Organisms Diversity & Evolution

, Volume 15, Issue 2, pp 215–233 | Cite as

New Paramecium (Ciliophora, Oligohymenophorea) congeners shape our view on its biodiversity

  • Sascha Krenek
  • Thomas U. Berendonk
  • Sergei I. Fokin
Original Article


Paramecium is one of the best known and most intensely studied ciliate genera. It currently comprises 18 morphospecies including the P. aurelia complex of 15 sibling species. Here, we describe the new morphospecies Paramecium buetschlii sp. nov. from a freshwater pool in Norway, featuring unusual combinations of morphological characters and a high genetic diversity relative to other congeners. Three further investigated Paramecium spp. from Germany, Hungary, and Brazil are treated as cryptic species, because they are difficult to discriminate from other members of the genus relying on morphological criteria only. However, DNA-based taxonomic markers (18S-rDNA and mitochondrial COI) clearly indicate they are separate species. Due to the lack of an appropriate systematic term within the International Code of Zoological Nomenclature for distinguishing cryptic from valid biological species, we propose the provisional status Eucandidatus as a component of the taxonomic name when describing new but cryptic eukaryotes. Based on our data, we postulate that even within Europe there is a higher biodiversity within this common ciliate group that is heavily used in the classroom. By uncovering potentially distinct species that have been classified under the same species names, our molecular analyses further suggest a higher current stock diversity in Paramecium than previously thought. We also would like to emphasize that under-sampling is another major issue in estimating protist diversity. Future large-scale studies based on extensive sampling not only in exotic and remote regions, but also in less frequently sampled areas, will therefore likely improve our understanding of species richness and diversity.


Cryptic species Molecular analysis New morphospecies Paramecium biodiversity Paramecium buetschlii 



This work was supported by a grant from the Italian Ministry of University and Research—MIUR (Ministerio Italiano dell’ Universita e della Ricerca) to S. I. Fokin and by the German Research Foundation (DFG, grant BE-2299/3-1,2,3 and BE 2299/5-1) to T. U. Berendonk, as well as by the European Commission FP7-PEOPLE-2009-IRSES project CINAR PATHOBACTER (247658) and by the BMBS COST Action BM1102. We are grateful to D. Ammermann for sampling in Porto Alegri, to Cora Baier and M. Horn for their help with 18S-rDNA sequence of “Eucandidatus P. brazilianum”, to M. Müller, who provided a possibility of our sampling at Balaton lake region and to Dana Barth for providing cells of P. buetschlii sp. nov. and DNA samples for molecular analyses. Further gratitude is expressed to two anonymous reviewers whose valuable comments allowed an essential improvement of the manuscript.

Conflict of interest

The authors have no conflict of interest to declare.

Ethical standards

All the experiments in this study comply with the current laws of the country in which they were performed and do not infringe human and animal rights.

Supplementary material

13127_2015_207_MOESM1_ESM.htm (144 kb)
Table S1 (HTM 143 kb)
13127_2015_207_MOESM2_ESM.htm (2.5 mb)
Table S2 (HTM 2602 kb)


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Copyright information

© Gesellschaft für Biologische Systematik 2015

Authors and Affiliations

  1. 1.Institute of HydrobiologyTechnische Universität DresdenDresdenGermany
  2. 2.Department of BiologyPisa UniversityPisaItaly
  3. 3.Department of Zoology InvertebrateSt. Petersburg State UniversitySt. PetersburgRussia

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