Leo leo massaicus from Kenya regarding cranial and dental characteristics, but argued that his type specimen differed in pelage colouration. In 1930, Reginald Innes Pocock subordinated the lion to the genus Panthera when he wrote about Asiatic lion specimens in the zoological collection of the British Museum of Natural History. In the following decades, there has been much debate among zoologists on the validity of proposed subspecies: In 1939, Glover Morrill Allen recognized Felis leo kamptzi and F. l. azandicus as valid taxa among ten lion subspecies. Three decades later, John Ellerman and Terence Morrison-Scott recognized only two lion subspecies in the Palearctic realm, namely the African (P. l. leo) and Asiatic lions (P. l. persica). Some authors considered P. l. nubicus a valid subspecies and synonymous with P. l. massaica, a specimen from Kenya. Some authors considered P. l. azandicus synonymous with P. l. massaicus and P. l. somaliensis, and P. l. kamptzi synonymous with P. l. senegalensis. In 2005, Wallace Christopher Wozencraft recognized P. l. kamptzi, P. l. bleyenberghi and P. l. azandica as valid taxa. In 2016, IUCN Red List assessors used P. l. leo for all African lion populations. In 2017, the Cat Classification Task Force of the IUCN Cat Specialist Group subsumed lion populations in North, West and Central Africa and Asia to P. l. leo, based on results of genetic research on lion samples. Phylogeny Since the beginning of the 21st century, several phylogenetic studies were conducted to aid clarifying the taxonomic status of lion samples kept in museums and collected in the wild. Scientists analysed between 32 and 480 lion samples from up to 22 countries. They all agree that the lion comprises two evolutionary groups, one in the northern and eastern parts of its historical range, and the other in Southern and East Africa; they are estimated to have genetically diverged between 245,000 and 50,000 years ago. Tropical rainforest and the East African Rift possibly constituted major barriers between the two groups. The two lion groups overlap in Ethiopia, as lion samples from Bale Mountains National Park clustered with lion samples from Central Africa, whereas other samples from this country clustered with samples from East Africa. Three clades can be distinguished within P. l. leo. Lion samples from North Africa and India clustered into a single clade, and the lions in West Africa and northern parts of Central Africa also form distinct