Xenodermus

Xenodermus javanicus is found in the Malay Peninsula (Malaysia, Thailand, and one old record from the southernmost tip of Myanmar) and parts of the Greater Sunda Islands (Sumatra, Java, and Borneo, as well as some smaller islands).[1][2] It inhabits damp areas near water, including forests, swamps, marshes, and rice fields, at elevations below 1,300 m (4,300 ft), but most commonly between 500–1,100 m (1,600–3,600 ft) above sea level.[1]

Xenodermus javanicus has a distinct head and long tail. The body is slender and compressed. The total length is about 50 cm (20 in).[6][7] Males can be distinguished from females by examining the overall size, tail thickness, tail length, and cloacal vent for the presence of a hemipenial bulge. Females will be larger than males and have thinner, shorter tails while lacking a hemipenial bulge. Conversely, males will be smaller in comparison, have thicker, longer tails and exhibit a hemipenial bulge.[5]

Scalation of "Xenodermus javanicus"[8]

Xenodermus javanicus has an unusual chromosomal number of 2n=32, contrasting with the most typical snake karyotype with a stable chromosomal number of 2n=36. The karyotype includes heteromorphic ZZ/ZW sex chromosomes with a heterochromatic W.[9]

Xenodermus javanicus are rare in the northern parts of their range, but are common in Java. There seem to be no major threats to them, and they can persist in wet agricultural lands such as rice fields. They could be potentially threatened by agricultural pollutants.[1]