Prosinodendron krelli from the Yixian Formation, China: A missing link among Lucanidae, Diphyllostomatidae and Passalidae (Coleoptera: Scarabaeoidea)

Prosinodendron krelli Bai, Ren and Yang gen. et sp. nov. (Scarabaeoidea: Lucanidae), an exceptionally well-preserved, new lucanid fossil, is described and illustrated from the Yixian Formation of western Liaoning Province, northeastern China. Based on its unique combination of characters, it is considered to be a missing link among Lucanidae, Diphyllostomatidae and Passalidae. A key to known fossil species of Lucanidae and adjacent families from Mesozoic is given. The close phylogenetic relationship of these three families of the Scarabaeoidea is supported by the fossil evidence.