In Singapore, the spotted keelback appears to be restricted to the Bukit Timah and Central Catchment Nature Reserves and is regarded as ‘uncommon’ (Baker & Lim, 2012: 114, 161). There are two earlier records at the edge of the forest from the Venus Drive area (Ng, 2014: 20; Groenewoud, 2015: 90). The illustration of Xenochrophis maculatus in Baker & Lim (2012: 114) shows a snake with whitish upper labials. A snake photographed attacking the rear end of a four-lined tree frog (Polypedates leucomystax) by Tan & Chew (1992: 50 as Macropophis maculatus) has yellow upper labials. Two physically interacting examples observed at Venus Loop in May 2015 by Groenewoud (2015: 90) show different colouration on the upper labials and neck. One is yellow, and the other is white. Although this colour difference may indicate sexual dichromatism, it is yet to be proven. The upper labials and neck area of the featured subject is bright yellow (Fig. 2). Some individuals have white upper labials and neck (see Ng, 2014: 20 and illustration in Baker & Lim, 2012: 114). Although no mention is made regarding the colour of the throat and ventral part of the neck, the upper labials is known to be white or yellow (Tweedie, 1983: 92 as Macropophis maculatus; Baker & Lim, 2012: 114), or yellow (Das, 2010: 343).

Opinions and declarations Rendered by the International Commission on Zoological Nomenclature