Rusty-topped delma (Delma borea)

Rusty-topped delma fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Rusty-topped delma description

The rusty-topped delma (Delma borea) is an unusual lizard with a long, snake-like body that lacks obvious limbs. Although it has completely lost its front limbs, the rusty-topped delma does have tiny, vestigial hind limbs in the form of scaly flaps ^{(2) (5) (6) (7)}, which completely encase the much-reduced limb bones and toes ^{(5) (6)}. These flaps give this and other species in the Pygopodidae family the name ‘flap-footed lizards’ ^{(2) (5)}.

As in other Delma species, the rusty-topped delma’s tail is much longer than its body and is easily broken, although it can be regenerated ⁽²⁾. Delma species are most closely related to geckos, and like geckos they have lidless eyes covered by transparent scales, which the lizard can wipe clean with its wide, flat tongue ^{(2) (5)}.

The rusty-topped delma’s scales are smooth and shiny ^{(2) (6) (7)}, and in comparison to other Delma species its body is relatively small and stout ⁽³⁾. The rusty-topped delma is brown to reddish-brown or grey above ^{(2) (4)}, with a whitish throat and underside ^{(3) (4)}. Juveniles and young adults have three to four conspicuous dark bands on the head and the back of the neck, but these often fade as the lizard matures ^{(2) (3) (4)}. The male and female rusty-topped delma are thought to be similar in size and appearance ⁽⁶⁾.

If disturbed, the rusty-topped delma may produce a low buzzing or squeaking sound ^{(6) (7)}.

Also known as

blackbanded scalyfoot.

Size

Snout-vent length: c. 9.8 cm ^{(2) (3)}

Total length: up to 40 cm ⁽⁴⁾

Rusty-topped delma biology

In general, Delma species are quite secretive, and retreat rapidly through thick vegetation if disturbed ⁽²⁾. The rusty-topped delma is capable of shedding its tail as a defence mechanism if threatened by a predator, but a new tail quickly grows back ^{(2) (4)}.

The rusty-topped delma is likely to feed on a range of insects and other invertebrates ^{(2) (4) (5) (7)}. Like other species in the Pygopodidae family, the rusty-topped delma lays two eggs per clutch ^{(2) (4) (5) (6) (7)}, with each egg being elongate and having a parchment-like shell ^{(5) (6) (7)}.

Rusty-topped delma range

The rusty-topped delma is found across northern Australia, a fact which is reflected in its scientific name, borea, which comes from the Greek for ‘north’ ⁽⁶⁾. Its distribution stretches from north-western Queensland, across the Northern Territory to Western Australia, including several offshore islands ^{(1) (2) (3) (4) (6)}. It also ranges into central parts of the continent, as far south as north-western South Australia ^{(1) (3) (6)}.

Rusty-topped delma habitat

The rusty-topped delma typically inhabits spinifex (Triodia) grasslands on rocky or stony soils ^{(2) (4) (6)}, but tends to avoid grassland in sandy areas ⁽⁶⁾. This species has also been collected from disturbed areas such as rubbish heaps ⁽⁶⁾, and may take shelter under rocks, logs, among roots or in cracks in the ground ^{(4) (7)}.

Like other flap-footed lizards (Pygopodidae species), the rusty-topped delma is likely to have evolved its long, limbless body form to enable it to move easily through low, dense vegetation ⁽⁵⁾.

Rusty-topped delma status

The rusty-topped delma has yet to be classified by the IUCN.

Rusty-topped delma threats

Little information is currently available on the potential threats to the rusty-topped delma.

Rusty-topped delma conservation

There are no specific conservation measures currently known to be in place for this small, unusual lizard, and it has not been listed on Australia’s Environment Protection and Biodiversity Conservation Act. However, all reptiles are protected on Barrow Island, off the coast of Western Australia, so the rusty-topped delma may receive some protection there ⁽⁴⁾.

Find out more

Find out more about the rusty-topped delma and its conservation:

• Moro, D. and MacAulay, I. (2010) A Guide to the Reptiles and Amphibians of Barrow Island. Chevron Australia, Perth. Available at:
  http://www.chevronaustralia.com/environment/protectingenvironment/nature-books.aspx

More information on conservation in Australia:

• Australian Wildlife Conservancy:
  http://www.australianwildlife.org/
• Australian Conservation Foundation:
  http://www.acfonline.org.au/

Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

Glossary

Invertebrates

Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.

Vestigial

Describing a structure or organ that has diminished in size, through evolution, to the point where it no longer functions. Only traces may remain.

References

1. The Reptile Database (November, 2012)
   http://reptile-database.reptarium.cz/search.php
2. Wilson, S. (2005) A Field Guide to Reptiles of Queensland. Reed New Holland, Sydney.
3. Maryan, B., Aplin, K.P. and Adams, M. (2007) Two new species of the Delma tincta group (Squamata: Pygopodidae) from northwestern Australia. Records of the Western Australian Museum, 23: 273-305.
4. Moro, D. and MacAulay, I. (2010) A Guide to the Reptiles and Amphibians of Barrow Island. Chevron Australia, Perth. Available at:
   http://www.chevronaustralia.com/environment/protectingenvironment/nature-books.aspx
5. Wilson, S.K. (2012) Australian Lizards: A Natural History. CSIRO Publishing, Collingwood, Australia.
6. Kluge, A.G. (1974) A taxonomic revision of the lizard family Pygopodidae. Miscellaneous Publications, Museum of Zoology, University of Michigan, 147: 1-221.
7. Kluge, A.G. (1976) Phylogenetic relationships in the lizard family Pygopodidae: an evaluations of theory, methods and data. Miscellaneous Publications, Museum of Zoology, University of Michigan, 152: 1-72.