First pod record of Mucuna (Papilionoideae, Fabaceae) from the late Miocene of the Yen Bai Basin, northern Vietnam

The genus Mucuna Adans. (Papilionoideae, Fabaceae) contains approximately 105 extant species. It is widely distributed in pantropical areas, with its center of diversity located in Asia. Recent molecular phylogenetic analyses investigated the historical biogeography of the genus; however, a lack of fossil evidence has limited a fuller understanding of the genus. Here, we present the first macrofossil record of Mucuna in the form of pod, collected from late Miocene sediments of the Yen Bai Basin, northern Vietnam. This fossil specimen is characterized by linear-oblong, compressed, torulose, slightly curved pods containing at least three to five seeds, a pair of thickened marginal wings, and an apex with a cone-shaped beak. Detailed morphological observation indicates that these fossil pods belong to Mucuna, and are provisionally assigned to M. cf. birdwoodiana Tutcher. Our discovery supports the hypothesis that Mucuna originated in Asia; moreover, it implies that the genus has been present and has adapted to the humid tropical climate in northern Vietnam since at least the late Miocene. (C) 2021 Published by Elsevier B.V.

Automated summary

The study reports a new fossil record of Mucuna found in the late Miocene sediments of the Yen Bai Basin in northern Vietnam, revealing a possible Asian origin of the genus and its presence and adaptation to the humid tropical climate of northern Vietnam since at least the late Miocene.