''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 A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...

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. They most often perish once placed into captivity; only a few herpetoculturists have been successful in keeping them.

Distribution and habitat

''Xenodermus javanicus'' is found in the

Malay Peninsula The Malay Peninsula is located in Mainland Southeast Asia. The landmass runs approximately north–south, and at its terminus, it is the southernmost point of the Asian continental mainland. The area contains Peninsular Malaysia, Southern Tha ...

(

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

, and one old record from the southernmost tip of

Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...

) and parts of the

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

(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 Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero 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; have thinner, shorter tails, and lack 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 contrasting with the most typical snake

karyotype A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by de ...

with a stable chromosomal number of The karyotype includes heteromorphic ZZ/ZW

sex chromosome Sex chromosomes (also referred to as allosomes, heterotypical chromosome, gonosomes, heterochromosomes, or idiochromosomes) are chromosomes that carry the genes that determine the sex of an individual. The human sex chromosomes are a typical pair ...

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 Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

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 to defend themselves. They may also emit a foul-smelling odour called a ''musk''.

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