Spiny-tailed monitor

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Spiny-tailed monitor
Spiny-tailed-monitor.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Varanidae
Genus: Varanus
Subgenus: Odatria
Species:
V. acanthurus
Binomial name
Varanus acanthurus
Boulenger, 1885
Subspecies
  • V. a. acanthurus
  • V. a. brachyurus
  • V. a. insulanicus
Spiny-tailed Monitor.png
Distribution of the spiny-tailed monitor
"Red ackie" (V. a. acanthurus) RedAckie.jpg
"Red ackie" (V. a. acanthurus)

The spiny-tailed monitor [2] (Varanus acanthurus), also known as the Australian spiny-tailed monitor, the ridge-tailed monitor [3] the Ackie dwarf monitor, and colloquially simply ackie monitor, [4] is an Australian species of lizard belonging to the genus of monitor lizards (Varanus).

Contents

Description

The spiny-tailed monitor, a somewhat small monitor lizard, can attain a total length of up to 70 cm (27 in), although there are unconfirmed reports of wild individuals growing up to 34 inches. [5] The tail is about 1.3-2.3 times as long as the head and body combined. The upper side is a rich, dark brown and painted with bright-yellowish to cream spots, which often enclose a few dark scales. Its tail is round in section and features very spinose scales. There are 70-115 scales around the middle of the body. [3] The spiny-tailed monitor is distinguished from the similar-looking species V. baritji and V. primordius by the presence of pale longitudinal stripes on the neck. [2]

Distribution and habitat

This arid-adapted [6] lizard is found in northern Western Australia, in the Northern Territory and in the western and north-western parts of Queensland. [6] The spiny-tailed monitor inhabits is associated with arid rocky ranges and outcrops. [2] [3] V. a. acanthurus is native to northern Australia, from Broome on the west coast, through the Kimberley and the Top End, to the Gulf of Carpentaria. V. a. brachyurus can be found in the center, western, and eastern parts of the ackie's total range, as far west as Carnarvon and as far east as Mt. Isa. V. a. insulanicus' range is limited to Groote Eylandt and the Wessel Islands. [7]

Subspecies and taxonomy

The spiny-tailed monitor is part of an Indonesian and Australian radiation of dwarf monitor lizards, the subgenus Odatria . [8] [9]

Three subspecies of V. acanthurus are recognized:

Varanus primordius was at one point considered a subspecies (V. a. primordius), but has since been elevated to full species status.

In the pet trade, two "variants" of spiny-tailed monitors are commonly available. The "red ackie" monitor is likely the subspecies V. a. acanthurus, while the "yellow ackie" is likely V. a. brachyurus. The red ackie is generally larger and less commonly available than the yellow ackie. [5] [11]

The taxonomic status of the three subspecies is uncertain. [10] In 2006, the results of a study on the mtDNA of Australian monitors were published, according to which the two continental subspecies do not form natural (monophyletic) taxonomic entities. V. a. insulanicus was found to be monophyletic, but it is more closely related to V. baritji than to other V. acanthurus. Therefore, V. a. insulanicus might represent a distinct species. [9] Wilson and Swan (2010) still accept V. a. insulanicus as a valid subspecies of V. acanthurus, which is easily distinguished from other spiny-tailed monitors by its dark colouration and more banded pattern. [2]

Two spiny-tailed monitors at the Cincinnati Zoo Varanus acanthurus25.JPG
Two spiny-tailed monitors at the Cincinnati Zoo
Head view Ackies Dwarf Monitor.jpg
Head view

Ecology

Spiny-tailed monitors are diurnal, typically solitary ground-dwellers. This species is most often found in its shelter, mainly under rock slabs, wedged among boulders or in rock crevices, and in burrows. Only rarely do they hide in spinifex. [3] Sheltering underground gives them access to humid microclimates which helps keep them hydrated enough to survive the otherwise arid nature of their habitat. Their diet is consistent with the diet of intensive foragers, implying that they likely spend quite a bit of their time hunting. [12]

Diet

They prey mainly on arthropods, such as grasshoppers, beetles, cockroaches, spiders, isopods, caterpillars, cicadas, snails, stick insects, centipedes, crickets, and ticks. [12] Small lizards such as skinks, geckos, dragon lizards, or possibly smaller monitor lizards are also eaten, making up about a third of its diet, as well as marsupial joeys. [13] [14] [15] Approximately 70% of its water requirement comes from food. [6]

In captivity, they are sometimes fed cat and dog food as well as processed canned food. This isn't recommended as this type of food doesn't contain the correct nutrients for this species. [16] A varied diet rich with different vertebrate and invertebrate prey (such as Dubia roaches, crickets, mealworms, eggs, shrimp, and, on a monthly basis, rodents) is important to the health of captive spiny-tailed monitors, as they naturally have a wide range of prey in the wild. [12] [17]

Reproduction

There are a number of methods of sexing ackie monitors, although the hemipenal transillumination technique [18] is generally considered to be the easiest and most accurate. Sex can also be guessed using visual markers, but it is typically not nearly as accurate. Male ackie monitors are generally larger, have blockier heads, and have grippy scales on the underside of their tail. Females are generally smaller with narrower, pointier heads, and smooth scales under their tail.[ citation needed ]

In captivity, a clutch consists of up to 18 eggs. The young hatch after three to five months of incubation, and measure 15 cm (6 in). The knowledge on reproduction in the wild is sparse. Males most likely mature at 30 cm (12 in) snout-vent length, females mature at 25–36 cm (10–14 in) snout-vent length. Ovulation occurs in August and November. The eggs are deposited in self-dug tunnels. [6] In the wild, females have been shown to share massive burrows, nesting communally. [19]

Related Research Articles

<span class="mw-page-title-main">Monitor lizard</span> Genus of reptiles

Monitor lizards are lizards in the genus Varanus, the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recognized.

<span class="mw-page-title-main">Bengal monitor</span> Species of lizard

The Bengal monitor, also called the common Indian monitor, is a monitor lizard distributed widely in the Indian Subcontinent, as well as parts of Southeast Asia and West Asia. This large lizard is mainly a terrestrial animal, and its length ranges from about 61 to 175 cm from the tip of the snout to the end of the tail. Young monitors may be more arboreal, but adults mainly hunt on the ground, preying mainly on arthropods, but also taking small terrestrial vertebrates, ground birds, eggs and fish. Although large Bengal monitors have few predators apart from humans who hunt them for meat, younger individuals are hunted by many predators.

<span class="mw-page-title-main">Desert monitor</span> Species of lizard

The desert monitor is a species of monitor lizard of the order Squamata found living throughout North Africa and Central and South Asia. The desert monitor is carnivorous, feeding on a wide range of vertebrates and invertebrates.

<span class="mw-page-title-main">Asian water monitor</span> Species of lizard

The Asian water monitor is a large varanid lizard native to South and Southeast Asia. It is one of the most common monitor lizards in Asia, ranging from coastal northeast India, Bangladesh, Sri Lanka, mainland Southeast Asia, and southern China to Indonesian islands where it lives close to water. It is listed as Least Concern on the IUCN Red List. It was described by Laurenti in 1768 and is among the largest squamates in the world.

<span class="mw-page-title-main">Sand goanna</span> Species of lizard

The sand goanna, also known commonly as Gould's monitor, the racehorse goanna, and the sand monitor, is a species of large Australian monitor lizard in the family Varanidae.

<span class="mw-page-title-main">Black tree monitor</span> Species of reptile

The black tree monitor or Beccari's monitor is a species of lizard in the family Varanidae. The species is a relatively small member of the family, growing to about 90–120 cm (35–47 in) in total length. V. beccarii is endemic to the Aru Islands off New Guinea, living in an arboreal habitat. The skin color of adults is completely black, to which one common name refers.

<span class="mw-page-title-main">Savannah monitor</span> Species of lizard

The savannah monitor is a medium-sized species of monitor lizard native to Africa. The species is known as Bosc's monitor in Europe, since French scientist Louis Bosc first described the species. It belongs to the subgenus Polydaedalus.

<span class="mw-page-title-main">Yellow-spotted monitor</span> Species of reptile

The yellow-spotted monitor, also known as the Argus monitor, is a monitor lizard found in northern and western regions of Australia and southern New Guinea.

<span class="mw-page-title-main">White-throated monitor</span> Subspecies of lizard

The white-throated monitor is a lizard found in southern Africa. They are usually gray-brown with yellowish or white markings, and can reach up to 2 metres (6.6 ft) in length. They are found in Southern Africa, northwards to Angola, Zambia, and Mozambique.

<span class="mw-page-title-main">Rock monitor</span> Species of reptile

The rock monitor is a species of monitor lizard in the family Varanidae. The species is endemic to Sub-Saharan Africa. It is on average the largest lizard found on the continent, and is locally called leguaan or likkewaan.

<span class="mw-page-title-main">Rosenberg's monitor</span> Species of lizard

The Rosenberg's monitor is an Australian species of varanid reptile found in southern regions of the continent. They are large and fast predators with rugged bodies and long tails, having a combined length up to 1.5 metres, that will consume any smaller animal that is pursued and captured or found while foraging. They occur in the Australian Capital Territory, New South Wales, South Australia, Victoria, where it may be rare or locally common, and more frequently observed in Western Australia, where it is sometimes abundant.

The black-spotted ridge-tailed monitor, also called commonly the black-spotted spiny-tailed monitor, the lemon-throated monitor, the northern ridge-tailed monitor, Whites monitor, and the yellow-throated monitor, is a subspecies of lizard in the family Varanidae. The subspecies is native to Australia's tropical Northern Territory. It is listed as Least Concern on the IUCN Red List as it is considered common and not threatened. It was first described in 1987. It is also known as White's dwarf goanna.

<span class="mw-page-title-main">Blue-tailed monitor</span> Species of lizard

The blue-tailed monitor, blue-tailed tree monitor or Kalabeck's monitor, is a monitor lizard of the Varanidae family. It belongs to the V. doreanus group of the subgenus Euprepiosaurus.

<span class="mw-page-title-main">Dumeril's monitor</span> Species of lizard

Dumeril's monitor is a species of lizard in the family Varanidae. The species is endemic to Southeast Asia.

<span class="mw-page-title-main">Black-palmed rock monitor</span> Species of lizard

The black-palmed rock monitor is a member of the Varanidae family found in Australia. Also known as the twilight monitor or the long-tailed rock monitor, it is a member of the subgenus Odatria, and is found in the northern part of Australia in the Northern Territory and Western Australia, as well as Queensland. Specifically, its distribution extends from Mount Isa in the east to the Kimberleys in the west. Its habitat is areas of rock escarpment, and large populations may be found in small areas.

<span class="mw-page-title-main">Mitchell's water monitor</span> Species of lizard

Mitchell's water monitor is a semiaquatic species of monitor lizard in the family Varanidae. The species is native to Australia. The species is native to the Northern regions of Australia, and is on IUCN's Red List as a critically endangered species. They can be distinguished by the orange or yellow stripes along their neck and dark spots along their back. They are mainly carnivorous, and eat small prey such as lizard, birds, and insects.

<i>Varanus spinulosus</i> Species of lizard

Varanus spinulosus, the Solomon Island spiny monitor, Isabel monitor, or spiny-neck monitor, is a species of monitor lizard. It is endemic to the Solomon Islands archipelago and is also known from Santa Isabel Island, San Jorge Island and Bourgainville Island.

<i>Varanus storri</i> Species of lizard

Storr's monitor is a species of monitor lizard in the family Varanidae. The species is endemic to Australia.

<i>Varanus <span style="font-style:normal;">(</span>Odatria<span style="font-style:normal;">)</span></i> Subgenus of reptiles

Odatria, commonly known as dwarf monitors, consists of small monitor lizards found in Australia and Indonesia. Species in this subgenus include the smallest monitor species in the world, the tiny 16 gram Dampier Peninsula monitor, but also includes some more medium sized species such as the 240 gram black-palmed rock monitor.

<i>Varanus <span style="font-style:normal;">(</span>Hapturosaurus<span style="font-style:normal;">)</span></i> Subgenus of reptiles

Hapturosaurus, sometimes known as the tree monitors, is a subgenus of lizards, consisting of slender-bodied arboreal monitor lizards mostly found in the tropical rainforests of Indonesia and Papua New Guinea.

References

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  2. 1 2 3 4 5 Wilson S, Swan G. 2010. A complete guide to reptiles of Australia. New Holland Publishers, Sydney, Auckland, London, Cape Town. ISBN   978-1-877069-76-5. P 392.
  3. 1 2 3 4 5 Cogger H. 2000. Reptiles & Amphibians of Australia. Ralph Curtis Publishing, Sanibel Island, Florida. ISBN   0-88359-048-4. Pp 359-361.
  4. "Cincinnati Zoo & Botanical Garden". Archived from the original on 2012-09-05. Retrieved 2012-08-28.
  5. 1 2 "Spiny-Tailed Monitor Lizard Care Tips". Reptiles Magazine. 2011-12-01. Retrieved 2020-08-29.
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  7. Monitor lizards natural history, captive care, breeding. Bernd Eidenmüller, Grant Husband (Rev., enl. and updated ed.). Frankfurt, M. 2007. ISBN   978-3-89973-471-3. OCLC   185009165.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)
  8. Böhme W. 2003. Checklist of the living monitor lizards of the world (family Varanidae). Zoologische Verhandelingen 341, pp 3–43.
  9. 1 2 Fitch AJ, Goodman AE, Donnellan SC. 2006. A molecular phylogeny of the Australian monitor lizards (Squamata:Varanidae) inferred from mitochondrial DNA sequences. Australian Journal of Zoology 54, p 253-269.
  10. 1 2 Auliya, Marc; Koch, André (2020). Visual Identification Guide for the Monitor Lizard Species of the World (Genus Varanus). Bundesamt für Naturschutz. doi:10.19217/skr552. ISBN   9783896242907.
  11. Kuhn, Peter; Julander, Justin (1999). "Husbandry and Captive Breeding of the Red Acanthurus Monitor Varanus acanthurus: A Giant Dwarf". Vivarium. 10.
  12. 1 2 3 King, Dennis (2008). "The Diet and Foraging Strategy of Varanus acanthurus" (PDF). Biawak. 2 (1): 11–17.
  13. Losos, Jonathan B.; Greene, Harry W. (1988-12-01). "Ecological and evolutionary implications of diet in monitor lizards". Biological Journal of the Linnean Society. 35 (4): 379–407. doi:10.1111/j.1095-8312.1988.tb00477.x. ISSN   0024-4066.
  14. "Ackie's Dwarf Monitor". 14 January 2021.
  15. "Varanus Acantiiurus".
  16. "Ackie Monitor". Reptile Range. Retrieved 9 August 2022.
  17. "Ackies Monitor Care: Size, Enclosure, Lifespan, Diet". 21 June 2020.
  18. Brown, Danny (2009). "Hemipenal Transillumination as a Sexing Technique in Varanids" (PDF). Biawak. 3 (1): 26–29.
  19. Doody, J. & Clulow, Simon & McHenry, Colin & Brown, Michael & Vas, Gary & Canning, Gordon. (2017). Varanus acanthurus (Spiny-tailed Monitor Lizard). Communal nesting and commensalism. Herpetological Review. 48. 203.