Opisthotropis laui, Yang, Sung & Chan, 2013

Yang, Jian-Huan, Sung, Yik-Hei & Chan, Bosco Pui-Lok, 2013, A new species of the genus Opisthotropis Günther, 1872 (Squamata: Colubridae: Natricinae) from Guangdong Province, China, Zootaxa 3646 (3), pp. 289-296 : 290-295

Opisthotropis laui sp. nov.

Holotype. KIZ 0 60100 , female from Beifengshan Forest Park, Mt. Gudou , Jiangmen City, Guangdong Province, China (22°14'20'' N, 112°55'05'' E, ca. 300 m above sea level), collected by Bosco P.L. Chan and Michael W.N. Lau on 26 July 2002, preserved in 80% alcohol and deposited at Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China ( KIZ),

Diagnosis. Opisthotropis laui sp. nov. differs from other species of Opisthotropis by the combination of the following characters: dorsal scales weakly keeled throughout, in 25:23:23 rows; 10 supralabials; 11 infralabials; two internasals, longer than wide, not touching with the loreal; one loreal, not touching with the eye; one preocular; two postoculars; one anterior temporal scale; 152 ventrals; 53 subcaudals; body and tail dark olive above, with light yellow cross bars. See Table 1 for the detailed morphological comparison of the new species with other congeners.

In the appearance, Opisthotropis laui sp. nov. greatly resembles O. cheni and O. guangxiensis since all three species present narrow light cross bars on dorsum ( Zhao et al., 2006; David et al., 2011; Fig. 3 ). Opisthotropis laui sp. nov. differs from O. cheni by having dorsal scale rows 25:23:23 (vs. 17:17: 17 in O. cheni ), weakly keeled throughout (vs. all but the outer one weakly keeled in O. cheni ); one preocular (vs. absent in O. cheni ); more supralabials (10 vs. 7–9 in O. cheni ); more infralabials (11 vs. 8–10 in O. cheni ); loreal not touching the eye (vs. touching in O. cheni ). Opisthotropis laui sp. nov. differs from O. guangxiensis by having dorsal scale rows 25:23:23 (vs. 17:17: 17 in O. guangxiensis ), weakly keeled throughout (vs. smooth throughout in O. guangxiensis ); more infralabials (11 vs. 8–9 in O. guangxiensis ); fewer ventral scales (152 vs. 166–174 in O. guangxiensis ).

Description of holotype. Specimen KIZ 0 60100, female, SVL 241.8 mm, TL 56.9 mm; HL 12.4 mm. Head small, indistinct from neck; eye small, pupil round; nostril directed dorsally; rostral broader than high, just visible from above; nasal not divided below nostril, surrounded by the first three supralabials, rostral, internasal, prefrontal and loreal on both sides; two narrow internasals, nearly twice as long as broad, in contact with rostral anteriorly, and not in contact with loreal; one prefrontal, about 2.2 times as width as long, pentagonal and tapering anteriorly; one frontal, length about 1.1 times as width, about equal to its distance from snout tip, nearly triangular and tapering posteriorly; one paired parietals, about 1.3 times longer than the frontal; one loreal, not in contact with eye, and surrounded by third – fifth supralabials, nasal, prefrontal and preocular on both sides; one preocular, in normal size, not in contact with frontal; two postoculars, lower one much smaller than upper one; one extremely small pre-subocular present on left side, absent on right side; 10/10 (left/right, hereafter) supralabials, only the sixth supralabial touching the eye on left side, and the 5–6 supralabials touching the eye on right side; 11/11 infralabials, the first one touching each other behind the mental; two pairs of chin shields, anterior pair of chin shields longer than posterior pair; anterior pair of chin shields in contact with the first five infralabials on both sides, posterior pair separated from each other by two scales; 1+2 temporal scales on both sides; rear-head region weakly keeled; temporal region smooth; dorsal scale rows in 25:23:23 (Sq1:Sq2:Sq3), weakly keeled throughout; ventrals 152, last two divided; 53 pairs of subcaudals.

Coloration. Eye black; body and tail dark olive above with 42 (28 at dorsal body, 14 at dorsal tail) complete or incomplete light yellow crossbars edged with black; anterior four supralabials dark olive, posterior ones light yellow with dark upper margin; anterior five infralabials dark olive, posterior ones light yellow; chin shields and ventrals uniformly light yellow; subcaudals light yellow with dark margins.

Etymology. We name this new species, “ laui ”, in honor of Michael Wai-Neng Lau from Hong Kong, in recognition of his long-term contribution to biodiversity, in particular herpetological research and conservation in Southern China. As common names we suggest “Lau’s Mountain Stream Snake” (English name), and “Liu Shi Hou Leng She” (Chinese name).

Distribution and natural history. Currently, Opisthotropis laui sp. nov. is only known from its type locality at Beifengshan Forest Park in Mt. Gudou, Jiangmen City, Guangdong Province, China ( Fig. 4 ). Mt. Gudou is an isolated mountain range situated along the coastline at the western side of the Pearl River Estuary, and has been protected as a nature reserve since 2001. The summit, known as Shizitou, is 982 m a.s.l.. Original vegetation of the mountain range has been largely destroyed in the past. Currently it supports secondary forest at various successional stages, as well as shrubland and grassland; the stream valleys generally support more mature natural forest. The only specimen of the new species was found swimming in a small stream at night ca. 2145h, which is shallow, rocky, and ca. 3 m wide, with young but closed-canopy natural forest. The stream drains pass Taishan City, Guangdong Province, before emptying into the Pearl River Delta.

Figures

FIGURE 3. (A) General aspect in life of the holotype of Opisthotropis laui sp. nov., (B) General aspect in life of O. cheni (from Mangshan National Nature Reserve, Hunan Province, China), (C) General aspect in life of O. guangxiensis (from Dawuling Nature Reserve, Guangdong Province, China). Photographs by Michael W. N. Lau (A), Jian-Huan Yang (B) and Lee Kwok Shing (C).

FIGURE 4. Map of Southern China showing the type locality of Opisthotropis laui sp. nov., Mt. Gudou, Jiangmen City, Guangdong Province, China (star).