No doubt, beetles are the most diverse group of animals. The order coleoptera currently comprises of about 400 000 species which represents ~40% of all insects. The idea of barcoding all of them seems very challenging and a quick look at BOLD 'only' shows some 26 000 public BINs for this group. However, if we take the second largest insect order, lepidoptera, as an example for how things can be done, it starts to look a little more promising. At this point BOLD holds some 100 000 public BINs for moths and butterflies. About 180 000 species are currently known for this order. The impressive number of DNA Barcodes in this group is the result of a decade of dedicated efforts. I don't see any reason why this shouldn't work with beetles and as a newly published study shows I am not alone in my thinking
The colleagues in Germany provide a DNA barcode reference library for Coleoptera for 15,948 individuals belonging to 3,514 species (53% of the German fauna) with representatives from 97 of 103 families (94%). This release is a direct result of the Barcoding Fauna Bavarica project which is led by the Bavarian State Collection of Zoology. Bavaria is the largest German state and contains almost all major habitat types in Germany which the exception of the coastal regions. As a result the state harbors 90% of the terrestrial and freshwater species known from the entire country.
Within five years some 540 000 beetle specimens were collected of which more than 25 000 specimens were submitted for sequence analysis. Almost 16 000 of them yielded full length DNA Barcodes and although the beetle fauna in central Europe was thought to be well known the dataset held some surprises:
The relatively high number of 1089 specimens, representing 176 potentially overlooked species was surprising, especially because many of these cases did not involve the specious and taxonomically difficult Staphylinidae, Curculionidae and Elateridae but the well-studied Carabidae, Cerambycidae, Haliplidae and Hydrophilidae.
The study not only presents advances in building a reference library for the German coleoptera but also a good starting point for future taxonomic work. The authors conclude:
Despite the fact that taxonomic research on German Coleoptera has been underway for more than 200 years, our study revealed 209 cases where the results from DNA barcoding and traditional taxonomy are discordant...We encourage the coleopteran scientific community to join the DNA barcoding projects on BOLD, to aid clarification of the status of species and to assist in the description of possibly overlooked species. Discussion and commenting on specific specimens on BOLD is possible for all registered users.