The Australian water dragon (Intellagama lesueurii), which includes the eastern water dragon (Intellagama lesueurii lesueurii) and the Gippsland water dragon (Intellagama lesueurii howittii) subspecies, is a semi aquatic agamid species native to eastern Australia from Victoria northwards to Queensland. There may be a small introduced population on the south-east coast of South Australia.
The Gippsland water dragon is generally the more southern of the two subspecies and the more cold adapted and heat sensitive.
Visually distinguishing the Gippsland water dragon from the Eastern water dragon is relatively easy, as long as their skin is reasonably clean and not stained from the water, as identification of the two subspecies depends largely on observable differences in colours and patterns.
The Gippsland water dragon may be distinguished by its green-blue colour, especially during the breeding season, when this overall colouration is quite distinct. Another key difference is the absence of a prominent dark stripe behind the eye in the Gippsland water dragon, which is characteristic of the Eastern water dragon. The gular region of the two subspecies is also quite different, with Intellagama l. howittii having orange-yellow streaked with darker striping, which is sometimes quite striking, particularly in mature males, whereas Intellagama l. lesueurii typically has a pale, unmarked throat that is sometimes immaculate white in mature males. The belly and chest of Intellagama l. howittii are also quite different to Intellagama l. lesueurii, usually being blackish green, especially in mature males, and the limbs are often quite dark, sometimes even black. Whereas in Intellagama l. lesueurii the chest and belly are usually bright to deep red, particularly in mature males. Intellagama l. lesueurii also have relatively strong dark transverse bars across the back, whereas these dark bars are often much reduced in the Gippsland water dragon.
Etymology
The specific name, lesueurii, is in honor of French naturalist Charles Alexandre Lesueur.
Taxonomy and systematics
The species was first described by John Edward Gray in 1831 as Lophura lesueurii, from a specimen collected by Lesueur & Péron at "Parramatta" or "Port Jackson". Gray listed three species of Lophura: Cuvier's (Lophura Cuvierii Gray), Lesueur's (Lophura Lesueurii Gray), and beautiful (Lophura Concinna Gray, Physignathus Concinnus Cuvier). Gray separated Physignathus (P. concinnus & P. Lesueurii) from Lophura (L. amboinensis & L. Shawii). The Australian water dragon remained in Physignathus along with the Asian water dragon P. cocincinus until Wells and Wellington published the genus Intellagama in 1985.
The subspecies howitii was described by Frederick McCoy in 1884 as "the Gippsland water lizard". According to his description, it differs from the Queensland subspecies in the proportions of the head and the supra-ocular scales. Its sub-specific epithet commemorates geologist and magistrate Alfred William Howitt, who collected three specimens from the upper reaches of the Buchan River and sent them to McCoy. Two of the specimens cannot be located, in the collection of the National Museum of Victoria, which was designated the lectotype by Coventry in 1970.
Description
Australian water dragons have long powerful limbs and claws for climbing, a long muscular laterally-compressed tail for swimming, and prominent nuchal and vertebral crests. (A nuchal crest is a central row of spikes at the base of the head. These spikes continue down the spine, getting smaller as they reach the base of the tail.)
Including their tails, which comprise about two-thirds of their total length, adult females grow to about 60 cm (2 feet) long, and adult males can grow slightly longer than one metre (39 inches) and weigh about 1 kg. Males show bolder colouration and have larger heads than females. Colour is less distinct in juveniles.
Species variation
The Australian water dragon is the only species of the genus Intellagama. They are also prone to becoming road kill due to the attraction of warm bitumen and concrete for basking. Types of vegetation reportedly consumed include figs, lilly-pilly fruits, berries, and other fruits and flowers.