at the posterior margin of the head; two black horizontal stripes are in the supraocular and postocular regions, extending only to the posterior margin of the head.

Holotype description.

An adult male with a total length of 506 mm (SVL 398 mm, TaL 108 mm); relatively short tail (TaL / TL ratio 0.21); body slender, slightly compressed; head distinct from neck, snout wide and blunt, projecting beyond lower jaw; head elongate, clearly distinct from neck; snout round in dorsal view; eye slightly enlarged, pupil vertical and slightly elliptical; rostral approximately as wide as high, slightly visible from above; nasal undivided; internasal elongated; prefrontal, approximately trapezoidal, bordering orbits; frontal shield-shaped, slightly longer than wide; parietals large, longer than wide, gradual narrowing posteriorly, median suture approximately equal to length of frontal; one loreal, in contact with eye; two subocular scales, the anterior scale is diminutive, and the posterior scale is fused with the postocular scale, extending anteriorly beneath the eyes; temporals 2 + 3 / 2 + 3; 7 / 8 supralabial scales; 9 / 9 infralabials; 3 chin-shield pairs; dorsal scales exhibit a smooth texture and are arranged in 15 rows along the body, while the dorsal scale does not exhibit enlargement; 190 ventral scales; 70 subcaudals scales, paired; single cloacal plate. Prefrontal and postfrontal bones do not exhibit contact, asymmetric teeth number in maxilla, palatine, pterygoid, and dentary bones (MX 5 / 5, PAL 3 / 3, PT 10 / 9, DT 18 / 21).

Coloration in life.

Dorsal surface of the head exhibits a dense arrangement of small, black spots; three distinct black vertical stripes appear on the lateral aspect of the head and do not converge; the central horizontal stripe, posterior to the supraorbital scales, extends posteriorly toward the neck. A horizontal stripe posterior to the eyes terminates at the posterior margin of the head. Furthermore, two black horizontal stripes in the supraocular and postocular regions extend only to the posterior margin of the head. The dorsal surface is further distinguished by a yellowish-brown coloration featuring 47 irregular and discontinuous black horizontal stripes. In contrast, the ventral side exhibits a grayish-white coloration, adorned with scattered fine black spots.

Coloration in preservative.

In its preserved form (Fig. 4 ), the specimen’s coloration resembles its living appearance. However, the once yellowish – red dorsal surfaces of the head and body fade to a pinkish – brown, with a notable reduction in vibrancy. The black stripes along the sides of the body and tail remain visible, preserving their contrast despite the fading in other areas. The pinkish – yellow belly and ventral portion of the head and tail also lighten to a pinkish – white. Moreover, the iris becomes grayish-black, while the pupil becomes white, reflecting additional changes in pigmentation due to the preservation process.

Variation.

The three adult male specimens exhibited nearly identical morphological characteristics. The fundamental statistics related to the morphological measurements are presented in Suppl. material 1: tables S 2, S 3. The number of posterior temporals ranged from two to three. The number of vertical black stripes on each side of the body ranged from 48 to 53, while the iris color in the paratypes varied from reddish-yellow to yellow.

Distribution and habitat.

Based on the existing distribution data, it is speculated that this species is mainly distributed in the Dabie Mountain area at the junction of Anhui, Henan, and Hubei Province (Fig. 1 ). It inhabits mountainous regions, frequently residing near low shrubs adjacent to streams in low-altitude areas, and primarily feeds on slugs and snails.

Comparison.

Comparisons between the new species and its congeners are summarized in Table 2 . Pareas dabieshanensis sp. nov. was previously classified as P. boulengeri . However, this newly identified species can be differentiated from P. boulengeri in southwest China based on a higher number of subcaudal scales (68–74 vs. 57–66), two subocular scales (vs. one and fused suboculars with postoculars) (Fig. 5 ), and prefrontal and postfrontal bones do not exhibit contact (vs. contact) (Fig. 6 ).

Pareas dabieshanensis sp. nov. can be distinguished from P. andersonii , P. macularius , P. margaritophorus , and P. modestus by its yellow – brown dorsum featuring irregular dark bands (vs. uniform grey to black to dark coloration with bicolored spots), the loreal contacting the eye (vs. the loreal not contacting the eye), a greater number of ventral scales (184–187 vs. 141–162, 151–173, 133–160, or 151–159, respectively), and a greater number of subcaudals (68–74 vs. 35–47, 57–66, 35–54, or 35–46, respectively).

Pareas dabieshanensis sp. nov. can be easily distinguished from P. abros , P. atayal , P. baiseensis , P. berdmorei , P. carinatus , P. formosensis , P. geminatus , P. guanyinshanensis , P. hamptoni , P. kaduri , P. komaii , P. kuznetsovorum , P. niger , P. nuchalis , P. temporalis , P. tigerinus , and P. xuelinensis by the presence of a loreal scale in contact with the eye (vs. the loreal scale not contacting the eye).

Pareas dabieshanensis sp. nov. can be distinguished from P. chinensis by the absence of preoculars (vs. one preocular), two subocular scales, one of which is fused with the postocular scale (vs. not fused), dorsal scales not enlarged (vs. one vertebral scale row enlarged), and dorsal scale smooth at midbody (vs. three keeled dorsal scale rows at midbody).

Pareas dabieshanensis sp. nov. differs from Pareas dulongjiangensis by lacking preoculars (vs. one preocular), having two subocular scales, one of which is fused with the postocular scale (vs. only one and suboculars fused with postoculars), dorsal scales not enlarged (vs. three vertebral scale rows enlarged), and a dorsal scale smooth at midbody (vs. five keeled dorsal scale rows at midbody).

Pareas dabieshanensis sp. nov. can be easily distinguished from Pareas iwasakii by the absence of preoculars (vs. one preocular), having postoculars fused with suboculars (vs. distinct and separated postoculars and suboculars), fewer ventral scales (184–187 vs. 190–193), fewer subcaudal scales (68–74 vs. 76–84), dorsal scales not enlarged (vs. one vertebral scale row enlarged), and dorsal scale smooth at midbody (vs. 5–7 keeled dorsal scale rows at midbody).

Pareas dabieshanensis sp. nov. differs from P. monticola with more infralabial scales (9 vs. 7–8) and a smooth dorsal scale at midbody (vs. 1–3 keeled dorsal scale rows at midbody).

Pareas dabieshanensis sp. nov. differs from P. nigriceps by having more infralabial scales (9 vs. 7), lacking preoculars (vs. one preocular), having two anterior temporals (vs. one anterior temporal), two subocular scales, one of which is fused with the postocular scale (vs. only one and suboculars fused with postoculars), dorsal scales that are not enlarged (vs. one enlarged vertebral scale row), and a smooth dorsal scale at midbody (vs. 9 keeled dorsal scale rows at midbody).

Pareas dabieshanensis sp. nov. differs from P. stanleyi by having more infralabial scales (9 vs. 7–8), postoculars fused with suboculars (vs. distinct and separated postocular and subocular), more ventral scales (184–187 vs. 151–160), more subcaudal scales (68–74 vs. 48–64), and a smooth dorsal scale at midbody (13 keeled dorsal scale rows at midbody).

Pareas dabieshanensis sp. nov. differs from P. victorianus by having more infralabial scales (9 vs. 6–7), two subocular scales, one of which is fused with the postocular scale (vs. only one and subocular fused with postocular), more ventral scales (184–187 vs. 164), more subcaudal scales (68–74 vs. 58), dorsal scales not enlarged (vs. one enlarged vertebral scale row), and a smooth dorsal scale at midbody (vs. eight keeled dorsal scale rows at midbody).

Pareas dabieshanensis sp. nov. differs from P. vindumi by having more supralabials (7–8 vs. 6), more infralabials (9 vs. 6), two subocular scales, one of which is fused with the postocular scale (vs. only one and subocular fused with postocular), more ventral scales (184–187 vs. 178), and more subcaudal scales (68–74 vs. 61).

Pareas dabieshanensis sp. nov. differs from P. yunnanensis by having more infralabials (9 vs. 6), lacking preoculars (vs. 1–2 preoculars), having two subocular scales, one of which is fused with the postocular scale (vs. only one and subocular fused with postocular), more ventral scales (184–187 vs. 169–175), more subcaudal scales (68–74 vs. 59–65), dorsal scales not enlarged (vs. one enlarged vertebral scale row), and a smooth dorsal scale at the midbody (vs. 5–7 keeled dorsal scale rows at midbody).

Remarks.

In 1974, the Sichuan Institute of Biology first discovered Pareas chinensis in the Dabie Mountains of Anhui Province. The amphibian and reptile fauna of Anhui suggest that this species is also present in Qianshan and Huoshan County ( Chen 1991). Additionally, Chen et al. (2006) identified P. boulengeri for the first time in the Jingangtai National Nature Reserve, in the Dabie Mountains of Henan Province. Pan et al. (2014) further confirmed the presence of this species in the Dabie Mountains of Anhui and reclassified P. chinensis as P. boulengeri . This species has been detected in multiple localities within the Dabie Mountains ( Pan et al. 2014; this study). Furthermore, P. dabieshanensis sp. nov. is likely found in eastern Hubei, which is geographically connected to western Anhui; however, further confirmation is required through additional voucher specimens.

Figures

Figure 1. Data locations pertinent to this research. The black dots indicate current distribution points of Pareas boulengeri, as documented in GBIF. The red, blue, and yellow circles denote the sampling sites for P. boulengeri, P. dabieshanensis, and P. orientalis, respectively. This map includes both actual sampling sites and approximate locations associated with sequence data obtained from NCBI. The dotted circles in red, blue, and yellow represent the potential distribution ranges of the three species under investigation.

Figure 4. Pareas dabieshanensis sp. nov. in preservative (AHU 2024042601). A. Dorsal view; B. Ventral view; C. Right lateral view of the head; D. Left lateral view of the head; E. Ventral view of the head; F. Dorsal view of the head. Scale bars: 10 mm.

Figure 5. Comparative analysis of head scaling. Specimens include. A. Pareas boulengeri (LPSSC 2024070502); B. A living specimen (GZNU 2018052302); C. The holotype of P. dabieshanensis sp. nov. (AHU 2024051501); D. A living specimen (AHU 2021050201); E. The holotype of P. orientalis sp. nov. (AHU 2024051501); and F. A living specimen (AHU 2024051502). Photos by Cai-wen Zhang, Shan Shen, and Tao Luo.

Figure 6. Three-dimensional model of the skull of Pareas boulengeri, P. dabieshanensis sp. nov., and P. orientalis sp. nov. Left, right lateral view; middle, left lateral view; right, dorsal view. A – C. Pareas boulengeri (LPSSY 2021070801); D – F. The holotype of P. dabieshanensis sp. nov. (AHU 2024051501); H – J. The holotype of P. orientalis sp. nov. (AHU 2024051501). Implemented by Cai-wen Zhang and Jing-song Shi. Scale bars: 2 mm.