Ultrastructure, SSU rRNA gene sequences and phylogenetic relationships of Flamella Schaeffer, 1926 (Amoebozoa), with description of three new species.

We isolated and described three new freshwater amoebozoan species that could be unambiguously assigned to the genus Flamella Schaeffer, 1926 by light microscopy. The phylogenetic position of the genus Flamella within the Amoebozoa was unknown, and gene sequence data were lacking. We sequenced the SSU rRNA gene of five Flamella spp., including a previously described F. aegyptia Michel et Smirnov, 1999. The phylogenetic trees inferred from these data showed, that Flamella is monophyletic and robustly branches within Amoebozoa. It belongs to a clade comprising Filamoeba spp., "Arachnula" sp., some protostelids and several SSU rRNA sequences of unidentified or uncultured eukaryotes. This clade consistently branched close to Archamoebae, Mycetozoa, Acramoeba dendroida and Multicilia marina; in contrast to the previous hypotheses, Flamella spp. did not show any relatedness either to Leptomyxida, or to Flabellinea. The ultrastructure of trophic amoebae and especially cysts of the species studied showed considerable similarity to Comandonia operculata Pernin et Pussard, 1979. We therefore suggest that Comandonia may be a junior synonym of Flamella, although more ultrastructural data about Comandonia operculata are necessary to test this hypothesis.