The African elephant was first named by German naturalist Johann Friedrich Blumenbach in 1797 as Elephas africana. The genus Loxodonta was commonly believed to have been named by Georges Cuvier in 1825. Cuvier spelled it Loxodonte and an anonymous author romanised the spelling to Loxodonta; the International Code of Zoological Nomenclature recognises this as the proper authority. In 1942, 18 subspecies of African elephant were recognised by Henry Fairfield Osborn, but further morphological data has reduced the number of classified subspecies, and by the 1990s, only two were recognised, the savannah or bush elephant (L. a. africana) and the forest elephant (L. a. cyclotis); the latter has smaller and more rounded ears and thinner and straighter tusks, and is limited to the forested areas of western and Central Africa.[ A 2000 study argued for the elevation of the two forms into separate species (L. africana and L. cyclotis respectively) based on differences in skull morphology. DNA studies published in 2001 and 2007 also suggested they were distinct specieswhile studies in 2002 and 2005 concluded that they were the same species. Further studies (2010, 2011, 2015) have supported African savannah and forest elephants' status as separate species.The two species are believed to have diverged 6 million years ago.The third edition of Mammal Species of the World lists the two forms as full speciesand does not list any subspecies in its entry for Loxodonta africana. This approach is not taken by the United Nations Environment Programme's World Conservation Monitoring Centre nor by the IUCN, both of which list L. cyclotis as a synonym of L. africana. Some evidence suggests that elephants of western Africa are a separate species, although this is disputed. The pygmy elephants of the Congo Basin, which have been suggested to be a separate species (Loxodonta pumilio) are probably forest elephants whose small size and/or early maturity are due to environmental conditions.