Gillens monitor lizard
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Gillens monitor lizard ( Varanus gilleni ) |
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| Varanus gilleni | ||||||||||||
| Lucas & Frost , 1895 |
Gillens monitor lizard ( Varanus gilleni ) is a species of scale reptiles from the genus of monitor lizards ( Varanus ). It inhabits the arid regions in Western and Central Australia.
features
Gillens monitor lizard is a small monitor lizard of up to 38 cm total length, the tail length is 1.2-1.3 times the head-trunk length . The nostrils are round to oval and lie in the middle between the tip of the snout and the eyes. The head is quite flat, broad and short. The scales on the legs are fine. The hind legs are shorter than the front legs, the claws strongly curved. The tail is laterally compressed at the base, but becomes increasingly round in cross-section. The scales on the tail are regularly arranged in transverse rings and are not keeled.
The top of the body is gray-brown and turns pale gray towards the sides of the body. On the back there is a ribbon drawing made up of reddish-brown dots and short lines. There are dark brown stripes on the tail.
When Gillen's monitor goes on the ground, it leaves grinding marks in the sand: a clear, comparatively deeply indented grinding mark on the tail (sinusoidal with low amplitude) and footprints. From the very similar traces of the Black Lizard ( Varanus tristis ), the traces of Gillens Waran can be distinguished by their smaller stride relative to their body size , but reliable determination is difficult. Other monitor tracks, on the other hand, show different patterns and can thus be distinguished regardless of size.
distribution and habitat
Gillens monitor lizard occurs in northern South Australia , the southern Northern Territory and the central parts of Western Australia . It inhabits semi-arid to dry, wooded areas with casuarina ( Casuarina ), eucalyptus ( Eucalyptus ) and acacia ( Acacia , especially Mulga ).
Way of life
Like all monitor lizards, Gillens monitor lizard is a diurnal loner. It may have a dormant period during the dry season. Above all, it is a tree dweller who is rarely seen on the ground. He hides under dead bark and in tree hollows. It can use its tail as a grasping organ when climbing. The activity starts early in the morning with sunbathing and then foraging for food; at the hottest midday hours, the lizard retreats under the bark. In the afternoon they can go looking for food again. Typical war commentaries are described of this type.
Gillens monitor lizard is a carnivore. He looks for prey mainly in trees, less often on the ground. The diet consists primarily of geckos , large insects, and grasshoppers, but also includes bird eggs and small mammals. Gilles monitor lizards "hunt" the tails of geckos that are too big for them, which the geckos shed during the autotomy . It is noticeable that Gilles monitor lizard feeds on vertebrates to a large extent, despite its small size.
Natural enemies of Gillen's monitor lizard are ravens, small birds of prey, snakes and other monitor lizards.
This species has been bred several times in captivity, but the reproduction of this monitor in the wild is poorly known. The first German breeding took place in 2006 in Wilhelma Stuttgart, the European first breeding in 2003 in Rotterdam . Males reach sexual maturity with 10, females with 9.5 cm KRL. The males are apparently from June to November (October peak) spermatogenetisch that females of January to March and September to November (October peak) ready to mate. Usually 4 eggs are laid, larger or smaller clutches are also possible. In captivity, young animals hatched after 84-131 days.
The age record for Gillens Waran is 4½ years.
Systematics
It was first described in 1895 by the Anglo-Australian naturalist Arthur Henry Lucas and the Australian herpetologist Charles Frost . On the basis of its habitus, the hemipenis fine structure and mitochondrial DNA , V. gilleni can be classified in the subgenus Odatria , which also includes all other Australian dwarf monitor lizards .
V. gilleni is, according to studies by Fitch et al. (2006) paraphyletic . In their cladistic analysis, they included samples of a species that was still unknown at the time (specimen numbers WAM R108999 & WAM R135340), which is now described as Varanus bushi (Aplin, Fitch & King 2006, holotype WAM R108999). Two samples from V. gilleni did not form a monophylum when the samples from V. bushi were included , as can be seen in the cladogram below .
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Danger
Gillen's monitor lizard is not considered to be endangered, but it could suffer local population losses through clearing and feeding damage by cattle on trees (with the associated decline of trees).
swell
- H.-G. Horn (2004): Varanus gilleni . In: ER Pianka & DR King (Eds.): Varanoid Lizards of the World , pp. 355-365. Indiana University Press, Bloomington & Indianapolis. ISBN 0253343666
- ^ JO Farlow & ER Pianka (2000): Body Form and Trackway Pattern in Australian Desert Monitors (Squamata: Varanidae): Comparing Zoological and Ichnological Diversity . PALAIOS 15 (3), pp. 235-247
- ↑ a b c d e according to Horn (2004) and the literature cited there
- ^ A b S. Wilson & G. Swan (2008): A complete guide to the reptiles of Australia , pp. 362-363. New Holland Publishers, Sydney, Auckland, London, Cape Town, 2nd edition. ISBN 9781877069468
- ↑ a b c A. J. Fitch, AE Goodman & SC Donnellan (2006): A molecular phylogeny of the Australian monitor lizards (Squamata: Varanidae) inferred from mitochondrial DNA sequences . Australian Journal of Zoology 54, pp. 253-269
- ↑ Varanus bushi in The Reptile Database ; Retrieved February 22, 2011.
