A new species of the genus Opisthotropis Günther, 1872 (Squamata: Natricidae) from the highlands of Kon Tum Province, Vietnam Author David, Patrick Author Pham, Cuong The Author Nguyen, Truong Quang Author Ziegler, Thomas text Zootaxa 2011 2758 43 56 journal article 10.5281/zenodo.276769 f0d9b732-7675-4d3c-9902-2619c3576c4d 1175-5326 276769 Key to the species of Opisthotropis and related genera On the basis of recent taxonomic modifications and of new material available subsequent to Ziegler et al . (2008) , we provide a new key to the genus Opisthotropis and related genera. This key, as well as Table 1 above, are based on specimens examined by us and the references listed in the Materials and Methods. 1 Posterior upper maxillary teeth distinctly enlarged; nostrils rounded, dorsolateral, laterally directed; first supralabials distinctly longer than high................................................................... Parahelicops annamensis - Upper maxillary teeth subequal; nostrils crescentic, in dorsal position, directed upwards; first supralabials distinctly higher than long............................................................................................ 2 2 15 or 17 scale rows at midbody and on neck............................................................... 3 - 19 rows at midbody, 19–23 rows on neck.................................................................. 16 3 15 scale rows at midbody, 15–17 scale rows on neck.......................................................... 4 - 17 rows at midbody.................................................................................... 7 4 Internasal in contact with loreal................................................................... O . jacobi - Internasal not in contact with loreal....................................................................... 5 5 1 preocular; 1 anterior temporal; dorsal scales entirely smooth.................................................. 6 - 2 preoculars; 2 anterior temporals; dorsal scales keeled posteriorly...................................... O . kikuzatoi 6 9 SL; body dark with pale crossbars.......................................................... O . guangxiensis - 8 SL; body black with a tallow spot on each dorsal scale............................................. O . maculosa 7 Dorsal scales strongly keeled (endemic to Sumatra).................................................. O . rugosa - Dorsal scales smooth or weakly keeled on posterior part of body................................................ 8 8 No preocular; elongate loreal entering orbit....................................................... O . latouchii - At least 1 preocular................................................................................... 9 9 Internasal in contact with loreal......................................................................... 10 - Internasal not in contact with loreal...................................................................... 12 10 Dorsal pattern uniformly blackish-brown; dorsal scales keeled posteriorly.................................... O . atra - Dorsal pattern uniformly greyish-brown; dorsal scales smooth................................................. 11 11 Greyish-olive above; 189–194 VEN; endemic to southern Vietnam ................................... O . daovantieni - Greyish-brown above; 183 VEN; endemic to northern Thailand ....................................... O . spenceri 12 Dorsal scales entirely smooth; dorsum with pale crossbars............................................... O . cheni - Dorsal scales at least keeled on posterior part of body; dorsal pattern not mainly made of crossbars.................... 13 13 2 anterior temporals........................................................................ O . tamdaoensis - 1 anterior temporal................................................................................... 14 14 Body uniformly dark with pale-edged scales; 2 suboculars........................................... O . andersonii - Body pattern not as such; no suboculars................................................................. 15 15 A black lateral stripe separating abruptly pale colour of venter from dark dorsum colour; 159–173 VEN; 9–11 SL; 1 preocular; dorsal scales keeled throughout body............................................................. O . lateralis - No black lateral stripe separating pale colour of venter from dark dorsum colour; 147–155 VEN; 6–8 SL; 2 preoculars; dorsal scales smooth on anterior part of body............................................................ O . maxwelli 16 Internasal in contact with loreal......................................................................... 17 - Internasal not in contact with loreal..................................................................... 19 17 1 prefrontal................................................................... Opisthotropis cucae sp. nov. - 2 prefrontals......................................................................................... 18 18 Dorsal scales smooth; 195 VEN; endemic to the Philippines ............................................ O . alcalai - Dorsal scales keeled; 160–176 VEN; endemic to Borneo............................................... O . typica 19 Dorsal scales strongly keeled........................................................................... 20 - Dorsal scales smooth or only weakly keeled posteriorly...................................................... 21 20 Dorsal scales with strong, thick keels; 136–140 VEN; 8–9 SL; dorsal pattern uniform..................... O . boonsongi - Dorsal scales with strong but narrow keels; 146–154 VEN; 13–16 SL; body with black stripes............. O . kuatunensis 21 Dorsal scales keeled on posterior part of body; 190–205 VEN; strong dorsal pattern made of broad, black, pale-centred cross- bars........................................................................................ O . balteata - Dorsal scales entirely smooth; 145–155 VEN; subdued pattern with faint dark crossbands or dark, large blotches.......... Paratapinophis praemaxillaris