Baltic amber Ibaliidae (Hymenoptera: Cynipoidea): a new genus with implications for the phylogeny and historical biogeography of the family

The first definitive ibaliid wasp (Cynipoidea: Ibaliidae) is described and illustrated from a female preserved in middle Eocene (Lutetian) Baltic amber. Archaeibalia succinica Liu & Engel gen. et sp.n. is distinct from all other members of the family, cladistically placed as sister to all other Ibaliidae, and classified in its own subfamily, Archaeibaliinae Liu & Engel subfam.n. The genus was putatively a parasitoid of wood-boring insects in hardwood trees. Given that the species is exceptionally rare in Baltic amber (a single individual) despite a habitat that would have placed it in immediate proximity with resin flows, the host of A. succinica was probably not living in the 'Baltic amber tree'. The historical biogeography and evolution of ibaliids is reconsidered based on the present paleontological evidence.