A Fossil Paederinae from a Lacustrine Deposit at Orapa Diamond Mine in Botswana

Abstract

A staphylinid beetle morphotype, Mesostaphylinus orapa sp. n., is described based on a single well–preserved compression fossil from an Upper Cretaceous lacustrine deposit at Orapa Diamond Mine in Botswana. Mesostaphylinus Zhang is placed in the extant subfamily Paederinae based on general habitus and an unambiguous synapomorphy, the concealed antennal insertions. Mesostaphylinus is a genus of convenience for fossils belonging in Paederinae, but lacking diagnostic features (e.g., maxillary palpomeres) to assign and delineate them into appropriate tribes and subtribes. The fossil described here is morphologically similar to M. laiyangensis Zhang, M. fraternus Zhang, Wang and Xu, M. elongatus Solodovnikov and Yue, M. yixianus Solodovnikov and Yue, and M. antiquus Solodovnikov and Yue. Compared to other fossil staphylinid beetles that have been described thus far, the fossil also portrays morphological conservatism, morphological stasis, or arrested evolution dating back to the Cretaceous, thereby suggesting a punctuated equilibrium pattern of evolution.