We describe four new species of Flabellula, Leptomyxa and Rhizamoeba and publish new SSU rRNA gene and actin gene sequences of leptomyxids. Using these data we provide the most comprehensive SSU phylogeny of leptomyxids to date. Based on the analyses of morphological data and results of the SSU rRNA gene phylogeny we suggest changes in the systematics of the order Leptomyxida (Amoebozoa: Lobosa: Tubulinea). We propose to merge the genera Flabellula and Paraflabellula (the genus Flabellula remains valid by priority rule). The genus Rhizamoeba is evidently polyphyletic in all phylogenetic trees; we suggest retaining the generic name Rhizamoeba for the group unifying R. saxonica, R.matisi n. sp. and R. polyura, the latter remains the type species of the genus Rhizamoeba. Based on molecular and morphological evidence we move all remaining Rhizamoeba species to the genus Leptomyxa. New family Rhizamoebidae is established here in order to avoid paraphyly of the family Leptomyxidae. With the suggested changes both molecular and morphological systems of the order Leptomyxida are now fully congruent to each other.

Department of Genetics and Evolution University of Geneva Sciences 3 1211 Geneva Switzerland

Department of Invertebrate Zoology Faculty of Biology St Petersburg State University Universitetskaja nab 7 9 199034 St Petersburg Russia

Department of Invertebrate Zoology Faculty of Biology St Petersburg State University Universitetskaja nab 7 9 199034 St Petersburg Russia; Laboratory of Cytology of Unicellular Organisms Institute of Cytology RAS Tikhoretsky ave 4 194064 St Petersburg Russia

Department of Terrestrial Ecology Institute of Zoology University of Cologne 50674 Cologne Germany

Department of Zoology Faculty of Natural Sciences Comenius University Mlynská dolina B 1 842 15 Bratislava Slovak Republic

Faculty of Science Masaryk University Kotlářská 2 611 37 Brno Czech Republic

UMR7144 groupe EPEP CNRS Station Biologique Place Georges Teissier 29680 Roscoff France

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