''Xenodermus javanicus'', also known as the dragon snake, Javan tubercle snake, Javan mudsnake, or rough-backed litter snake, is a small non-venomous, semi-fossorial snake species belonging to the monotypic genus ''Xenodermus''. This species is best known for their characteristic dorsal scales and interesting defense mechanism in which they stiffen their entire bodies when threatened. ''X. javanicus'' is nocturnal and subsists on a diet of frogs, tadpoles and small fish. While they are known to perish once placed into captivity, some herpetoculturists have been successful in keeping them.

Distribution and habitat

''Xenodermus javanicus'' is found in the Malay Peninsula (

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is b ...

, and one old record from the southernmost tip of

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...

) and parts of the

Greater Sunda Islands The Greater Sunda Islands ( Indonesian and Malay: ''Kepulauan Sunda Besar'') are four tropical islands situated within Indonesian Archipelago, in the Pacific Ocean. The islands, Borneo, Java, Sulawesi and Sumatra, are internationally recognised ...

(Sumatra, Java, and Borneo, as well as some smaller islands). It inhabits damp areas near water, including forests, swamps, marshes, and rice fields, at elevations below , but most commonly between above sea level.

Description

''Xenodermus javanicus'' has a distinct head and long tail. The body is slender and compressed. The total length is about . 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. Dragon Snake Scalation

Differentiation of sex chromosomes and karyotype characterization

''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 chromosome A sex chromosome (also referred to as an allosome, heterotypical chromosome, gonosome, heterochromosome, or idiochromosome) is a chromosome that differs from an ordinary autosome in form, size, and behavior. The human sex chromosomes, a typical ...

s with a heterochromatic W.

Behavior

Breeding

''Xenodermus javanicus'' undergo reproduction by egg and have low fecundity (2–4 eggs).

Activity pattern

''Xenodermus javanicus'' are nocturnal.

Diet

''Xenodermus javanicus'' subsist mainly on frogs, tadpoles and small fish.

Behaviors

''Xenodermus javanicus'' exhibit a peculiar property when encountering perceived threats in which they stiffen their entire body.

Conservation status

''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.

References

{{Taxonbar, from1=Q2707077, from2=Q14090403 Xenodermidae Monotypic snake genera Snakes of Southeast Asia Reptiles of Brunei Reptiles of Indonesia Reptiles of Malaysia Reptiles of Myanmar Reptiles of Thailand Taxa named by Johannes Theodor Reinhardt Reptiles of Borneo