Revised key to the species of Xylophis

This is based on the key presented by Gower & Winkler (2007). Other than incorporation of X. mosaicus sp. nov., the main modification is that Gower & Winkler considered X. perroteti to have only one pair of genials, with the more posterior pair identified here (and by, for example, Smith 1943: 342) being small and separated widely by the intervening first ventral. Note that, following Gower & Winkler (2007), the ‘first ventral’ here is the anteriormost midline ventral scale behind the mental.

1 Dorsal scales in 13 rows at midbody; supraocular notably larger than postocular; six or more infralabials................ 2

- Dorsal scales in 15 rows at midbody; supraocular and postocular shields subequal in size; five infralabials............... 3

2 First ventral separates the posterior genials and contacts the anterior genials........................................................................... X. perroteti (including its putative junior subjective synonym X. microcephalum)

- Posterior genials in midline contact, preventing contact between first ventral and anterior genials........................................................................................................... X. mosaicus sp. nov.

3 Ventrals 120–135; prefrontal shields much longer than internasals; second infralabial notably longer than first, the two together being about as long as the third infralabial........................................................................................................ X. stenorhynchus (including its putative junior subjective synonym X. indicus)

- Ventrals 106–120+; prefrontals and internasals subequal in midline length; second infralabial only marginally longer than first, the two together being shorter than the third infralabial............................................... X. captaini