The diverse superfamily Oestroidea with more than 15 000 known species includes among others blow flies, flesh flies, bot flies and the diverse tachinid flies. Oestroidea exhibit strikingly divergent morphological and ecological traits, but even with a variety of data sources and inferences there is no consensus on the relationships among major Oestroidea lineages. Phylogenomic inferences derived from targeted enrichment of ultraconserved elements or UCEs have emerged as a promising method for resolving difficult phylogenetic problems at varying timescales. To reconstruct phylogenetic relationships among families of Oestroidea, we obtained UCE loci exclusively derived from the transcribed portion of the genome, making them suitable for larger and more integrative phylogenomic studies using other genomic and transcriptomic resources. We analysed datasets containing 37-2077 UCE loci from 98 representatives of all oestroid families (except Ulurumyiidae and Mystacinobiidae) and seven calyptrate outgroups, with a total concatenated aligned length between 10 and 550 Mb. About 35% of the sampled taxa consisted of museum specimens (2-92 years old), of which 85% resulted in successful UCE enrichment. Our maximum likelihood and coalescent-based analyses produced well-resolved and highly supported topologies. With the exception of Calliphoridae and Oestridae all included families were recovered as monophyletic with the following conclusions: Oestroidea is monophyletic with Mesembrinellidae as sister to the remaining oestroid families; Oestridae is paraphyletic with respect to Sarcophagidae; Polleniidae is sister to Tachinidae; Rhinophoridae sister to (Luciliinae (Toxotarsinae (Melanomyinae Calliphorinae))); Phumosiinae is sister to Chrysomyinae and Bengaliinae is sister to Rhiniidae. These results support the ranking of most calliphorid subfamilies as separate families.
