Tam Dao Stream Snake

Etymology

Etymology According to the original description, the specific name “ tamdaoensis ” refers to the type locality of this species, Tam Dao Mountain ridge (Vinh Phuc Province) in Vietnam (Ziegler et al. 2008). The English name was “Tam Dao Mountain Stream Snake”. As this species is now also reported from China, we suggest its Chinese name as “三岛后棱蛇” (Sān Dăo Hòu Léng Shé), derived from its scientific name.

Expanded description and distribution of Opisthotropis tamdaoensis Ziegler, David & Vu, 2008 (Squamata, Natricidae), first record from Yunnan Province of China

Description of the specimens from China (n = 2)

Description of the specimens from China (n = 2) The morphological measurements and scalation features are listed in Table 2. Body medium size, TL 558 mm (except the juvenile), cylindrical, slenderly built; head short and broad, HL/HW 1.18, dorsally depressed, indistinct from neck (except the juvenile); snout moderate; pupil round; tail relatively short, TaL/TL 0.161–0.182, tapering posteriorly. Head scalation. Rostral arc, broad, approximately twice as long as high, visible from above. Internasal two, crescent-shaped, in contact with each other medially behind the rostral, not in contact with loreal, posteriorly in contact with prefrontal. Prefrontal one, in contact with internasal, nasal, loreal, pre-ocular, frontal and supraocular. Frontal one, sub-hexagonal, in contact with supra-ocular and parietals. Parietals large and in contact medially. Nasal directed dorsally, polygonal, not divided, in contact with rostral anteriorly, with the 1 st and 2 nd supralabials ventrally, with loreal and prefrontal posteriorly and with internasal dorsally. Nostril long, oval, piecing in middle of nasal, oblique, directed upwards. Loreal one, not entering the orbit, in contact with the 2

Expanded description and distribution of Opisthotropis tamdaoensis Ziegler, David & Vu, 2008 (Squamata, Natricidae), first record from Yunnan Province of China

Extended diagnosis

Extended diagnosis (1) Nasal not divided below nostril; (2) loreal usually 1, not in contact with internasals; (3) pre-oculars 1–2, postoculars 2 subocular, usually 1; (4) anterior temporals 1–2, posterior temporals 2–4; (5) supralabials usually 9, only the fifth or fifth to sixth supralabial (rarely none) in contact with the orbit; (6) infralabials usually 9–10; (7) first pair of chin shields longer than the second pair; (8) dorsal scales smooth anteriorly, keeled posteriorly, in (17–19)-17-17 rows; (9) tails telatively short, TaL/TL 0.143–0.161; (10) pre ventrals 0–4, ventrals 160–176, precloacal divided; 4856 divided subcaudals; (11) uniform olive-grey dorsum, with a dark longitudinal lateral stripe within the dark flank colouration, ventral side pale or light yellow, without sharp transition towards the dark dorsal colouration, subcaudal region may bear dark mottling.

Expanded description and distribution of Opisthotropis tamdaoensis Ziegler, David & Vu, 2008 (Squamata, Natricidae), first record from Yunnan Province of China

Distribution

Distribution O. tamdaoensis is currently only known from two localities, where one is from its type localities, Silver Stream in Tam Dao, Vinh Phuc Province, northern Vietnam and the other one is from Baisha River, Nanxi Town, Hekou Yao Autonomous County, Honghe Hani and Yi Autonomous Prefecture, Yunnan Province, China. The Vietnamese specimens were found at elevations in between 750 to 1,500 m above sea level and the Chinese specimens were found at 152 m above sea level, thus the elevation range of O. tamdaoensis is from 152 m to 1,500 m a.s.l. (Ziegler et al. 2008, Ziegler et al. 2017).

Expanded description and distribution of Opisthotropis tamdaoensis Ziegler, David & Vu, 2008 (Squamata, Natricidae), first record from Yunnan Province of China