†Passalopalpidae, a new family from the Cretaceous Burmese amber, as the possible sister group of Passalidae Leach (Coleoptera: Scarabaeoidea)

Abstract

A new family of Scarabaeoidea is revealed from the Cretaceous amber of Myanmar (earliest Cenomanian, near 100 Ma), on a series of males and females, most in perfect condition. Passalopalpidae fam. nov., Passalopalpus cheni gen. et sp. nov., are probably extinct since a long time. Observations were made on the whole body (head, thorax, abdomen) and appendages (mouthparts, antennae, legs, wings). Most characters are remarkable and plesiomorphic, compared to Passalidae Leach, as well as to some other Scarabaeoidea. Morphological characteristics demonstrate that the fossil species is typically « passaloid », but that it cannot belongs to Passalidae. Passalopalpidae and Passalidae are clearly distinct families, with strong assumption to be sister groups. The systematic interpretation of the fossil could fill a historic gap: the sister group of Passalidae had been established previously never in a solid way. Passalids are Gondwanian, whereas passalopalpids lived on former eastern Laurasia. Vicariance of both taxa, each on one of the super-continents, seems to support recent hypotheses of phylogeny and paleobiogeography for Passalidae. Other preliminary notes are given on the morphology, biology and phylogenetic relationships of passalopalpids.