Concept
The Nile monitor (Varanus niloticus) is a large member of the monitor family (Varanidae) found throughout most of Sub-Saharan Africa and along the Nile, with invasive populations in North America. The population in West African forests and savannahs is sometimes recognized as a separate species, the West African Nile monitor (V. stellatus). It is one of the largest lizards in the world reaching and even surpassing the perentie by size. Other common names include the African small-grain lizard, as well as iguana and various forms derived from it, such as guana, water leguaan or river leguaan (leguan, leguaan, and likkewaan mean monitor lizard in South African English, and can be used interchangeably). A feral population of the lizards, descended from escaped or intentionally released pets, has become established in several locations in Florida. Members of the Nile monitor species group were already well known to Africans in ancient times. For example, they were commonly caught, likely as food, in the Djenné-Djenno culture at least a millennium ago. The Nile monitor twice was given a scientific name by Carl Linnaeus: First as Lacerta monitor in 1758 in the 10th edition of Systema Naturae, the starting point of zoological nomenclature. He described it again in 1766 as Lacerta nilotica. Despite being older, the name proposed in 1758 is invalid because it was rejected in ICZN opinion 540, making the name of 1766 valid. The genus Varanus was coined in 1820 by Blasius Merrem. Six years later Leopold Fitzinger moved the Nile monitor into this genus as Varanus niloticus, the currently accepted scientific name for the species. As traditionally defined, the Nile monitor is a species complex. The ornate monitor (V. ornatus) and West African Nile monitor (V. stellatus) were described as species in 1802 and 1803 by François Marie Daudin. In 1942, Robert Mertens moved them both into the Nile monitor (V. niloticus); as synonyms or as a valid subspecies.
