Description of a new species of Glaresidae (Coleoptera: Scarabaeoidea) from the Jehol Biota of China with a geometric morphometric evaluation

Glaresis tridentata Bai, Beutel & Ren sp. nov. (Scarabaeoidea: Glaresidae) from the Yixian Formation of western Liaoning Province, NE China is described and illustrated. A geometric morphometric analysis of three character systems (head, metatibia and aedeagus) was carried out including 136 specimens from 44 species of three genera of extant and extinct Glaresidae. The variation in these features between Glaresis tridentata Bai, Beutel & Ren sp. nov. and the other species was estimated based on Principal Component Analysis (PCA), Canonical Variate Analysis (CVA), Discriminant function analysis (DFA) and Minimum Spanning Tree (MST) approaches. The results suggest that Glaresidae, likely the sister group of all other extant Scarabaeoidea, had been established in the Early Cretaceous and contained larger species than today. The assignement of the new species to the genus Glaresis is supported. The validity of the genera Lithoglaresis and Cretoglaresis is questionable.