Ctenophorus spinodomus

Ctenophorus spinodomus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Iguania
Family:	Agamidae
Genus:	Ctenophorus
Species:	C. spinodomus
Binomial name
	Ctenophorus spinodomus; Sadlier, Colgan, Beatson, & Cogger, 2019
	Distribution of Ctenophorus spinodomus

Last updated November 01, 2023

Ctenophorus spinodomus commonly known as Eastern Mallee Dragon, is a species of agamid lizard endemic to the arid and semi-arid regions of southeastern Australia. Belonging to the genus Ctenophorus, which comprises a diverse group of 35 species this small lizard is characterised by striking colours and unique behaviours. Commonly known as dragon lizards, spinodomus is derived from the Greek words "spinos" (thorn) and "domos" (house), referring to its preference for burrowing habitats among spiny vegetation.^[1]

Description

The Eastern Mallee Dragon exhibits a range of physical features that distinguish it from other agamid lizards in the genus and which plays a crucial role in their survival.

Adult males have a continuous row of 15–22 femoral pores on each side, arranged in an arching pattern toward the midline and have a pale brown to medium sandy orange dorsal surface with a pale dorsolateral stripe bordered by dark edges. They also feature dark blotches on the dorsal surface, while the upper-lateral surface displays large dark markings. The mid-lateral surface exhibits a pale stripe, sometimes with scattered flecks. The tail has pale spots along the dorsolateral edge and the side of the tail is dark, forming a distinct stripe bordered by a pale stripe for the basal third.^[1] The ventral surface is pale with dark scattered speckling on the throat and a dark chest patch broken by white flecks which may align along the midline forming a poorly defined T-shape.^[1]

Adult females have a similar pattern but with lighter tones, and the ventral surface lacks significant dark markings.^[2] They can also be identified by the presence of a fine, typically uninterrupted pale dorsolateral stripe extending from the neck to just past the hind limbs.^[1]

Eastern Mallee Dragons are relatively small typically growing to around 15.5–18 cm in total length ^[3] with adult females being generally larger than males in body size.^[1] Adult males have longer tails and hind limbs than females with tail length approximately 2.1–2.4 times the body length in males and 1.95–2.15 times in females.^[1]

Taxonomy

Recent taxonomic revisions in the classification of Australia’s agamid lizards have led to the discovery of numerous new species with considerable ecological and morphological diversity.^[2] Researchers have studied the relationships between these species and found there are several subgroups that share a common ancestor with species delimitation methods, supporting their differentiation.^[2]

Previous populations of the Mallee Military Dragon (Ctenophorus fordi) found within the Triodia Mallee habitat of inland southeast Australia showed significant differences in their physical features to other populations of the species, having evolved separately due to their geographical isolation, and were reclassified in 2019 as the Eastern Mallee Dragon.^[1]

Distribution and Habitat

The Eastern Mallee Dragon is endemic to the eastern Mallee region of Australia, encompassing the red sand-plains and Mallee woodlands of south central and south western New South Wales and along the northern side of the Murray River into South Australia.^[2] It is well adapted to the arid and semi-arid landscapes of this region with its range highly restricted to the presence of Triodia hummock grass for foraging, shelter and social interactions.^[3] Triodia hummock grass occurs as a groundcover associated with Mallee woodlands in what is known as Triodia Mallee vegetation, with Eastern Mallee Dragons also requiring this habitat to be in combination with a red sand substrate to provide nesting and overwintering sites.^[1]

Ecology

Eastern Mallee Dragons are diurnal, terrestrial ^[3] agamid lizards which follow a primarily annual life cycle, though some individuals may extend into a second, and rarely a third, season. A significant increase in adult mortality begins in late December and continues into January, resulting in the loss of as much as 85% of the population during this period.^[1]

Males tend to have larger home ranges, averaging around 0.032 hectares, while females exhibit smaller home ranges, with an average of about 0.015 hectares. Juveniles have even smaller ranges, approximately 0.007 hectares, compared to adults. Notably, there is minimal shift in home range size, migration is negligible and territorial behaviour has not been observed among these lizards.^[1]

The species is more common in landscapes featuring extensive Triodia Mallee vegetation and their presence is particularly associated with a substantial coverage of spinifex and the presence of healthy, large hummocks, which typically occurs around 20–50 years post-fire, with a peak around 35 years. After this peak period, population densities gradually decline.^[1] They follow a diel (24 hourly) cycle based on the utilisation of Triodia clumps at different times of the day. Like many reptiles, Eastern Mallee Dragons are ectothermic and rely on external heat sources to regulate their body temperature.^[1] They are often seen basking in the sun, especially in the morning and late afternoon. During the night, individuals seek shelter within Triodia and bask among the spines of the clump to attain a suitable body temperature for activity.^[1] Upon emergence, they tend to remain within a few meters and during the hottest part of the day, retreat within the nearest Triodia clumps, where humidity levels are higher than the ambient environment, and the temperature is notably lower than the surroundings, especially compared to the substrate.^[1] During the winter period, few individuals remain inactive within Triodia and instead observations suggest that they dig into the soil and seek shelter underground.^[1]

Reproduction

Eastern Mallee Dragons are oviparous, meaning they lay eggs. The breeding season typically occurs in the warmer months of the year, with egg-laying often taking place in late spring or early summer, and the highest egg deposition rates typically around mid-November.^[1] Males compete by engaging in combat displays including head-bobbing and tail-waving, to establish dominance and attract females.^[2] Females usually lay clutches of 2-3 eggs, burying them in a well-prepared underground nest chamber which is constructed and sealed on the same day as laying.^[1] Incubation takes place in the warm, protected environment of the nest, with hatching occurring in under 8 weeks. Hatchlings are relatively independent from birth and must fend for themselves, with an average of only 20% of hatchlings reaching reproductive maturity.^[1]

Diet

Eastern Mallee Dragons feed almost exclusively on ants, foraging in open areas adjacent to spinifex and are also known to be opportunistic feeders consuming other insects.^[4]

Threats

As a habitat specialist the Eastern Mallee Dragon is highly susceptible to habitat loss and increased predation as Triodia Mallee vegetation is fragmented due to agricultural land clearing and natural processes such as fire.^[1] These lizards are rarely detected in remnant patches however occur in high abundance in reserve areas.^[5] Eastern Mallee Dragons spend successional stages of development Triodia hummocks post fire and one outcome of extensive wildfires is the formation of a widespread, uniform age group of regenerating Triodia Mallee. In cases where entire fragments are completely burned and there is no internal population for recolonisation, there is potential for the local extinction of the Eastern Mallee Dragon.^[1]

Related Research Articles

Ctenophorus is a genus of lizards, commonly known as comb-bearing dragons, found in Australia. They are in the dragon lizard family, known as Agamidae.

The Australian water dragon, which includes the eastern water dragon and the Gippsland water dragon subspecies, is an arboreal 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 species 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 southern ningaui is a tiny marsupial carnivore belonging to the Dasyuridae family. Similar in appearance to Ningaui ridei, found throughout central Australia, this species occurs in spinifex on semi-arid sandplains across the southern coast of the continent. The fur is a tawny or greyish olive colour, light grey below, and distinguished by shades of cinnamon. The southern ningaui prefers smaller prey, including insects and spiders, but capable of killing and consuming larger animals such as cockroaches and skinks. Their narrow muzzle is used with quick and fierce bites about the head to despatch their meal. The species was first described in 1983, and placed within the genus Ningaui.

The striated grasswren is a small, cryptically coloured ground-dwelling species of wren-like bird in the family Maluridae, endemic to Australia. It occupies a large discontinuous range across arid and semi-arid areas of western, central and southern Australia where it is associated with spinifex (Triodia) grass.

The mallee emu-wren is a species of bird in the Australasian wren family, Maluridae. It is endemic to Australia.

Ctenophorus maculosus, commonly known as the Lake Eyre dragon or salt-lake ground-dragon, is a species of agamid lizard endemic to South Australia. C. maculosus mainly inhabits the edges of salt lakes in South Australia, from which its common names are derived. It survives in this harsh habitat through adaptive mechanisms to tolerate high temperatures and lack of free water. The female C. maculosus possesses unique male rejection techniques which are currently the focus of further research.

<span class="mw-page-title-main">Central netted dragon</span> Species of lizard

The central netted dragon or central netted ground dragon is a species of agamid lizard occurring in a wide range of arid to semiarid regions of Australia. It is widespread across the continent, commonly found in open, sandy, desert habitats. It is a popular pet and can often be found in zoos.

Ctenophorus pictus, commonly known as the painted ground-dragon or painted dragon, is a species of lizard from the family Agamidae. It is endemic to the drier areas of southern and central Australia.

The Barrier Range dragon is an agamid lizard which has been newly described (2013) as a separate species from the tawny dragon. This species is endemic to Australia, restricted to just three sites in western New South Wales (NSW).

Strophurus elderi, also known commonly as the jewelled gecko, is a terrestrial, nocturnal species of gecko, a lizard in the family Diplodactylidae. Previously classified within the genus Diplodactylus, S. elderi is one of 22 geckos belonging to the genus Strophurus. The species is endemic to the arid regions of central and north-western Australia.

The gibber earless dragon also known as the smooth-snouted earless dragon, is a species of agamid lizard endemic to Australia. It is one of a documented species of the genus Tympanocryptis, a group of small terrestrial lizards that feed off invertebrates and are characterised by the absence of an external ear structure.

The Mallee military dragon, also commonly known as the Mallee dragon and the Mallee sand-dragon, is a species of lizard in the family Agamidae. The species is native to the arid parts of southern Australia.

Ctenophorus gibba, commonly known as the bulldust ground-dragon or gibber dragon, is a species of agamid lizard occurring in the sparsely vegetated gibber plains of northern South Australia.

<i>Ctenophorus isolepis</i> Species of lizard

Ctenophorus isolepis, commonly known as the central military dragon, military dragon or military sand dragon, is a species of agamid lizard occurring in the arid parts of central and western Australia.

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Ctenophorus caudicinctus, commonly known as the ring-tailed dragon or ring-tailed bicycle-dragon is a native species of agamid lizard occurring in rocky ranges and outcrops of Australia. Ctenophorus caudicinctus is most commonly found in the Pilbara region and offshore islands of Western Australia. The ctenophorus has 28 known species in the northern, southern, and western parts of Australia. It is recognized to be the most speciose group of Australian agamids.

Ctenophorus mckenziei, more commonly known as the dwarf-bicycle dragon, is a species of endemic Australian lizard within the family Agamidae and genus Ctenophorus. Originally identified as the agamid Amphibolurus mckenziei, the lizard had been identified within the regions of Western Australia and South Australia in which it occupied the shrubbery and woodland areas as its habitat. It was subsequently transferred to the genus Ctenophorus along with other Agamid species in which it shared similar morphology and characteristics. The name mckenziei is in reference to Norman Leslie Mckenzie, who was a zoologist and discovered the existence of the lizard. Listed on the IUCN red list page, threats to its population numbers are evaluated as least concern; however, their numbers are threatened by habitat loss, climate change, and feral predators.

Ctenophorus parviceps, commonly known as the Gnaraloo heath dragon or northwestern heath dragon is a species of agamid lizard occurring in pale coastal sands and shell grit with open heaths and beach spinifex, between the North West Cape and Carnarvon, Western Australia and on Bernier Island. The Gnaraloo heath dragon is a lizard that can be found along the coast of Western Australia between Exmouth Gulf and Shark Bay, and is also known as the northwestern heath dragon. It is native to Australia and usually inhabits sandy coastal dunes. The species' longevity is 3–50 years and its population density is extremely low. The Gnaraloo heath dragon is a member of the Agamidae family, which contains 15 genera. The lizard is under the Ctenophorus genus which has up to 33 species. This genus shows the most morphological and ecological diversity out of the three large agamid genera. 83% of the lizards in this genus lack a crest, while 17% possess crests. They are smaller than most agamids but do have relatively large heads. The Gnaraloo heath dragon can be differentiated from related species by a series of spines on the tail's base, a pale-grey brown broad vertebral band along its back, and hour-glass bars extending upwards to meet the pale vertebral band. It is usually 45mm in terms of length, measuring from snout to vent.

The Mallee Worm-lizard , also known as the Pink-nosed Worm-lizard and the Red-tailed Worm-lizard, is a slender pygopid species that is endemic to Australia, with recorded distribution across the four southern mainland states, although, its distribution is restricted in Western Australia and New South Wales.

The Hemiergis millewae, commonly known as the Millewa skink or Triodia earless skink, is a species of hemiergis lizards that is endemic to Australia. It is a specialist species, highly dependent on Spinifex for food and shelter, and has only been observed in semi-arid Mallee woodlands of southern and eastern Australia. It is considered endangered throughout parts of its range.

References

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Sadlier, Ross A.; Colgan, Donald J.; Beatson, Cecilie A.; Cogger, Harold G. (2019-08-28). "Ctenophorus spinodomus sp. nov., a new species of dragon lizard (Squamata: Agamidae) from Triodia Mallee habitat of southeast Australia". Records of the Australian Museum. 71 (5): 199–215. doi:10.3853/j.2201-4349.71.2019.1700. ISSN 2201-4349.
1 2 3 4 5 Edwards, Danielle L.; Hutchinson, Mark N. (June 2023). "Sand Dragons: Species of the Ctenophorus maculatus Complex (Squamata: Agamidae) of Australia's Southern and Western Interior". Journal of Herpetology. 57 (2): 176–196. doi:10.1670/22-021. ISSN 0022-1511.
1 2 3 Swan, Gerry; Sadlier, Ross; Shea, Glenn (2022). A field guide to reptiles of New South Wales (4th ed.). Australia: Reed New Holland. p. 85. ISBN 9781925546835.
↑ Bell, Kristian J.; Doherty, Tim S.; Driscoll, Don A. (2021-03-31). "Predators, prey or temperature? Mechanisms driving niche use of a foundation plant species by specialist lizards". Proceedings of the Royal Society B: Biological Sciences. 288 (1947): 20202633. doi:10.1098/rspb.2020.2633. ISSN 0962-8452. PMC 8059954 . PMID 33784871.
↑ Simpson, R. E. L.; Nimmo, D. G.; Wright, L. J.; Wassens, S.; Michael, D. R.; Simpson, R. E. L.; Nimmo, D. G.; Wright, L. J.; Wassens, S.; Michael, D. R. (2023-07-24). "Decline in semi-arid reptile occurrence following habitat loss and fragmentation". Wildlife Research. doi:10.1071/WR23034. ISSN 1448-5494.

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[:0-1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Sadlier, Ross A.; Colgan, Donald J.; Beatson, Cecilie A.; Cogger, Harold G. (2019-08-28). "Ctenophorus spinodomus sp. nov., a new species of dragon lizard (Squamata: Agamidae) from Triodia Mallee habitat of southeast Australia". Records of the Australian Museum. 71 (5): 199–215. doi:10.3853/j.2201-4349.71.2019.1700. ISSN 2201-4349.

[:1-2] 1 2 3 4 5 Edwards, Danielle L.; Hutchinson, Mark N. (June 2023). "Sand Dragons: Species of the Ctenophorus maculatus Complex (Squamata: Agamidae) of Australia's Southern and Western Interior". Journal of Herpetology. 57 (2): 176–196. doi:10.1670/22-021. ISSN 0022-1511.

[:2-3] 1 2 3 Swan, Gerry; Sadlier, Ross; Shea, Glenn (2022). A field guide to reptiles of New South Wales (4th ed.). Australia: Reed New Holland. p. 85. ISBN 9781925546835.

[4] Bell, Kristian J.; Doherty, Tim S.; Driscoll, Don A. (2021-03-31). "Predators, prey or temperature? Mechanisms driving niche use of a foundation plant species by specialist lizards". Proceedings of the Royal Society B: Biological Sciences. 288 (1947): 20202633. doi:10.1098/rspb.2020.2633. ISSN 0962-8452. PMC 8059954 . PMID 33784871.

[5] Simpson, R. E. L.; Nimmo, D. G.; Wright, L. J.; Wassens, S.; Michael, D. R.; Simpson, R. E. L.; Nimmo, D. G.; Wright, L. J.; Wassens, S.; Michael, D. R. (2023-07-24). "Decline in semi-arid reptile occurrence following habitat loss and fragmentation". Wildlife Research. doi:10.1071/WR23034. ISSN 1448-5494.

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