PHYLOGENY AND HISTORICAL BIOGEOGRAPHY OF THE CYNIPOID WASP FAMILY IBALIIDAE (HYMENOPTERA)

The Ibaliidae are a small family of cynipoid wasps, the members of whi ch parasitize woodboring siricid larvae in hardwoods and conifers. The 19 currently recognized extant species occur mainly in the Northern H emisphere. No fossils are known despite the presumed old age of the fa mily. We present a cladistic analysis of ibaliid relationships at the species-level, mainly based on external skeletal characters of adults. The results indicate that the three genera (Eileenella, Heteribalia, Ibalia) and two subgenera of Ibalia (Ibalia s. str. and Tremibalia) re cognized in the current classification are monophyletic. Three differe nt categories of characters were compared for their phylogenetic usefu lness. Homoplasy was found to be lowest for main structures, higher fo r sculptural characters, and still higher for colour differences. The historical biogeography of the family was reconstructed using dispersa l-vicariance analysis in combination with palaeogeographical data. The results suggest that the family primarily diversified within the east ern Palaearctic-northern Oriental region. The nominate subgenus of Iba lia dispersed early to the western Nearctic, where it radiated; two sp ecies later spread throughout the Holarctic. The other subgenus of Iba lia shows an early eastern Palaearctic-eastern Nearctic disjunction wh ich presumably dates back to the Eocene-Oligocene transition.