The knowledge of cell biology of a eukaryotic group is essential for correct interpretation of ecological and molecular data. Although diplonemid protists are one of the most species-rich lineages of marine eukaryotes, only very fragmentary information is available about the cellular architecture of this taxonomically diverse group. Here, a large serial block-face scanning electron microscopy data set complemented with light and fluorescence microscopy allowed the first detailed three-dimensional reconstruction of a diplonemid species. We describe numerous previously unknown peculiarities of the cellular architecture and cell division characteristic for diplonemid flagellates, and illustrate the obtained results with multiple three-dimensional models, comprehensible for non-specialists in protist ultrastructure.

Faculty of Sciences University of South Bohemia České Budějovice Czech Republic

Institute of Parasitology Biology Centre Czech Academy of Sciences České Budějovice Czech Republic

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On the possibility of yet a third kinetochore system in the protist phylum Euglenozoa