They can make a gentle, squeaky vocalization. They sometimes oscillate the throat (similar to frogs) and the forked tongue is sometimes flicked (similar to snakes). The differences between the sexes are clearly noticeable from an age of about three years. Overall the sexes are alike, but males have a distinctly broader head and broader tail base than females.
Argus monitor genus species skin#
There are both reports of the skin shedding in one piece (similar to snakes), or in smaller pierces (as typical of lizards). The skin is shed infrequently, possibly less than once a year. The tail is prehensile and if it is lost, it is not regenerated. The upperparts are orangish-brown, and the underside is mottled dark brown and whitish, pale yellowish, ochre or rusty. Despite the name, they are capable of hearing, although lack a tympanum, an ear opening and other externally visible signs of ears. AppearanceĮarless monitor lizards have a cylindrical body, long neck, short limbs, long sharp claws, small eyes, semitransparent lower eyelids, and six longitudinal rows of strongly keeled scales.
It is associated with the same microhabitat as Tropidophorus water skinks and in some places its range overlaps with T. At a site with a high density of earless monitor lizards the water was clear and had a neutral pH. Its habitat is tropical with air and water temperatures that generally are about 22–29 ☌ (72–84 ☏), and captives reportedly prefer 24–28 ☌ (75–82 ☏). These are typically in rainforests, but it is also found in streams flowing through degraded habitats such as agricultural land, mature fruit tree gardens and palm oil plantations, and reportedly may occur in rice paddies. It is found in lowlands at altitudes below 300 m (1,000 ft) near streams and marshes. There are no records from Sabah, Central Kalimantan or South Kalimantan. It is not known from Brunei, but may occur there and has been recorded c. Until late 2012, its known range in North Kalimantan was a part of East Kalimantan. Here it is known from Sarawak in East Malaysia, as well as West and North Kalimantan in Indonesia. The earless monitor lizard is endemic to the Southeast Asian island of Borneo. The extinct Cherminotus known from Late Cretaceous fossil remains in Mongolia has been considered a member of Lanthanotidae, but this is disputed. The most recent common ancestor diverged in the mid- Cretaceous. Together they form a clade and its sister group is Shinisauridae at a higher level the sister groups of these three are Helodermatidae and others families in Anguimorpha. Most authorities continue to recognize them as separate families as the divergence between them is deep, but some have suggested that the earless monitor lizard should be included as a subfamily, Lanthanotinae, of the Varanidae. More recent genetic evidence has found that the nearest relative of the earless monitor lizard is Varanidae. Several earlier studies have placed the earless monitor lizard together with Helodermatidae and Varanidae (true monitor lizards) in Varanoidea. Both are part of a broader Anguimorpha, but the relationship among the various families has been a matter of dispute. The similarity is in part the result of convergent evolution and they should be recognized as separate families.
Further studies were conducted in the 1950s where it was found that although it is related to Helodermatidae, this relationship is relatively distant. In 1899 George Albert Boulenger relegated it to the family Helodermatidae, together with the beaded lizards and gila monster. The uniqueness of the species was recognized from the start and Steindachner placed it in its own family, Lanthanotidae. The genus name Lanthanotus means "hidden ear" and the species name borneensis refers to its home island of Borneo. The earless monitor lizard was described in 1878 by Franz Steindachner. It is the only living species in the family Lanthanotidae and it is related to the true monitor lizards. The earless monitor lizard ( Lanthanotus borneensis) is a semiaquatic, brown lizard native to the Southeast Asian island of Borneo.