Detlef Bernhard

The representatives of the genus Paramecium are well-studied ciliates and can be used in water quality assessment and the determinations of saprobic levels. For these applications, a clear and unambiguous identification of ciliate assemblages is essential, which is typically based on morphological characters requiring a sound taxonomic knowledge and experience in species determination including microscopic identification of both living and stained specimens. Therefore, we developed and applied specific PCR primers for the detection of species belonging to the genus Paramecium and the Paramecium aurelia complex. These primers were successfully tested with different Paramecium species including representatives of the P. aurelia complex as well as closely related species like Frontonia sp. and Tetrahymena sp. in both experimental and environmental samples. These primers can be used in a simultaneous approach achieving fast and reliable results with regard to determination of ciliate community and water assessment.

Representatives of the genus Stentor (Stentoridae, Heterotrichea) are striking ciliates in environmentalwater samples because of their size (up to 4 mm) and their trumpet-like shape. Important for species identification are the following main characteristics: (1) the presence or absence of endosymbiotic algae (zoochlorellae); (2) the colour of the pigmented cortical granules, and (3) the shape of the macronucleus. The complete small subunit rDNA (SSU rDNA) of 19 further representatives of the genus Stentor was sequenced to examine the phylogenetic relationships within this genus and to determine the taxonomic value of these main characteristics. The detailed phylogenetic analyses yielded a separation of all species possessing a single compact macronucleus from those species with an “elongated” macronucleus (moniliform or vermiform). The data also indicate that the uptake of algae as well as the loss of pigmentation happened independently in different lineages. Furthermore, a high level of intraspecific variation within several species was found. Thus, S. muelleri and S. (sp.) cf. katashimai appear to represent distinct species and S. multiformis is composed of a species complex.