DNA barcoding and phylogenetic analyses of the genus Coleosporium (Pucciniales) reveal that the North American goldenrod rust C-solidaginis is a neomycete on introduced and native Solidago species in Europe

Recently, an unknown rust fungus of the genus Coleosporium appeared in Germany and Switzerland on giant goldenrod, Solidago gigantea, an invasive neophyte from North America, and on the indigenous European goldenrod, S. virgaurea. For identification, DNA barcodes were assembled in the course of the German Barcode of Life (GBOL) project and the investigation of neomycetes in Switzerland. Phylogenetic analyses were performed using ITS and LSU sequences of Coleosporium species representing various host plants and geographic regions. These analyses resulted in the first molecular evidence of the North American rust Coleosporium solidaginis in Europe. Coleosporium solidaginis is split into two subclades that are closely related to Coleosporium asterum, a species on Aster s.l., which was formerly synonymized with C. solidaginis. The genus is divided into an American and a Eurasian clade. This phylogenetic pattern indicates that the geographic distribution, rather than the relationship with host plants, played a major role in the evolution of Coleosporium species. This finding particularly applies to the European species, which are genetically uniform according to the ITS and LSU sequences. Taxonomical consequences are discussed. Coleosporium solidaginis is fragmentarily distributed in Europe. The place of its introduction and host shift to S. virgaurea remains uncertain. Life cycle and propagation are mainly restricted to asexual urediniospores. Telia were found only once and the aecial stage was not observed at all on pine trees. The ecological impact of this neomycete is still unknown, but C. solidaginis has the potential to harm wild and cultivated goldenrods in Europe.