The rock monitor (Varanus albigularis), also called commonly the black-throated monitor, is a species of monitor lizard in the family Varanidae. The species is endemic to Central, East, and southern Africa. It is the second-longest lizard found on the continent, and the heaviest-bodied; locally, it is called leguaan or likkewaan.
First described by François Marie Daudin in 1802, V. albigularis has been classified as a subspecies of V. exanthematicus, but has since been declared a distinct species based upon differences in hemipenal morphology. The generic name Varanus is derived from the Arabic word waral ورل, which is translated to English as "monitor". The specific name albigularis comes from a compound of two Latin words: albus meaning "white" and gula meaning "throat".
The subspecies of V. albigularis are:
- White-throated monitor, V. a. albigularis
- Angolan white-throated monitor, V. a. angolensis
- Eastern white-throated monitor, V. a. microstictus
- Black-throated monitor, V. a. ionidesi  (but may be synonymous with V. a. microstictus)
Varanus albigularis is the heaviest-bodied lizard in Africa, as adult males average about 6 to 8 kg (13 to 18 lb) and females weigh from 3.2 to 5 kg (7.1 to 11.0 lb). Large mature males can attain 15 to 17 kg (33 to 37 lb). It is the second longest African lizard after the Nile monitor (Varanus niloticus). Varanus albigularis reaches 2 meters (6 ft 7 in) in total length (including tail), with its tail and body being of equal size. Mature specimens more typically will measure 0.85 to 1.5 meters (2 ft 9 in to 4 ft 11 in). The head and neck are the same length, and are distinct from each other. The bulbous, convex snout gives an angular, box-like appearance. The forked tongue is pink or bluish, and the body scales are usually a mottled gray-brown with yellowish or white markings.
An intelligent lizard, several specimens of V. albigularis have demonstrated the ability to count as high as six in an experiment conducted by Dr. John Philips at the San Diego Zoo in 1999. Philips offered varying numbers of snails, and the monitors were able to distinguish numbers whenever one was missing.
V. albigularis is found in Central Africa (Democratic Republic of the Congo/Zaire), Southern Africa (Namibia, Botswana, Republic of South Africa, Swaziland, Zimbabwe, Mozambique, Zambia, Angola), the African Great Lakes (Kenya, Uganda, Tanzania), and the Horn of Africa (Ethiopia, Somalia).
People living with the HIV/AIDS virus in Yumbe district of Uganda have been reported injecting themselves with the blood of rock monitors, which they believe to be a cure for the virus. Many are reportedly discontinuing antiretroviral therapy to pursue this anecdotal treatment. As a result, V. albigularis is reported to have become an expensive item in the Ugandan black market, selling for more than US$175 each.
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