Crassiungula gen. nov., an Enigmatic Genus of Scarabaeoids from Mid-Cretaceous Kachin Amber (Coleoptera: Scarabaeoidea)

Mesozoic fossils play a crucial role in filling gaps in the evolutionary history of beetles. They provide insights into early evolution and morphological diversification that cannot be obtained through other data sources. A new genus and species of Scarabaeoidea, Crassiungula lawrencei gen. et sp. nov., is described from mid-Cretaceous Kachin amber. This fossil exhibits a unique combination of morphological traits that precludes its assignment to any currently recognized scarabaeoid family. The most striking features of Crassiungula are its highly modified mesotarsus and mesopretarsal claws: tarsomeres 1–4 are short and flattened; tarsomere 5 has a ventral hook-like projection; and the pretarsal claws are asymmetrical, with a multisetose empodium. The discovery of Crassiungula highlights the morphological diversity and evolutionary complexity of Cretaceous scarabaeoids. Further discoveries of better-preserved specimens may help refine its phylogenetic placement and deepen our understanding of the evolutionary history of Scarabaeoidea.