A new genus and species of Eucoilinae, Rovnoeucoila tympanomorpha Buffington and Perkovsky, from a Rovno Amber inclusion, is described. This new taxon differs from extant eucoilines by having a clearly segmented metasoma and singular flagellomere morphology in the antenna. The new taxon is included in the re-analysis of a fossil calibrated, relaxed molecular clock divergence date analysis of Figitidae. The new analysis infers a mean crown group age for Eucoilinae at approximately 10 million years younger than previously estimated. The age of the eucoiline tribe Diglyphosematini does not change substantially in our new dating analysis, and is much younger when compared to the age of its host lineage Agromyzidae (Diptera); we discuss potential implications of this situation within the context of natural enemy selection in biological control projects that include parasitoid Hymenoptera.