The species identification problem in mirids (Hemiptera: Heteroptera) highlighted by DNA barcoding and species delimitation studies

Assessment of the DNA barcode libraries for the study of the poorly-known rove beetle (Staphylinidae) fauna of West Siberia

Staphylinidae, or rove beetles, are one of the mega-diverse and abundant families of the ground-living terrestrial arthropods that is taxonomically poorly known even in the regions adjacent to Europe where the fauna has been investigated for the longest time. Since DNA barcoding is a tool to accelerate biodiversity research, here we explored if the currently-available COI barcode libraries are representative enough for the study of rove beetles of West Siberia. This is a vast region adjacent to Europe with poorly-known fauna of rove beetles and from where not a single DNA barcode has hitherto been produced for Staphylinidae. First, we investigated the faunal similarity between the rove beetle faunas of the climatically compatible West Siberia in Asia, Fennoscandia in Europe and Canada and Alaska in North America. Second, we investigated barcodes available for Staphylinidae from the latter two regions in BOLD and GenBank, the world's largest DNA barcode libraries. We conclude that the rather different rove beetle faunas of Fennoscandia, on the one hand and Canada and Alaska on the other hand, are well covered in both barcode libraries that complement each other. We also find that even without any barcodes originating from specimens collected in West Siberia, this coverage is helpful for the study of rove beetles there due to the significant number of widespread species shared between West Siberia and Fennoscandia and due to the even larger number of shared genera amongst all three investigated regions. For the first time, we compiled a literature-based checklist for 726 species of the West Siberian Staphylinidae supplemented by their occurrence dataset submitted to GBIF. Our script written for mining unique (i.e. not redundant) barcodes for a given geographic area across global libraries is made available here and can be adopted for any other regions.

Cryptic Diversity in Cladosporium cladosporioides Resulting from Sequence-Based Species Delimitation Analyses

Cladosporium cladosporioides is an extremely widespread fungus involved in associations ranging from mutualistic to pathogenic and is the most frequently represented Cladosporium species in sequence databases, such as Genbank. The taxonomy of Cladosporium species, currently based on the integration of molecular data with morphological and cultural characters, is in frequent need of revision. Hence, the recently developed species delimitation methods can be helpful to explore cryptic diversity in this genus. Considering a previous study that reported several hypothetical species within C. cladosporioides, we tested four methods of species delimitation using the combined DNA barcodes internal transcribed spacers, translation elongation factor 1-α and actin 1. The analyses involved 105 isolates, revealing that currently available sequences of C. cladosporioides in GenBank actually represent more than one species. Moreover, we found that eight isolates from this set should be ascribed to Cladosporium anthropophilum. Our results revealed a certain degree of discordance among species delimitation methods, which can be efficiently treated using conservative approaches in order to minimize the risk of considering false positives.