Lycodon yunnanensis ( Werner, 1922 ), 2024

Lycodon yunnanensis ( Werner, 1922) View in CoL comb. nov.

( Table 1 View TABLE 1 ; Figs. 2 View FIGURE 2 , 6–8 View FIGURE 6 View FIGURE 7 View FIGURE 8 )

Dinodon yunnanensis Werner 1922: 221 View in CoL

— Holotype: NHMW 23417 ; adult female from Yunnanfu , now Kunming City, Yunnan Province, China collected by H. Handel-Mazzetti.

Dinodon yunnanensis View in CoL — Zhao & Adler (1993: 246, in part); Zhao et al. (1998: 180, in part); Zhao (2006: 216, in part); Zhang et al. (2011: 67, in part), Vogel & Luo (2011: 35, 37, 40, in part); Vogel & David (2019: 522, 528, in part).

Lycodon fasciatus View in CoL (non Lycodon fasciatus Anderson, 1879 View in CoL )— Schmidt (1927: 523); Bourret (1936: 155, in part); Pope (1929: 426, in part); Pope (1935: 188–190, in part); Zhao et al. (1998: 180–181, in part); Zhao (2006: 216, in part); Yang & Rao (2008: 298, in part); Vogel & Luo (2011: 40, in part); Zhang et al. (2011: 67); Wallach et al. (2014: 401, in part).

Ophites fasciatus View in CoL — Zhao & Adler (1993: 246, in part).

Lycodon synaptor View in CoL (non Lycodon synaptor Vogel & David, 2010 View in CoL )— Guo et al. (2013: 145, 147, 148; in part); Siler et al. (2013: 272; in part); Guo et al. (2015: 4, 168; in part); Wostl et al. (2017: 543, 544; in part); Luu et al. (2018: 263, 265, 270; in part); Janssen et al (2019: 6, 18; in part); Luu et al. (2019: 226, 271; in part); Vogel & David (2019: 516, 522, 523, 528; in part); Che et al. (2020: 284; in part); Li et al. (2020: 11; in part); Wang et al. (2020: 86, 91–93, 95, 98; in part); Wang et al. (2021: 62–86; in part); Lyu et al. (2022: 161, 162; in part); Nguyen et al. (2024: 563–581, in part).

Specimens examined (n = 16, all from Yunnan Province, China). CAS 55147 (adult male, no specified locality); KIZ 83007, NHMW 21703:2, KIZ 059341, KIZ 059915 (four adult males), NHMW 21703:2 (one subadult male) from Kunming City; ZMB 65453 (adult male) from Dali City, Dali Prefecture; MCZ 16735, MCZ 18965 (two subadult male) colleted by John Graham from Kunming City; NHMW 23417 (Holotype of Dinodon yunnanensis View in CoL ), KIZ 73009, KIZ 77004, KIZ 059340 (four adult females), NHMUK 1930.11.16.4 (one subadult female) from Kunming City ; KIZ 059916 (one subadult female) from Jianshui County, Honghe Prefecture ; KIZ 058904 (one adult female) from Jingdong County , Puer City.

Diagnosis. Medium-sized species, maximum total length 550 mm, relative tail length about 0.18–0.21; loreal present, in contact with eye; dorsal scale rows 17–17–15; 5–7 upper dorsal scale rows feebly keeled at midbody; 186–202 ventrals; 67–80 subcaudals, paired; cloacal plate undivided; 8 supralabials with 3 rd –5 th SL touching the eye; 1 preocular, 2 postoculars; temporals 2+3; dorsal crossbands narrow, whitish colored with speckled on a dark body, 20–36 crossbands on dorsum, 7–12 crossbands on tail; first dorsal crossband starting at ventrals 8–15, on the base 3–7 ventrals, width of the first crossband occupying 1.0–3.0 vertebral scales; venter with discreet bands throughout throat usually dark (based on Werner 1922 and our data).

Etymology. The specific epithet is a toponymic adjective given in reference to Yunnan Province, China. Recommended common names: Yunnan Wolf Snake (English) and Rắn khuyết Vân nam (Vietnamese).

Description of the holotype of Dinodon yunnanensis ( Fig. 2 View FIGURE 2 ). Body elongate, somewhat laterally compressed; head flattened anteriorly, well distinct from the neck; snout depressed and elongate; nostril oval, large, in the middle of the nasal. Eye moderate, with a vertically elliptic pupil.

Body size. SVL 394 mm, TaL 94 mm, TL 488 mm, ratio TaL/TL 0.193.

Body scalation. Dorsal scale rows 17–17–15; dorsal scale rows anteriorly smooth, remaining scale rows feebly keeled at midbody and posteriorly, except for the outermost row, which is always smooth; scales of the vertebral row not enlarged; no apical pits; 193 ventral scales, laterally angulate; 67 subcaudals, paired and laterally angulate; cloacal plate undivided.

Head scalation. Rostral wider than high, triangular, hardly visible from above; posterior rostral scale suture bordering internasals and forming a straight angle in dorsal profile; nasal vertically divided by a furrow below and above the nostril; nasal surrounded by the first two supralabials, rostral, internasal, prefrontal and loreal; internasals paired, anterior sutures slightly concave in dorsal profile, in contact with rostral anteriorly, nasal, and prefrontal; each internasal slightly wider than long; prefrontals paired, large, subrectangular, prefrontal shorter than frontal; each prefrontal in contact with internasals, nasals, loreal, and frontal; supraoculars paired, subrectangularly-shaped, posterior end of each scale slightly wider than anterior end; frontal small, hexagonal, shield shaped, slightly longer than wide, tapering posteriorly; parietals paired, longer than wide; loreal 1/1, subrectangular, longer than high, in contact with eye on a short height; preocular 1/1; subocular absent; postoculars 2/2, the uppermost scale slightly larger than the lowermost; temporals 2+2; supralabials 8/8, first and second in contact with nasal, second and third in contact with loreal, third and fifth in contact with eye, sixth supralabial largest; infralabials 9/9, first to four in contact with the anterior pair of chin shields; mental subtriangular in ventral profile, longer than wide; posterior chin shields equal in size relative to anterior shields.

Coloration in preservation. Body and tail dark blackish-brown, with 23 crossbands on body and 7 on tail, narrow and white, slight speckled; these crossbands, about 2 dorsal scale long, widen at their ventrolateral limit; the first crossband, beginning at the level of ventrals 11. The head is uniformly blackish-brown; the underside of the head is dark in the anterior half and cream in the posterior one; the throat is cream, with a dark cloudy spot on the preventrals and the first ventral. The venter is dark, with faint cream bands rather regular, 2 ventrals wide and with 3–4 ventrals in between; within these crossbands some ventrals are dark on one half and cream on the other, especially in the posterior part of the body.

Variation (see Table 1 View TABLE 1 and Figs. 2 View FIGURE 2 , 6–8 View FIGURE 6 View FIGURE 7 View FIGURE 8 for the details). The longest known specimen is 698 mm long (male; SVL 550 mm, TaL 148 mm; KIZ 83007). The longest known female is 663 mm long (SVL 525 mm, TaL 138 mm; KIZ 77004). Ratio TaL/TL 0.18–0.21 (males: 0.20–0.21 [avg. 0.21], females: 0.18–0.21 [avg. 0.19]).

Body scalation. 17 (rarely 19)–17–15 DSR; 186–195 VEN, without sexual dimorphism; 67–80 SC, without sexual dimorphism.

Head scalation. SL 8, IL 8 (rarely 9 or 10); loreal touching the eye; preocular present, rarely absent (1/ 16 specimens); temporals 2+3, rarely 2+2 (3/ 16 specimens).

Dentition. Based on three specimens (CAS 55147 and ZMB 65453): a total of 10 maxillary teeth, with the following formula: 5 small anterior teeth + 2 strongly enlarged teeth + a wide gap + 2 small teeth + a small gap + 2 strongly enlarged, posterior teeth.

Main characters of pattern. The dorsum is dark blackish-brown with 20–36 crossbands on the body and 7–12 crossbands on the tail; crossbands whitish colored with speckled; body crossbands approximately 1–3 dorsal scales wide along the vertebral scale row, the first one starting at ventral scale 8–15. On the neck an inverted V shaped pink marking. The head is uniformly blackish-brown; when present (sometimes absent), a broad nuchal collar extends from the 6 th and 7 th supralabial across the lower posterior temporal across the posterior half of the parietals. The venter is dark brown, with faint cream bands rather regular; within these crossbands some ventrals are dark on one half and cream on the other, especially in the posterior part of the body.

Comparisons. Lycodon yunnanensis comb. nov. is morphologically and phylogenetically placed within the Lycodon fasciatus group (e.g. Nguyen et al. 2024a; and this study see Fig. 5 View FIGURE 5 ) and is overall most similar to other species from the Lycodon fasciatus group, of which we gave the list of included species above. Therefore, the comparisons with these 15 species appear to be the most pertinent. The main diagnostic characters separating Lycodon yunnanensis from these 15 species are summarized in Table 2 View TABLE 2 .

Lycodon yunnanensis comb. nov. is distinguished from L. butleri by having: slightly smaller maximum size in male (max SVL 550 mm vs. 648 mm); lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190– 195 [avg. 192.9] in females vs. 216–227 [avg. 223.0] in males, 221–228 [avg. 224.5] in females); lower number of SC in both sexes (74–80 [avg. 76.8] in males, 67–77 [avg. 71.6] in females vs. 81–97 [avg. 90.5] in males, 88–92 [avg. 90.5] in females); lower number of TB in both sexes (8–12 [avg. 10.3] in males, 7–11 [avg. 8.4] in females vs. 14–25 [avg. 19.8] in males, 15–23 [avg. 18.9] in females).

Lycodon yunnanensis comb. nov. is distinguished from L. davidi by having: lower number of VEN in males (186–202 [avg. 194.4] vs. 224); lower number of SC in males (74–80 [avg. 76.8] vs. 99); lower number BB in males (22–36 [avg. 26.6] vs. 84); lower number of TB in males (8–12 [avg. 10.3] vs. 38); bands on venter present (vs. absent); loreal touching the eye (vs. not touching).

Lycodon yunnanensis comb. nov. is distinguished from L. cavernicolus by having: lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190–195 [avg. 192.9] in females vs. 245 in male, 232 in female); lower number of SC in both sexes (74–80 [avg. 76.8] in males, 67–77 [avg. 71.6] in females vs. 113 in male, 92 in female); lower number of BB in both sexes (22–36 [avg. 26.6] in males, 20–25 [avg. 23.0] in females vs. 45 in male, 36 in female); lower number of TB in both sexes (8–12 [avg. 10.3] in males, 7–11 [avg. 8.4] in females vs. 41 in male, 29 in female)

Lycodon yunnanensis comb. nov. is distinguished from L. gammiei by having: smaller size in females (max SVL 525 mm vs. 1.110 mm); lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190–195 [avg. 192.9] in females vs. 205–217 [avg. 211.0] in males, 205–208 [avg. 216.1] in females); lower number of SC in both sexes (74–80 [avg. 76.8] in males, 67–77 [avg. 71.6] in females vs. 101–110 [avg. 105.5] in males, 101–112 [avg. 107.0] in females); lower number of BB in both sexes (22–36 [avg. 26.6] in males, 20–25 [avg. 23.0] in females vs. 42–57 [avg. 49.5] in females, 43–58 [avg. 49.9] in females); lower number of TB in both sexes (8–12 [avg. 10.3] in males, 7–11 [avg. 8.4] in females vs. 18–23 [avg. 20.5] in males, 16–21 [avg. 18.8] females); colour of crossbands (whitish vs. yellow); loreal touching the eye (vs. not touching).

Lycodon yunnanensis comb. nov. is distinguished from L. gongshan by having: smaller maximum size in both sexes (max SVL 550 mm in males, 525 mm in females vs. 740 mm in males, 798 mm in females); lower ratio TaL/TL in females (0.18–0.21 [avg. 0.19] vs. 0.22–0.23 [avg. 0.22]; lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190–195 [avg. 192.9] in females vs. 203–216 [avg. 210.3] in males, 210–215 [avg. 212.0] in females); lower number of SC in both sexes (74–80 [avg. 76.8] in males, 67–77 [avg. 71.6] in females vs. 79–96 [avg. 85.7] in males, 92–94 [avg. 93.0] in females); lower number of BB in both sexes (22–36 [avg. 26.6] in males, 20–25 [avg. 26.6] in females vs. 26–46 [avg. 36.4] in males, 32–36 [avg. 34.3] in females); lower number of TB in females (7–11 [avg. 8.4] vs. 12–15 [avg. 14.0]).

Lycodon yunnanensis comb. nov. is distinguished from L. liuchengchaoi by having: slight smaller maximum size in both sexes (max SVL 550 mm in males, 525 mm in females vs. 676 mm in males, 670 mm in females); slight lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190–195 [avg. 192.9] in females vs. 202–204 [avg. 203.0] in males, 200–228 [avg. 207.3] in males); lower number of BB in males (22–36 [avg. 26.6] vs. 40–45 [avg. 43.3]; colour of crossbands (cream vs. yellow).

Lycodon yunnanensis comb. nov. is distinguished from L. multifasciatus by having: lower ratio TaL/TL in both sexes (0.20–0.21 [avg. 0.21] in males, 0.18–0.21 [avg. 0.19] in females vs. 0.24 in males, 0.23–0.26 [avg. 0.25] in females); lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190–195 [avg. 192.9] in females vs. 237 in male, 227–232 [avg. 229.8] in males); lower number of SC in both sexes (74–80 [avg. 76.8] in males, 67–77 [avg. 71.6] in females vs. 117 in males, 106–108 [avg. 107.0] in females); lower number of BB in both sexes (22–36 [avg. 26.6] in males, 20–25 [avg. 23.0] in females vs. 72 in male, 51–60 [avg. 56.8] in females); lower number of TB in both sexes (8–12 [avg. 10.3] in males, 7–11 [avg. 8.4] in females vs. 35 in male, 25–32 [avg. 28.7] in females); ventral pattern (banded vs. uniform); loreal touching the eye (vs. not touching).

Lycodon yunnanensis comb. nov. is distinguished from L. multizonatus by having: higher ratio TaL/TL in males (0.20–0.21 [avg. 0.21] vs. 0.16–0.18 [avg. 0.17]); higher number of SC in males (74–80 [avg. 76.8] vs. 56–75 [avg. 65.5]); lower number of BB in males (22–36 [avg. 26.6] vs. 55–62 [57.8]); cloacal plate (undivided vs. divided); ventral pattern (banded vs. uniform); colour of crossbands (cream vs. pink).

Lycodon yunnanensis comb. nov. is distinguished from L. obvelatus by having: slight higher ratio TaL/TL in males (0.20–0.21 [avg. 0.21] vs. 0.19); slight lower number of TB in males (8–12 [avg. 10.3] vs. 13); dorsal scales keeled (vs. smooth); ventral pattern (banded vs. uniform); colour of crossbands (cream vs. salmon).

Lycodon yunnanensis comb. nov. is distinguished from L. pictus by having: lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190–195 [avg. 192.9] in females vs. 209–215 [avg. 212.0] in males, 213–218 [avg. 215.0] in females); lower number of SC in both sexes (74–80 [avg. 76.8] in males, 67–77 [avg. 71.6] in females vs. 82–90 [avg. 86.8] in female, 85–91 [avg. 89.0] in females); dorsal scales keeled (vs. smooth); ventral pattern (banded vs. uniform).

Lycodon yunnanensis comb. nov. is distinguished from L. ruhstrati abditus by having: smaller maximum size in both sexes (max SVL 550 mm in males, 525 mm in females vs. 761 mm in males, 762 mm in females); lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190–195 [avg. 192.9] in females vs. 206–224 [avg. 217.2] in males, 220–229 [avg. 224.2] in females); lower number of SC in both sexes (74–80 [avg. 76.8] in males, 67–77 [avg. 71.6] in females vs. 85–102 [avg. 93.9] in males, 82–106 [avg. 97.1] in females); lower number of BB in males (22–36 [avg. 26.6] vs. 31–46 [avg. 36.9]; lower number of TB in males (8–12 [avg. 10.3] vs. 14–23 [avg. 16.7]); loreal touching the eye (vs. not touching).

Lycodon yunnanensis comb. nov. is distinguished from L. ruhstrati ruhstrati by having: smaller maximum size in both sexes (max SVL 550 mm in males, 525 mm in females vs. 810 mm in males, 672 mm in females); slight lower ratio TaL/TL in both sexes (0.20–0.21 [avg. 0.21] in males, 0.18–0.21 [avg. 0.19] in females vs. 0.22–0.25 [avg. 0.23] in males, 0.21–0.24 [avg. 0.23] in females); lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190–195 [avg. 192.9] in females vs. 211–228 [avg. 217.7] in males, 216–228 [avg. 220.4] in females); lower number of SC in both sexes (74–80 [avg. 76.8] in males, 67–77 [avg. 71.6] in females vs. 105–114 [avg. 107.4] in males, 97–108 [avg. 103.0] in females); lower number of BB in both sexes (22–36 [avg. 26.6] in males, 20–25 [avg. 23.0] in females vs. 37–46 [avg. 41.6] in males, 33–40 [avg. 36.4] in females]; lower number of TB in both sexes (8–12 [avg. 10.3] in males, 7–11 [avg. 8.4] in females vs. 16–25 [avg. 21.3] in males, 14–22 [avg. 18.5] in females); loreal touching the eye (vs. not touching).

Lycodon yunnanensis comb. nov. is distinguished from L. serratus by having: lower ratio TaL/TL in males (0.20–0.21 [avg. 0.21] vs. 0.24); lower number of SC in males (74–80 [avg. 76.8] vs. 84); lower number of BB in males (22–36 [avg. 26.6] vs. 66]; lower number of TB in males (8–12 [avg. 10.3] vs. 26); dorsal scales keeled (vs. smooth); colour of crossbands (whitish vs. tawny olive); ventral pattern (banded vs. uniform).

Lycodon yunnanensis comb. nov. is distinguished from L. sidiki by having: smaller maximum size in males (max SVL 550 mm vs. 650 mm); slight lower ratio TaL/TL in males (0.20–0.21 [avg. 0.21] vs. 0.21–0.24 [avg. 0.23]); lower number of VEN in females (190–195 [avg. 192.9] vs. 207–212 [avg. 209.8] in females); slight lower number of SC in both sexes (74–80 [avg. 76.8] in males, 67–77 [avg. 71.6] in females vs. 80–91 [avg. 84.8] in males, 77–84 [avg. 81.3] in females); slight lower number of TB in males (8–12 [avg. 10.3] vs. 13–16 [avg. 14.5].

In particular, Lycodon yunnanensis comb. nov. is distinguished from the morphologically similar L. fasciatus by having: smaller maximum size in both sexes (max SVL 550 mm in males, 525 mm in females vs. 706 mm in males, 604 mm in females); lower number of VEN in both sexes (186–202 [avg. 194.4] in males, 190–195 [avg. 192.9] in females vs. 197–213 [avg. 203.8] in males, 201–214 [avg. 208.0] in females); lower number of SC in females (67–77 [avg. 71.6] vs. 74–90 [avg. 80.8]); lower number of BB in females (20–25 [avg. 23.0] vs. 26–37 [avg. 32.5]; slight lower number of TB in both sexes (8–12 [avg. 10.3] in males, 7–11 [avg. 8.4] in females vs. 10–20 [avg. 16.0] in males; 10–18 [avg. 15.3] in females); crossbands narrow and whitish without speckled (vs. slight whider and brown or grayish-brown with speckled); dorsum dark blackish-brown (vs. slight blackish-brown), throat usually dark (vs. usually light) ( Fig. 9 View FIGURE 9 ).

Finally, Lycodon yunnanensis comb. nov. is distinguished from the morphologically similar L. synaptor by having: larger maximum size in females (max SVL 550 mm vs. 395 mm); loreal touching the eye (vs. not touching); lower number of VEN in females (190–195 [avg. 192.9] vs. 201–203 [avg. 202.2]; lower number of BB in females (20–25 [avg. 23.0] vs. 30–31 [avg. 30.5]; dorsal crossbands whitish colored with speckled (vs. unspeckled); slight higher number of FB in females (9–15 [avg. 11.6] vs. 5–9 [avg. 7.0]); slight higher number of BaB in females (4–6 [avg. 4.9] vs. 3); slight higher number of BV in females (1.5–2.5 [avg. 1.9] vs. 0.5–1.0 [avg. 0.8]).

Distribution ( Fig View FIGURE 10 . 10). Currently, Lycodon yunnanensis is known from the central, western, and southern regions of Yunnan Province (Kunming City, Chuxiong City, Jingdong County, Lincang City, Dali City, Yuxi City, Mengzi City, Jianshui County, and Jinping County), possibly in Guangxi Autonomous Region (Darongshan NP) and Guangdong Province (Dawuling NR) of China, as well as in northern Vietnam (Sa Pa District in Lao Cai Province and possibly in Phia Oac-Phia Den NP in Cao Bang Province), based on data from Vogel & David (2010), Vogel & Luo (2011), Zhang & Rao (2008), Che et al. (2020), Li et al. (2020), Wang et al. 2021, Wu et al. (2023), and our data. Given its geographic proximity, its occurrence in several secondary and evergreen forests of Southern China as well as of northern Vietnam and northern Laos is anticipated.

Natural history notes and conservation status. Prior to this study, the biological data of Lycodon yunnanensis were very limited. This species is distributed to an altitude of 2,005 – 2,090 m asl. in Kuming City, Yunan Province, China (S.Y. Zhang and Y.S. Xiao pers. comm.).It is a terrestrial and nocturnal species closely associated with secondary forest and evergreen forest. The species is often seen on the road or on the side of the road at night, a species of genus Scincella Mittleman ( Scincidae ) is usually sympatric with this species, and it is presumed that this species feeds on small skinks, more ecological information of this species is still missing. Lycodon yunnanensis is distributed over a large area including many protected areas. The species appears to be quite uncommon in its native regions. The main threats to this species are habitat loss and degradation or are occasionally the victims of misidentifications venomous krait snakes (such as B. multicinctus Blyth , B. wanghaotingi Pope ) and are needlessly killed. Across its range, the species seems to not be common. We tentatively suggest Lycodon yunnanensis be considered a Least Concern (LC) species, following the IUCN’s Red List Categories ( IUCN Standards and Petitions Committee 2024).