Molecular phylogenetics of dinophytes harboring diatoms as endosymbionts (Kryptoperidiniaceae, Peridiniales), with evolutionary interpretations and a focus on the identity of Durinskia oculata from Prague

• Published in: Molecular phylogenetics and evolution 2018-01, Vol.118, p.392-402
• Main Authors: Kretschmann, Juliane, Žerdoner Čalasan, Anže, Gottschling, Marc
• Format: Article
• Language: English
• Subjects: Czech Republic; Diatoms - cytology; Diatoms - genetics; Epitype; Likelihood Functions; Molecular sequence diagnostics; Morphology; Phylogeny; Ribosomal RNA; RNA, Ribosomal - chemistry; RNA, Ribosomal - genetics; Sequence Analysis, DNA; Sequence comparison; Taxonomy
• ISSN: 1055-7903; 1095-9513
• DOI: 10.1016/j.ympev.2017.10.011

[Display omitted] •Multilocus analysis of Peridiniales with diatoms as endosymbionts well resolved.•Two independent colonisation events from marine to freshwater environment.•Molecular sequence diagnostics: Delimitation of protist species.•Identity clarified: Epitype designation for species described 130 years ago. Peridinialean dinophytes include a unique evolutionary group of algae harboring a diatom as an endosymbiont (Kryptoperidiniaceae), whose phylogenetic origin and internal relationships are not fully resolved at present. Several interpretations of the thecal plate pattern present in Durinskia oculata currently compete and lead to considerable taxonomic confusion. Moreover, it is unclear at present whether the species is restricted to freshwater habitats, or occurs in the marine environment as well. We collected material at the type locality of D. oculata in the Czech Republic and established monoclonal strains. Dinophyte cells were studied using light and electron microscopy, and we also determined DNA sequences of several rRNA regions (including the Internal Transcribed Spacers) for molecular characterization and phylogenetics. The morphology of strain GeoM∗662 indicated a plate formula of Po, X, 4′, 2a, 6″, 5c, 5s, 5‴, 2⁗, which was sustained also in form of a microscopic slide serving as an epitype. In the molecular DNA tree based on a matrix composed of concatenated rRNA sequences, strain GeoM∗662 showed a close relationship to other species of Durinskia, and the freshwater species clearly differs from the marine members. Two independent colonization events from the marine into the freshwater environment can be inferred within the Kryptoperidiniaceae. We provide a summarizing cladogram of dinophytes harboring a diatom as endosymbiont with evolutionary novelties indicated as well as a morphological key to the 6 species of Durinskia that are currently accepted.