Hai Ha Mountain Stream Keelback

Description of male specimen ANU 20240076

Description of male specimen ANU 20240076 Measurements and scalation. Body slender and cylindrical (TL 428.0 mm); head short and broad, dorsally depressed, barely distinct from neck (HL/HW 1.87); snout moderate (SnL/SnW 0.74); eyes in medium size (ED/SoL 0.97); pupil round; interorbital distance large (IOD/HW 0.66); minute granular asperities absent on head scales; tail relatively long, tapering posteriorly (TaL 113.9 mm, TaL/TL 0.27); nostril oval-shaped, locating in the upper middle part of nasal, directed upwards. Dorsal scales in 15 rows throughout the body; the outermost rows of dorsal scales slightly enlarged, while the rest ones homogeneous in size, smooth throughout; vertebral scales not enlarged; preventrals 1, ventrals 168; cloacal plate divided; subcaudals 87 paired, with single terminal rigid tip, smooth entirely. Rostral crescent-shaped, wider than high, visible from above; nasals large, wider than high, divided below nostril by a distinct furrow; nasals in contact with the first two supralabials, rostral, internasal, prefrontal and loreal; internasals paired, trapezoid, longer than wide, curved outward posteriorly, in contact with rostral, nasal, and prefrontal;

First description of the male and hemipenial morphology of Opisthotropis haihaensis Ziegler et al., 2019 (Serpentes, Natricidae), with updated diagnosis and distribution

Description of additional female specimen ANU 20240077

Description of additional female specimen ANU 20240077 Measurements and scalation. Body slender and cylindrical (TL 485.0 mm); head short and broad (HL/HW 1.76), dorsally depressed, barely distinct from neck; snout moderate (SnL/SnW 0.60); eye small, (ED/SoL 0.81); pupil round; interorbital distance large (IOD/HW 0.60); minute granular asperities absent on head scales; tail relatively long, tapering posteriorly (TaL 94.9 mm, TaL/TL 0.20); nostril oval-shaped, locating in the upper middle part of nasal, directed upwards. Dorsal scales in 15 rows throughout the body; the outermost rows of dorsal scales slightly enlarged, while the rest ones homogeneous in size, smooth throughout; vertebral scales not enlarged; preventrals 1, ventrals 165; cloacal plate divided; subcaudals 71, paired, with single terminal rigid tip, smooth entirely. Rostral crescent-shaped, wider than high, visible from above; nasals large, wider than high, divided below nostril by a distinct furrow; nasals in contact with the first two supralabials, rostral, internasal, prefrontal and loreal; internasals coalesced into one, pentagonal, wider than long, concaved inward posteriorly, in contact with rostral, nasal

First description of the male and hemipenial morphology of Opisthotropis haihaensis Ziegler et al., 2019 (Serpentes, Natricidae), with updated diagnosis and distribution

Variation.

Variation. The newly collected specimens conform to both the holotype (IEBR A.2016.34 ) from Vietnam and specimen SYS r000537 from China in general morphology, but exhibit the following differences (Tables 2, 3): shorter total and snout-vent lengths: TL 428.0–485.0 mm, SVL 314.1–387.1 mm (vs. TL 500.2–509.0 mm, SVL 391.3–396.0 mm); lower number of supralabials: 7 (vs. 8); broader range of tail length: TaL 113.9 mm and TaL/TL 0.27 in the male; TaL 94.9 mm and TaL/TL 0.20 in the female (vs. TaL 108.9–113.0 mm and TaL/TL 0.22 in females); wider range of subcaudal counts: 87 in the male and 71 in the female (vs. 75–79 in females); variation in supralabials entering the orbit: 4 th and 5 th or only 4 th or 5 th (vs. consistently 4 th and 5 th ).

First description of the male and hemipenial morphology of Opisthotropis haihaensis Ziegler et al., 2019 (Serpentes, Natricidae), with updated diagnosis and distribution

Revised diagnosis.

Revised diagnosis. Opisthotropis haihaensis can be distinguished from all congeners by the following combination of characters: (1) adult females reach a total length (TL) of 485–509 mm, and the only examined adult male measures 428 mm in TL; (2) the tail is relatively long, with a TaL/TL ratio of 0.20–0.22 in females and 0.27 in the male; (3) the species exhibits 7–8 supralabials, with the 4 th and 5 th or either the 4 th or 5 th , entering the orbit; (4) the 6 th supralabial is not elongated and is nearly or less than half the length of the anterior temporal; (5) preocular one, postoculars one or two; (6) the internasals do not contact the loreal, and the prefrontals are separated from the supraoculars, while the frontal is in contact with the preocular; (7) the temporal formula is either 1 or 1+1; (8) the species has 164–169 ventrals and 87 subcaudals in the male and 71–79 in females; (9) dorsal scales in 15–15–15 rows and are smooth on the body, with the tail scales either smooth or indistinctly keeled; (10) the chin shields are yellow with brownish black mottling, and the body and tail dorsum is dark, each dorsal scale bearing a distinct pale spot; (11) the maxillary t

First description of the male and hemipenial morphology of Opisthotropis haihaensis Ziegler et al., 2019 (Serpentes, Natricidae), with updated diagnosis and distribution