Paper wasps (Hymenoptera: Vespidae, Polistinae) from Xiede (Eocene, central Tibetan Plateau): systematics and paleoecological implications

The species-rich Polistes Latreille, 1802 is the only cosmopolitan genus among social wasps. In contrast to its extant high diversity and wide distribution, its fossil record is sparse and geographically limited, especially in Asia. Here, we report the discovery of a new species, Polistes tibetensis Xu, Carpenter & Somavilla, sp. nov. from the Upper Eocene Niubao Formation (∼39 Ma), in Tibet, documented based on both male and female specimens. It represents both the oldest Polistes and the oldest Polistinae fossil record in Asian deposits to date. It could be confidently assigned to the subgenus Polistes (Polistes) based on cladistic analysis. As a confirmed crown-group fossil, P. tibetensis is expected to refine the temporal calibration of the phylogenetic tree of Polistes. Combining these findings with paleoecological niche modeling suggests that the paleoclimate of Xiede site around 39 Ma was characterized by cold winters and high seasonality. Thus, the discovery of these new fossils could provide insights into the divergence time of crown-Polistes, as well as shed light on the paleoclimate and paleoecology of the central Tibetan Plateau at that time.