Oligodon cyclurus

David, Patrick, Vogel, Gernot & Pauwels, Olivier S. G., 2008, A new species of the genus Oligodon Fitzinger, 1826 (Squamata: Colubridae) from southern Vietnam and Cambodia, Zootaxa 1939, pp. 19-37 : 34-35

Key to the Oligodon cyclurus -group

We include in this key all known members of the Oligodon cyclurus -group. This group of Oligodon is mainly characterized by long and deeply forked hemipenes, neither spinose or papillate, 17–23 dorsal scale rows, 10– 12 maxillary teeth, a full complement of head scales, including a loreal and a presubocular, anal plate entire; and a body usually blotched or reticulated pattern, never prominently striped. We also include in the key the Indo-Malayan species Oligodon purpurascens , as currently defined ( Tweedie, 1983). This latter species has often been confused with members of the O. cyclurus -group.

1. 21 or 23 DSR at neck and midbody .............................................................................. Oligodon fasciolatus

- No more than 19 rows at midbody...............................................................................................................2

2. 19 DSR at neck and midbody.......................................................................................................................3

- 17 or 19 rows at neck, no more than 18 DSR at midbody............................................................................6

3. Overall body colour grey or greyish-brown; dorsal pattern reticulated with a broad vertebral stripe ........... ..................................................................................................................................... Oligodon formosanus

- Overall body colour shades of ochre or brown; dorsal pattern usually blotched; vertebral stripe reduced to a narrow line or absent..................................................................................................................................4

4. Hemipenes long, thin, strongly forked and calyculate; unknown south of central Thailand; pattern made either of dorsal blotches broad and long (3 dorsal scales long) or strongly reticulate with fasciatures.......5

- Hemipenes long, single, with large papilla; unknown north of southern peninsular Thailand; dorsal blotches narrow (1 or 2 dorsal scales long) .............................................................. Oligodon purpurascens

5. Dorsal scale row reduction from 17 to 15 posterior to VEN 115; dorsal blotches, when present, rather narrow and dark brown or black; northeastern India, Myanmar, Yunnan, and extreme western Thailand......... .......................................................................................................................................... Oligodon cyclurus

- Dorsal scale row reduction from 17 to 15 DSR at most at VEN 115; dorsal blotches, when present, rather long and broad, with a lighter centre; southern Vietnam, southern Laos and Cambodia............................... ......................................................................................................................................... Oligodon ocellatus

6. 17 DSR at neck; hemipenes extend to SC 13 .................................................................. Oligodon chinensis

- 19 DSR at neck; hemipenes extend to SC 28 ............................................ Oligodon saintgironsi spec. nov.