Oligodon nagao, David, Patrick, Nguyen, Truong Quang, Nguyen, Tao Thien, Jiang, Ke, Teynié, Tianbo Chen Alexandre & Ziegler, Thomas, 2012
|
publication ID |
https://doi.org/ 10.5281/zenodo.214038 |
|
publication LSID |
lsid:zoobank.org:pub:9FC2166A-A0B8-4844-9EF6-8E325AD8F531 |
|
DOI |
https://doi.org/10.5281/zenodo.5679604 |
|
persistent identifier |
https://treatment.plazi.org/id/03B0BD2A-1159-BB5C-FF00-FE47FAA72312 |
|
treatment provided by |
Plazi |
|
scientific name |
Oligodon nagao |
| status |
sp. nov. |
Oligodon nagao sp. nov.
( Figs. 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )
Oligodon joynsoni (nec Simotes longicauda joynsoni Smith, 1917 , a valid species, now Oligodon joynsoni ).—Anonymous 2002: 22, front cover.— Zhao 2006: 229.— Zhang 2009: 97, 99 & 100: Fig. 100.
Holotype. VNMN A.2012.1, adult male, from Huu Lien forest, Huu Lung District, Lang Son Province, Vietnam, at elevation of about 300 m a.s.l.; collected by Tao Thien Nguyen on 30 June 2009.
Paratypes. Four specimens, all adult males: MNHN 2012.0216, from Huu Lien forest, Huu Lung District, Lang Son Province, Vietnam, at elevation of about 300 m a.s.l.; collected by Tao Thien Nguyen, 2 July 2009.— IEBR A.2012.6, from Duc Quang Commune, Ha Lang District, Cao Bang Province, Vietnam; collected by Truong Quang Nguyen et al., 14 October 2011 (22o42.859’N, 106o39.853’E, elevation 476 m).— KIZ 0 14591, from Nonggang National Nature Reserve, Longzhou County, Guangxi Autonomous Region, People’s Republic of China; collected by Tianbo Chen, October, 2011.— ZFMK 93281, from Ban Nathan, Hin Boun District, Khammouane Province, Laos PDR (17o58.854’N, 104o49.517’E, elevation 172 m); collected by Alexandre Teynié et al., 17 May 2012, during the mission “ Opération Canopée, Inventaire de la Biodiversité Forestière du Laos 2012-2015 ”.
Diagnosis. A large species (TL up to at least 786 mm) of the genus Oligodon characterized by the combination of (1) 9 or 10 maxillary teeth, the last three or four strongly enlarged, (2) hemipenes not forked but divided into two lobes, thick and bulbous, reaching in situ the 16th SC, smooth, each lobe with a papilla, (3) 17–17–15 (or 17–15–15 DSR in one specimen); (4) cloacal plate entire, (5) complete complement of head scales, including 1 loreal on each side, (6) 8 supralabials (7 in one specimen), fourth and fifth (third and fourth in one specimen) entering orbit, (7) 184–193 ventrals in five males (females unknown), (8) tail relatively short in males (ratio TaL/TL: 0.135–0.146), (9) dorsal pattern made of a dark background colour with 27–37 darker, pale centered, butterfly-shaped blotches on the body and 5–8 on the tail, and (10) venter cream, heavily marked with dark pigmentation.
Description of holotype. Body elongate, cylindrical and robust; head short (3.7 % of SVL), ovoid, rather broad and distinct from thick neck, thick but depressed anteriorly; snout long, narrowing anteriorly, slightly rounded, extending well beyond lower jaw, about 1.9 times as long as eye diameter; large, oval nostril piercing laterally the central part of nasal; eye rather small, its diameter about 0.9 times the distance between eye and lip, round pupil; tail average, robust at its base, tapering progressively to a point.
Measurements.SVL: 561 mm; TaL: 92 mm; TL: 653 mm; ratio TaL/TL: 0.141; HL: 20.95 mm; SnL: 6.35 mm.
Dentition. Maxillary teeth: left maxilla with 9 teeth under the formula: 6 subequal teeth + 3 strongly enlarged, blade-like teeth, without diastema.
Hemipenis.In situ, the hemipenis is massive, unforked, with simple sulcus, and reaches the 16th SC; first basal quarter of the hemipenis covered with calyces; no spines; a long papilla each, about 5 SC long, emerging from the tip.
Body scalation. DSR: 17–17–15, all smooth; scales of the outer dorsal scale row distinctly enlarged. 189 VEN (+ 1 preventral), strongly angulated; 45 SC, all paired; cloacal entire; terminal caudal scale pointing. The dorsal scale row reductions are as follows:
5+6 ↔ 5 (VEN 115) (left)
17 ————————— 15
5+6 ↔ 5 (VEN 119) (right)
Head scalation. Head scalation complement complete, including 2 internasals, 2 prefrontals, 2 supraoculars, 1 frontal, and 2 parietals. Rostral large, wider than high, well visible from above, inserting deeply and broadly between internasals on about one half of their total length; 1 / 1 large, elongate, pentagonal nasal, 1.9 times as long as high, entire, most of scale area being occupied by the nostril; internasals subrectangular, narrow, separated by a short suture, much wider than long, 0.7 times as long as the suture between prefrontals and only 0.4 times as long as prefrontal; prefrontals large, pentagonal, much wider than long, 0.5 times as long as frontal but separated by a suture only 0.25 times as long as frontal; supraoculars subrectangular, relatively large, about 1.6 times as long as broad, 0.4 times as wide as frontal; frontal large, hexagonal, wide, rather squat, 1.2 times longer than wide; parietals moderate, longer than wide, extending on about 30 % of HL, about 1.05 times longer than frontal, abruptly truncated posteriorly with a straight posterior margin; no nuchal scale behind parietal; 1 / 1 small loreal scale, subrectangular, 1.4 times longer than high; 8 / 8 SL, first and second in contact with nasal, second and third in contact with loreal, fourth and fifth entering orbit, sixth and seventh SL largest; 1 / 1 narrow preocular, in contact with prefrontal but not reaching the frontal; 1 / 1 minute presubocular; 2 / 2 small, narrow postoculars, lowest one slightly largest; 1 + 3 temporals on each side, anterior one large, long and high, rather squat, posterior ones rather small; 8 / 8 IL, first in contact with each other, first to fifth in contact with anterior chin shields (fifth in contact only punctually); mental small; anterior chin shields 2.2 times as long as short posterior ones.
Colour and pattern. Body is dark greyish-brown, somewhat darker or more grey on the lower sides, with all scales finely but densely dotted with blackish-brown; outer margins of scales of the vertebral row and upper margins of each adjacent row beige or pale greyish-brown, and central part of scales of the vertebral row densely dotted with brown, producing an irregular paler brown vertebral stripe more visible on the neck; a series of 27 blackish-brown dorsal blotches, somewhat paler greyish-brown in their centre, edged by darker pigmentation, about 3 DSR long and a total of 5 to 7 DSR broad, i.e. covering the vertebral scale row and the 2 or 3 adjacent DSR (DSR 6th or 7th); first blotch located at 13 scales behind parietals; first 11 blotches butterfly-shaped, bisected along the vertebral line although in narrow contact, posterior ones rather “bat-like”; on each side, a faint, irregular dark blotch on each side of the paler vertebral on 7th and 8th DSR in between each dorsal blotch; an elongate, irregularly shaped lateral, blackish-brown blotch on 3rd and 4th and sometimes also on the lower edge of 5th DSR, just below each dorsal blotch, about 1 or 1.5 DSR long. The tail is as the body, with a much better defined vertebral stripe due to the pale greyish-brown colour of the two upper tail rows; 8 blackish-brown dorsal blotches, somewhat paler in their centre, edged with darker pigmentation, progressively more bisected towards the end of the tail, no blotch on the lateral side of the tail; 1st scale row of the tail and lower half of 2nd row uniformly blackish-brown.
The head is greyish-brown as the body, much paler on the sides of the snout and rostral; a dark brown crossband across the anterior part of the head extends on internasals, prefrontals and the anterior part of the frontal, then obliquely downwards on each side through the eyes down to 5th–6th SL; a strong diagonal dark brown streak, extends obliquely downwards from the parietals across the temporal region down to the corner of the mouth, then onto the lower side of the neck, where it borders the 3rd to 5th ventral; a rounded dark brown blotch in the middle of frontal; another rounded dark brown blotch on the distal part of frontal and anterior part of parietals; a large and conspicuous dark brown chevron on the occiput, its apex reaching forward the posterior central part of parietals, and its branches extending straight posteriorly on 6th, 7th and lower half of 8th DSR of the neck, each branch contrasting sharply with the pale, brown vertebral stripe on the neck; on each side of the neck, an oblique, elongate dark brown streak in short contact with each branch of the nuchal chevron; nasal, loreal, outer margins of prefrontals and supralabials pale yellow with irregular greyish-brown spots; 5th and 6th SL, and anterior part of 7th SL with an oblique dark brown streak. The chin and throat are creamish-yellow with faint greyish-brown spots on infralabials; one such spot on each anterior chin shield.
The venter is pale yellow, uniform on the first 6 ventrals, then with rectangular dark greyish-brown blotches irregularly arranged on the outer part of each or one out of two ventrals, then on each ventral; the blotches become progressively wider and, after midbody, the dark pigmentation covers much of ventrals, in leaving only narrow streaks in the middle of each ventral; tips of ventrals dark greyish-brown but separated throughout the venter from the greyish-brown blotches by a narrow, yellow streak which produces on each side a discontinuous ventrolateral stripe. The ventral surface of the tail is pale yellow, with dark brown rectangular blotches on the outer parts of subcaudals; these blotches disappear progressively and the ventral surface of the last quarter of the tail is uniformly pale yellow.
Variation. Besides the holotype, four other males are known. The main morphological characters of all known specimens are summarized in Tables 1 and 2. The great homogeneity in variation is noteworthy, at the exception of the number of supralabials. All other external morphological characters, either in morphometry or scalation, agree with those described for the holotype, including the single cloacal, 1 loreal and 1 small presubocular on each side. Other variations are as follows:
Dorsal scale rows. Four of the five specimens have 17 DSR at midbody at the exception of MNHN 2012.0216. In this latter specimen, the first reduction (17 ® 16 DSR) occurs at the level of 91st VEN; the second reduction (16 ® 15 DSR) occurs at the level of the 93rd VEN, so just before midbody, here considered to be located at the level of the 94th VEN. We consider this value of 15 DSR exactly at midbody to be an anomaly.
Head scalation. Four of the five available specimens have 8 supralabials on each side. The specimen from Laos, ZFMK 93281 has 7 / 7 supralabials, third and fourth entering orbit. All specimens have 8 infralabials on each side at the exception of specimen KIZ 0 14591 which has 7 scales at left.
Hemipenis. In MNHN 2012.0216, the organ also reaches 16th SC. In KIZ 0 14591, in situ, hemipenes reach the 13th SC with the origin of musculus retractor penis magnus at 31st SC. The everted organ may be described as such: hemipenis bulbous, not forked but partly divided into two large lobes; sulcus simple; a papilla present at the tip of each lobe, the papilla of the left side of the snake longer and distinctly thicker than the papilla of the right lobe; calyces present on the first basal quarter of the copulatory organ length.
Dentition. There are 9 or 10 maxillary teeth. The formula of maxillary teeth of specimen MNHN 2012.0216 is 6 + 4 enlarged teeth, especially the last two ones; in IEBR 2012.6, the formula is 6 + 3 teeth.
Dorsal pattern. It is quite similar in all these specimens. The number of dorsal blotches varies from 27 to 37 on the body and 5 to 8 on the tail for a total ranging from 35 to 42. Specimen MNHN 2012.0216 is more distinctly brown than the holotype and lateral blotches are smaller and more irregular. Other elements of the dorsal pattern are similar. In life ( Fig. 5 View FIGURE 5 ), upper dorsal surfaces of specimens IEBR A.2012.6 and ZFMK 93281 were greenishbrown, with dark dorsal blotches, golden in their centre and edged with blackish-brown. In alcohol, the paler center is not as visible and turns to pale greyish-brown.
Comparisons. Our comparisons of Oligodon nagao sp. nov. with other species of the genus is based on data available in Smith (1943), Wagner (1975), Pauwels et al. (2002), Zhao (2006), David et al. (2008a-b, 2011), Das (2010), Tillack & Günther (2010), Zhang et al. (2011), David & Vogel (2012), and Geissler et al. (2012), and as well as on examined specimens (see Appendix).
See Materials and Methods for abbreviations. All specimens are males.
Number Body + tail SVL TaL TL Ratio TaL/ DSR VEN SC
blotches (mm) (mm) (mm) TL
VNMN A.2012.1 27 + 8 561 92 653 0.141 17–17–15 189 45
MNHN 2012.0216 30 + 6 628 107 735 0.146 17–15–15 188 47
IEBR A.2012.6 32 + 6 680 106 786 0.135 17–17–15 191 44
KIZ 0 14591 37+5 623 104 727 0.143 17–17–15 193 46
ZFMK 93281 31+6 609 98 707 0.139 17–17–15 184 43 Number SL SL / orbit PreOc PosOc Temporals IL IL / chin shields VNMN A.2012.1 8 / 8 4–5 / 4–5 1 / 1 2 / 2 1+3 / 1+3 8 / 8 1–5 MNHN 2012.0216 8 / 8 4–5 / 4–5 1 / 1 2 / 2 1+2 / 1+2 8 / 8 1–4 IEBR A.2012.6 8 / 8 4–5 / 4–5 1 / 1 2 / 2 1+2 / 1+2 8 / 8 1–4 KIZ 0 14591 8 / 8 4–5 / 4–5 1 / 1 2 / 2 1+2 / 1+2 7 / 8 1–4 ZFMK 93281 7 / 7 3–4 / 3–4 1 / 1 2 / 2 1+2 / 1+2 8 / 8 1–4
Smith (1943) defined informal groups in the genus Oligodon on the basis of the hemipenial morphology. The distinctiveness of these groups was confirmed by Green et al. (2010). Among the 50 species or so of the genus for which the hemipenial morphology is known according to Green et al. (2010), only the groups of Oligodon taeniatus and Oligodon cyclurus have deeply forked hemipenes. Species of all other groups have non-forked copulatory organs. Among these groups, only the groups of O. cruentatus , O. cinereus , O. octolineatus , O. purpurascens and O. modestus have organs with long papillae but spines are absent only in species of the groups of O. cinereus , O. octolineatus , O. modestus , and O. purpurascens . We consider that Oligodon nagao sp. nov. has affinities with only one of these groups. As members of the groups of O. purpurascens , O. octolineatus and O. modestus include species inhabiting the Malay Peninsula, Indo-Malayan Archipelago and the Philippine Islands, affinities are rather with the group of O. cinereus for both zoogeographical and morphological reasons.
Oligodon nagao sp. nov. differs from members of the groups of O. cinereus and O. purpurascens as follows. Oligodon nagao sp. nov. has a dorsal pattern made of 27–37 dark, butterfly-shaped blotches vs. a pattern uniform in O. c. cinereus and O. inornatus , or reticulate in O. c. cinereus and O. joynsoni , or made of solid black crossbars in O. cinereus tamdaoensis (Bourret, 1935) , or of black-edged pale crossbars in O. cinereus pallidocinctus (Bourret, 1934) , one morph of O. albocinctus (Cantor, 1839) and O. melanozonatus , or, lastly, striped in O. woodmasoni . Additional differences are given in Tables 3 View TABLE 3 and 4 below. In contrast, one morph of O. albocinctus , O. purpurascens , and O. splendidus has a blotched dorsal pattern. Oligodon nagao sp. nov. differs from the blotched morph (Form II of Smith 1943) of O. albocinctus by (1) 17 vs. 19 or 21 DSR, (2) a much shorter tail, ratio Tal/TL 0.135–0.146 vs. 0.171–0.200 in males of O. albocinctus , and (3) a largely dark venter vs. pale with rectangular blotches. Oligodon nagao sp. nov. differs from O. purpurascens by (1) 17 vs. 19 or 21 DSR, (2) a shorter tail, ratio TaL / TL 0.135–0.146 vs. 0.152–0.188 in males of O. purpurascens , and a higher number of dorsal blotches, 27–37 vs. 10–18 in O. purpurascens . Oligodon nagao sp. nov. differs from O. splendidus (Günther, 1875) by 17 vs. 21 DSR, (2) 2 prefrontals vs. 4, and (3) 27–37 vs. 14–17 dorsal blotches. Lastly, O. maculatus , endemic to the Philippines has also 17 DSR and a blotched dorsal pattern but this latter species has no more than 164 ventrals ( Alcala 1986), 7 supralabials and only 20–24 dorsal blotches.
When it was discovered in China in 1998 (Anonymous 2002), Oligodon nagao sp. nov. was confused with Oligodon joynsoni . This rare species is currently known from three provinces of northern Thailand (Chiang Mai, Lampang and Loei) and from an unknown locality in Laos ( David et al. 2011). On the basis of the five specimens examined by us, of four specimens cited by Taylor (1965; see David et al. 2011), and of Wagner (1975), Oligodon nagao sp. nov. differs from O. joynsoni by (1) a different pattern, O. joynsoni having no dorsal blotches but only more or less visible reticulations on a very dark background, (2) 9–10 maxillary teeth vs. 11–12 in O. joynsoni , and (3) 1 versus usually 2 anterior temporals in O. joynsoni .
Currently, the Oligodon cyclurus group is composed of nine species (see above) which have both forked, non spinose and non papillate hemipenes (although short papillae are present in O. formosanus ). With 17 (or 15) DSR at midbody, Oligodon nagao sp. nov. differs from O. cyclurus (19), O. formosanus (19), O. kheriensis (19), O. fasciolatus (21 or 23), O. juglandifer (19), and O. ocellatus (19). Furthermore, Oligodon nagao sp. nov. differs from O. cyclurus by (1) 17 vs. 19 DSR, (2) 9–10 vs. 12–13 maxillary teeth, (3) 184–193 VEN vs. 161–172 in males, (4) 1 anterior temporal vs. always 2, and (5) a blotched pattern vs. dorsal reticulations.
The three remaining species of the O. cyclurus -group have 17 DSR at midbody. Besides the morphology of hemipenes, Oligodon nagao sp. nov. differs from males of O. saintgironsi by (1) a shorter tail (0.135–0.146 vs. 0.191–0.203), (2) a higher number of ventrals, 184–193 vs. 166–170, and (3) a distinct pattern; both species have dorsal blotches but they differ in shape (see David et al. 2008b). Oligodon nagao sp. nov. differs from O. macrurus by (1) a shorter tail in males, 0.135–0.146 vs. 0.329–0.373, (2) a lower number of SC in males, 43–47 vs. 73–94, (3) 7–8 vs. 9–10 IL, (4) a lower number of maxillary teeth, 9–10 vs. 14–15, and (5) a totally different dorsal pattern, O. macrurus being uniform or showing only faint reticulations on a rather pale background. Lastly, Oligodon nagao sp. nov. differs from males of O. chinensis , which occurs in the same region, by (1) a shorter tail, 0.135–0.146 vs. 0.187–0.195, (2) a higher number of ventrals, 184–193 vs. 175–184, (3) a lower number of SC, 43–47 vs. 60–64, (4) 1 anterior temporal vs. usually 2 (in 19 out of 28 occurrences) in O. chinensis , and (5) a distinct dorsal pattern, with more dorsal blotches, 27–37 vs. 11–14 blotches of different shape. Additional data on members of the O. cyclurus group can be found in David et al. (2008b, 2011).
Nevertheless, because dissected hemipenes are not always available, we further compare our new species with species of Oligodon inhabiting the Asian mainland and Taiwan with either 17 or 15 DSR at midbody, regardless of their current group; species from Sri Lanka, the Indo-Malayan Archipelago and the Philippines, not present in the region of Oligodon nagao sp. nov., are excluded. The number of DSR at midbody is a major diagnostic character in the genus Oligodon (see David et al. 2008a-b). This number is usually constant within a given species but may sometimes vary due to an anomalous position of the dorsal scale row reductions, as it is likely the case with Oligodon nagao sp. nov. Data are summarized in Tables 3 View TABLE 3 and 4.
Oligodon nagao sp. nov. might be confused only with O. joynsoni , of which we examined five specimens to which we add the four specimens identified by Taylor (1965) as O. cinereus swinhonis and O. cinereus multifasciatus (see David et al. 2011). However none of these specimens has a blotched pattern as Oligodon nagao sp. nov. On the basis of this constant character, together with differences in dentition and head scalation, we consider Oligodon nagao sp. nov. to be a species distinct from O. joynsoni .
Etymology. This new species is named in honour of the Nagao Natural Environment Foundation, Japan, for the support of natural sciences research and conservation in developing countries in Asia.
As common names, we suggest Nagao Kukri Snake (English name), R ắ n khi ế m na-gao (Vietnamese name), and Fang Ban Xiao Tou She (Chinese name, meaning the “Kukri Snake with rectangular blotches on the back”).
Distribution ( Fig. 6 View FIGURE 6 ). Oligodon nagao sp. nov. is currently known from a small area straddling over Vietnam and China, and from central Laos, as follows:
Vietnam. Known from the provinces of Lang Son (Huu Lung District) and Cao Bang (Ha Lang District). People’s Republic of China. Known from Guangxi Autonomous Region (Longzhou County). Laos. Known from Khammouane Province (Hin Boun District).
Natural history. This species has been found only in karst environment. The Vietnamese and Chinese specimens were all collected at night in karst forests. The specimen from Cao Bang was found at night (21:00) near the limestone cliff surrounded by secondary forest made of short hardwood, shrubs and vines. No water was observed in the vicinity. The Laotian specimen was collected in a large cave of a karst massif located in the corridor connecting Phou Hin Boun National Park to Nakai Nam Theu National Park. In this totally mineral biotope, this adult male was active around noon in nearly complete darkness on the ground beneath a large boulder. A few amphibian species were found there, such as Hylarana nigrovittata and Micryletta inornata , as well as some other reptile species: Cyrtodactylus sp. and Triceratolepidophis sieversorum . The Oligodon specimen did not attempt to bite when it was collected but it showed the usual behaviour of many species of the genus Oligodon when they feel threatened, i.e. showing the bright colour of the ventral side of its tail curled in a spiral.
TABLE 3. Main characters of mainland Oligodon species with 15 dorsal scale rows at midbody. Exceptional values are placed in brackets. See Materials and Methods for abbreviations, with the addition of: Cloacal plate: D—divided; E—entire;? — data unavailable.
| Species Oligodon nagao sp. nov. | Hemipenes Not forked | Hemipenes length DEN (SC) 16 9–10 | Cloacal plate E | VEN 184–193 | SC 43–47 |
|---|---|---|---|---|---|
| O. brevicauda O. dorsalis | ? Forked | ? 7–8 11 6–7 | D D | 158–176 162–188 | 25–29 27–51 |
| O. erythrorachis O. hamptoni | ? Not forked | ? 7–8 11 7–8 | D D | 154 160–175 | 46 30–32 |
| O. inornatus O. jintakunei | Not forked? | 10–12? 11–12? 6 | E D | 169–174 189 | 31–42 46 |
| O. lacroixi O. lungshenensis | Not forked Not forked | 6–8 8–12 10? | D D | 162–178 166–180 | 29–? 31–38 |
| O. melaneus | Not forked | 15 7 | D | 152–160 | 39–40 |
| O. nikhili | ? | ?? | D | 144 | 33 |
| O. ornatus O. taeniolatus | Not forked Forked | 9 6–8 9–11 6–7 | D D | 156–182 158–218 | 27–44 29–59 |
| O. torquatus | Not forked | 8 15–16 | D | 114–169 | 25–34 |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
