Lycodon namdongensis, Luu & Ziegler & Ha & Le & Hoang, 2019

Luu, Vinh Quang, Ziegler, Thomas, Ha, Nghia Van, Le, Minh Duc & Hoang, Tuoi Thi, 2019, A new species of Lycodon Boie, 1826 (Serpentes: Colubridae) from Thanh Hoa Province, Vietnam, Zootaxa 4586 (2), pp. 261-277 : 267-271

Lycodon namdongensis sp. nov.

Figs. 2 ¯4

Holotype: VNUF R.2017.23 (field number: TT 17.23), adult male, collected on 13 June 2017 by Vinh Quang Luu, Nghia Van Ha, Oanh Van Lo, and Ngoan Van Ha in the karst forest, Nam Dong Nature Reserve , Quan Son District, Thanh Hoa Province, Vietnam (20°18.298’N; 104°54.776’E, at an elevation of 616 m a.s.l.)

Diagnosis: Lycodon namdongensis sp. nov is characterized by the following morphological characters: dorsal scales in 17¯17¯15 rows, all smooth; supralabials 8; infralabials 10; one large loreal on each side, separated from the eye; cloacal plate single; ventral scales 218 (plus two preventral scales); subcaudals 85; a total length of 723 mm in the single male; tail / total length ratio 0.205; dorsal head pattern whitish grey; dorsal surface of body with 23 narrowed greyish cream bands; dorsal surface of tail with 14 cream bands; ventral surface of body mostly cream with a few dark spots posteriorly; ventral surface of tail dark grey.

Description of the holotype: Head elongate (HL 20.4 mm), moderately distinct from the neck, longer than wide (HW/HL ratio 0.54), depressed (HH/HL ratio 0.40), narrow anteriorly (IN/IO ratio 0.68); snout elongate (SnL/HL ratio 0.33); nostril lateral, oval shaped, located in the middle of the nasal; eye large (ED/HL ratio 0.13), pupils vertically elliptic; rostral triangular, much broader than high, hardly visible from above; nasal divided into two scales by a vertical ridge along posterior edge of nostril; two square internasals, as wide as long, bordered by two large, subpentagonal prefrontals posteriorly; frontal single, enlarged, pentagonal, narrow posteriorly; parietals longer than wide, in contact with each other medially, with upper anterior and posterior temporals, paraparietal laterally and three nuchal scales posteriorly; loreal 1/1 (on the left side the normal sized loreal posteriorly is followed by an additional, very tiny one), elongate, not entering orbit; supralabials 8/8, first and second in contact with nasal, only fifth entering orbit on left side, and third to fifth entering orbit on right side, sixth largest; infralabials 10/10, first pair in broad contact with each other, first to fifth in contact with anterior chin shields; anterior and posterior pairs of chin shields elongate, of about the same size and shape, separated by a medial groove, anterior pair slightly larger than the posterior; preoculars 3/1 (the lower two, tiny preoculars on the left side represent separated upper parts of supralabials 3¯4); postoculars 2/2; anterior temporals 2/2, posterior temporals 2/ 2, upper anterior ones distinctly thinner than lower ones.

Left maxilla arched, with an angulous apex, distinctly bent inwards anteriorly. A total of 12 maxillary teeth or teeth alveola, with the following formula: four small anterior teeth, with the last two ones being somewhat enlarged + two strongly enlarged teeth, thick, and not much curved + a wide gap, of about the length of the largest teeth before + three small teeth + a small gap + three posterior teeth, with the first two of them being enlarged.

Body elongate, SVL 575 mm; TaL 148 mm; TL 723 mm; ratio of tail length/total length 0.205; ventrals 218 (plus two preventrals); subcaudals 85, divided, weakly notched laterally; cloacal single; DSR 17¯17¯15; all dorsal scale rows smooth; the vertebral scales not enlarged ( Table 1 ).

Colouration in life: Head pattern whitish grey; dorsal surface of the head dark in the anterior half and slightly cream posteriorly; ventral side of the head cream, dark-grey anteriorly; dorsal surface of body dark grey with 23 narrowed greyish cream dorsal bands, each band with dark flank spots; first body band starting at ventral scale 25, one vertebral scale covered by this band, and slightly extended laterally to a width of 2–4 (mostly 2) scales; ventral surface mostly cream with a few small dark spots posteriorly; dorsal surface of tail with 14 cream bands, ventral surface of tail dark grey with irregular blotches corresponding to light crossbands, however, these bands do not form complete rings.

Hemipenis: The left hemipenis is only in part everted, hemipenis cylindrical at base, lower part smooth, upper part densely covered with spines, slightly widened.

Comparisons: Lycodon namdongensis sp. nov. can be distinguished from its closest relative L. futsingensis by having more ventral scales (218 versus 193–208), ventral pattern mostly cream with a few small dark spots posteriorly (versus speckled posteriorly), first body band starting at ventral scale 25 (versus 13–21), and first body band covered by one vertebral scale (versus 5–10) ( Vogel et al. 2009; Luu et al. 2013a; Neang et al. 2014), in concert with an uncorrected p -distance of 6.5%; from L. flavozonatus by having cloacal plate single (versus divided), dorsal scale rows being completely smooth (versus 10–12 keeled dorsal scale rows at midbody), a distinctly lower body band count (23 versus 51–78), belly pattern mostly cream with a few small dark spots (versus yellow with large black spots) ( Orlov & Ryabov 2004); from L. meridionalis by having whitish grey head pattern (versus with yellow-black marble markings), fewer ventral scales (218 versus 234–246), dorsal scale rows being completely smooth (versus distinctly keeled), dorsal pattern banded (versus blotched), fewer subcaudal scales (86 versus 98–106), ventral surface mostly cream with a few dark spots posteriorly (versus yellow with dark spots posteriorly), and fewer tail bands (14 versus 25–35) ( Bourret 1935; Orlov & Ryabov 2004; Gawor et al. 2016); from L. banksi by having a loreal not entering the orbit (versus entering the orbit), fewer ventral scales (218 versus 241), dorsal scale rows being completely smooth (versus feebly keeled), dorsal pattern banded (versus blotched) ( Luu et al. 2018); from L. rufozonatus by having a distinctly lower body band count (23 versus 44–52), having fewer dorsal scale rows at neck (17 versus 19), whitish grey dorsal head pattern (versus dark brown with yellow borders), and body bands cream with a few small dark spots laterally (versus yellow or cream, speckled posteriorly) ( Boulenger 1893; Deuve 1970); from L. semicarinatus by dorsal scale rows being completely smooth (versus keeled along anterior half), whitish grey dorsal head pattern (versus black), first and second labials dark grey (versus yellow with black sutures), and belly pattern mostly cream with a few small dark spots posteriorly (versus yellow) ( Boulenger 1893); from L. capucinus by having more ventrals (218 versus 182–211), fewer supralabials (8 versus 9–10), banded dorsal pattern (versus reticulated), cloacal single (versus divided), and more subcaudal scales (86 versus 59–74) ( Neang et al. 2014); from L. cardamomensis by having more light bands on dorsum (23 versus 12–14), fewer dorsal scale rows at neck (17 versus 19), dorsal scale rows being completely smooth (versus keeled on midbody), and more tail bands (14 versus 6–7) ( Neang et al. 2014; Do et al. 2017); from L. davidi by having dorsal scale rows being completely smooth (versus middorsal scale rows weakly keeled), slightly fewer ventrals (218 versus 224), body cross-bands greyish cream with dark spots laterally (versus pale tan brown) ( Vogel et al. 2012); from L. laoensis by having more ventrals (218 versus 169–192), more subcaudals (85 versus 60–76), fewer supralabials (8 versus 9–10), anterior chinshields slightly longer than posterior ones (versus anterior chinshields 2 to 3 times longer than posterior ones), cloacal single (versus divided) ( Vogel & David 2010; Neang et al. 2014); from L. rosozonatum by having fewer dorsal scale rows at neck and at midbody (17–17 versus 19–19, respectively), the vertebral scale row not enlarged (versus distinctly enlarged), dorsal scale rows being completely smooth (versus three to nine upper dorsal scale rows plus vertebral row weakly keeled), and fewer dorsal bands (23 versus 28–35) ( Hu et al. 1975); from Lycodon ruhstrati abditus by dorsal scale rows being completely smooth (versus three to five dorsal scale rows plus vertebral row distinctly keeled), fewer subcaudals (85 versus 90–103), first body band starting at ventral scale 25 (versus 12–17), and first body band covering one vertebral scale (versus 5–6) ( Vogel et al. 2009; Luu et al. 2013a); from L. zoosvictoriae by having more ventral scales (218 versus 213), dorsum banded (versus blotched), dorsal scale rows being completely smooth (versus weakly keeled), dorsal head whitish grey (versus dark brown), dorsal tail banded (versus blotched) ( Neang et al. 2014); from L. multifasciatus by having fewer ventral scales (218 versus 229–237), fewer subcaudals (85 versus 106–119 in males), dorsal scale rows being completely smooth (versus upper dorsal and vertebral rows keeled), tail bands (14 versus 25–42), first body band starting at ventral scale 25 (versus 7–11), and first body band covered by one vertebral scale (versus about 6) ( Maki 1931; Vogel et al. 2012); from L. ophiophagus by having more ventral scales (218 versus 211–212), fewer subcaudals (85 versus 87–90), and first body band covered by one vertebral scale (versus about 8) ( Vogel et al. 2009; Vogel et al. 2012); from L. paucifasciatus by having fewer dorsal scale rows at neck (17 versus 19), dorsal scale rows being completely smooth (versus upper rows plus vertebral row keeled), fewer subcaudals (85 versus 92 in males), first body band starting at ventral scale 25 (versus 10–15), first body band covered by one vertebral scale (versus 9.5–11), and more light tail bands (14 versus 8–11) ( Smith 1943; Vogel et al. 2009; Vogel et al. 2012; Neang et al. 2014); from L. synaptor by having more ventral scale rows (218 versus 201–203), fewer light bands on dorsum (23 versus 30–31), more subcaudals (85 versus 68–69), and dorsal scale rows being completely smooth (versus 6–7 dorsal scale rows keeled) ( Vogel & David 2010) (for more details see Table 1 ).

The new species has a loreal which is not in contact with the orbit and thus differs from the following species of the Lycodon fasciatus group which have the loreal entering the orbit: L. butleri Boulenger ; L. fasciatus ; L. subcinctus . In addition, the new species differs from L. butleri by having fewer dorsal bands (23 versus 28–37), fewer tail bands (14 versus 17–23), belly pattern mostly cream (versus banded & spotted) ( Grismer et al. 2014); from L. fasciatus by having dorsal scale rows being completely smooth (versus weakly keeled), dorsal head pattern whitish grey (versus dark), first body band starting at ventral scale 25 (versus 5–18), first body band covered by one vertebral scale (versus 3–12), ventral pattern mostly cream (versus banded) ( Vogel & David 2010; Neang et al. 2014); from L. subcinctus by the presence of a preocular scale (versus absent), having dorsal scale rows being completely smooth (versus weakly keeled), single cloacal (versus divided), and more body bands (23 versus 9–15) ( Neang et al. 2014) (for more details see Table 1 ).

Distribution: Lycodon namdongensis sp. nov. is currently known only from the type locality in the Nam Dong NR, Thanh Hoa Province, Vietnam. Distribution of the new species and other Lycodon species from Vietnam was shown in Figs. 5 and 6 .

Etymology: We name this species after its type locality, Nam Dong NR, where the new Lycodon was discovered and propose the following common names: Namdong Wolf Snake (English), Namdong Wolfszahnnatter (German), Rǻn khuyḗt nam động (Vietnamese).

Natural history: The holotype was collected at 7:54 PM, while crawling on the forest path, at an elevation of 616 m a.s.l. The surrounding habitat was shrubs in secondary karst forest ( Fig. 7 ). The humidity at the time of collection was approximately 66% and the air temperature was 28.4 o C.

Figures

FIGURE 2. Dorsal view of the holotype of Lycodon namdongensis sp. nov. (VNUF R.2017.23) in life. Photo: N. V. Ha

FIGURE 5. Map showing the records of the Lycodon fasciatus group in Vietnam (Smith 1943; Nguyen et al. 2009; Geissler et al. 2011; Orlov et al. 2011; Jestrzemski et al. 2013; Phan et al. 2014; Do et al. 2016; Vassilieva et al. 2016).

FIGURE 6. Map showing the type locality of Lycodon namdongensis sp. nov. in Thanh Hoa Province (yellow cross) and other records of the Lycodon ruhstrati group from in Vietnam (Boulenger 1893; Smith 1943; Deuve 1970; Hu et al. 1975; Ziegler et al. 2007; Nguyen et al. 2009; Vogel & David 2010; Geissler et al. 2011; Orlov et al. 2011; Neang et al. 2014; Luu et al. 2013a,b; Jestrzemski et al. 2013; Phan et al. 2014; Grismer et al. 2014; Ziegler et al. 2014; Gawor et al. 2016; Ngo & Duong 2016; Nguyen et al. 2016; Do et al. 2016; Vassilieva et al. 2016; Pham et al. 2017; Do et al. 2017; Luu et al. 2018).

FIGURE 7. Macrohabitat of Lycodon namdongensis sp. nov. at the type locality. Photo N. V. Ha