Lycodon latifasciatus, Nguyen & Lee & Jiang & Ding & Chit & Poyarkov & Vogel, 2025

Lycodon latifasciatus sp. nov.

urn:lsid:zoobank.org:act:1EBEF5EA-E5BA-4786-BB18-424D0358FFEC

( Figs. 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 , 5A–C View FIGURE 5 , 6A–B View FIGURE 6 , 7A View FIGURE 7 , Appendix Fig. S1 View FIGURE 1 ; Tables 1–3 View TABLE 1 View TABLE 2 View TABLE 3 , Appendix Table S4)

Lycodon cf. fasciatus View in CoL — Che et al. (2020: 683–87).

Lycodon sp. — Li et al. (2020: 11); Vogel et al. (2024: 120).

Lycodon sp. 2 — Wu et al. (2023: in Appendix).

Holotype. CAS 245367 About CAS (adult male) from Laung Nguk Village , Lahe Township, Khandi District, Sagaing Region, Myanmar (26.159833°N, 95.522527°E; altitude ca. 950 meters asl.) collected by M. Hlaing, S.L. Oo, Z.H. Aung, and Y.M. Win on 19 May 2009. GoogleMaps

Paratypes (n = 4). China: Xizang AR—CIB DL.2015.25.52 (one adult male), from Beibeng Township, Medog County collected by L. Ding; CIB DL.050 , CIB DL.053 (two adult males) from Damu Township , Medog County collected by L. Ding. Myanmar: Sagaing Region — ZMMU Re- 16728 (one adult male; field ID NAP-09559) from Zalon Taung Mt., Ban Mauk District (24.51628°N, 95.81705°E; altitude 660 meters asl.) collected by N.A. Poyarkov, P. Pawangkhanant, V.A. Gorin, and May Thu Chit on 02 August 2019 GoogleMaps .

Referred specimens (n = 2). China: Xizang AR — CIB. DL.2015.122.51 (subadult male), from Beibeng Township , Medog County collected by L. Ding. Myanmar: Sagaing Region — ZMMU Re-16729 (immature female; field ID NAP-09560) same collection data as ZMMU Re-16728 specimen GoogleMaps .

Diagnosis. A medium-sized species of Lycodon with a maximum total length of 871 mm; relative tail length 0.21–0.23; dorsal scale rows 17–17–15, first 5–9 upper dorsal scale rows keeled at midbody, remaining rows smooth; ventrals 206–216; subcaudals 90–96, paired; cloacal plate undivided; supralabials usually eight (rarely nine) with third to fifth scales in contact with eye; infralabials eight or nine (rarely seven), the first five (rarely four) in contact with anterior chin shields; preocular 1/1, blocking prefrontals from contacting eye; loreal usually in narrow contact with eye; postoculars 2/2; temporals 2+2 (rarely 2+3). Dorsum dark brown in life with 29–36 orange or orange brown light body crossbands and 13–21 tail crossbands; first light crossband starting between ventrals 4–11, 5–8 ventral scales long at base and 2–4 vertebral dorsal scales long; in life, head dark brown in adults, white spots present across most supralabials, underside of head white, scale sutures of chin and throat with dark brown mottling; venter with discrete light and dark crossbands, small irregular spots prevalent posteriorly.

Description of holotype ( Fig. 3 View FIGURE 3 ). Specimen CAS 245367 in excellent condition, small ventral incision at midbody; right and left hemipenis both partially everted, but right organ more fully prepared than left ( Fig. 7A View FIGURE 7 ). Body elongate, laterally compressed. Tail gracile, tapering to a blunt and enlarged terminal scute. Head ovate in dorsal profile, distinct from neck ( Fig. 3E View FIGURE 3 ); temporal and parietal region slightly raised in lateral profile; snout relatively elongate, depressed downwards, upper jaw projecting further than lower jaw, no distinct canthus rostralis ( Fig. 3C–D View FIGURE 3 ). Nostrils round, circular, positioned medially within nasal. Eyes moderate relative to head; pupil elliptical, vertical.

Measurements. SVL 680 mm, TaL 191 mm, TL 871 mm, TaL/TL ratio 0.22, HeadL 18.8 mm, HeadW 11.0 mm, SnL 5.5 mm, SnW 3.8 mm, EyeD 2.5 mm, FrontalL 4.7 mm, FrontalW 4.4 mm, InterorbD 5.6 mm.

Body scalation. Dorsal scales arranged in 17-17-15 rows; all dorsal scales smooth anteriorly, keeled at midbody and posteriorly except for the first four outermost rows on either side at midbody and the two outermost rows posteriorly, which are smooth; vertebral row of dorsal scales not enlarged; apical pits absent. Ventral scales 216, laterally angulate, forming a slight keel; subcaudals 96, paired, laterally angulate; total body scales 313; subcaudal ratio 0.31; cloacal plate undivided.

Head scalation. Rostral subtriangular, wider than high, barely visible from above, its posterior edge bordering internasals forming a broad ‘gull-wing’ shaped obtuse angle (~147º) ( Fig. 3E View FIGURE 3 ). Nasals vertically divided by indistinct suture above and below nostril, longer than high, in contact with internasal, loreal, prefrontal, rostral and first two supralabials. Each portion of nasal subhexagonal, anterior portion slightly smaller than posterior. Internasals paired, rectangular, anterior edges concave, 1.5 times wider than length of entire scale, 1.9 times wider than medial suture, each scale in contact with rostral, nasal and prefrontal. Prefrontals paired, 3.9 times larger than internasals, subrectangular, anterior edges straightened, 1.2 times longer than wide, medial suture 1.1 times longer than wide and 3.0 times longer than internasal suture, each prefrontal contacting internasals, nasals, loreal, and frontal. Supraoculars paired, subrectangular, posterior suture straightened, anterior suture concave, 1.5 times longer than wide, posterior edge 2.2 times wider than anterior edge, each supraocular in contact with upper preocular, upper postocular, frontal and parietal. Frontal small, hexagonal and shield shaped, 1.6 times longer than prefrontal suture, 1.1 times longer than wide; anterior edge of frontal straightened, positioned in-line with eyes in dorsal profile; posterior vertex of frontal bordering parietals acute angled (~81º). Parietals paired, subpentagonal, entire scale 1.9 times longer than wide, medial suture 1.1 times longer than wide and 1.1 times shorter than frontal; anterior edge of parietal straightened, its suture with frontal and supraoculars obtuse angled and directed laterally (~121º). A total of 11 scales behind the upper postoculars surround both parietals. Loreal 1/1, subrectangular, roughly 2.4 times longer than high, in narrow contact with eye on either side. Preocular 1/1, vertical and subrectangular. Presubocular and subocular scales absent. Postoculars 2/2, vertical and subrectangular, bottommost scale slightly larger. Temporals 2+2, lowermost anterior temporal largest. A single slightly enlarged paraparietal scale present behind posterior temporal row, each surrounded by 6/6 scales with 3/3 scales positioned immediately below. Supralabials 8/8, the first and second in contact with nasal, second and third in contact with loreal, third to fifth in contact with eye; sixth supralabial largest, first supralabial smallest. Infralabials 9/9, first to fifth in contact with anterior chin shields, fifth and sixth contacting posterior chin shields. Mental subtriangular, 1.8 times wider than long. Posterior chin shields roughly same length as anterior shields. Gular scales 3/3 (excluding two preventrals) behind posterior row of chin shields.

Color of holotype in preservative. After 15 years in preservative, dorsal ground color dark brown with a series of 36 light crossbands on the body and 17 on the tail ( Fig. 3A View FIGURE 3 ). First three anteriormost crossbands tan, each narrower than darker brown crossbands with inconspicuous light brown mottling within them. First light crossband starting at 7 th ventral scale, 8 ventral scales long at base, 2.5 vertebral dorsal scales long. Remaining light crossbands wider than dark bands after 7 th band, usually 4.0 vertebral dorsal scales in length, each with light brown mottling within them. Margins of dorsal crossbands tan at midbody; posteriormost crossbands with irregular, jagged edges that buffer the dark bands and cause them to narrow medially. Color of light tail crossbands same as body, except the last six bands are tan with less light brown pigmentation intruding inside. Head dark brown, mostly plain, edges of loreal, prefrontals and temporals with subdued light brown mottling. Light brown, indistinct mottling on rostral and anterior edges of internasals. A very subdued “Y” shaped nuchal collar present in parietal region ( Fig. 3E View FIGURE 3 ), starting medially from the parietal suture, bifurcating posteriorly along the temporals and paraparietal before expanding posterolaterally to the nape. Bottommost half of nasal and first supralabial light brown. Bottom halves of supralabials 2–7 with distinct tan spots, rounded in shape. Underside of head tan, mental and infralabial sutures dark brown. Throat tan, plain, gular scales with scattered dark brown pigment along their edges. Ventral surface with alternating series of dark brown and tan colored bands, all rectangular in shape ( Fig. 3B View FIGURE 3 ). Anteriorly, first three dark ventral bands are extremely diffuse, present only as small dark brown spots, whereas the remaining dark bands are bold. Posteriorly, ventral bands begin to intrude into each other along the ventral scales, occasionally forming irregular dark brown spots. Each dark ventral band 2–3 ventral scales wide, light bands 3–5 ventral scales wide. Arrangement and color of bands on tail underside same as posterior ventral surface. Color of holotype in life unknown.

General description and variation (see Table 1 View TABLE 1 and Figs.: 4, 5A–C, 6A–B, 7A). Based on seven specimens (including holotype and paratypes). The holotype (adult male) is the longest specimen in terms of total length (TL 871 mm). The longest female is 670 mm long (SVL 513 mm, TaL 157 mm; CIB DL.053). Ratio TaL/TL 0.21– 0.23 (x̄ = 0.219±0.009; n = 8). In general habitus like holotype, elongate overall (Appendix Fig. S1 View FIGURE 1 ). Tail gracile, terminal scute blunt ended. Head ovate, distinct from neck, temporal and parietal region slightly raised; snout elongate, depressed in lateral profile, no canthus rostralis. One of the paratypes (CIB DL.050) is partially crushed and as a result has a more flattened head and more rounded snout in lateral profile (Appendix Fig. S1A–B View FIGURE 1 ). Nostrils rounded, positioned medially. Eyes moderate, pupil elliptical. No sexual dimorphism was evident in body or head proportions.

Body scalation. Dorsal scales in 17-17-15 rows. Three specimens (holotype + DL.050, DL.053) have entirely keeled scales at midbody and posteriorly, except for the outermost four rows (which are smooth). In one specimen ( CIB DL.2015.25.52), only the outermost three rows are smooth. Ventral scales 206–216 (x̄ = 209.6±3.4; n = 7). Keeling along the ventral scales is highly pronounced in CIB DL.053, less distinct in the holotype and one other specimen ( CIB DL.2015.25.52) and essentially absent in CIB DL.050 and two other specimens from Myanmar ( ZMMU Re-16728–29). Subcaudal scales 90–96 (x̄ = 93.0±2.3; n = 7), paired. Total body scales 297–312 (x̄ = 302.6±5.1; n = 7). Subcaudal ratio 0.30–0.31 (x̄ = 0.307±0.004; n = 7). No body scale counts exhibited sexual dimorphism.

Dentition. In the holotype, a total of 11 maxillary teeth with the following formula: four small anterior teeth that gradually increase in size posteriorly + three enlarged teeth + four strongly enlarged, posterior teeth, each grouping of teeth separated by a diastema. Tooth counts were not taken in the paratypes or referred specimens.

Description of the hemipenis. Based on the partially everted right organ of the holotype ( Fig. 7A View FIGURE 7 ) and the description provided by Che et al. (2020, according to our translation). The hemipenis of the holotype is short, spinose, unilobed in asulcate profile, weakly bilobed in sulcate view ( Fig 7A View FIGURE 7 1–A View FIGURE 1 2 View FIGURE 2 ). Hemipenis broader distally, sulcate side slightly bulbous. Base of organ covered with small scattered spinules on asulcate and sulcate sides. Three to four rows of slightly enlarged hook shaped spines positioned above proximal third of the organ. Hook-like spines less prevalent on sulcate side, but form a distinctly raised skirt demarcating the base from the remaining hemipenial body ( Fig. 7A View FIGURE 7 2 View FIGURE 2 ). Remaining distal two-thirds of organ covered with small spinous calyces of equal size with a slightly lower number of spines apically. Sulcus spermaticus distinct, simple, arranged centripetally across hemipenis before terminating at apex with no distinct nude area; sulcus lips nude, not distinctly raised. According to Che et al. (2020), the retracted hemipenis extends to the 10 th subcaudal scale and the insertion of the retractor penis magnus begins at the 26 th subcaudal scale. The everted hemipenis is unilobed, its distal half with small spines, the medial one-fourth with larger hook-like spines, and the proximal one-fourth with sparse small spines; the sulcus spermaticus extends to the apex with well defined sulcal lips.

Head scalation. Head scalation exhibits variation relative to the holotype. Rostral wider than high, barely visible from above. Posterior suture of rostral bordering internasals forming a ‘gull-wing’ shaped obtuse angle (~147–159º). Nasals longer than high, shape varying from subpentagonal to subhexagonal, in contact with internasal, loreal, prefrontal, rostral and first two supralabials. Anterior portion of nasal smaller than posterior, each segment higher than long. Internasals paired, rectangular, anterior edges concave, 1.0–1.4 times wider than length of entire scale (equal only in ZMMU Re-16728) and 1.1–1.9 times wider than medial suture; each internasal in contact with rostral, nasal and prefrontal. Prefrontals paired, subrectangular, area 2.9–4.1 times larger than internasals, entire scale 1.1–1.3 times longer than wide, medial prefrontal suture 1.0–1.3 times longer than wide, roughly equal (1.0 times) in CIB DL.053 and ZMMU Re-16728. Each prefrontal in contact with internasals, nasals, loreal, and frontal; supraocular also contacts prefrontal in CIB DL.053 and supraocular contacts the prefrontal on the right side in CIB DL.2015.122.52. Supraoculars paired, subrectangular, 1.3–1.9 times longer than wide, posterior end of scale 1.6–3.5 times wider than anterior end. Frontal small, hexagonal, shield shaped, 1.1–1.2 times longer than wide, 1.4–1.7 times longer than prefrontal suture. Position of anterior edge of frontal variable, in-line with eyes in dorsal profile ( CAS 245367 About CAS and ZMMU Re-16728) but projected past the eyes in some specimens from Medog County ( CIB DL.50, DL.053, DL.2015.122.52), posterior vertex of frontal bordering parietals acute angled (~77– 83º). Parietals paired, entire scale 1.9–2.5 times longer than wide, medial parietal suture 1.1–1.7 times longer than wide with specimens from Myanmar ( CAS 245367 About CAS and ZMMU Re-16728–29) having a longer frontal than medial parietal suture (1.1 times longer), while specimens from Medog County have a shorter frontal (frontal 0.8–0.9 times as long). Anterior edge of parietal straightened, its suture with frontal and supraoculars forming a laterally directed obtuse angle (~118–132º); Parietals surrounded by 9–11 scales behind upper postoculars. Loreal 1/1, subrectangular, longer than high, narrowly contacting eye on either side, occasionally blocked from contacting eye in specimens from Zalon Taung ( ZMMU Re-16728–29) ( Fig. 3D View FIGURE 3 ). Preocular 1/1, vertical and subrectangular. No presubocular or subocular. Postoculars 2/2, vertical and subrectangular, bottommost scale slightly larger in most specimens, roughly equal in CIB DL.053 and DL.2015.122.52. Temporals normally 2+2, 2+ 3 in CIB DL.50, DL.53 and DL.2015.25.52, and 2+2/2+ 3 in ZMMU Re-16729, lowermost anterior temporal largest but uppermost anterior temporal longer in ZMMU Re-16728 and CIB DL.2015.122.52. Paraparietal scale behind posterior temporal row in four specimens ( CAS 245367 About CAS , ZMMU Re-16729, CIB DL.050, DL.053), present as uppermost posterior temporal in remaining specimens. Paraparietal scale always slightly enlarged, surrounded by 6–9 scales (6/ 6 in CAS 245367 About CAS and CIB DL.053, 7/ 8 in ZMMU Re-16729 and CIB DL.050, 8/ 9 in remaining specimens) and 3–5 scales positioned below them (3/ 3 in CAS 245367 About CAS , 4 About CAS / 4 in CIB DL.053, 5/ 5 in CIB DL.2015.25.52 and DL.050). Supralabials 8/ 8 in all except two specimens (8/ 9 in DL.2015.25.52 and DL.050), first and second contacting nasal, second and third contacting loreal, and third to fifth contacting eye; sixth or seventh supralabial normally largest, occasionally both scales equal in size; first supralabial smallest. Infralabials normally 9/9 (9/ 8 in CIB DL.2015.25.52; 8/ 9 in CIB DL.050 and DL.2015.122.52; 8/ 8 in ZMMU Re-16729), first to fifth infralabials in contact with anterior chin shields, fifth and sixth contacting posterior chin shields. In one specimen only four infralabials contact the anterior chin shields, with CIB DL.2015.25.52 bearing 5/4. Mental subtriangular in ventral profile, wider than long. Anterior chin shields slightly longer than or equal to size of posterior shields. Gular scales 2–3 present behind posterior chin shields; usually one preventral scale, but two present in CAS 245367 About CAS and ZMMU Re-16728.

Color in preservation: Dorsal ground color in adults dark brown, black in two specimens, including one juvenile ( ZMMU Re-16729 and CIB DL.050).A total of 29–36 light crossbands on the body (x̄ = 32.6±2.8; n = 7) and 13–21 on the tail (x̄ = 16.3±2.4; n = 7), each light body crossband expanding in width ventrolaterally. Anterior light crossbands tan or white, orange in more recently preserved specimens ( CIB DL.053 and ZMMU Re-16728–29) (Appendix Fig. S1 View FIGURE 1 ), all narrower in length than darker bands. Brown mottling within anterior crossbands prominent in holotype but limited in other specimens. First light crossband starting between ventral scale 4.0–11.0 (x̄ = 7.50±2.95; n = 7), its length 5.0–8.0 ventral scales long at base (x̄ = 6.83±1.17; n = 7) and 2.0–4.0 vertebral dorsal scales long (x̄ = 2.58±0.74; n = 7). Remaining light crossbands light brown or orange, 3–5 vertebral dorsal scales in length, their margins plain tan or white, wider than dark crossbands after 6 th to 12 th band. Small brown inconspicuous mottling occasionally present within light crossbands, but never forming spots or blotches. In immature specimen ( ZMMU Re-16728), dark crossbands narrower than in adults, each band constricted in width vertebrally and laterally. Tail crossbands same color as body bands, those closer to terminal scute less defined than those near cloaca. Color of head dark brown in most specimens ( CAS 245367 About CAS , ZMMU Re-16728, CIB DL.053), black in juveniles ( ZMMU Re-16729) and some adults ( CIB DL.050) (Appendix Fig. S1 View FIGURE 1 ). Dorsal surface of head plain, subdued light mottling present along edges of loreal, prefrontals and temporals. A small beige colored spot present on the edge of the preocular and prefrontal in two specimens ( ZMMU Re-16728 and CIB DL.053). Light brown collar present from the posterior edges of the parietals to the temporal and paraparietal region, dissipating posterolaterally along the nape, forming a “Y” shape dorsally along the parietals in the holotype or a “M” shape in two specimens from Zalon Taung ( ZMMU Re-16728–29). Nuchal collar less distinct in specimens from Medog County ( CIB DL.050, DL.053, DL.2015.122.52), present dorsally only as a diffused pair of parietal spots. Bottom halves of supralabials with distinct white or tan spots, absent on the first and last supralabial in most specimens, occasionally intruding the first supralabial and nasal ( CIB DL.050 and DL.053, ZMMU Re-16728). Underside of head and throat cream or white, edges of mental and infralabial sutures dark brown. Ventral surface dark brown with faint cream bands, plain and rectangular, the first two or three dark ventral bands indistinct and mottled on the ventral surface, remaining dark bands distinct, rectangular. Dark brown spotting present posteriorly within each band. Each dark band 2–3 ventral scales wide, light bands 3–5 scales wide. Arrangement and color of bands on the underside of tail same as posterior ventral surface, identical as the holotype.

Color in life. In life, dorsal ground color dark brown, except in juveniles (ZMMU Re-16729) where it is black. Light crossbands in adult specimens orange, color of crossbands consistent anterior and posteriorly but in some specimens the posterior crossbands become orange brown. In ZMMU Re-16728, there is a dark brown medial line present along the keels of each dorsal scale, creating a striated pattern within each crossband ( Fig. 4A View FIGURE 4 ). This pattern is also evident in some specimens from Medog County, China ( Fig. 5C View FIGURE 5 ). In juveniles (ZMMU Re-16729), the light crossbands are orange anteriorly and gradually become beige posteriorly, with very faint small dark brown mottling present in the medial portion of each crossband ( Fig. 5B View FIGURE 5 ). Dorsal surface of head dark brown, nuchal collar and snout orange or tan. Supralabial spots tan or white. Underside of head and ventral surface white, darker crossbands and mottling brown.

Etymology. The epithet “ latifasciatus ” is an adjective in nominative singular (adjusted to the masculine gender of the genus name), that combines the words “ latus ” meaning “broad”, or “wide”, and “ fascia ”, meaning “band”, in reference to the distinct dorsal coloration that putatively distinguishes this new species from other Lycodon . It is also used in reference to the close relationship the new species has to Lycodon fasciatus , a taxon bearing a similar sounding epithet and geographic distribution. We recommend the English common name “East Himalayan Banded Wolf Snake”.

Comparisons. Lycodon latifasciatus sp. nov. is assigned to the Lycodon fasciatus group (eg. Wostl et al. 2017; Janssen et al. 2019; Wang et al. 2021; Nguyen et al. 2024a; Vogel et al. 2024; this study) based on its phylogenetic position ( Fig. 2 View FIGURE 2 ). It agrees with the typical morphology of this group by having 17 dorsal scale rows at midbody with keeled scales on the vertebral and middorsal rows, the presence of a preocular scale, lack of contact between the prefrontal scale and the eye, and a dorsal and ventral color pattern consisting of light and dark crossbands ( Table 2 View TABLE 2 ). Briefly, the presence of ventral crossbands with spotting distinguishes L. latifasciatus sp. nov. from L. cavernicolus , L. gammiei , L. liuchengchaoi , L. multifasciatus , L. pictus , L. ruhstrati (including L. ruhstrati ruhstrati and L. ruhstrati abditus ), L. sidiki , and L. synaptor , which either lack ventral crossbands or have plain light ventral crossbands without any spotting present. Further, the dorsal coloration of L. latifasciatus sp. nov. in life, consisting of a brown dorsum and orange or light brown crossbands, easily distinguishes it from L. butleri , L. ruhstrati ruhstrati , L. ruhstrati abditus , L. sidiki , L. synaptor and L. yunnanensis , which have white or gray crossbands that lack orange or light brown pigment in adults and juveniles. The presence of 29–36 light body crossbands in L. latifasciatus sp. nov. also distinguishes it from L. davidi , L. multizonatus , and L. serratus , in addition to L. cavernicolus , L. ruhstrati abditus , L. gammiei and L. multifasciatus , which have 36 or more light body crossbars. Lastly, L. latifasciatus sp. nov. has a higher number of subcaudal scales than L. fasciatus , L. liuchengchaoi , L. obvelatus , in addition to L. multizonatus , L. pictus , L. serratus , L. synaptor and L. yunnanensis (90–96 scales versus less than 90 scales in compared species). Lycodon latifasciatus sp. nov. is most similar morphologically to L. fasciatus and L. gongshan , which co-occur in China and Myanmar (see Table 3 View TABLE 3 , Figs. 5–7 View FIGURE 5 View FIGURE 6 View FIGURE 7 ). As such, we provide more detailed comparisons with these species below.

From L. fasciatus (data after the versus when in parentheses), L. latifasciatus sp. nov. is distinguished by having orange or orange brown light crossbands that are consistent in coloration anteriorly and posteriorly in life (versus light crossbands variable: brown, orange brown, orange, or reddish brown; usually darkening in color posteriorly; Fig. 5D–F View FIGURE 5 ), and by differences in the degree of dark coloration on the underside of the head (dark brown mottling restricted to scale sutures on the infralabials, chin shields and gulars versus dark brown mottling continuous, engulfing first 4–5 infralabials and outer edge of anterior chin shields, rarely on gulars; see Fig. 6 View FIGURE 6 ). In addition, L. latifasciatus sp. nov. has a higher number of subcaudals (90–96 versus 74–90), a higher mean number of total body scales (297– 312 [x̄ = 302.6±5.1] versus 278–302 [x̄ = 288.9±5.7]; p <0.00001), a higher mean subcaudal ratio (0.30–0.31 [x̄ = 0.307±0.004] versus 0.26–0.30 [x̄ = 0.283±0.011]; p <0.00001), a lower mean number of infralabials (8–9, rarely 7 versus usually 9–10, rarely 8; p = 0.00062), and usually a shorter length between the first ventral scale and the first light crossband (4.0–11.0 ventrals [x̄ = 7.50±2.95] versus 5.0–18.0 ventrals [x̄ = 10.91±3.37]; p = 0.02772). The everted hemipenis in L. latifasciatus sp. nov. has smaller hook-shaped spines along the proximal third of the organ that form a distinct skirt separating the remaining distal two-thirds of hemipenial body in asulcate view ( Fig. 7A View FIGURE 7 ), whereas the proximal spines in L. fasciatus are larger and more continuous with the remaining distal two-thirds of the hemipenis in L. fasciatus ( Fig. 7B View FIGURE 7 ).

Compared to L. gongshan bearing the typical color morphotype, L. latifasciatus sp. nov. have distinct light spots on most supralabials, whereas typical L. gongshan lack conspicuous supralabial spots or have subdued light pigment on the supralabials. Dark brown pigmentation on the underside of the head in L. latifasciatus sp. nov. is restricted to the sutures of the infralabials and anterior chin shields, whereas L. gongshan (including the second morphotype) have dark black pigment engulfing the entire first three or four infrabials and anterior chin shields ( Fig. 6E–F View FIGURE 6 ). L. latifasciatus sp. nov. is further distinguished from L. gongshan by having a lower number of infralabials in contact with the anterior pair of chin shields (5/5, rarely 4/5 or 5/4 versus 4/4, rarely 4/5), usually having the supraocular separate from the prefrontal (versus supraocular and prefrontal usually in contact), a broader length between the first ventral and first light crossband (2.0–4.0 scales [x̄ = 2.58±0.74] versus 1.0–2.0 scales [x̄ = 1.14±0.38]; p = 0.00055), and a slightly higher number of tail bands (13–21 [x̄ = 16.3±2.7] versus 9–16 [x̄ = 12.9±2.8]; p = 0.02543). The second color morphotype of L. gongshan described by Huang et al. (2021) from Zayu County, Xizang AR, China is distinguished from L. latifasciatus sp. nov. by having an olive brown dorsal ground color with 67 irregularly shaped black body crossbars, conspicuous white or yellow mottling across most of the body and a speckled ventral surface with subdued black crossbands and spotting extending across the dorsal surface, concentrated midventrally.

Distribution. Currently, Lycodon latifasciatus sp. nov. is known from three localities in Northern Myanmar and Southwestern China ( Fig. 1 View FIGURE 1 , Appendix Table S4). In Myanmar it is known from the Sagaing Region (Khandi and Ban Mauk districts) and in China it is known from Xizang AR (Beibeng and Damu Townships, Medog County). Given the continuity of similar habitats in Myanmar and China, it is likely L. latifasciatus sp. nov. has a wider distribution, particularly in the Indo-Himalayan foothills of northeast India and adjacent regions of Kachin State, Myanmar. Additional localities may also be found within the lowland regions of Medog and Zayu Counties in Xizang AR, China.

Natural history. Current specimen records suggest Lycodon latifasciatus sp. nov. is terrestrial, nocturnal, and closely associated with tropical semi-deciduous forests and evergreen forests, where it has been collected between 700–1500 meters in elevation. Specimens in Xizang AR were often found on the side of roads during light rain at night ( Che et al. 2020). Lycodon latifasciatus sp. nov. was collected in sympatry with Lycodon septentrionalis Günther at all three localities where it occurs and has also been found in near-sympatry with L. gammiei in China in Beibeg Township, Medog County ( Shu et al. 2024). Records of Lycodon fasciatus do occur within close proximity of L. latifasciatus sp. nov., and like L. gongshan , this species may eventually be documented in sympatry as well.

Conservation status. Lycodon latifasciatus sp. nov. is known from three localities, of which only Zalon Taung in Myanmar is situated within a protected area, that being Zalon Taung National Forest. At the time the two specimens from that locality were collected, the forests surrounding Zalon Taung were listed as a proposed national park. This species appears quite uncommon across its native range, but whether that is due to a lack of survey effort, low densities or low detectability is uncertain. It is also unknown whether L. latifasciatus sp. nov. tolerates disturbed habitats, so the extent deforestation and other forms of habitat destruction or modification threaten this species cannot be determined. Owing to a lack of ecological data and localized geographic distribution, we suggest Lycodon latifasciatus sp. nov. should be listed as Data Deficient (DD), following the IUCN’s Red List Categories ( IUCN Standards and Petitions Committee 2024).

Remarks. We did not examine four voucher specimens corresponding to the genetic samples published by Li et al. (2020) (e.g., SYS r001822 and SYS r001829) as Lycodon sp. and Wu et al. (2023) (e.g., KIZ YPX-46120 and KIZ YPX-46121) as Lycodon sp. 2 , all originating from Medog County, Xizang AR, China. By all accounts, these samples and their specimens should be referrable to L. latifasciatus sp. nov. and we have no reason to doubt their identification based on their phylogenetic position in our study ( Fig. 2 View FIGURE 2 ).