Achalinus sheni Ma, Xu, Qi, Wang, Tang, Huang & Jiang, 2023

Ma, Yi-han, Liu, Jia-yu, Li, Hui, Zhou, Lin, Xu, Yu-hao, Peng, De-yong, Zhang, Zhi-qiang & Mo, Xiao-yang, 2024, First description of the female of Achalinus sheni (Serpentes, Xenodermidae), with expanded description of this species, Herpetozoa 37, pp. 189-195 : 189-195

Achalinus sheni Ma, Xu, Qi, Wang, Tang, Huang & Jiang, 2023

Specimen examined.

HNNU 2022001, adult female, collected by Hui Li, Lin Zhou on April 11, 2022, from Xinshao County (27 ° 23 ' 58 " N, 111 ° 33 ' 44 " E, 420 m a. s. l.), Shaoyang City, Hunan Province, China.

Description of the female specimen.

Adult female with a total length of 345.1 mm (SVL 294.8 mm and TaL 50.3 mm), tail relatively short, TL / ToL 0.149, body slender and cylindrical. Head distinct from neck, rostral small, triangular, only the upper tip is visible from above. Head length 9.16 mm, head width 3.95 mm, HL / HW 2.32. Eyes small, eye width 1.10 mm. Length of the suture between the internasals ( LSBI 1.40 mm) subequal to the length of the suture between the prefrontals ( LSBP 1.31 mm). Frontal pentagonal pointed backwards, much shorter than the parietals; each parietal bordered with an elongated nuchal, with no preoculars or postoculars. Nostril in anterior portion of nasal scale, posterior margin of nostril with a distinct nostril cleft. A single loreal scale present, extending from the nasal to the eye, distinctly wider than high. Temporals 2 + 2 + 3. aTMPs elongated, upper aTMP much smaller than the lower aTMP; upper aTMP and lower aTMP in contact with eye, lower aTMP also in contact with parietal scale. Supralabials 6, 4 th – 5 th contact the eye, the last much elongated. A single mental scale present. Two chin shields, the anterior pair longer than the posterior pair. Infralabials 5, the first contacting each other posterior to the mental and anterior to the 1 st chin shields, 1 st – 3 rd contact the 1 st chin shields. Dorsal scales 23-23 - 23, strongly keeled, dorsum with an inconspicuous longitudinal vertebral stripe. Ventrals (VEN) 173. Subcaudals (SC) 45, not paired. Cloacal plate (CP) entire (Table 3 ).

Coloration of the female specimen in life.

Scales possess a subtle iridescent quality which gives the dorsum a distinctive reflective brownish-black appearance. Dorsum dark brown and the five innermost dorsal scale rows a little darker, forming an inconspicuous longitudinal vertebral line. Chin shields are tan. On the ventral surface, an off-white shade prevails, with the edges of the ventral scales gradually transitioning from gray-white to black. Ventral side of tail brownish.

Coloration in preservative.

(Fig. 3 ) The dorsal surface of the body uniformly brownish-black, slightly tinged with iridescence and the longitudinal vertebral line appears a little darker. Chin shields light brown. Ventrals generally pale brown, darker on both sides, free margins of ventral scales grayish-white. Ventral surface of tail light brown.

Extended diagnosis.

Upon examining the additional adult males of Achalinus sheni from Xinshao County, it was observed that they possessed fewer ventral scales compared to specimens from the type locality. However, the number of subcaudal scales remained approximately the same for individuals from both locations. Upon inspection of adult female A. sheni collected in Xinshao County, it was noted that it exhibited an extremely short tail and consequently fewer subcaudals and more ventral compared to adult male individuals.

Comparison.

Compared to male individuals of A. sheni and A. yunkaiensis , female individuals of both species exhibit similar differences in the number of ventral scales and subcaudals. Compared to males, both female A. yunkaiensis and female A. sheni have fewer sublabial scales, which is consistent with the common characteristics of this genus. However, the number of sublabial scales of A. sheni is even less than that of female A. yunkaiensis (Table 4 ).

Figures

Figure 3. Adult female (HNNU 2022001) of Achalinus sheni. A. Dorsolateral view; B. Ventral view; C. The tail of the male and female; D. Dorsal head view; E. Ventral head view; F. Light side of head view; G. Ventral head view. Photos by Le-Qiang Zhu.