Oligodon wagneri, David, Patrick & Vogel, Gernot, 2012

David, Patrick & Vogel, Gernot, 2012, A new species of the genus Oligodon Fitzinger, 1826 (Squamata: Colubridae) from Pulau Nias, Indonesia, Zootaxa 3201, pp. 58-68 : 59-65

Oligodon wagneri sp. nov.

( Figs. 1–3 )

Holotype. MNHN 1891.0233, juvenile male, from “Poulo Nias”, i.e. Pulau Nias (Nias Island), Nias Archipelago, Sumatera Utara Province, off the northern part of the west coast of Sumatra, Indonesia, collected by Mr. Jules Claine and deposited on July 23rd, 1891.

Diagnosis. A species of the genus Oligodon characterized by the combination of: (1) 9 maxillary teeth, the last three strongly enlarged; (2) hemipenes not forked, thin and long, reaching 18th SC, covered with spines basally and flounces distally; (3) 15–15–15 DSR; (4) anal plate entire, (5) internasals and loreals present; (6) 7 supralabials, 3rd–4th entering orbit; (7) dorsal pattern made of 14 narrow, white crossbars on the body and 4 on the tail, alternating with three irregular white reticulations; and (7) venter heavily covered with subrectangular dark brown blotches.

Description of holotype. Body cylindrical and robust but elongate; head short, ovoid, depressed, barely distinct from thick neck; snout long, slightly pointed, protracted beyond lower jaw, about 1.8 times as long as eye diameter; large, crescentic nostril piercing laterally on central part of nasal; eye average, its diameter about 1.5 times distance between eye-lip, round pupil; tail average, tapering progressively.

Measurements. SVL: 197 mm; TaL: 38 mm; TL: 235 mm; ratio TaL/TL: 0.162; HL: 9.05 mm; SnL: 2.85 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 thin, not forked and reaches the 18th SC; proximal half of the organ spinose, the distal spines slightly shorter; distal half of the organ densely covered with smooth flounces; sulcus spermaticus simple, extending up to the tip of the organ between papillae; two short papillae extend on a length of 2 or 3 SC from the end of the organ. Body scalation. DSR: 15–15–15 scales, all smooth; scale of the outer dorsal scale row enlarged. 156 VEN (+ 1 preventral); 41 SC, all paired; anal entire; terminal caudal scale pointing. Head scalation. Head scalation 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 length; 1 / 1 relatively large, pentagonal nasals, divided in its lower half by a suture, most of its area being occupied by the nostril; internasals pentagonal, much wider than long, 0.8 times as long as prefrontals; the short suture between internasals is 0.7 times as long as the suture between prefrontals; prefrontals short, much wider than long, their suture only 0.2 times as long as frontal; supraoculars subrectangular, narrow, about 2.2 times as long as broad; frontal, large, hexagonal, long and wide, about 1.3 times longer than wide; parietals very large, extending on about 43% of HL, longer than wide, about 1.1 times longer than frontal, abruptly truncated posteriorly with a straight posterior margin; no nuchal scale behind parietal; 1 / 1 small loreal scale, subrectangular, 1.2 times longer than high; 7 / 7 SL, 1st–2nd in contact with nasal, 2nd–3rd in contact with loreal, 3rd–4th SL entering orbit, 5th–6th SL largest; 1 / 1 narrow preoculars, in contact with prefrontals but not reaching the frontal; no subocular; 2 / 2 small postoculars, of equal size; 1 + 2 temporals on each side, anterior one rather small and elongate, upper posterior one elongate and very large; 8 / 8 IL, 1st IL in contact each with the other, 1st–4th IL in contact with anterior chin shields; mental small; anterior chin shields 2.1 times as long as the very short posterior ones.

Colour and pattern. Body and tail chestnut-brown, with irregular darker areas on the upper part of the dorsum (the paler posterior part of the body is due to the discoloration in preservative); numerous irregular cream dots throughout the body, usually arranged along vertical or oblique discontinuous lines of dots every 2 or 3 DSR, forming discontinuous, wavy crossbars on the sides of the body from the 1st DSR up to the vertebral row where these dots are larger than on the sides; a series of 14 on the body + 4 on the tail white transverse crossbars, short but wide, no more than 1 or 1.5 DSR long but 3–4 DSR wide; these vertebral crossbars are more or less broadly edged with dark brown; the vertebral crossbars are separated from each other by two or three irregular cream reticulations formed by large cream dots issued from the lateral lines of dots. The tail is as the body but without reticulations between the narrow dorsal crossbars and with a series of minute white dots on every 2 or 3 scales of the first scale row above the subcaudals, on each side.

Head very pale grey above and on the sides; rostral, areas around nasals, 1st SL and anterior half of 2nd SL dark greyish-brown, with a paler area on the tip of the rostral and two pale grey blotches at the edge between the 1st SL and rostral; an anterior dark greyish-brown crossband extending on the greatest part of prefrontals and anterior half of the frontal between each eye, downwards up to the posterior half of 3rd SL, 4th SL and anterior half of 5th SL; a short dark greyish-brown triangular blotch on the upper rear corner of each eye, not in contact with the anterior crossband; a large, vertical, irregular dark greyish-brown bar on the posterior half of 6th SL; a short, semicircular or peer-shaped brown blotch on the frontal just before the parietals; a broad, anteriorly truncated dark greyish-brown occipital stripe covers much of the parietals and extends obliquely posteriorly in widening downwards on each side across the temporals to the corner of the mouth then, downwards and backwards, connects with the chestnut-brown colour of the body near the level of 1st and 2nd ventrals on the neck; the branches of this stripe are separated from the anterior transversal band by a narrow, oblique area of pale grey background colour; another very pale grey streak, parallel to the previous one, separates on each side the posterior greyish-brown occipital stripe from the brown background colour of the body, each branch of the pale area looking like a nuchal streak extending obliquely downwards and backwards from the nuchal scale and tips of parietals and reaching the 3rd and 4th ventrals; the two lateral branches do not connect each other on the occiput and are separated by a greyish-brown area. The chin and throat are cream, heavily and irregularly covered with numerous, dark brown irregular blotches especially on chin shields, on the infralabials and on the middle of the throat.

The venter is cream, with numerous rectangular dark brown blotches on each ventral; on 1st–4th VEN, the dark blotches are narrow and restricted to the outer parts of ventrals, producing a short, longitudinal cream streak, followed by an area up to 28th VEN where the brown colour covers much of each ventral and leaving only small, irregular cream blotches on ventrals, after VEN 28th, the venter is cream with rectangular blotches on every ventral, either covering one outer half the scale or both tips, the scheme irregularly alternating every two ventrals; sometimes two large blotches on the same ventral, making the scale nearly entirely dark brown. The ventral surface of the tail is as venter but dark brown rectangular blotches are limited to the outer tips of subcaudals, at the exception of a larger blotch on the outer part of every two or three subcaudals, no dot or streak in the middle of the tail.

Variation. This species is known only from its holotype.

Comparison. Our comparison of Oligodon wagneri sp. nov. to other species of the genus is based on data available in De Rooij (1917), Taylor (1922), Smith (1943), Leviton (1963), Wagner (1976), Manthey & Grossmann (1997), Pauwels et al. (2002), Das (2010), and Tillack & Günther (2010), as well as on specimens deposited in collections (see in the Appendix).

The number of DSR around the neck (one head length behind the head) and at midbody is a major diagnostic character in the genus Oligodon (see David et al. 2008). This number is usually constant within a given species. Previously, this character has been regarded as variable in some species but most of these are currently regarded as complexes, such as Oligodon cyclurus (Cantor, 1839) (see David et al. 2011). An exception might be Oligodon purpurascens (Schlegel, 1837) which has 19 or 21 DSR at midbody.

Among the about 70 species recognized in the genus Oligodon , only 26 have 15 DSR either constantly along the length of body or at least at midbody. Some morphological data for these 26 species are summarized in Table 1. All other species of the genus have 13, 17, 19, 21 or rarely 23 rows at midbody or throughout the body. Of the 26 species that have 15 DSR at midbody, 24 display the condition consistently: O. brevicauda Günther, 1862 , O. calamarius (Linnaeus, 1758) , O. dorsalis (Gray, 1834) , O. erythrorachis Wall, 1910 , O. everetti Boulenger, 1893 , O. hamptoni Boulenger, 1918 , O. inornatus (Boulenger, 1914) , O. jintakunei Pauwels, Wallach, David & Chanhome, 2002 , O. lacroixi Angel & Bourret, 1933 , O. lungshenensis Zheng & Huang, 1978 , O. melaneus Wall, 1909 , O. modestus Günther, 1864 , O. nikhili Whitaker & Dattari, 1982 , O. notospilus Günther, 1873 , O. ornatus Van Denburgh, 1909 , O. petronellae Roux in De Rooij, 1917, O. praefrontalis Werner, 1913 , O. propinquus Jan, 1862 , O. sublineatus Duméril, Bibron & Duméril, 1854 , O. taeniolatus (Jerdon, 1853) , O. torquatus (Boulenger, 1888) , O. vertebralis (Günther, 1865) , and O. waandersi (Bleeker, 1860) , as well as Oligodon wagneri sp. nov. Exceptionally, two species, both occurring in Sumatra and its region, have usually 17 and unusually 15 DSR at midbody: O. bitorquatus Boie, 1827 (rare value recorded only in one of the syntypes of O. subquadratum Duméril, Bibron & Duméril, 1854 ) and O. signatus (Günther, 1864) (value recorded in the holotype of Simotes annulifer var. annulata Van Lidth de Jeude, 1922; synonymized with O. signatus by Tillack & Günther 2010).

The 26 species with 15 DSR at midbody can be divided into those with a maximum of 15 DSR around the neck or those with 17 DSR around the neck with a reduction to 15 DSR before midbody. Some species fall into both categories ( O. everetti , O. inornatus , O. sublineatus , and O. taeniolatus ). The first category (15–15–15 DSR) includes O. wagneri sp. nov. and the 18 following species: O. brevicauda , O. calamarius , O. dorsalis , O. everetti , O. hamptoni , O. inornatus , O. jintakunei , O. lacroixi , O. modestus , O. notospilus , O. ornatus , O. petronellae , O. propinquus , O. signatus (value recorded in the holotype of Simotes annulifer var. annulata Van Lidth de Jeude, 1922; synonymized with O. signatus by Tillack & Günther 2010), O. sublineatus , O. torquatus , O. vertebralis , and O. waandersi . By its formula of 15–15–15 DSR, O. wagneri sp. nov. differs from O. bitorquatus , O. erythrorachis , O. melaneus , and O. nikhili which always have 17 DSR around the neck. The complete dorsal scale row formulas of O. lungshenensis and O. praefrontalis are unknown.

The structure and length of the hemipenes are major diagnostic characters in the genus Oligodon ( Smith 1943; Wagner 1976). Oligodon wagneri sp. nov. differs from O. dorsalis , O. sublineatus and O. taeniolatus by its unforked (vs. forked) hemipenes. Among the species with unforked hemipenes, O. wagneri sp. nov. differs by its hemipenes being longer (reaching the 18th SC) than in O. calamarius (up to 9–10th), O. dorsalis (11th), O. hamptoni (11th), O. inornatus (10–12th), O. ornatus (9th), O. propinquus (5th), O. sublineatus (13th), O. taeniolatus (9–11th), O. torquatus (8th), and O. waandersi (5–7th). In contrast, hemipenes are shorter in O. wagneri sp. nov. than in O. everetti (up to 35th SC) and in O. signatus (25–26th). Hemipenes length in O. wagneri sp. nov. is more or less equal to that of O. bitorquatus , O. melaneus , and O. modestus .

With 9 maxillary teeth, Oligodon wagneri sp. nov. has more than O. brevicauda (7–8), O. calamarius (7), O. dorsalis (6–7), O. erythrorachis (7–8), O. everetti (7–8), O. hamptoni (7–8), O. jintakunei (6), O. melaneus (7), O. modestus (7–8), O. notospilus (7–8), O. ornatus (6–8), O. petronellae (7–8), O. signatus (7–8), O. sublineatus (6– 8), and O. taeniolatus (6–7). The numbers can be considered equal or nearly equal with those of O. bitorquatus (6– 9), O. lacroixi (8–12), O. propinquus (9), O. vertebralis (8–9), and O. waandersi (8–9). In contrast, O. wagneri sp. nov. has fewer maxillary teeth than O. inornatus (11–12) and O. torquatus (15–16).

Oligodon wagneri sp. nov. differs from O. brevicauda , O. calamarius , O. dorsalis , O. erythrorachis , O. hamptoni , O. inornatus , O. jintakunei , O. lacroixi , O. melaneus , O. modestus , O. nikhili , O. notospilus , O. ornatus , O. praefrontalis , O. sublineatus , O. taeniolatus , O. torquatus , and O. waandersi by its entire (undivided) anal plate.

Oligodon wagneri sp. nov. has a complete head scalation complement, and thus differs from O. brevicauda , O. hamptoni , O. jintakunei , O. praefrontalis , and O. hamptoni which lack internasals. Furthermore, the loreal scale, present in O. wagneri sp. nov., is absent in O. brevicauda , O. erythrorachis , O. lacroixi , O. modestus , O. ornatus , and O. praefrontalis . The loreal is either present or absent in O. hamptoni and O. waandersi . It is usually present but may be absent in O. bitorquatus .

Oligodon wagneri sp. nov. has more ventral scales than O. calamarius , O. everetti , O. nikhili , O. notospilus , O. propinquus , O. signatus (males only), and O. vertebralis , and fewer than O. brevicauda , O. dorsalis , O. hamptoni , O. inornatus , O. jintakunei , O. lacroixi , O. lungshenensis , O. praefrontalis , and O. taeniolatus (Table 1).

Among species present in Sunda Islands and neighbouring areas, O. wagneri sp. nov. differs from O. bitorquatus , O. everetti , O. jintakunei , O. signatus by a shorter tail, i.e. a lower ratio Tail length / Total length in males. In contrast, the new species differs from O. praefrontalis and O. waandersi by its longer tail.

In the region of Sumatra, only O. petronellae , O. signatus and, possibly O. praefrontalis may have 15–15–15 DSR. In O. signatus , this occurrence is rare and has been met only in the holotype of Simotes annulifer var. annulata . The description of O. praefrontalis did not mention the complete scale row formula, and the holotype and sole specimen of this species is lost. A summary of morphological characters of the nine species of Oligodon recorded from the region of Sumatra appears in Table 2.

Species Hemipenes Hemipenes DSR MT Anal VEN

length (SC)

O. wagneri sp. nov. Not forked 18 15–15– 15 9 E 156

O. bitorquatus Not forked 15–16 17–(15) 17–15 6–9 E 136–165 [136–160] O. octolineatus Not forked 25–27 17–17–17 8–10 E 155–197 [155–175] O. petronellae Not forked? 15–15–15 7–8 E 144–163 [144–155] Oligodon wagneri sp. nov. is most similar superficially to O. petronellae . However it differs readily from this species by its dorsal pattern of pale, transverse vertebral blotches or crossbars vs. elongate vertebral blotches anteriorly, turning to rhombic blotches posteriorly; furthermore, the dorsal surface of O. wagneri sp. nov. is heavily dotted with pale dots which are absent in O. petronellae .

Oligodon wagneri sp. nov. generally differs from O. signatus by its dorsal scale formula, 15–15–15 DSR vs. usually 17–15–15. When O. signatus has 15–15–15 DSR, O. wagneri sp. nov. differs by (1) a much shorter tail, with a ratio TaL/TL of 0.162 vs. 0.181–0.249 in O. signatus , (2) more ventrals, 156 vs. 144–150 in males of O. signatus , (3) a dorsal pattern of pale, transversal vertebral blotches or crossbars in O. wagneri vs. pale, long crossbars, the first ones shaped as long, narrow chevrons, the posterior ones as narrow crossbars in O. signatus , and (4) a heavily ornate venter with large, dark brown blotches in O. wagneri sp. nov. vs. venter uniform with a dark brown blotch on the tip of each ventral in O. signatus .

Lastly, Oligodon wagneri is most similar in colour pattern to O. bitorquatus . However, O. wagneri sp. nov. differs from this latter species by (1) the number of dorsal scale rows, 15–15–15 vs. 17–17–15 or exceptionally 17– 15– 15 in O. bitorquatus , (2) a shorter tail, with a ratio TaL/TL equal to 0.162 vs. 0.172–0.195 in males of O. bitorquatus , (3) vertebral blotches transversally elongate or appearing as narrow crossbars in O. wagneri sp. nov. vs. rounded vertebral blotches anteriorly in O. bitorquatus , (4) one or two enlarged nuchal scales behind parietals in O. bitorquatus , absent in O. wagneri sp. nov., and (5) hemipenis spinose on its proximal half in O. wagneri vs. on only its first proximal quarter in O. bitorquatus . Furthermore, O. bitorquatus is known from the islands of Java, Panaitan, Sumbawa, and, in Sumatra, only from Lampung Province (Bandar Lampung; Lake Ranau on the border between the provinces of Sumatera Selatan and Lampung; Gunung Rajabasa; David & Vogel, unpublished), all substantially further south than the island of Nias.

Etymology. This new species is named in honour of Mr. Frederick W. Wagner, who noticed the distinct specific status of this new species and for his contribution to the systematics of the genus Oligodon . Although unpublished, his works ( Wagner 1975, 1976) are good bases to the taxonomy of this difficult genus. As common names, we suggest Wagner’s kukri Snake (English), Oligodon de Wagner (French), Wagners Kukrinatter ( German) and Kepel Nias (Bahasa Indonesia).

Distribution. Oligodon wagneri sp. nov. is known only from the type locality in Nias Island, Nias Archipelago, off the west coast of Sumatra, Indonesia, without precise locality data. We considered the possibility of an erroneous type locality. The type specimen was collected by Mr Jules Claine (1856–1938), a French diplomat and traveller, and an accomplished photographer. He travelled extensively in Sumatra, Singapore, Pinang Island and West Malaysia in 1889-1890. A description of his trips in Malaysia can be found in Claine (1892). Claine became the French consul in Puerto Rico in 1892 and seemingly never visited again the Indo-Malayan Region. There is no mention of a visit in Nias Island in Claine (1892) but the collection deposited in the Paris Museum of Natural History on July 23rd, 1891 contains 15 specimens of reptile species indeed present in Nias or in the adjacent part of Sumatra, plus the holotype of O. wagneri sp. nov. There remains a possibility that some of these specimens may have been collected on Penang Island, off the west coast of West Malaysia. Nevertheless, the characters of O. wagneri sp. nov. do not agree with any known species from West Malaysia.

Natural history. There are no data about the holotype. Nias Island is a large oceanic island off the northern part of the west coast of Sumatra (ca. 01°30’N, 97°33’E). Its highest point reaches 887 m a.s.l. This island, which receives about 2,800 mm of precipitation per year, is subject to the equatorial climate. In spite of these favourable natural circumstances, only patches of lowland rainforests and inland swamps are still present ( Collins et al. 1991); most of the original forest has been cleared.

Figures

FIGURE 1. Holotype of Oligodon wagneri sp. nov. (MNHN 1891.0233, juvenile male). Dorsal view and lateral view of head, left side. Drawing by Dick Visser.

FIGURE 2. Holotype of Oligodon wagneri sp. nov. (MNHN 1891.0233, juvenile male). General view. Photograph by Patrick David.

FIGURE 3. Holotype of Oligodon wagneri sp. nov. (MNHN 1891.0233, juvenile male). General ventral view. Photograph by Patrick David.