Diatoms are one of the most abundant and arguably the most species-rich group of protists. Diatom species delimitation has often been based exclusively on the recognition of morphological discontinuities without investigation of other lines of evidence. Even though DNA sequences and reproductive experiments have revealed several examples of (pseudo)cryptic diversity, our understanding of diatom species boundaries and diversity remains limited. The cosmopolitan pennate raphid diatom genus Pinnularia represents one of the most taxon-rich diatom genera. In this study, we focused on the delimitation of species in one of the major clades of the genus, the Pinnularia subgibba group, based on 105 strains from a worldwide origin. We compared genetic distances between the sequences of seven molecular markers and selected the most variable pair, the mitochondrial cox1 and nuclear encoded LSU rDNA, to formulate a primary hypothesis on the species limits using three single-locus automated species delimitation methods. We compared the DNA-based primary hypotheses with morphology and with other available lines of evidence. The results indicate that our data set comprised 15 species of the P. subgibba group. The vast majority of these taxa have an uncertain taxonomic identity, suggesting that several may be unknown to science and/or members of (pseudo)cryptic species complexes within the P. subgibba group.

Department of Botany Faculty of Science Palacký University Olomouc Šlechtitelů 27 CZ 78371 Olomouc Czech Republic

Department of Bryophyta and Thallophyta Botanic Garden Meise Nieuwelaan 38 1860 Meise Belgium

Ecosystem Management Research Group Department of Biology Faculty of Science University of Antwerp Universiteitsplein 1 2610 Wilrijk Belgium

Laboratory of Aquatic Ecology and Evolutionary Biology University of Leuven Charles Deberiotstraat 32 3000 Leuven Belgium

Laboratory of Protistology and Aquatic Ecology Department of Biology Faculty of Science Ghent University Krijgslaan 281 S8 9000 Gent Belgium

Citace poskytuje Crossref.org

Global radiation in a rare biosphere soil diatom