Mahonia fossils from the Oligocene of South China: Taxonomic and biogeographic implications

Mahonia is a genus with an East Asia-North America disjunct distribution today. Although Mahonia has a rich fossil record in North America dating back from Eocene to Miocene and some Oligocene to Pleistocene fossils from Europe, few fossils have been reported from East Asia. Here, three compressed fossil leaflets are described as a new species Mahonia ningmingensis Hu et Chen n. sp. from the Oligocene Ningming Formation in Guangxi, South China. This new fossil species shows leaf architectural characters of Group Orientales and has similarity with extant Mahonia bodinieri, Mahonia bealei, Mahonia breviracema, and Mahonia nittens. The leaf fossils described here represent the oldest records and lowest latitude occurrence of Mahonia in East Asia and reveal that the Group Orientales already existed in East Asia at least in the Oligocene. This record extends the stratigraphic range of Mahonia in East Asia and provides evidence for the hypothesis that migration of Mahonia between North America and East Asia might have taken place over both the North Atlantic Land Bridge and Bering Land Bridge.