AUTHOR=Li Yan-Da , Tihelka Erik , Yamamoto Shûhei , Newton Alfred F. , Xia Fang-Yuan , Liu Ye , Huang Di-Ying , Cai Chen-Yang 

TITLE=Mesozoic Notocupes revealed as the sister group of Cupedidae (Coleoptera: Archostemata)

JOURNAL=Frontiers in Ecology and Evolution

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2023.1015627

DOI=10.3389/fevo.2023.1015627

ISSN=2296-701X

ABSTRACT=<p>Despite encompassing only about 50 extant species, beetles of the suborder Archostemata have a rich fossil history, being known from the Permian and dominating coleopteran assemblages in the Mesozoic before declining in richness towards the Late Cretaceous. Given the limited diversity of extant archostematans, fossils provide a valuable line of evidence for reconstructing the relationships among its constituent families. Here we re-evaluate the phylogenetic position of the Triassic–Cretaceous genus <italic>Notocupes</italic>, the most species-rich archostematan taxon in the fossil record. Exquisitely preserved fossils from the Middle Jurassic Haifanggou Formation (Daohugou; ~165 Ma) and mid-Cretaceous amber (~99 Ma) reveal critical differences from Ommatidae in the presence of separated procoxae and overlapping abdominal ventrites. Our analyses confirm that <italic>Notocupes</italic> is not a member of Ommatidae, but is closely related to Cupedidae. Our fossils reveal that <italic>Notocupes</italic> possessed unique adaptations for protecting their appendages, such as unusual dorsal pronotal grooves for the reception of antennae and epipleural grooves for the reception of legs, shedding light on ecological interactions in Mesozoic saproxylic habitats. The high similarity between Jurassic and Cretaceous <italic>Notocupes</italic> provides an exceptional example of long-term morphological stasis, suggesting a consistent microhabitat for the group.</p>