A reevaluation of the amoeba genus Vahlkampfia based on SSUrDNA sequences

Abstract

Summary The amoebae of the genus Vahlkampfia share the two negative morphological characters which define the genus (no flagellate stage; no pores in the cysts) but, otherwise, are phenotypically diverse. The aim of this investigation was to test the monophyly of the genus and to investigate further the phylogeny of the family Vahlkampfiidae. The small subunit ribosomal DNA (SSUrDNA) of six Vahlkampfia species was sequenced and aligned with published sequences of species representing five genera of the family Vahlkampfiidae. The degree of SSUrDNA sequence variation within the Vahlkampfia genus was discovered to be as high as between other vahlkampfiid genera. Furthermore, the SSUrDNA sequences of three Vahlkampfia species are more similar to those of Tetramitus rostratus, Paratetramitus jugosus and Didascalus thorntoni than they are to those of four other Vahlkampfia species, and evolutionary distances within this group are similar to those within the monophyletic genus Naegleria . These results, and the phylogenetic trees generated from the data, are incongruent with the current classification for the family, which is based on comparisons of phenotype. Consequently, it is proposed that Vahlkampfia species be divided between four genera; Tetramitus, Vahlkampfia, Neovahlkampfia n.g. and Paravahlkampfia n.g.