The fossil record of the planthopper family Achilidae, with particular reference to those in Baltic amber (Hemiptera: Fulgoromorpha)

The family Achilidae (Hemiptera, Fulgoromorpha, commonly called planthoppers) is one of the least known and least understood groups, due to their cryptic lifestyle. They appear in the fossil record in the Lower Cretaceous, with a single genus and two species from the Crato Formation of Brazil. The oldest amber inclusion is reported from the earliest Late Cretaceous amber of Burma. Surprisingly, Achilidae are relatively common among the larger inclusions that can be found in Eocene Baltic amber. The first description of a fossil species was in the mid-19th Century. Currently, there are 13 genera and 16 species known from fossils, of which nine genera and 11 species are from Baltic amber. However, many of them need reconsideration, revisionary studies and placement in the phylogenetic context of the family. Former studies on inclusions in this amber revealed several unique forms (extinct tribes Ptychoptilini and Waghildini), or taxa ascribable to the sparse Recent tribe Achilini. This paper provides an overview of the knowledge of fossil Achilidae, particularly those from Baltic amber. The Eocene appears to be the heyday of the family; however, this hypothesis should be tested with further detailed studies.