Savannah monitor

Savannah monitor
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Reptilia
Order:Squamata
Family:Varanidae
Genus:Varanus
Subgenus:Polydaedalus
Species: V. exanthematicus
Binomial name
Varanus exanthematicus
(Bosc, 1792)

The savannah monitor (Varanus exanthematicus) is a medium-sized species of monitor lizard native to Africa. The species is known as Bosc’s monitor in Europe, since French scientist Louis Bosc first described the species.[1] It belongs to the subgenus Polydaedalus, along with the Nile, the ornate and other monitors.

Etymology

The specific name exanthematicus is derived from the Greek word exanthem /ɛkˈsænθɪm/, meaning an eruption or blister of the skin.[2] French botanist and zoologist Louis Augustin Guillaume Bosc[3] originally described this lizard as Lacerta exanthematica in reference to the large oval scales on the back of its neck.[1]

Description

Savannah monitors are stoutly built, with relatively short limbs and toes, and skulls and dentition adapted to feed on hard-shelled prey. They are robust creatures, with powerful limbs for digging, powerful jaws and blunt, peglike teeth. Maximum size is rarely more than 100 cm. Their diet is much more restricted than that of other African monitor lizards, consisting mainly of snails, millipedes, orthopterans, beetles, and other invertebrates.

The skin coloration pattern varies according to the local habitat substrate. The body scales are large, usually less than 100 scales around midbody, a partly laterally compressed tail with a double dorsal ridge and nostrils equidistant from the eyes and the tip of the snout.[4]

The Savannah monitor is often confused with the white-throat monitor (Varanus albigularis), which can grow to lengths of 5-6 ft. While similar in overall appearance, this species possesses significant morphological and ecological differences and is recognized as a very distinct species.

Diet

Information about the diet of savannah monitors in the wild has been recorded in Senegal[5] and Ghana.[6][7] It feeds almost exclusively on arthropods and molluscs. In Senegal, Iulus millipedes were the most common prey of adults; in Ghana, small crickets formed the bulk of the diet of animals less than 2 months old; orthopterans (especially Brachytrupes), scorpions and amphibians were the most common prey of animals 6-7 months old .

In captivity

The Savannah monitor is readily available in the pet trade. Juvenile animals are collected from several countries in West Africa (mainly Ghana, Togo, Benin and Nigeria) and exported worldwide. Animals sold as "captive bred", captive farmed or ranched are the offspring of gravid females collected during the breeding season whose eggs are incubated by exporters. Adult specimens frequently become unwanted pets and are reported as being the most common monitor lizards by animal rescue agencies. However the vast majority (estimated 90%) die within a year of capture and captive breeding is very rare. The skins of the species are important in the international leather trade and originate mainly from Chad, Mali and Sudan.

Range

Its range extends throughout sub-Saharan Africa from Senegal east to Sudan and south almost to the Congo River and Rift Valley, where they are replaced by V. albigularis.[6] V. exanthematicus is primarily a ground-dwelling species that shelters in burrows, although it is sometimes found in bushes or low trees.[4] In the coastal plain of Ghana, V. exanthematicus juveniles are often associated with the burrows of the giant cricket Brachytrupes.[8]

Threats

V. exanthematicus is listed as least concern by IUCN.[9] The species is hunted for its leather and meat and for the international pet trade. The trade in wild collected savannah monitors is not of a global conservation concern due to the vast range of the species, in addition to the collection for the pet trade often occurring over a relatively small area.[10] An average of 30,574 live specimens were imported into the US each year between 2000 and 2009; total imports of live specimens into the US between 2000 and 2010 was 325,480 animals. During the same period, 1,037 skins, shoes, and products of the species were imported into the US. Trade in live animals comes mainly from Ghana (235,903 animals exported between 2000 and 2010), Togo (188,110 animals exported between 2000 and 2010), and Benin (72,964 animals exported between 2000 and 2010). During the same period, total worldwide declared exports of skins and products of the species totalled 37,506.[11] However, substantial undeclared trade in the species occurs from Sudan, Nigeria, and elsewhere[9]


References

  1. 1 2 Bosc, Louis. Lacerta exanthematica. Act. Soc. Hist. Nat. Paris 1. p. 25.
  2. ↑ Simpson JA, Weiner ESC (editors) (1989). Oxford English Dictionary. Oxford, England: Clarendon Press.
  3. ↑ Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. ("Bosc", p. 32).
  4. 1 2 Bennett, Daniel; Ravi Thakoordyal (2003). The Savannah Monitor, the Truth about Varanus exanthematicus. UK: Viper Press. p. 84. ISBN 0-9526632-9-5.
  5. ↑ Cisse, M (1972). "L'alimentaire des Varanides au Senegal". Bulletin L'Institute Fond. Afr. Noire. 34: 503–515.
  6. 1 2 Bennett, Daniel (2004). "Chapter 5.2: Varanus exanthematicus". In Pianka, Eric R. Varanoid Lizards of the World. Indiana University Press. pp. 95–103. ISBN 0-253-34366-6.
  7. ↑ Bennett, Daniel (2000). "Preliminary data on the diet of juvenile Varanus exanthematicus in the coastal plain of Ghana". Herpetological Journal. 10: 75–76.
  8. ↑ Bennett, Daniel (2000). "Observations of Bosc's monitor lizard (Varanus exanthematicus) in the wild". Bulletin of Chicago Herpetological Society. 35: 177–180.
  9. 1 2 Bennett, D.; Sweet, S. (2010). "Varanus exanthematicus". In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. IUCN. Retrieved 5 April 2012.
  10. ↑ http://www.mampam.com/index.php?option=com_content&task=view&id=173&Itemid=87
  11. ↑ "CITES Trade Database". CITES. Retrieved 5 April 2012.

Further reading

  • Bennett D (2000). "The density and abundance of juvenile Varanus exanthematicus (Sauria: Varanidae) in the coastal plain of Ghana". Amphibia-Reptilia 21 (3): 301–306.
  • Bennett, Daniel; Thakoordyal, Ravi (2003). The Savannah Monitor Lizard: the truth about Varanus exanthematicus. Glossop, England: Viper Press. 84 pp. ISBN 978-0952663294.
  • (1993). "The Savanna Monitor (Varanus exanthematicus) in Africa and in your home". The Iowa Herpetological Society, June: 2-4 (Reprinted in International Reptile Breeders Association (IRBA), Monitor 1 (2): 10-12, 1994).
  • Bennett D, Sweet SS (2010). "Varanus exanthematicus ". IUCN Red List of Threatened Species. Version 2011.2. www.iucnredlist.org.


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