Oligodon tuani Nguyen & Le & Vo & Murphy 2022, sp. nov.
Creators: name: Nguyen, Sang Ngoc
name: Le, Manh Van
name: Vo, Thi-Dieu-Hien
name: Murphy, Robert W.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Colubridae
Oligodon
Oligodon tuani

description: Oligodon tuani sp. nov.
(Figs. 2–4)
Holotype. ITBCZ 7899, subadult male, collected near Cam Ly Stream, Da Lat City, Lam Dong Province, Vietnam (coordinates 11°56’54”N, 108°24’60”E; elevation 1490 m a.s.l.) by Tuan Minh Nguyen on 15 September 2020 (Figs. 2 & 3).
Paratypes. ITBCZ 7944, adult male, collected on 15 October 2020 by Tuan Minh Nguyen, coordinates 11°57’36”N, 108°23’30”E, elevation 1431 m a.s.l., from Cam Ly Road, vicinity of Da Lat City, Lam Dong Province, Vietnam; ITBCZ 7868, subadult female, collected on 12 September 2020 by Tuan Minh Nguyen, coordinates 12°01’02”N, 108°29’28”E; elevation 1520 m a.s.l., from Da Sar, Lac Duong District, vicinity of Da Lat City, Lam Dong Province, Vietnam; and ITBCZ 8215, adult female, collected from Ward no. 10, Dalat City, Lam Dong Province, Vietnam, coordinates 11°55’56”N, 108°26’58”E, elevation 1440 m a.s.l., on 24 March 2022 by Tuan Minh Nguyen (Fig. 4).
Diagnosis. Oligodon tuani sp. nov. can be distinguished from its congeners by a combination of the following morphological characters: (1) large size in adults (TL ≤ 888 mm); (2) 19 dorsal scale rows at neck and midbody and 15 rows before vent; (3) TaL/TL ratio 0.184 in adult male and 0.123 in adult female; (4) ventrals 173–179 in males and 187–193 in females; (5) subcaudals 58 or 59 in males and 44 or 45 in females; (6) presubocular present; (7) 8 supralabials, fourth and fifth entering orbit; (8) cloacal plate undivided; (9) 10 maxillary teeth, posterior three enlarged; (10) vertebral stripe present; (11) temporal streak present but faint and interrupted; (12) long and deeply forked hemipenes, extending to 25 th subcaudal, without spines and papillae but with small and transversal folds and distal calyces; and (13) 13–15+3–4 dorsal blotches.
Description of holotype. Subadult male, total length 585 mm; head ovoid, faintly distinct from the poorly defined neck; body robust and rather elongate; SVL 475 mm; tail quite long (TaL/TL = 0.188), 110 mm in length; eye small with round pupil, eye diameter about half of snout length.
Head scalation. Rostral thick, triangular and curved on to upper snout surface, visible from above, pointed posteriorly, touching internasals, nasals and first supralabial on both sides; the portion of rostral visible from above shorter than its distance from frontal; supralabials 8/8, the 4 th and 5 th bordering eye; 1/1 loreal; 1/1 presubocular; 1/1 preocular; 2/2 postoculars; nasal divided vertically; 2+2/2+2 temporals, anterior ones elongated; prefrontal wider than long and larger than internasal; frontal large and hexagonal, slightly longer than wide (5.7 mm vs. 4.5 mm); parietals larger than the frontal, bordered laterally by the upper temporals and anteriorly by frontal, supraoculars and postoculars; 9/9 infralabials, first pair medially in contact with each other, first four in contact with anterior chin shield, the 5 th largest and touching posterior chin shield; two pairs of gular scales between posterior chin shields and preventral scale.
Body scalation. Dorsal scales smooth, in 19–19–15 rows; scale row reductions from 19 to 17 at ventrals 97 and 98 and from 17 to 15 at ventrals 124 and 132; vertebral scales similar to other dorsal scales in size and shape; ventrals 173 (plus 1 preventral), angulate; cloacal plate entire; subcaudals 59, all paired; terminal caudal scale forming a pointed cap.
Dentition. Maxillary teeth 10, curved posteriorly, smaller and shorter anteriorly; posterior three being enlarged and blade-shaped.
Hemipenis. Hemipenis long and thin with two lobes, deeply forked at the level of 6 th SC and tip of each organ reaching the SC 25, without spines and papillae; each lobe with numerous smooth, small and transversal folds, with a deep diagonal groove; smooth hexagonal calyces on the distal part of the organ. The sulcus is prominent and divided at the level of the fork (Fig. 3).
Coloration. In life, overall dorsal coloration brown to olive with 13 darker blotches on body and 4 on tail. A dark brown band from eye to eye through preoculars, supraoculars, frontal, prefrontals and internasals, continues over the 4 th and 5 th supralabials ending at lower part of the 6 th supralabial. Head with another dark brown arrowshaped marking, its apex pointing forward and reaching the posterior part of frontal, backwards obliquely crossing neck and reaching the 6 th ventral. Temporal streak faint and discontinuous, distinct posteriorly, reaching the level of ventrals. Numerous scattered dorsal black spots confined to edges of the body scales. Edge of each body scale and intervening skin yellowish to white. Vertebral stripe distinct, broader and more distinct on the anterior part of body and on the tail. Ventral color cream anteriorly to pinkish centrally and posteriorly with black rectangular blotches. Ventral surface of tail white to pinkish with black spots. In alcohol, the color became paler, but the pattern remains; venter cream to white with black blotches and dots, pinkish color disappears.
Variation. Paratype ITBCZ 7944 has two preoculars on each side and its presubocular is absent on the left side. Paratype ITBCZ 8215 has 15 blotches on body and faint a vertebral stripe. Table 1 summarizes variation in size and scalation of the holotype and three paratypes.
Natural history. All specimens were collected during the day. ITBCZ 7868 and 7944 were found dead on the road and the surrounding habitat is pine forest as well as flower and vegetable plantations. ITBCZ 7899 was found near Cam Ly Stream on the pine hill bordered by a vegetable plantation and residential area. ITBCZ 8215 was collected on a pine-covered hill and near a residential area. (Fig. 4E)
Sexual dimorphism. Tail of adult male longer than that of adult female (TaL/TL = 0.184 vs. 0.123). Males have more subcaudals (58 or 59 vs. 44 or 45) but fewer ventrals (173–179 vs. 187–193) than females.
Distribution. The new species is currently known only from Da Lat City and its vicinity, Lam Dong Province, Vietnam (Fig. 1).
Etymology. We name the new species in honor of Mr. Tuan Minh Nguyen (Lam Dong Province, Vietnam) in recognition of his significant contribution to us including the type series of the new species and many other important samples of reptiles in recent years. We recommend “Langbian kukri snake” and “Rắn khiếm Langbian” for as the common English and Vietnamese names of the new species, respectively.
Comparisons. Oligodon tuani sp. nov. has deeply forked hemipenis without both papillae and spines and thus differs from the following species that have conspicuous papillae on the hemipenes: O. barroni (Smith), O. deuvei David, Vogel & Rooijen, O. mouhoti (Boulenger), O. pseudotaeniatus David, Vogel & Rooijen, and O. taeniatus (Günther) (David et al. 2008b). The new species differs from O. catenatus (Blyth), O. cruentatus (Günther), O. dorsalis (Gray & Hardwicke), O. eberhardti Pellegrin, O. hamptoni Boulenger, O. planiceps (Boulenger), and O. theobaldi (Günther) by having smooth and forked (vs. spinose and unforked) hemipenis (Smith 1943).
Oligodon tuani sp. nov. has 19 dorsal scale rows at midbody and thus differs from the following species that have 13 or 15 dorsal scale rows: O. annamensis Leviton, O. jintakunei Pauwels, Wallach, David & Chanhome, O. inornatus (Boulenger), O. kampucheaensis Neang, Grismer & Dattry, O. lacroixi Angel & Bourret, O. macdougalli Wall, O. nagao David, Nguyen, Nguyen, Jiang, Chen, Teynie & Ziegler, O. rostralis Nguyen, Tran, Nguyen, Neang, Yushchenki & Poyarkov, O. teyniei David, Hauser & Vogel, O. torquatus (Boulenger), and O. vertebralis Günther (Smith 1943; Vassilieva 2015; Nguyen et al. 2020; David et al. 2012, 2022).
Oligodon tuani sp. nov. differs from O. albocinctus (Cantor) by having more supralabials (8 vs. 7), supralabials 4 and 5 (vs. 3 and 4) touching the eye, dorsum with blotches (vs. cross-bars), and hemipenis without papillae (with short pointed papillae) (Smith 1943); O. arenarius Vassilieva by having a larger size (TL 888 mm vs. 389 mm), more midbody scale rows (19 vs. 17), more maxillary teeth (10 vs 6–8), and more ventrals (173–193 vs. 131–144) (Vassilieva 2015); from O. booliati Leong & Grismer by having more supralabials (8 vs. 6 or 7), more ventrals (173–193 vs. 143–153), and dorsal color pattern (blotches vs. cross-bars) (Leong & Grismer 2004); from O. cattienensis Vassilieva, Geissler, Galoyan, Poyarkov, Devenger & Bohme by having more midbody scale rows (19 vs. 17), more subcaudals in males (58 or 59 vs. 32–36) and in females (44 or 45 vs. 32); fewer maxillary teeth (10 vs. 11 or 12), fewer number of dorsal blotches (13–15+3–4 vs. 24–33+5), and remarkably longer hemipenis (extending to SC 25 vs. 11 or 12) (Vassilieva et al. 2013); from O. cinereus (Günther) by having more midbody scale rows (19 vs. 17), more ventrals in females (187–193 vs. 165–185), more subcaudals (44–59 vs. 29–43), fewer maxillary teeth (10 vs. 11–14), remarkably longer hemipenis (extending to SC 25 vs. 11–14), and different dorsal color pattern (blotches vs. uniform or cross-bars or reticulations) (Smith 1943; David et al. 2012); from O. condaoensis Nguyen, Nguyen, Le & Murphy by having more midbody scale rows (19 vs. 17), more subcaudals in males (58 or 59 vs. 37) and in females (44 or 45 vs. 33–34), fewer maxillary teeth (10 vs. 11–13), remarkably longer hemipenis (extending to SC 25 vs. 13 or 14), and different dorsal color pattern (blotches vs. uniform or faint stripe) (Nguyen et al. 2016); from O. huahin Pauwels, Larsen, Suthanthangjai, David & Sumontha by having more midbody scale rows (19 vs. 17 or 15), more subcaudals in males (58 or 59 vs. 35–41), more maxillary teeth (10 vs. 6), remarkably longer hemipenis (extending to SC 25 vs. 14), and different dorsal color pattern (blotches vs. uniform or faint stripe) (Pauwels et al. 2017); from O. joynsoni (Smith) by having more midbody scale rows (19 vs. 17), fewer maxillary teeth (10 vs. 11 or 12), remarkably longer hemipenis (extending to SC 25 vs. 14), and different dorsal color pattern (blotches vs. cross-bars or reticulations) (Smith 1943; David et al. 2012, 2022); from O. macrurus (Angel) by having a shorter tail (TaL/TL = 0.184 –0.188 vs. 0.240), more midbody scale rows (19 vs. 17), more ventrals (173–193 vs. 143–152), fewer subcaudals (44–59 vs. 76–83), a shorter hemipenis (LHSC = 25 vs. 29) (Smith 1943; Geissler et al. 2011); from O. moricei David, Vogel & Rooijen by having more midbody scale rows (19 vs. 17), more ventrals (187–193 vs. 175 in females), more subcaudals (44 or 45 vs 41 in females), and dorsal blotches (vs. stripe) (David et al. 2008b); from O. phangan Pauwels, Thongyai, Chantong & Sumontha by having fewer maxillary teeth (10 vs. 12), more midbody scale rows (19 vs. 17), more ventrals (173–193 vs. 163–166), and more subcaudals (44–59 vs. 33–42) (Pauwels et al. 2021); from O. promsombuti Pauwels, Thongyai, Chantong & Sumontha by having fewer maxillary teeth (10 vs. 12), more midbody scale rows (19 vs. 17), more subcaudals (44–59 vs. 40), and remarkably longer hemipenis (extending to SC 25 vs. 13) (Pauwels et al. 2021); from O. purpurascens (Schlegel) by having faint and interrupted temporal streak (vs. distinct and continuous temporal streak), different dorsal color pattern (blotches vs. conspicuous red and banded coloration or brownish dull coloration), and forked hemipenis without papillae (vs. unforked with papillae) (Boulenger 1894; Rooijen et al. 2011; Pauwels et al. 2017; David et al. 2022); from O. saiyok Sumontha, Kunya, Dangsri & Pauwels by having fewer maxillary teeth (10 vs. 13), more midbody scale rows (19 vs. 17), more subcaudals (58 or 59 vs. 43 in males, 44 or 45 vs. 38 in females), and remarkably longer hemipenis (extending to SC 25 vs. 18) (Sumontha et al. 2017); from O. signatus (Gunther) by having more midbody scale rows (19 vs. 15–17), more ventrals (173–179 vs. 141–149 in males, 187–193 vs. 151–157 in females), and dorsal blotches (vs. cross bands or transverse rhomboidal spots) (Boulenger 1894; David et al. 2022); and from O. splendidus (Günther) by having fewer midbody scale rows (19 vs. 21), a distinct vertebral stripe (vs. vertebral stripe absent), and remarkably longer hemipenis (extending to SC 25 vs. 19) (Smith 1943).
Oligodon tuani sp. nov. is similar to its congeners in the O. cyclurus species complex. However, the new species can be distinguished from O. chinensis by having more midbody scale rows (19 vs. 17), fewer subcaudals in females (44 or 45 vs. 47–53), remarkably longer hemipenis (extending to SC 25 vs. 12–14), and dorsal blotches (vs. cross bars) (David et al. 2008a; Nguyen et al. 2017); from O. culaochamensis by having a shorter tail (TaL/TL 0.184 vs. 0.218 –0.219 in males, 0.123 vs. 0.166 –0.169 in females), more ventrals in both males (173–179 vs. 167–169) and females (187–193 vs. 179–182), fewer subcaudals in both males (58 or 59 vs. 63–66) and females (44 or 45 vs. 51 or 52 in females), and remarkably longer hemipenis (extending to SC 25 vs. 20) (Nguyen et al. 2017); from O. cyclurus in having a longer tail (TaL/SVL 0.225 vs. 0.127 –0.156 in males, 0.140 vs. 0.107 –0.138 in females), more ventrals in both males (173–179 vs. 160–173) and females (187–193 vs. 168–172), more subcaudals in both males (58 or 59 vs. 37–48) and females (44 or 45 vs. 30–44 in females), and remarkably longer hemipenis (extending to SC 25 vs. 15–18) (David et al. 2008a); from O. formosanus by having a longer tail in males (TaL/SVL 0.225 vs. 0.165 –0.195) and shorter tail in females (TaL/SVL 0.140 vs. 0.149 –0.164), more subcaudals in males (58 or 59 vs. 49–55), remarkably longer hemipenis (extending to SC 25 vs. 15–18), and dorsal blotches (vs. reticulate pattern) (David et al. 2008a); from O. ocellatus by having a longer tail (TaL/SVL 0.225 vs. 0.112 –0.141 in males, 0.140 vs. 0.094 –0.114 in females), more ventrals in both males (173–179 vs. 156–165) and females (187–193 vs. 152–180), more subcaudals in both males (58 or 59 vs. 32–44) and females (44 or 45 vs. 26–33 in females), and remarkably longer hemipenis (extending to SC 25 vs. 15–17) (David et al. 2008a); and from O. saintgironsi by having a larger size (TL max 888 mm vs. 676 mm), a longer tail in males (TaL/SVL 0.225 vs. 0.191 –0.203) and shorter tail in females (TaL/SVL 0.140 vs. 0.161), more midbody scale rows (19 vs. 17 or 18), first scale reduction occurring at the level of ventrals 97–111 (vs. 62–86), more ventrals in both males (173–179 vs. 166–170) and females (187–193 vs. 184), fewer subcaudals in females (44 or 45 vs. 53), and slightly shorter hemipenis (extending to SC 25 vs. 27 or 28) (David et al. 2008a).
Oligodon tuani sp. nov. is also morphologically similar to O. fasciolatus. However, it differs from O. fasciolatus by having fewer dorsal scale rows at neck (19 vs. 21–23), at midbody (19 vs. 21) and before the vent (15 vs. 17), remarkably longer hemipenis (extending to SC 25 vs. 14–21), temporal streak faint and discontinuous (vs. distinct and continuous), ventral surface with black rectangular blotches (vs. pure white or immaculate) (Gunther, 1864; David et al. 2008a; this study). The main morphological characters of the O. cyclurus species complex are summarized in Table 2.
description: Published as part of Nguyen, Sang Ngoc, Le, Manh Van, Vo, Thi-Dieu-Hien & Murphy, Robert W., 2022, A new species of the genus Oligodon Fitzinger, 1826 (Squamata: Colubridae) from Langbian Plateau, Vietnam, pp. 555-566 in Zootaxa 5196 (4) on pages 557-564, DOI: 10.11646/zootaxa.5196.4.5, http://zenodo.org/record/7235759