Iva Dyková

Five amoeba strains isolated from organs of fish were selected by morphology as possible members of the genus Vexillifera Schaeffer, 1926. Phylogenetic analyses of SSU rDNA sequences revealed that four of these strains form a best supported clade together with Vexillifera minutissima (strain CCAP 1590/3) and V. bacillipedes (sequence of the type culture was newly generated in this study). Comparison of trophozoite morphology and SSU rDNA sequences identified one of the five fish-isolated strains as closely related to V. bacillipedes, and characteristics of another three strains allowed to establish three new species: Vexillifera multispinosa, V. fluvialis and V. tasmaniana. The enlargement of dataset of Vexillifera SSU rDNA sequences enables us to doubt the identification of ATCC strain 50883 designated as V. armata. Since sequence of this strain branched in our analysis in a distant phylogenetic position within Korotnevela and Neoparamoeba clade, the Vexillifera origin of this sequence is called in question. The same applies to the newly generated sequence of the type strain of V. expectata, previously characterised by its morphology only.
 

As a result of light microscopical, ultrastructural and molecular study of three amoeba strains isolated from organs of three freshwater fish hosts, Stenamoeba amazonica sp. n. and S. limacina sp. n. are described as new amoeba species. The mutual comparison of isolated strains has extended the knowledge of morphological diversity within the genus Stenamoeba Smirnov, Nassonova, Chao et Cavalier-Smith, 2007. Molecular data obtained for these strains have complemented the phylogenetic tree that so far has contained only one nominal species within the single-genus Stenamoeba clade.