Using DNA barcode data to add leaves to the Trichoptera tree of life

The Trichoptera barcode of life initiative has gathered barcodes for a large portion of Trichoptera species diversity. Although the primary use of these data is species identification, they can also be used to generate species-level phylogenetic hypotheses. In order to ameliorate the well-documented difficulties of resolving deep divergences with the COI barcode fragment, we used a method of defining well-supported nodes from other data sources and filling out the "leaves" within these defined nodes of the Trichoptera tree of life with trees generated from the barcode fragment. We demonstrate the potential of this approach with the generation of a tree for Xiphocentronidae + Psychomyiidae. Using this example, we present two suspicious clades that warranted a more careful analysis, and demonstrate that a simple analysis of barcodes can generate and help answer other, related questions. We find that Zelandoptila is supported as belonging to Ecnomidae rather than Psychomyiidae, and we placed an unidentified specimen from the Smithsonian National Museum of Natural History collection as sister to Beraeidae.