The study presents and evaluates the results of DNA barcoding of about 5,360 specimens of sawflies and horntails. A total of 4,362 sequences covering 1,037 species are included in the analysis. It covers about 12% of all species of ‘Symphyta’, with representatives of all extant families (except the the Anaxyelidae, of which sequences were already present in BOLD and GenBank).
Species with low levels of taxonomic uncertainty can be readily identified using DNA barcodes. These taxa include, for example, the Cephidae, Diprionidae, Megalodontesidae, Siricidae, Xiphydriidae, most Argidae and most species of the tenthredinid subfamilies Tenthredininae, Blennocampinae and Heterarthrinae. For these species, the present barcode library will provide a valuable identification tool for ecologists and applied entomologists. It allows not only the identification of adults but can also be used for reliable identification of larvae, most of which are external (the majority) or internal feeders on a wide range of herbaceous or woody eudicot plants.
A significant level of cryptic species diversity was apparent in many groups. Although the status of most putative cryptic species still needs to be evaluated, detailed examination of specimens often revealed parallels between genetic and morphological variation.
Applications include the identification of immature stages without the need to rear them, community analyses based on metabarcoding of bulk samples and association of the sexes of adults. Barcode-based identification of larvae has the potential to rapidly improve biological knowledge on sawflies by reducing the need for risky and time-consuming rearing. In a similar way, correct association of the sexes will in many cases be made easier. This and other applications of DNA barcoding (e.g. metabarcoding) rely heavily on the existence of comprehensive barcode libraries, and the study recommends that future efforts should aim at complementing the reference library of ‘Symphyta’ barcodes, but should also examine the causes for barcode incongruence in some groups. The authors suggest that, in addition to addressing methodological issues, an integrative taxonomic approach is called for in order to disentangle problematic species and species groups of ‘Symphyta’.
The study was supported by Bayerisches Staatsministerium für Bildung und Kultus, Wissenschaft und Kunst, project Barcoding Fauna Bavarica, and by Bundesministerium für Bildung und Forschung, project German Barcode of Life. The sequence analyses for this study were supported, in part, by Genome Canada through the Ontario Genomics Institute, while informatics support was provided through a grant from the Ontario Ministry of Research and Innovation.
Schmidt, S., Taeger, A., Morinière, J., Liston, A., Blank, S. M., Kramp, K., Kraus, M., Schmidt, O., Heibo, E., Prous, M., Nyman, T., Malm, T. and Stahlhut, J. (2017), Identification of sawflies and horntails (Hymenoptera, ‘Symphyta’) through DNA barcodes: successes and caveats. Molecular Ecology Resources 17, 670–685. DOI:10.1111/1755-0998.12614