Dumeril's monitor explained

Dumeril's monitor (Varanus dumerilii)^[1] is a species of lizard in the family Varanidae. The species is endemic to Southeast Asia.

Description

Adult Dumeril's monitors can reach up to 4.5feet in total length (including tail) although typical total length is 4feet.

Adult Dumeril's monitors are largely dark brown, with occasional brighter indistinct crossbars. "The major color is a dark varnish black which is interrupted by several yellow crossways bars on the back." The head of juveniles is shiny orange-red or sometimes yellow. This juvenile coloration disappears after only 4–8 weeks.

The long tail is laterally compressed with a keel.^[2]

It is at times confused with the sympatric black rough-necked monitor due to the large nuchal scales in both species, which is why Dumeril's monitors are sometimes called brown rough-necked monitors.

Etymology

The specific name, dumerilii, is in honour of French zoologist André Marie Constant Duméril.^[3]

In Thailand, V. dumerilii is known by the common name, túdtū̀ (ตุ๊ดตู่), which is an animal that appeared in children's folk songs.^[4]

Taxonomy

Varanus dumerilii is a species of monitor lizard within the subgenus Empagusia.

Subspecies "Varanus dumerilii heteropholis"

Two subspecies have been historically described:

• Varanus dumerilii dumerilii
• Varanus dumerilii heteropholis

In 1892, the species V. heteropholis was named by Boulenger on the basis of a taxidermied and possibly tanned specimen owned by Charles Hose, collected from Borneo's Mt. Dulit. The same taxonomic label was attached to two additional specimens from the same locality. In 1942, Mertens listed it instead as V. d. heteropholis, as a subspecies of V. dumerilii.

In 1993, Sprackland classified V. d. heteropholis as a synonym of V. d. dumerilii, after examining specimens including the holotypes of both putative subspecies. Although the appearance of the V. d. heteropholis holotype was considered somewhat strange even when accounting for the alterations caused by the taxidermy process, the traits previously described as unique to V. d. heteropholis were found to fit within the range of variation in V. d. dumerilii, albeit on the extreme ends, such that V. dumerilii has no subspecies.^[5]

Geographic range

Dumeril's monitor is found in southern Burma and north of the Isthmus of Kra to Kanchanaburi Province in Thailand,^[6] as well as in Peninsular Malaysia, Singapore, throughout Borneo, Sumatra, Riau, Bangka–Belitung and other smaller islands of Indonesia.^[7]

Habitat

The preferred natural habitat of V. dumerilii is dense evergreen forests with high humidity ^[8] and mangrove swamps,^[9] at altitudes from sea level to .

Diet

V. dumerilii is a crab specialist;^[10] however, it has been observed eating snails, other molluscs, insects, fish, frogs, turtle eggs, birds, and smaller rodents.^[11] Little is known overall about this species compared to other monitor lizards.^[12]

Behavior

V. dumerilii is arboreal and diurnal.

Reproduction

V. dumerilii is oviparous.^[7] Clutch size is 4–23 eggs, with up to 3 clutches a year. Hatchlings have a snout-to-vent length (SVL) of about, and a tail slightly longer than SVL.

Conservation

The species has been successfully bred in captivity, ie, both in zoos and private collections. Due to its demand in the pet trade, and because it is not a nationally protected species within Indonesia, Indonesia has exported up to 1,060 individuals per year between 2010 and 2018. The EU has prohibited the import of wild caught specimens since 1997. The species has been regularly collected for the pet trade since around 1976.

References

1. Web site: EOL.org . 2010-04-18 . https://web.archive.org/web/20100412020442/http://www.eol.org/pages/14506 . 2010-04-12.
2. Book: Auliya, Marc . Visual Identification Guide for the Monitor Lizard Species of the World (Genus Varanus) . Koch . André . 2020 . Bundesamt für Naturschutz . 978-3-89624-290-7 . 552 . DE . 10.19217/skr552.
3. [species:Bo Beolens|Beolens, Bo]
4. Web site: Thai . ตุ๊ดตู่ . . Sanook.com . 16 June 2016.
5. [species:Robert G. Sprackland|Sprackland RG]
6. Cota M, Chan-ard T, Mekchai S, Laoteaw S (2008). "Geographical Distribution, Instinctive Feeding Behavior and Report of Nocturnal Activity of Varanus dumerilii in Thailand". Biawak 2 (4): 152-158.
7. www.reptile-database.org
8. [species:Komsorn Lauprasert|Lauprasert K]
9. Web site: Lincoln Children's Zoo . 2010-04-18 . https://web.archive.org/web/20090625110113/http://www.lincolnchildrenszoo.org/animals/reptiles/monitor . 2009-06-25.
10. [species:Uwe Krebs|Krebs U]
11. Web site: Varanus Dumerilii. biocyclopedia.com. 14 April 2023.
12. Web site: Monitor-lizards.net . https://web.archive.org/web/20100519024250/http://www.monitor-lizards.net/species/empagusia/dumerilii.html . 2010-05-19.

Further reading

• Amer, Sayed A. M.; Kumazawa, Yoshinori (2008). "Timing of a mtDNA gene rearrangement and intercontinental dispersal of varanid lizards". Genes Genet. Syst. 83: 275–280.
• Auffenberg W (1988). Gray's monitor lizard. Gainesville: University of Florida.
• Ávalos, J. de; Martínez Carrión, P. (1997). "Warane ". Reptilia (Münster) 2 (5): 16-21. (in German).
• Barbour T (1921). "Aquatic skinks and arboreal monitors". Copeia 1921 (1): 42-44.
• Boulenger GA (1885). Catalogue of lizards in the British Museum (Natural History). Second Edition. Volume II ... Varanidæ ... London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiii + 497 pp. + Plates I-XXIV. (Varanus dumerilii, pp. 312–313).
• Brandenberg T (1983). Monitors in the Indo-Australian Archipelago. Leiden: E.J. Brill. 121 pp.
• Coborn, John (1987). Snakes and lizards: Their care and breeding in captivity. Newton Abbott: David and Charles Publishing.
• Cota M, Chan-ard T, Mekchai S, Laoteaw S (2008). "Geographical Distribution, Instinctive Feeding Behavior and Report of Nocturnal Activity of Varanus dumerilii in Thailand". Biawak 2 (4): 152-158.
• Cox MJ, van Dijk PP, Nabhitabhata J, Thirakhupt K (1998). A Photographic Guide to Snakes and other Reptiles of Peninsular Malaysia, Singapore and Thailand. Sanibel Island, Florida: Ralph Curtis Books Publishing. 144 pp. .
• Davis R, Darling R, Darlington A (1986). "Ritualised combat in captive V. dumerilii ". Herpetological Review 17 (4): 85-86.
• Davis RB, Phillips LG (1991). "A method of sexing Dumeril's monitor Varanus dumerili ". Herp. Review 22 (1): 18-19.
• Harrison JL, Boo-Liat L (1957). "Monitors of Malaya". Malay Nature Journal 12 (1): 1-10.
• Horn H-G, Schulz B (1977). "Varanus dumerilii, wie ihn nicht jeder kennt ". Das Aquarium 11 (9): 37-38. (in German).
• Lekagul B (1969). "Monitors of Thailand". Conservation News of S.E. Asia 8: 31-32.
• Losos JB, Greene HW (1988). "Ecological and evolutionary implications of diet in monitor lizards". Biological Journal of the Linnean Society 35: 379-407.
• Mertens R (1942). "Die Familie der Waranae (Varanidae) ". Abhandlungen der Senckenberischen Naturforschenden Gesellschaft 462; 465; 466. (in German).
• Nutphand W (no date). The Monitors of Thailand. Bangkok: Mitphadung Publishing Office.
• Pitman CRS (1962). "More snake and lizard predators of birds". Bulletin of the British Ornithologists' Club 82 (3): 45-55.
• Radford L, Payne FL (1989). "The reproduction and management of Varanus dumerilii ". International Zoo Yearbook 28: 153-155.
• Raven HC (1946). "Predators eating green turtle eggs in the East Indies". Copeia 1946 (1): 48.
• de Rooij N (1915). The Reptiles of the Indo-Australian Archipelago. Leiden: E.J. Brill.
• Schlegel H (1839). Abbildungen neuer oder unvollständig bekannter AMPHIBIEN, nach der Natur oder dem Leben entworfen herausgegeben und mit einem erläuternden Texte begleitet. Düsseldorf: Arnz & Comp. xiv + 141 pp. (Monitor dumerilii, new species, p. 78). (in German).
• Smith MA (1922). "On a Collection of Reptiles and Batrachians from the mountains of Pahang, Malay Peninsula". Journal of the Federated Malay States 10: 263-282. (Varanus dumerilii, p. 269).
• Smith HC (1930). "The monitor lizards of Burma". Journal of the Bombay Natural History Society 34: 367-373.
• Taylor EH (1963). "Lizards of Thailand". University of Kansas Science Bulletin 44 (14): 687-1077. (Varanus dumerilii, pp. 915, 918-920).
• Sprackland RG (1976). "Notes on Dumeril's monitor lizard Varanus dumerili (Schlegel)". Sarawak Museum Journal 24 (45): 287-291.

External links

• Photo of Dumeril's Monitor at Whozoo.org