Oligodon ocellatus (Morice, 1875)

Pauwels, Olivier S. G., Thongyai, Kanokorn, Chantong, Pajapon & Sumontha, Montri, 2021, Two new Kukri Snake species (Colubridae: Oligodon) from the Nakhon Si Thammarat Mountain Range, and addition of O. ocellatus to the fauna of Thailand, Zootaxa 4908 (4), pp. 537-557 : 549-551

Addition of Oligodon ocellatus to the herpetofauna of Thailand

In their description of Oligodon jintakunei, Pauwels et al. (2002) listed as such the following specimen among the comparative preserved material they examined: “ Oligodon ‘ ocellatus ’ - FMNH 143301, Chong Mek, Thailand ”. At that time Oligodon ocellatus was poorly characterized versus its closest relatives and a positive identification was difficult. Meanwhile David et al. (2008) reviewed Oligodon ocellatus , confirmed O. analepticos as a synonym of the latter, and described the closely related O. saintgironsi . Oligodon ocellatus is known from Cambodia, southern Laos and southern Vietnam (David et al. 2008; Teynié & David 2010; Uetz et al. 2020).

The preserved specimen FMNH 143301, an adult male, has not yet been re-examined in light of the taxonomic and morphological revision of David et al. (2008). It shows a robust but elongate body ( Fig. 11 ). Tail robust, tapering. SVL 354 mm; TaL 58 mm; ratio TaL/TL 0.14. Round pupil. 1 PV + 163 VEN (the last VEN is forked on the right side), laterally slightly angulated; a single anal and 39 divided SC. 19-19-15 DSR, all smooth; no apical pit. DSR reduction from 19 to 17 occurs above the 96 th VEN (left and right) by fusion of DSR 5 and 6. DSR reduction from 17 to 15 occurs above the 109 th (left) and 111 th (right) VEN by fusion of DSR 4 and 5. Two internasals, in broad contact, shorter than prefrontals. Two prefrontals, subrectangular, distinctly wider than long. 1/1 supraoculars, distinctly longer than wide; 8/8 SL, the 4 th and 5 th in contact with orbit; 9/9 IL, 1 st pair in contact behind mental, IL 1 to 4 in contact with anterior chin shields. First pair of chin shields much longer than 2 nd pair, and about the same width. LOR 1/1, in contact on each side with post-nasal, prefrontal, PreOc, and 2 nd and 3 rd SL. PreOc 1/1, the upper one much taller. PreSubOc 1/1, much smaller than PreOc; no SubOc; PosOc 2/2, of subequal size. Tem 2+2 on each side. A dark mark on forehead, extending below the eyes to SL 5 and 6. Two dark marks extending from the frontal to the angle of the mouth. A chevron with its apex on the middle of the frontal, extending posteriorly to the first DSR above the 10 th VEN; 11 blotches on dorsum, separated by three reticulations; 3 more such blotches above tail, with less contrasted reticulations in between. Underside of head, body and tail uniformly cream, without any blotch or speckling.

David et al. (2008) provided the following diagnosis for Oligodon ocellatus : “A species of the genus Oligodon cyclurus -group, characterized by long and deeply forked hemipenes, reaching 15th–17th SC, thin, smooth and not spinose throughout; 19-19-15 (rarely 13) dorsal scale rows; reductions between 19 and 17 rows occurring between VEN 79–107 (mean 90.3); a very short tail, TaL/TL 0.097 –0.141; 9–11 maxillary teeth, the last two or three strongly enlarged; anal plate single; head scalation complete, including a presubocular; 8 (rarely 7) supralabials; 2 anterior temporals; and a typically blotched dorsal pattern, with large blotches in most specimens, or sometimes merely a reticulated pattern with very faint blotches.” They added that it showed 157–180 VEN and 26–44 SC. The specimen FMNH 143301 perfectly fits with this description .

Chong Mek (15°07’59.0”N, 105°28’01.0”E) is located in the Sirindhorn District of Ubon Ratchathani Province in eastern Thailand, about 90 airline km east of the city of Ubon Ratchathani. It is a border town between Thailand and Laos. This is thus the first formal record of the species from Thailand. The closest known locality is Ban Kiatngong (= Ban Khiet Ngong) in Xe Pian National Bio-Diversity Conservation Area , Champassak Province, southern Laos ( Teynié & David 2010); it is located at about 75 airline km SE of the new Thai locality .

We take this opportunity to confirm the presence of Oligodon mouhoti in Uthai Thani Province, western Thailand. The photograph of a live juvenile individual was provided by Cox et al. (1998) to illustrate their account for this species. Its coloration and pattern are diagnostic for the species: two dark longitudinal paravertebral stripes edging a yellowish vertebral stripe; two narrower dorsolateral stripes; two large rounded, black blotches on the upper surface of the tail, one at its base, the other one near the tip; and five major markings on upper head surface; it shows no dark hexagonal or butterfly-like dorsal blotches on the body. No locality was indicated for the photograph, but P. P. van Dijk (pers. comm. to OSGP, Feb. 1999) took it in the part of Huai Kha Khaeng Wildlife Sanctuary located in Uthai Thani Province. The individual’s total length was about 12 cm (van Dijk, pers. comm.). The species was not recorded from Uthai Thani Province by David et al. (2008); it was listed by Cox et al. (2012: 290) from Uthai Thani Province but without more detail on location or voucher reference.

Figures

FIGURE 11 A–B. Preserved Oligodon ocellatus (FMNH 143301) in dorsal (A) and ventral (B) views. Photographs by A. Resetar.