Trachischium monticola ( Cantor, 1839 )

Wang, Kai, Jiang, Ke, Jin, Jieqiong, Liu, Xu & Che, Jing, 2019, Confirmation of Trachischium guentheri (Serpentes: Colubridae) from Tibet, China, with description of Tibetan T. monticola, Zootaxa 4688 (1), pp. 101-110 : 106-108

Trachischium monticola ( Cantor, 1839)

( Figs. 2–4 )

Calamaria monticola Cantor, 1839 , Proc. Zool. Soc., 1839: 50. Type locality: Naga Hills in Asám [= Assam], India.

Specimens examined: One adult male (KIZ 016468) from Maniweng, Medog County, Nyingchi Prefecture, Tibet, China; four females (KIZ 06620, 07392, 07393, and 011067) from Yarang, Medog County, Nyingchi Prefecture, Tibet, China. All specimens collected by Ke JIANG, Xu LIU, Fang YAN and Dadu ZOU in July 2015.

Description. Body elongate, cylindrical and slender, SVL 181–257 mm; head short (HL/SVL 4.4–5.1%), ovoid, not distinct from a thick neck; snout rounded, extended slightly beyond lower jaw; nostril oval and small; eye rather small, pupil rounded; tail short (TAL/TOL 11.7–12.6% for females; all males have incomplete tails), robust at its base, tapering progressively to end; tip of tail pointed.

Rostral small, slightly visible from above; nasal single, irregular pentagon shaped, with nostril positioned middle anteriorly; internasals 2, wider than long, in contact with nasal, loreals, rostral, and prefrontals; prefrontals 2, much larger than internasals, irregular pentagonal, wider than long, half as long as frontal; supraoculars narrow, long, 2 times longer than wide; frontal large, irregular hexagonal shaped, 1.5 times longer than wide; parietals large, longer than wide, 1.4 times longer than frontal; loreal scale 1/1, rectangular, 1.5 times longer than deep, in contact with nasal, internasal, prefrontal, preocular, and first two supralabials; supralabials 6/6, 2-2-2, first two in contact with nasal, third and fourth entering orbit, sixth largest; preocular 1/1, narrow, about 1.7 times deeper than long, in contact with prefrontal; presubocular absent; postoculars 2/2, twice deeper than long, the upper one larger than lower one; temporals 1+1, anterior one much slender; infralabials 6/6, first pair in contact with each other, first to fourth in contact with anterior chin shields. Maxillary teeth subequal, 20-21 on left,

Dorsal body scales all smooth, 15 rows throughout. Ventrals 130 in male, 132–134 in females, not angulated; cloacal divided; subcaudals paired, 26–29 in females; terminal caudal scale sharp, pointed ( Tables 1 and 2 ).

Everted left hemipenis reaching 6 th subcaudal; cylindrical, bilobated distally at about 1/4 its length; lobes rather distinct; small spines present throughout, enlarged from tip to base gradually, and having single enlarged spine at middle of base; sulcus simple, reaches the end of bifurcation, lips not prominent ( Fig. 4 ).

Coloration in life. Same as other congeners, body surfaces of the snake are iridescent. The background coloration of the dorsal head is neutral gray. Faint yellow patterns are unevenly sprinkled on the dorsal and lateral surfaces of head and body; and such sprinkled patterns form solid yellow patches at the center of ventrolateral body scales as well as head scales (including rostral, internasal, nasal, prefrontal, loreal, supraocular, supralabrial, infralabial, and anterior temporal scales). A distinct, faint yellow, collar pattern are present on each side of the neck, which are not connected medially or ventrally. Background coloration of remaining surfaces of the dorsal and lateral body is reddish brown. Two black-edged, dark reddish orange, dorsolateral strips are present on the body from the neck to the tip of tail, one on each side. Ventral surface of the head is mostly uniform cream color; ventral surfaces of neck and the first one-fifth portion of the body are faint yellowish, with a single somewhat distinct yellow transverse streak across each individual ventral scale. Ventral coloration transition to uniform faint orange gradually toward posterior direction ( Fig. 2 ).

Coloration in preservative. The ornamentation pattern does not change significantly after preservation, but coloration does faint after preservation, in which the faint yellow sprinkles and orange dorsolateral stripes become pale grayish white, the reddish dorsal coloration become dark grey, and the ventral surface of body becomes white.

Natural history. All specimens were collected during daytime, in which the male specimen was crossing a road, while all female specimens were dug from thick leaf litter. The species inhabits tropical rainforest floor in Medog County, southeastern Tibet ( Fig. 2E ). Sphenomorphus indicus , S. maculatus , and Dopasia gracilis were some of the fossorial/semi-fossorial lizards that inhabit the same microhabitat. Possible predator may include Sinomicrurus macclellandi , which is also found in the same region.

Distribution. In China, Trachischium monticola is only known from a few localities in Medog County, Nyingchi Prefeture, Tibet ( Fig. 2E ). It is also reported from northeast India, Bangladesh, and Nepal ( Smith 1943; Schleich & Kästle 2002).

Figures

FIGURE 2. Live individuals of Trachischium tenuiceps (A), T. guentheri (B), and T. monticola (C) from Tibet, China and the microhabitats of T. tenuiceps and T. guentheri in Zhangmu, Nyalam County (D) and of T. monticola in Yarang, Medog County (E). Photos: K. Wang and K. Jiang.

FIGURE 3. Comparisons of of lateral (1), dorsal (2), and ventral (3) view of head between Trachischium guentheri KIZ 012569 (A), T. tenuiceps KIZ 011134 (B), and T. monticola KIZ 016468 (C). Photos: K. Wang and K. Jiang.

FIGURE 4. Hemipenis comparison between Trachischium guentheri (A) and T. monticola (B). Photos: K. Wang and K. Jiang.