Christinus marmoratus

Christinus marmoratus, also known as marbled gecko or marbled southern gecko, is a species of Gekkonidae (gecko) native to southern mainland of Australia, from Victoria to Western Australia. The species is well adapted to a variety of habitats, including city dwellings.[1].

For the New Caledonian species called marbled gecko, see Oedodera marmorata

For the Australian genus called marbled geckos, see Christinus

Christinus marmoratus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Family:	Gekkonidae
Genus:	Christinus
Species:	C. marmoratus
Binomial name
Christinus marmoratus (Gray, 1845)
Synonyms
Phyllodactylus marmoratus

Christinus marmoratus

Taxonomy

The species was first formally described by John Edward Gray in 1845.[2][3] The name he gave placed this group in the genus Diplodactylus as Diplodactylus marmoratus. Gray's description was based on four specimens that were preserved in spirits. They were collected on the Abrolhos islands (off Western Australia), and were donated to the British museum from the collection of a "Mr. Gilbert". Gray examined another preserved specimen of D. marmoratus (from a different donor) which was discoloured, leading him to mistakenly describe it as a separate species (Goniodactylus australis) in the same publication. In 1885 Boulenger placed D. marmoratus in the genus Phyllodactylus (the leaf-toed geckos).[4] It remained in that genus until 1984, when a revision by Wells and Wellington placed it in the genus Christinus.[5]

A study conducted by King in 1977 showed that C. marmoratus exhibits considerable geographic variation in karyotype across its range.[6] Further investigation by Donnellan et al. (2000) led to the species being recognized as a composite of two subspecies; C. marmoratus marmoratus and C. marmoratus dactylus.[7] The two subspecies are commonly referred to as the Western Marbled Gecko and the Southern Marbled Gecko.

Description

A head close-up of a Marbled Gecko (Christinus marmoratus). Note the pads on its feet.

Adults reach an average (snout-vent) length of 50mm, and weigh about 2.5g.[8] C. marmoratus have fat reserves in their tails,[9] which can be disconnected from their body (autotomy) when threatened, to aid in escape. Tails take about eight months to regenerate. Fully regenerated tails are characterized by an abrupt change in dorsal skin colouring and pattern at the level of the original fracture plane. Original tails also have much more developed muscular bands.[10] C. marmoratus hatchlings do not have any fat in the tail, and they drop it more readily than adults do.[9]

Distribution and habitat

C. marmoratus is Australia’s most southerly gecko. It occurs from northeastern New South Wales to southwestern Western Australia, as well as a number of islands off the coasts of South Australia and Western Australia.[11] They use a variety of habitats including open shrubland, sclerophyll forest, riverine woodland and urban regions.[1][11][12][13]

Ecology and behaviour

Male and female Marbled Geckos engaged in coitus.

C. marmoratus is insectivorous and nocturnal.[12] During the hot summer months they generally use deep crevices and burrows as their daytime retreat sites, and in cooler weather they aggregate under rocks.[12] Riverine populations generally rest under the thick exfoliating bark of large eucalyptus trees during the daytime.[14] C. marmoratus are commonly found in aggregations of up to 10 individuals, and most aggregations contain one male.[8] Given that many geckos have been reported to engage in territorial behaviour,[15] it is surprising that C. marmoratus aggregate so commonly (Kearney et al. reported that one quarter of individuals they found were in aggregations).[8] It has been suggested that this activity may be related to mating success, increased vigilance[16] or simply attraction to high-quality habitat.[8] Angiletta and Werner (1998) found that the preferred body temperature of C. marmoratus was 27.7 °C., which is much higher than their average body temperatures during the day or night. Subsequent investigation by Kearney and Predavec (2000) revealed that C. marmoratus may thermoregulate by adjusting its posture, for instance, by raising or flattening the body to contact the rock substrate. They also seem to touch the rock with their snout before doing so, as if testing the temperature.[12] They do vocalise, however if they are not under attack (under which they may start squeaking) they rarely vocalise.

References

1. Browne-Cooper, Robert; Brian Bush; Brad Maryan; David Robinson (2007). Reptiles and Frogs in the Bush: Southwestern Australia. University of Western Australia Press. pp. 108, 109. ISBN 978-1-920694-74-6.
2. Gray, J. E. 1845. Catalogue of the specimens of lizards in the collection of the British Museum. Trustees of die British Museum/Edward Newman, London: xxvii + 289 pp.
3. "Christinus marmoratus Gray, 1845". Reptiles Database. J. Craig Venter Institute. Retrieved 26 January 2009.
4. Boulenger GA. 1885. Catalogue of the Lizards in the British Museum (Nat. Hist.) I. Geckonidae, Eublepharidae, Uroplatidae, Pygopodidae, Agamidae. London: 450 pp.
5. Wells RW, Wellington CR. 1985. A classification of the Amphibia and Reptilia of Australia. Australian Journal of Herpetology, Supplementary Series 1:1–61.
6. King M. 1977. Chromosomal and morphometric variation in the gekko Diplodactylus vittatus (Gray). Australian Journal of Zoology 25:43–57.
7. Donnellan SC, Aplin KP, Dempsey PJ (2000). Genetic and morphological variation in Australian Christinus (Squamata : Gekkonidae): preliminary overview with recognition of a cryptic species on the Nullarbor Plain. Australian Journal of Zoology 48:289–315.
8. Kearney M, Shine R, Comber S, Pearson D. 2001. Why do geckos group? An analysis of "social" aggregations in two species of Australian Lizards. Herpetologica 57:4, 411–422.
9. Daniels CB. 1984. The importance of caudal lipid in the gecko Phyllodactylus marmoratus. Herpetologica 40:3, 337–344.
10. Bellairs Ada, Bryant SV. 1985. Autotomy and regeneration in reptiles. In: Gans C, Billett F, editors. Biology of the reptilia. New York: John Wiley and Sons, 301–410
11. King M, Rofe R. 1976. Karyotypic variation in the Australian Gekko Phyllodactylus marmoratus (Gray) (Gekkonidae: Reptilia). Chromosoma 54:75–87.
12. Kearney M, Predavec M. 2000. Do nocturnal ectotherms thermoregulate? A study of the temperate gecko Christinus marmoratus. Ecology 81:11, 2984–2996.
13. Daniels CB., Flaherty SP., Simbotwe MP. 1986. Tail size and effectiveness of autotomy in a lizard. Journal of Herpetology 20:1, 93–96.
14. Taylor D, Daniels CB, Johnston G. In Press. The Marbled Gecko in Urban Parklands: Do Retreat Sites Limit Population Size During Winter? Herpetologica.
15. Marcellini D. 1977. Acoustic and visual display behaviour of gekkonid lizards. American Zoologist 17:251–260.
16. Stamps JA. 1988. Conspecific attraction and aggregation in territorial species. The American Naturalist 131:3, 329.

• Edgar r. Waite F.L.S, C.M.Z.S, 1929 The Reptiles and Amphibians of South Australia, Printed by Harbison Weir, Government Printer 31 January, p. 76, 7/- sixpence.