The yellow-spotted monitor (''Varanus panoptes''), also known as the Argus monitor, is a

monitor lizard 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 rec ...

found in northern and western regions of

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

and southern

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...

Taxonomy

The first description of the species was provided in a revision of the varanids of Western Australia, where the family is represented by diverse taxa in a wide variety of habitats. Early collections and descriptions of the region's species have historically been uncertain, leading the

ICZN The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the I ...

to issue an opinion that related to this taxon. A third subspecies was published in 1988, based on specimens from southern New Guinea. The describing author discovered that the specimen selected as the type of ''

Varanus gouldii The sand goanna (''Varanus gouldii'') is a species of large Australian monitor lizard, also known as Gould's monitor, sand monitor, or racehorse goanna. Taxonomy John Edward Gray described the species in 1838 as ''Hydrosaurus gouldii'', noting ...

'' was in fact assignable to this species, recently described by reptile specialist Glenn Storr. By issuing an opinion on the various taxonomic considerations, the voting members conserved the name published with

John Edward Gray John Edward Gray, FRS (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used f ...

's description and stabilised the nomenclature of this species name. Three

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. Not all specie ...

are recognised by the

Australian Faunal Directory The Australian Faunal Directory (AFD) is an online catalogue of taxonomic and biological information on all animal species known to occur within Australia. It is a program of the Department of Climate Change, Energy, the Environment and Water T ...

and the

Reptile Database The Reptile Database is a scientific database that collects taxonomic information on all living reptile species (i.e. no fossil species such as dinosaurs). The database focuses on species (as opposed to higher ranks such as families) and has entrie ...

: * ''Varanus panoptes rubidus'' Storr, 1980. The holotype of this subspecies was obtained near

Cue, Western Australia Cue is a small town in the Mid West region of Western Australia, located 620 km north-east of Perth. At the 2016 census, Cue had a population of 178. Cue is administered through the Cue Shire Council, which has its chambers in the historic ...

, at the midwest of the continent, and the population is endemic to the north and west of that state. (rubidus referring to its reddish coloration) *''Varanus panoptes panoptes'', Storr, 1980. The nominate subspecies occurring across the north of mainland Australia,

Arnhem Land Arnhem Land is a historical region of the Northern Territory of Australia, with the term still in use. It is located in the north-eastern corner of the territory and is around from the territory capital, Darwin. In 1623, Dutch East India Compa ...

, the Kimberley and

Cape York Peninsula Cape York Peninsula is a large peninsula located in Far North Queensland, Australia. It is the largest unspoiled wilderness in northern Australia.Mittermeier, R.E. et al. (2002). Wilderness: Earth’s last wild places. Mexico City: Agrupación ...

. * ''Varanus panoptes horni'', Böhme, 1988. A population that discovered in southern

that was recognised as having a close affinity to the description of this species. It is also known as Horn's monitor. The epithet ''panoptes'' was inspired by a mythological figure with one hundred eyes, the protector of Princess Io named

Argus Panoptes Argus or Argos Panoptes ( grc, Ἄργος Πανόπτης, All-seeing Argos) is a many-eyed giant in Greek mythology. Mythology Argus Panoptes (), guardian of the heifer-nymph Io and son of Arestor and probably Mycene (in other version so ...

. The species may be referred to as the floodplains goanna in the northern regions of Australia.

Description

A ground-dwelling species of '' Varanus'', it somewhat resembles the widespread

sand goanna The sand goanna (''Varanus gouldii'') is a species of large Australian monitor lizard, also known as Gould's monitor, sand monitor, or racehorse goanna. Taxonomy John Edward Gray described the species in 1838 as ''Hydrosaurus gouldii'', noting ...

(''Varanus gouldii''). Large, dark spots appear in rows along its back, becoming especially distinct at the center of the back where they are interspersed with smaller and paler spots. Bands of color occur toward the tip of the tail. The overall coloration is brownish in the nominate subspecies, ''V. panoptes panoptes'', and reddish in ''V. panoptes rubidus''. Argus Monitor and Lace Monitor

The yellow-spotted monitor displays great

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

, with the female reaching an average total length of three feet (90 cm), while the male reaches an average of . The largest specimens can have a length in and a mass in . It's the third largest lizard in

, after

perentie The perentie (''Varanus giganteus'') is the largest monitor lizard or goanna native to Australia. It is one of the largest living lizards on earth, after the Komodo dragon, Asian water monitor, crocodile monitor, and intersecting by size with ...

and

lace monitor The lace monitor or tree goanna (''Varanus varius'') is a member of the monitor lizard family native to eastern Australia. A large lizard, it can reach in total length and in weight. The lace monitor is considered to be a least-concern species ...

. The larger subspecies is ''V. panoptes panoptes'' and the smaller one is ''V. panoptes horni''. It is a reasonably lean monitor and does not put on the bulk that other monitors in Africa and Asia do. Most ''Varanus panoptes'' are yellow in color, with a background of brown or dark tan, but their color often varies on an individual basis or on their place of origin.

Breeding

, they lay 6 to 13

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

between January and February. Due to similar genetic structures, the yellow-spotted monitor is able to naturally hybridise with the Gould's monitor with a stable

hybrid zone A hybrid zone exists where the ranges of two interbreeding species or diverged intraspecific lineages meet and cross-fertilize. Hybrid zones can form ''in situ'' due to the evolution of a new lineage but generally they result from secondary contact ...

Behavior

''Varanus panoptes'' is a versatile

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill t ...

and inhabits a large variety of

biomes A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...

and

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s. They are primarily terrestrial, meaning they spend a great deal of time on the ground. This species is an avid digger and will dig large burrows or take over an already existing burrow, where they spend a sizable portion of their time. Despite this, they will eagerly

forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also use ...

in trees and in the water. These large lizards are quite fast and will run up to 100 meters away to the nearest tree or burrow when they are chased. ''Varanus panoptes'' is

riparian A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks a ...

in habits and as such, it can usually be found around a permanent source of water. ''Varanus panoptes'' will often "tripod" in

captivity Captivity, or being held captive, is a state wherein humans or other animals are confined to a particular space and prevented from leaving or moving freely. An example in humans is imprisonment. Prisoners of war are usually held in captivity by a ...

and in the wild, raising up on their hind legs and supporting themselves with their tail. This unusual behavior is used to spot potential prey or enemies from a distance or when they are threatened. They exhibit this behavior regularly in captivity. This habit provides them a unique characteristic that separates them from most other monitors. Its

prey Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

consists of almost anything that it can overpower. This includes

fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all th ...

s, small

birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

rodents Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of j ...

and even other

monitors Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, West ...

. They hunt for prey by keying in on movement, chasing it down and overpowering it. In captivity, this monitor has been observed swinging rodent prey around rapidly by the tail in what appears to be an attempt to stun the animal, before biting at the prey's neck. ''Varanus panoptes'' frequently preys on the dwarf monitors that it shares its range with. Spiny-tailed goannas and Kimberley rock monitors are eaten regularly. ''Varanus panoptes'' have great senses, with smell being the most acute. Like all monitors, ''Varanus panoptes'' has a forked tongue and a

vomeronasal organ The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth (the hard palate) in various tetrapo ...

in the roof of its mouth. It uses this organ in the same manner as snakes and other varanids do and can often be seen flicking their tongues in search of a meal. Recent studies suggest that the infestation of

cane toads The cane toad (''Rhinella marina''), also known as the giant neotropical toad or marine toad, is a large, terrestrial true toad native to South and mainland Central America, but which has been introduced to various islands throughout Ocean ...

, a novel and toxic species, has severely damaged the population structure of ''Varanus panoptes'' within the

Top End The Top End of Australia's Northern Territory is a geographical region encompassing the northernmost section of the Northern Territory, which aside from the Cape York Peninsula is the northernmost part of the Australian continent. It covers a ra ...

. It is estimated that numbers have dropped by as much as 90% in many areas.

In captivity

Many individuals of this species are captive bred as a conservation effort against poisoning from the cane toad infestation of the species’ native range and as

exotic pets An exotic pet is a pet which is relatively rare or unusual to keep, or is generally thought of as a wild species rather than as a domesticated pet. The definition varies by culture, location, and over time—as animals become firmly enough est ...

. ''Varanus panoptes'' are fed insects, fish and mice. ''V. panoptes'' are husky lizards that can be a challenge to physically handle. They do not like to be restrained, and can use their sharp claws in their attempts to squirm free. If left to wander freely on open ground, their ability to suddenly flee makes escape likely. ''V. panoptes'' prefer to bask each morning and return to bask as needed to maintain optimal body temperatures at . Night-time temperatures may drop or more if the opportunity to warm up the next day exists.

References

Other sources

*Akeret, B. 2006. Bau einer Großterrarienanlage für Warane und Hornvipern. Draco 7 (26): 38- *Anonymous 2000. ''Hydrosaurus gouldii'' Gray, 1838 (currently ''Varanus gouldii'') and ''Varanus panoptes'' Storr, 1980 (Reptilia, Squamata): specific names conserved by the designation of a neotype for H. gouldii. Bull. Zool. Nomenclature 57 (1): 63-65 *Bennet, D.F. 2003. Australische Warane. Reptilia (Münster) 8 (5): 18-25 *Bennet, D.F. 2003. Der Varanus-gouldii-Komplex. Reptilia (Münster) 8 (5): 26-28 *Bennet, D.F. 2003. Australian Monitors. Reptilia (GB) (30): 12-19 *Bennet, D.F. 2003. The ''Varanus gouldii'' group. Reptilia (GB) (30): 27-29 *Böhme, W. 1988. Der Arguswaran (''Varanus panoptes'', Storr 1980) auf Neuguinea: ''Varanus panoptes horni'' spp. n. Salamandra 24 (2/3): 87-101. *Böhme,W. 2003. Checklist of the living monitor lizards of the world (family Varanidae). Zool. Verhand., Leiden 341: 6-43 *Böhme,W. & T. ZIEGLER 1998. Comments on the proposed conservation of the names ''Hydrosaurus gouldii'' Gray, 1838 and Varanus panoptes STORR, 1980 (Reptilia, Squamata) by the designation of a neotype for ''Hydrosaurus gouldii'' (Case 3042; see BZN 54: 95-99, 249-250; 55: 106-111). Bull. Zool. Nomenclature 55 (3): 173-174. *Cogger, H.G. (2000). Reptiles and Amphibians of Australia, 6th ed. Ralph Curtis Publishing, Sanibel Island, 808 pp. *Lenk, P.; Eidenmueller, B.; Staudter, H.; Wicker, R.; Wink, M. 2005. A parthenogenetic Varanus. Amphibia-Reptilia 26 (4): 507-514 *Packard, Gary C. and THOMAS J. BOARDMAN 2009. Bias in interspecic allometry: examples from morphological scaling in varanid lizards. Biological Journal of the Linnean Society, (2009), 96, 296–305. *Schardt, M. (2000). Aktuelle Übersicht zur Nomenklatur der australischen "Gouldswarane" sowie Angaben zur Haltung und Nachzucht von ''Varanus panoptes panoptes'' Storr, (1980). Herpetofauna 22 (129): 22-32 *Sprackland R G.; Smith H M. & Strimple P D. 1997. ''Hydrosaurus gouldii'' Gray, 1838 (currently ''Varanus gouldii'') and ''Varanus panoptes'' Storr, 1980 (Reptilia, Squamata): Proposed conservation of the specific names by the designation of a neotype for ''H. gouldii''. Bulletin of Zoological Nomenclature 54 (2): 95-99. {{Taxonbar, from=Q652309 Varanus Monitor lizards of New Guinea Monitor lizards of Australia Reptiles of the Northern Territory Reptiles of Queensland Reptiles of Western Australia Reptiles of Papua New Guinea Reptiles of Western New Guinea Reptiles described in 1980 Taxa named by Glen Milton Storr