Taxonomic requirements for better documenting and understanding biological invasions - the example of genetic weatherfish Misgurnus/Paramisgurnus sp. identification.
Management of biological invasions strongly depends on early and accurate detection of non-native species, yet species identification is often complicated for various reasons. One prominent example relates to the controversy about the genetic specimen assignment of Asian and Oriental weatherfish species introduced into Europe. Weatherfishes, comprising the genera Misgurnus and Paramisgurnus (Cobitidae) are small benthic freshwater fishes with a wide range of habitats in the temperate to subtropical regions of Eurasia. Many of the eleven described species have been introduced outside their native ranges, mainly through ornamental trade and as food. Due to their poorly known life cycles, unclear morphology, overlapping meristic features and frequent hybridisation, the challenges associated with accurate species identification in this group comprise cryptic species and cryptic invasions, unresolved classical and molecular taxonomy, haplotype sharing and incomplete molecular genetic reference databases. Based on our newly generated molecular phylogeny comprising 289 published weatherfish COI barcodes, the existence of distinct phylogenetic clusters is evident. Except for the endangered Central European species, Misgurnus fossilis, and an unnamed cluster from Vietnam, all clusters were polyphyletic. Haplotype sharing was frequently observed, as well as specimens only labelled to genus or higher taxonomic levels. We conclude that genetic analysis of type specimens or type regions to resolve the underlying taxonomy and complete the reference databases would be necessary as prerequisite for accurate species identification in the weatherfish group. Such information is crucial in assessing their worldwide species distribution patterns, ecosystem impacts and invasive potential. As molecular genetic databases are constantly growing, new taxa are being proposed, and taxonomies are being changed in light of new data, it is obligatory to consider past publications in light of the dynamics of species names and taxonomic phylogenies. We still recommend early sharing of exotic species records since such knowledge is particularly crucial when it comes to management of invasive species.