Amoeboid protists are extremely abundant and diverse in natural systems where they often play outstanding ecological roles. They can be found in almost all major eukaryotic divisions, and genomic approaches are bringing major changes in our perception of their deep evolutionary relationships. At fine taxonomic levels, the generalization of barcoding is revealing a considerable and unsuspected specific diversity that can be appreciated with careful morphometric analyses based on light and electron microscopic observations. We provide examples on the difficulties and advances in amoeboid protists systematics in a selection of groups that were presented at the VIIIth ECOP/ISOP meeting in Rome, 2019. We conclude that, in all studied groups, important taxonomical rearrangements will certainly take place in the next few years, and systematics must be adapted to incorporate these changes. Notably, nomenclature should be flexible enough to integrate many new high level taxa, and a unified policy must be adopted to species description and to the establishment of types.

Institute of Parasitology Biology Centre Czech Academy of Sciences 37005 Ceske Budejovice Czech Republic

Laboratory of Cellular and Molecular Protistology Zoological Institute of the Russian Academy of Sciences Universitetskaya nab 1 199034 Saint Petersburg Russia; Department of Invertebrate Zoology Faculty of Biology Saint Petersburg State University Universitetskaya nab 7 9 199034 Saint Petersburg Russia

Real Jardín Botánico de Madrid CSIC Plaza de Murillo 2 28014 Madrid Spain

Terrestrial Ecology Institute of Zoology University of Cologne Zülpicher Str 47b 50674 Köln Germany

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