Legume fruits from the Oligocene Ningming Formation of Guangxi, China, and their biogeographical and palaeoclimatic implications

New legume fossils can provide a historical perspective of their early evolution and biogeographic history. Three legume species, Albizia ningmingensis sp. nov., Leguminocarpum sp. 1 and Leguminocarpum sp. 2, from the Oligocene Ningming Formation of Guangxi, South China, are described on the basis of morphological and/or anatomical characteristics. Albizia ningmingensis sp. nov. bears a close resemblance to the extant species Albizia kalkora in morphology and anatomy and represents a reliable occurrence of Albizia in the Oligocene deposits of China. An incomplete fruit fossil is described as Leguminocarpum sp. 1, predominantly on the basis of anatomical characteristics. Fruits of Leguminocarpum sp. 2 are straight and strongly asymmetrical, with one straight suture and the other strongly constricted. The occurrence of Albizia fruits indicate that Albizia elements existed in the South China during the Oligocene. Our legume fossils, together with earlier records of three Bauhinia species, indicate that a flora with the unusual abundance of legumes was present in South China in the Oligocene. The legumes from the Ningming Formation, having a relatively high diversity, can contribute to the palaeoclimatic interpretation and indicate that the Oligocene Ningming flora most likely lived in a tropical-to-warm subtropical climate.