Fossil infructescence from southwestern China reveals Paleogene establishment of Cladrastis in Asia

While a recent molecular phylogeographical study shows that, Cladrastis, a small woody genus in the bean family (Leguminosae), may have been established in Asia after the middle to late Eocene, fossils of the genus have not been previously documented in the Paleogene of Asia. Here we report an infructescence and four fossil fruits of Cladrastis from the Paleogene of southeastern Yunnan, China, which we described as a new species, C. haominiae, and this represents the first Paleogene record of Cladrastis in Asia. These fossils are characterized by a long stipe, an acuminate or acute proximal/distal end, wide sutures, and elliptical seed(s) nearly parallel or forming a small angle to the long axis of the fruit. Our finding supports the Paleogene establishment of Cladrastis in Asia and provides new significant evidence for the Paleogene origin of Yunnan biodiversity.