Molecular phylogeny of the Heterotrichea (Ciliophora, Postciliodesmatophora) based on small subunit rRNA gene sequences.

A comprehensive molecular analysis of the phylogenetic relationships within the Heterotrichea including all described families is still lacking. For this reason, the complete nuclear small subunit (SSU) rDNA was sequenced from further representatives of the Blepharismidae and the Stentoridae. In addition, the SSU rDNA of a new, undescribed species of the genus Condylostomides (Condylostomatidae) was sequenced.

Phylogeny of the Stichotrichia (Ciliophora; Spirotrichea) reconstructed with nuclear small subunit rRNA gene sequences: discrepancies and accordances with morphological data.

The Stichotrichia, known as an especially various and taxonomically difficult group, were intensely studied with morphological, morphogenetic, and molecular methods in the last years. Nevertheless, a consistent classification is lacking and several important questions about the phylogenetic relationships within this group remain unsolved. In order to gain deeper insights into these relationships, the nuclear small subunit rRNA genes of seven species of the Stichotrichia, representatives of the families Oxytrichidae, Amphisiellidae, and Pseudourostylidae, were phylogenetically analysed.

A PCR-based method to distinguish the sibling species Stylonychia mytilus and Stylonychia lemnae (Ciliophora, Spirotrichea) using isocitrate dehydrogenase gene sequences.

A differentiation, based on morphological characters, between Stylonychia mytilus and Stylonychia lemnae is very difficult, especially for non-specialists. These two sibling species were considered as one species, S. mytilus, until detailed cytological and genetic studies could show the existence of two genetically isolated varieties.

Stylonychia lemnae strains from a North American site differ in a single nucleotide within the small subunit rDNA from Eurasian strains.

Stylonychia lemnae (Ciliophora, Spirotrichea), a member of the Stylonychia mytilus complex, shows a global distribution, occurring in many temperate fresh waters. As there are few descriptions of biogeographical patterns of ubiquitously occurring ciliated protozoans, we report a distinct sequence difference within the small subunit ribosomal DNA gene, which occurs only in the clones of S. lemnae isolated from the surroundings of Ithaca (USA) in comparison with clones of the same species from different regions in Europe, Asia, and South Africa.

Fluorescence in situ hybridization with specific oligonucleotide rRNA probes distinguishes the sibling species Stylonychia lemnae and Stylonychia mytilus (Ciliophora, Spirotrichea).

Based on morphological and morphogenetic characters alone, the sibling species Stylonychia lemnae and Stylonychia mytilus, members of the Stylonychia mytilus complex, can hardly be distinguished. However, biochemical investigations of the isoenzyme pattern of different enzymes showed a distinct differentiation between these two species. In the last few years, fluorescence in situ hybridization (FISH) techniques have become a suitable and reliable tool for identification and differentiation of closely related species of protozoa, such as ciliates.