Lace monitor

Bell's phase lace monitor

John White, the surgeon-general of New South Wales, described this species as the variegated lizard (Lacerta varia) in 1790.[4] George Shaw reported that several specimens were taken back to England.[5] French naturalist François Marie Daudin gave it the name Tupinambis variegatus in 1802, and noted two forms.[6] German naturalist Blasius Merrem established the genus Varanus in 1820,[7] with V. varius as the first mentioned member set as its type species by John Edward Gray in 1827.[8]

French zoologists André Marie Constant Duméril and Gabriel Bibron described two specimens in 1836, one in their possession and one from the collection of English zoologist Thomas Bell as Varanus bellii "Le Varan de Bell".[9] This turned out to be a banded colour phase of the lace monitor that coexists with normal-coloured individuals, and is either autosomal dominant or codominant genetically.[10] It is sometimes called the Bell's phase lace monitor.[10]

The lace monitor is monotypic; no subspecies are recognised. However, genetic analysis of its mitochondrial DNA (mtDNA) across its range revealed three main clades: a north Queensland clade separated by the Burdekin Gap from a clade spanning from southern Queensland through inland New South Wales across the Murray–Darling basin and into southeastern South Australia. This is divided from a third clade that spans coastal eastern Australia (northern New South Wales to eastern Victoria) by the McPherson Range and Great Dividing Range. This last clade is thought to have diverged from the first two clades around 2.7 million years ago, while these clades separated around 850,000 years ago.[11]

Genetic analysis of mtDNA shows the lace monitor to be the closest relative (sister taxon) of the Komodo dragon, with their common ancestor diverging from a lineage that gave rise to the crocodile monitor (Varanus salvadorii) of New Guinea.[12][13][14] The divergence between lace monitor and Komodo dragon lineages has been calculated to have occurred around 13 million years ago,[12] or 11.5 million years ago.[11]

The species is commonly known as lace monitor, tree goanna, or lacy.[15] It was known as wirriga to the Eora and Darug inhabitants of the Sydney basin,[16] and gugaa to the Wiradjuri people of southern New South Wales.[17]

Goanna head

The second-largest monitor in Australia after the perentie, the lace monitor can reach 2 m (7 ft) in total length, or 76.5 cm snout–vent length (SVL), and weigh up to 14 kg (30 lb). The male reaches sexual maturity when it has a SVL of 41.5 cm. Females are generally smaller than males, with a maximum SVL of 57.5 cm, and becoming sexually mature at a SVL of 38.5 cm.[15] The tail is long and slender and about 1.5 times the length of the head and body.[18][19] The tail is cylindrical at its base, but becomes laterally compressed towards the tip.[20]

Historically, it has been described as growing as much as 8 ft long. Regardless of the accuracy of these reports, lace monitors of such size likely no longer exist.[21]

Argus monitor (left), lace monitor (right)

Close up of lace monitor in Healesville Sanctuary, Victoria, Australia

These common terrestrial and often arboreal monitors are found in eastern Australia and range from Cape Bedford on Cape York Peninsula to south-eastern South Australia. They frequent both open and closed forests and forage over long distances (up to 3 km (1.9 mi) a day).

The lace monitor is considered to be a least-concern species according to the International Union for Conservation of Nature.[1]

They are mainly active from September to May, but are inactive in cooler weather and shelter in tree hollows or under fallen trees or large rocks.

Males fighting

Despite its large size and mass, the lace monitor is an adept climber. One was recorded climbing a brick wall to seek shelter in a thunderstorm.[22] Young lace monitors are even more arboreal than adults. They often spend most of their adult lives in the same area; one individual was recorded living in the same tree for years.[23]

A field study in Burragorang, New South Wales found that males over 5 kg ranged over home territories of 65.5 ± 10.0 hectares. They moved around much less in winter.[24]

Venom glands in lace monitors have been confirmed. The venom is similar to that produced by snakes but not enough to cause serious harm.[33] In late 2005, University of Melbourne researchers discovered that all monitors may be somewhat venomous. Previously, bites inflicted by monitors were thought to be prone to infection because of bacteria in their mouths, but the researchers showed that the immediate effects were more likely caused by envenomation. Bites on the hand by lace monitors have been observed to cause swelling within minutes, localised disruption of blood clotting, and shooting pain up to the elbow, which can often last for several hours.[34]

In vitro testing showed lace monitor mouth secretion impacts on platelet aggregation, drops blood pressure and relaxes smooth muscle; the last effect mediated by an agent with the same activity as brain natriuretic peptide. Liquid chromatography/mass spectrometry found ample proteins with molecular masses of 2-4 kilodaltons (corresponding with natriuretic peptide), 15 kilodaltons (type III Phospholipase A2), and 23-25 kilodaltons (cysteine-rich secretory proteins and kallikrein) in these secretions.[34]

Washington State University biologist Kenneth V. Kardong and toxicologists Scott A. Weinstein and Tamara L. Smith, have cautioned that labelling these species as venomous oversimplifies the diversity of oral secretions in reptiles, and overestimates the medical risk of bite victims.[35]

The lace monitor was eaten by the Wiradjuri people; local wisdom advised eating lace monitors that came down from trees as those that had eaten on the ground tasted of rotting meat.[17] The Tharawal ate the species' eggs, collecting them in sand on riverbanks in the Nattai and Wollondilly.[36] Goanna remains have been recovered in middens in what is now Sydney.[37] The lace monitor is bred in captivity as an exotic pet.

• 
  Molting in Queensland
• 
  Goanna coming down a tree outside Cooktown, Queensland
• 
  Climbing a tree
• 
  Climbing a tree
• 
  Wild lace monitor in Brisbane Forest Park, Queensland
• 
  Variety: Common form of patterning, Cairns, Queensland
• 
  Varanus varius prowling demonstrating camouflage
• 
  Lace monitor climbing a tree
• 
  Lace monitors fighting
• 
  Lace monitor (Glenrock State Conservation Area), Newcastle, New South Wales
• 
  Lace monitor at the pass, Byron Bay, New South Wales
• 
  Head closeup
• 
  Lace Monitor at Peacock - Richmond Range National Park
• 
  Yeramba Lagoon

• King, Dennis & Green, Brian. (1999). Goannas: The Biology of Varanid Lizards. University of New South Wales Press. ISBN 0-86840-456-X
• Wilson, Steven & Swan Gerry (2003). A Complete Guide to Reptiles of Australia. Reed New Holland Australia ISBN 1-876334-72-X
• Wilson, Stephen K. (1985). Australia's Reptiles. ISBN 0-207-17707-4.