Lycodon pictus Janssen, Pham, Ngo, Le, Nguyen & Ziegler 2019

Lycodon pictus Janssen, Pham, Ngo, Le, Nguyen & Ziegler, 2019

Figs 1-3

New record for Vietnam (n = 1): VNMN 011227 (Fig. 1), Ha Lang, Cao Bang, Vietnam, Coordinates 22°42’50’’ N, 106°40’74’’ E, 960 m a.s.l., collected by Nguyen Quoc Huy on 18 May 2019.

New record for China (n = 1): CIB 115609 (field no. GX2019069; Figs 2-3), Nonggang National Nature Reserve, Longzhou County, Guangxi Zhuang Autonomous Region, China, 106°57’18.77” E, 22°28’3.92” N, 233 m a.s.l., collected by Ren Jin-Long and Zeng Fan-Xing on 8 July 2019.

Description of the Chinese specimen: Head elongate, moderately distinct from neck, rather flattened, longer than wide, snout narrow, distinctly shorter than head width; nostril large, lateral, located in the middle of the nasal; eye large, pupils vertically elliptic; rostral triangular, much broader than high, hardly visible from above; nasal divided, narrowed medially; two internasals, anteriorly round, slightly wider than high, bordered by two large, hexagonal prefrontals posteriorly; frontal single, enlarged, pentagonal to hexagonal, narrowed posteriorly; parietals large, longer than wide, in contact with each other medially, with upper anterior and posterior temporals, paraparietal laterally and four nuchal scales posteriorly; paraparietals elongated, anterior part widened, about equal in length or slightly longer than posterior temporals; loreal 1/1, elongate, not entering orbit on right side, whereas the posterior corner entering orbit on the left side (Fig. 3C and D); supralabials 8/8, first and second in contact with nasal, third to fifth entering orbit, sixth largest, slightly higher than third on left side; infralabials 10/9, first pair in broad contact with each other, first to fifth/first to fourth in contact with anterior pair of chin shields; anterior and posterior pairs of chin shields elongate, second pair not meeting in midline; preocular 1/1, located on antero-upper part of eye; postoculars 2/2, lowermost smaller, bordering anterior temporals; anterior temporal 1/1, in contact with sixth supralabial; posterior temporals 3/3, upper one thinner than lower one. Left maxilla arched, with an angular apex, distinctly bent inwards anteriorly. A total of 13 maxillary teeth or teeth alveola, with the following formula: five small anterior teeth, slightly enlarged posteriorly + three strongly enlarged teeth, thick, and not much curved + a distinctly wide gap + three small teeth + a small gap + two enlarged posterior teeth.

Body elongate, TL 591 mm; SVL 467 mm; TaL 124 mm; preventral 1, ventrals 218, from behind neck region distinctly notched laterally; subcaudals 90, paired; precloacal plate single; DSR 17-17-15, all smooth; the vertebral scales not enlarged.

Coloration in preservative: Dorsal surface of head and neck with pigmentation, paler on lateral side of head, the lower part of supralabials yellowish cream, speckled with pale brownish blotches. Body brownish black, light body bands beginning after 1.5 times the head length behind the head, in total 29 transverse light bands on body and 14 light bands on tail; the first four body bands yellowish cream, and distinctly widened towards the venter, increased in size posteriorly; a dark mottling in the vertebral region more prominent posteriorly; the subsequent light body bands with two distinct indentations on each side, fused in the middle in the last third of the body.

Ventral surface of head and neck yellowish cream, belly cream and greyish cream in the last third part of body and on lower tail surface; the dark dorsal bands in part extending towards the venter, forming complete dark bands around the posterior body and on the tail; lateral side of the head cream below, with the lighter pattern beginning in the supralabial region; tip of lower jaw and infralabial region in part greyish brown; dorsal surface of the head and upper head sides a bit paler than the remaining head dorsum.

Variation of the new specimens: The Chinese specimen (CIB 115609) largely matches the morphological data of the original description of Lycodon pictus, except for having (1) a slightly shorter tail, TaL/TL 0.210 vs 0.215 in the single female paratype; (2) fewer infralabials 9/10 vs 10; (3) fewer anterior temporals 1 vs 2; however, Janssen et al. (2019) already documented the condition “2*” each for one side of both paratypes, meaning two anterior temporals with the lowermost not touching the postocular, thus referred to as posterior temporal herein, resulting in only one anterior temporal in afore mentioned cases in the type series already.

The Vietnamese specimen (VNMN011227) generally agrees with the morphological data of the original description of Lycodon pictus, except for having (1) a slightly longer tail, TaL/TL 0.219 vs 0.211 to 0.215 in the single juvenile and the single female from the type series for which TaL/TL ratio was available, (2) slightly fewer maxillary teeth (12 vs 13 or 14) and (3) fewer subcaudals 85 vs 90 or 91.

Both specimens showed more bands on the tail; 14 dark bands in CIB 115609 and 15 dark bands in VNMN011227 (vs 9 and 13); 14 light bands in CIB 115609 and 16 light bands in VNMN011227 (vs 9+ and 13).

Extended diagnosis: Lycodon pictus can be differentiated from its congeners by the following morphological characters: dorsal scales in 17–17–15 rows, all smooth; supralabials eight (rarely nine); infralabials ten (rarely nine); one elongated loreal on each side, either in contact with the eye or separated from it; precloacal plate single; ventral scales 212-218 (plus one or two preventral scales); subcaudals 85-91; a total length of 597+ mm in males and 543-591 mm in females; tail / total length ratio 0.210 -0.219 in females; maxillary teeth 12 to 14; dorsal surface of body with 28 or 29 light body bands; dorsal surface of tail with 9 to 15 dark bands, and 13 to 16 cream bands forming a distinct blotch in the vertebral region; ventral surface of body and tail mostly cream with the dark body bands in part extending towards the venter, sometimes forming complete dark bands around the body.

Distribution: Lycodon pictus is currently known from the type locality in Cao Bang Province, northern Vietnam and Longzhou County in Guangxi, southern China (Fig. 4).

Etymology: The specific name of the species, “ pictus ”, meaning painted or decorated in Latin, refers to the unique dorsal color pattern of this species (Janssen et al., 2019). Because this species is herein reported as a new member of the Chinese snake fauna, we suggest “Jin Bai Huan She (DZ白ẇffi)” as its Chinese common name, deriving from its scientific name.

Natural history: Lycodon pictus inhabits karst environment in between elevations of 233 m (Nonggang, Guangxi, China, this study, Fig. 5) and 701 m a.s.l. (type locality; Janssen et al., 2019). In southern China, the species was found at night between 00:00 and 1:00 am after light rain, active in a drainage ditch along a forest path, covered with dead leaves. The surrounding habitat was secondary karst forest, consisting of short hardwood, shrubs and vines. The snake did not attempt to bite when it was handled, neither aggressive nor defensive behavior was observed. In terms of the herpetofauna, several other amphibians and reptiles were observed during the survey period in 2019 in the same microhabitat, including Kurixalus odontotarsus (Ye & Fei in Ye et al., 1993), Rhacophorus kio (Ohler & Delorme, 2006), Draco maculatus (Gray, 1845), Acanthosaura lepidogaster (Cuvier, 1829), Goniurosaurus luii Grismer, Viets & Boyle, 1999, and Psammodynastes pulverulentus (Boie, 1827).