The masked water snakes of the genus Homalopsis Kuhl & van Hasselt, 1822 (Squamata, Serpentes, Homalopsidae), with the description of a new species Author Murphy, John C. Author Voris, Harold K. Author Traub, Joshua Author Cumberbatch, Christina text Zootaxa 2012 3208 1 26 journal article 45345 10.5281/zenodo.209953 ca93abd5-12f7-438f-b415-a16148a32bde 1175-5326 209953 Homalopsis Kuhl & Hasselt, 1822 Coluber Linnaeus, 1758 : 217 . Vipera Daudin 1803a : 220 . Homalopsis Kuhl & Hasslet 1822 : 101 Pythonia Blyth 1859 : 279 Pythonella Theobald 1868: 66 ( lapsus for Pythonia fide Williams & Wallach, 1989 ) Type species. Coluber horridus Daudin, 1803a (synonym of Coluber buccatus Linnaeus, 1758 ) by original designation. Content. Five species: Homalopsis buccata , H. hardwickii , H. nigroventralis , H. mereljcoxi sp. nov. , and H. semizonata . Diagnosis. Homalopsis can be distinguished from all other Southeast Asian snakes by their keeled and striated scales in 33–49 rows at midbody; crescent-shaped valvular nostrils; lower labials posterior to the eye are horizontally divided; and enlarged plates (frontal and parietals) on the crown. Snakes of the genus Cerberus are the species most likely to be confused with Homalopsis ; however, Cerberus have fewer than 30 scales rows at midbody and the frontal and parietals are ‘fragmented’ into small irregular scales. Distribution. Homalopsis ranges from Nepal (based on an anecdotal record, Zug & Mitchell 1995 ) and probably northeast India , eastward to Indochina and southward into the Malayan peninsula and the Indonesian Archipelago as far east as Borneo. One specimen has been reported from Makassar, Sulawesi (Rooji 1917) but De Lang &Vogel (2005) could not validate its presence on the island. Figure 5 shows the distribution of the five species recognized here. Regional works on India and Nepal rarely mention the presence of Homalopsis . Neither Ahmed et al. (2009) nor Whitaker & Captain (2004) mention the species in India and only Schleich & Kastle (2002) report it from Nepal , and their account is based solely upon the Zug & Mitchell (1995) comment.