Rosenberg's monitor
Rosenberg's monitor | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Family: | Varanidae |
Genus: | Varanus |
Subgenus: | Varanus |
Species: | V. rosenbergi
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Binomial name | |
Varanus rosenbergi |
The Rosenberg's monitor (Varanus rosenbergi) is an Australian species of
Taxonomy
The species was first described by German herpetologist
The specific name, rosenbergi, is in honor of German naturalist Hermann von Rosenberg.[9]The infrageneric classification of the species allies it to other taxa of the subgenus Varanus (Varanus).[5] A geographically remote population in the eastern states has distinct characteristics that may represent a cryptic species.[1] A description published as Pantherosaurus kuringai in 1985 is regarded as a synonym for this species.[10][7]
The common names include the heath monitor or the southern heath monitor,[1] along with those names that are a legacy of their description as the sand goanna Varanus gouldii.
Description
Like most other monitor lizards, these are fast-moving predators with long tails, stout limbs and clawed feet. They resemble the closely related and widespread sand goanna
The largest specimens are those found at Kangaroo Island, near the coast of South Australia, these are also darker than those on the mainland and possess a greater number of scale rows at the ventral side.[4] Fat layers in V. rosenbergi constitute around 7.6% of body weight, allowing energy reserves to be stored throughout the body and tail.[5] This monitor can reach a length of 1.5 metres. It is dark gray with yellow and white spotting and black bands on its body and all the way down the tail. The juvenile is tinged with orange.[11]
The comparative ratio of head and body lengths between the sexes, often evident in the monitor subgenus Odatria, is not easily discernible in this species and their subgenus Varanus.[12]
Behaviour
Reproductive behaviour, including guarding of nest sites, extends over a four-month period of a sexually active adult's year.
Incubation periods of V. rosenbergi broods are around seven months, or longer at Kangaroo Island, which is regarded as an extended period when compared to other
They are highly active carnivores, able to pursue large prey, and opportunistic generalists whose diet includes birds, reptiles, mammals, eggs, and carrion.[11][5] Analysis of the island population in South Australia revealed third of their diet is invertebrates, primarily species of
Water is obtained from prey when seasonal rainfall is low, and supplemented by drinking free water when available. Living in a sometimes saline environment, they are able to expel excess salts—primarily sodium chloride and a smaller amount of potassium—through gland structures at the nostrils. In winter months the water required by the goanna may be supplemented from free water or by pulmocutaneous exchange of moisture.[5]
The darker coloration of V. rosenbergi, a form of melanism, allows a greater degree of thermoregulation of their body in the cooler southern climates. They periodically bask in the sun throughout the day, or when the opportunity arises, laying in the soil if it is warm or clambering on to branches to avoid a net heat loss; heath monitors are mostly found in their burrows during the coldest parts of the year. Females may continue to be active at night, maintaining a body temperature 20 °C greater than the ambient temperature.[15][5]
Varanus rosenbergi conserves its energy requirements during cooler seasons of the year, entering a state of torpor, but demonstrates the ability to voluntarily arouse itself during these periods.[16]
The species will climb a tree to evade capture.[17]
Distribution
The distribution range of the species is in the south of the Australian continent, all occurrences are recorded below the southern 30° line of latitude. The range in
The heath monitor is found in habitat close to sea level and at elevations below 1500
The distribution range overlaps with Varanus gouldii and individuals of these species are sometimes
Ecology
The favoured types of habitat Varanus rosenbergi is associated with plant communities are most often sandy heathland, open woodland or
Reproduction
The reproductive habits of Varanus rosenbergi are closely associated with termite constructions, the above ground nest-mounds of some species, and is thought to rely on these to produce offspring.[1] The use of termitaria provides the newly hatched progeny the favourable conditions within the nest, warmth and regulated humidity, when conditions outside retard the activity of adults. Several other monitor species adopt termitaria as nest sites, those utilized by V. rosenbergi offer regular internal temperatures for most of the year, usually around 30 °C, and do not fall below 20 °C at the coolest times of the year.[15]
Parasites
Varanus rosenbergi is known to be host to nine species of intestinal nematodes, parasites known as roundworm, and is recorded near undisturbed habitat with high infection rates of Abbreviata, physalopteroid species of the Spirurida order.[19]
Individuals often carry blood-feeding ticks lodged to their skin, these are found around the cloaca or base of the tail or seeking areas of high blood flow at the head and neck by the female tick when pregnant. The infestation rate in the southwest region is around half of the adults and is absent in juveniles, the Kangaroo Island population has a higher rate, around 85% of those surveyed carrying the species
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South Australia, Kangaroo Island
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South Australia, Kangaroo Island
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South Australia, Kangaroo Island
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South Australia, Kangaroo Island
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Western Australia, Stirling Range
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Western Australia
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Western Australia, Cape Arid National Park
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Juvenile
References
- ^ a b c d e f g h i j Bennett, D., Sweet, S., Sanderson, C., Craig, M., Gaikhorst, G. & Lloyd, R. 2018. Varanus rosenbergi. The IUCN Red List of Threatened Species 2018: e.T178031A101744611. Downloaded on 17 July 2019
- ^ Varanus rosenbergi. ITIS.
- ^ Varanus gouldii rosenbergi Mertens, R. 1957. Ein neur melanisticher Waran aus dem Südlichen. Australien. (V. gouldii rosenbergi, subsp. nov.). Zoologischer Anzeiger 159: 17-20 [18].
- ^ Storr, G.M. (1980). "The monitor lizards (genus Varanus Merrem, 1820) of Western Australia". Records of the Western Australian Museum. 8 (2): 237–293.
- ^ ISBN 9780253343666.
- ^ BÖHME, WOLFGANG (1 January 2003). "Checklist of the living lizards of the world (family Varanidae)". BMC Evolutionary Biology - BMC EVOL BIOL. 341.
- ^ a b "Australian Faunal Directory". biodiversity.org.au.
- ^ .
- ISBN 978-1-4214-0135-5. (Varanus rosenbergi, p. 226).
- ^ Pantherosaurus kuringai Wells, R.W. & Wellington, C.R. 1985. A classification of the Amphibia and Reptilia of Australia. Australian Journal of Herpetology Supplementary Series 1: 1-61 [22]
- ^ a b Rosenberg's Goanna - profile. Threatened Species. Environment and Heritage. NSW Government.
- ^ Thompson, G.G. (2001). "The feasibility of using body proportions in Western Australian varanids (Varanus) as a method for determining a specimen's sex". Records of the Western Australian Museum. 20: 437–439.
- S2CID 45223790.
- S2CID 89687607.
- ^ a b c Rismiller, P.; McKelvey, M.; Green, B. (1999). "The behaviour and energetics of hatchling Varanus rosenbergi". Mertensiella. 11: 105–112.
- ISBN 9783662041628.
- ^ 'Eco Logical Australia 2016. Ginninderry Project, Rosenberg's Goanna habitat assessment. Prepared for the Riverview Group.'
- ^ Hayter, Rachel (23 November 2019). "These goannas are surviving against the odds in an unusual place, and scientists are baffled". ABC News. Retrieved 7 April 2020.
- .
Further reading
- King, R. A., et al. Varanoid Lizards of the World. Bloomington: Indiana University Press. 2007. pg. 225–29. ISBN 0-253-34366-6.
- King, D. & B. Green. Goannas: The Biology of Varanid Lizards. University of New South Wales Press. 1999. ISBN 0-86840-456-X
- Rismiller, P., et al. (2007). Life history studies of Rosenberg's goanna (Varanus rosenbergi) on Kangaroo Island, South Australia. Biawak 1(1): 42–43.
External links
- Varanus rosenbergi. The Reptile Database.