The genus was long assumed to be the most primordial taxon in the Stichotrichia [hypotrichs ()] based on its morphological features and was considered to be an intermediate between heterotrichs and the traditional hypotrichous assemblage. In order to evaluate the phylogenetic position of within the Hypotrichia, we sequenced the small-subunit rRNA gene and the alpha-tubulin gene for a Qingdao population of . Phylogenetic trees were constructed and compared to morphological and morphogenetic data. The results show that (i) is positioned near , both of which always form a sister clade to the assemblage including Stichotrichia, Hypotrichia, Oligotrichia and Choreotrichia, (ii) , which may represent an intermediate between heterotrichs () and the Stichotrichia–Hypotrichia complex, is probably an ancestor-like form of the latter group and (iii) in contrast to morphological characters, both molecular and ontogenetic data support the separation of from the hypotrichs (). Thus, might be placed in the class Spirotrichea at about subclass level, next to Phaconidiidia, Hypotrichia and Stichotrichia, which supports the establishment of a new subclass Protohypotrichia n. subclass within the class Spirotrichea, with characterizations including slightly differentiated somatic ciliature (i.e. cirri on the ventral side generally uniform and non-grouped, no clearly defined marginal cirral rows, ciliature on the dorsal side mixed with cirri and dikinetids, no clearly differentiated dorsal kineties) and a unique but intermediate morphogenetic pattern of cortical structures between Hypotrichia and Stichotrichia.


Article metrics loading...

Loading full text...

Full text loading...



  1. Berger, H.(1999).Monograph of the Oxytrichidae (Ciliophora, Hypotrichia) (Monographiae Biologicae vol. 78). Dordrecht: Springer.
  2. Berger, H.(2006).Monograph of theUrostyloidea (Ciliophora, Hypotricha) (Monographiae Biologicae vol. 85). Heidelberg: Springer.
  3. Chen, Z. & Song, W.(2002). Phylogenetic positions of Aspidisca steini and Euplotes vannus within the order Euplotida (Hypotrichia: Ciliophora) inferred from complete small subunit ribosomal RNA gene sequences. Acta Protozool 41, 1–9. [Google Scholar]
  4. Corliss, J. O.(1979).The Ciliated Protozoa: Characterization, Classification and Guide to the Literature, 2nd edn. Oxford: Pergamon.
  5. De Puytorac, P.(1994). Phylum Ciliophora Doflein, 1901. In Traité de Zoologie, Tome II, Infusoires Ciliés, Fasc. 2, Systématoque, pp. 1–15. Edited by P. de Puytorac. Masson: Paris (in French).
  6. Diener, D. R., Burchill, B. R. & Burton, P. R.(1983). Microtubules and filaments beneath the fission furrow of Stentor coeruleus. J Eukaryot Microbiol 30, 83–90. [Google Scholar]
  7. Eigner, P. & Foissner, W.(1994). Divisional morphogenesis in Amphisiellides illuvialis n. sp., Paramphisiella caudata (Hemberger) and Hemiamphisiella terricola Foissner and redefinition of the Amphisiellidae (Ciliophora, Hypotrichida). J Eukaryot Microbiol 41, 243–261.[CrossRef] [Google Scholar]
  8. Elwood, H. J., Olsen, G. J. & Sogin, M. L.(1985). The small-subunit ribosomal RNA gene sequences from the hypotrichous ciliates Oxytricha nova and Stylonychia pustulata. Mol Biol Evol 2, 399–410. [Google Scholar]
  9. Felsenstein, J.(1995).phylip: phylogeny inference package, version 3.57c. Department of Genome Sciences, University of Washington, Seattle, USA.
  10. Fitch, W. M. & Margoliash, E.(1967). Construction of phylogenetic trees. Science 155, 279–284.[CrossRef] [Google Scholar]
  11. Foissner, W.(1996). Ontogenesis in ciliated protozoa, with emphasis on stomatogenesis. In Ciliates: Cells as Organisms, pp. 95–177. Edited by K. Hausmann & P. C. Bradbury. Stuttgart: Gustav Fischer.
  12. Greenwood, S. J., Sogin, M. L. & Lynn, D. H.(1991). Phylogenetic relationships within the class Oligohymenophorea, phylum Ciliophora, inferred from the complete small subunit rRNA gene sequences of Colpidium campylum, Glaucoma chattoni, and Opisthonecta henneguyi. J Mol Evol 33, 163–174.[CrossRef] [Google Scholar]
  13. Grolière, C. A., Puytorac, P. & Detcheva, R.(1980). A propos d'observations sur la stomatogenése et l'ultrastructure du cilié Protocruzia tuzeti Villeneuve-Brachon, 1940. Protistologica 16, 453–466 (in French). [Google Scholar]
  14. Hammerschmidt, B., Schlegel, M., Lynn, D. H., Leipe, D. D., Sogin, M. L. & Raikov, I. B.(1996). Insights into the evolution of nuclear dualism in the ciliates revealed by phylogenetic analysis of rRNA sequences. J Eukaryot Microbiol 43, 225–230.[CrossRef] [Google Scholar]
  15. Jones, D. T., Taylor, W. R. & Thornton, J. M.(1992). The rapid generation of mutation data matrices from protein sequences. Comput Appl Biosci 8, 275–282. [Google Scholar]
  16. Kimura, M.(1980). A simple method of estimating evolutionary rates of base substitutions through comparative studies of nucleotide sequences. J Mol Evol 16, 111–120.[CrossRef] [Google Scholar]
  17. Kumar, S., Tamura, K. & Nei, M.(2004).mega3: integrated software for molecular evolutionary genetics analysis and sequence alignment. Brief Bioinform 5, 150–163.[CrossRef] [Google Scholar]
  18. Li, L. & Song, W.(2006). Phylogenetic position of the marine ciliate, Certesia quadrinucleata (Ciliophora; Hypotrichia; Hypotrichida) inferred from the complete small subunit ribosomal RNA gene sequence. Eur J Protistol 42, 55–61.[CrossRef] [Google Scholar]
  19. Lynn, D. H.(2003). Morphology or molecules: how do we identify the major lineages of ciliates (phylum Ciliophora)? Eur J Protistol 39, 356–364.[CrossRef] [Google Scholar]
  20. Lynn, D. H.(2008).The Ciliated Protozoa: Characterization, Classification, and Guide to the Literature, 3rd edn. Dordrecht: Springer.
  21. Lynn, D. H. & Small, E. B.(1997). A revised classification of the phylum Ciliophora Doflein, 1901. Rev Soc Mex Hist Nat 47, 65–78. [Google Scholar]
  22. Lynn, D. H. & Small, E. B.(2002). Phylum Ciliophora Doflein, 1901. In An Illustrated Guide to the Protozoa, 2nd edn, pp. 371–656. Edited by J. J. Lee, G. F. Leedale & P. C. Bradbury. Lawrence, KS: Society of Protozoologists.
  23. Lynn, D. H. & Strüder-Kypke, M. C.(2002). Phylogenetic position of Licnophora, Lechriopyla, and Schizocaryum, three unusual ciliates (phylum Ciliophora) endosymbiotic in echinoderms (phylum Echinodermata). J Eukaryot Microbiol 49, 460–468.[CrossRef] [Google Scholar]
  24. Nixon, K. C.(1999). The parsimony ratchet, a new method for rapid parsimony analysis. Cladistics 15, 407–414.[CrossRef] [Google Scholar]
  25. Nylander, J. A. A.(2004). MrModeltest version 2. Distributed by the author. Department of Systematic Zoology, Evolutionary Biology Centre, Uppsala University, Sweden.
  26. Posada, D. & Crandall, K. A.(1998).modeltest: testing the model of DNA substitution. Bioinformatics 14, 817–818.[CrossRef] [Google Scholar]
  27. Ronquist, F. & Huelsenbeck, J. P.(2003). MrBayes 3: Bayesian phylogenetic inference under mixed models. Bioinformatics 19, 1572–1574.[CrossRef] [Google Scholar]
  28. Roque, M.(1970). Observation sur Phacodinium metchnicoffi Certes, 1891. Ann Stat Biol 5, 297–302 (in French). [Google Scholar]
  29. Saitou, N. & Nei, M.(1987). The neighbor-joining method: a new method for reconstructing phylogenetic trees. Mol Biol Evol 4, 406–425. [Google Scholar]
  30. Schlegel, M., Elwood, H. J. & Sogin, M. L.(1991). Molecular evolution in hypotrichous ciliates: sequence of the small subunit RNA genes from Onychodromus quadricornutus and Oxytricha granulifera (Oxytrichidae, Hypotrichida, Ciliophora). J Mol Evol 32, 64–69.[CrossRef] [Google Scholar]
  31. Shao, C., Song, W., Hu, X., Ma, H., Zhu, M. & Wang, M.(2006). Cell division and morphology of the marine ciliate, Condylostoma spatiosum Ozaki and Yagiu (Ciliophora, Heterotrichida) based on a Chinese population. Eur J Protistol 42, 9–19.[CrossRef] [Google Scholar]
  32. Shi, X. L., Song, W. & Shi, X. B.(1999). Systematic revision of the hypotrichous ciliates. In Progress in Protozoology, pp. 77–154. Edited by W. Song, X. L. Shi, X. Hu, Y. Lei, J. Wei, Z. Chen, X. B. Shi & M. Wang. Qingdao: Qingdao Ocean University Press (in Chinese).
  33. Shin, M. K., Hwang, U. W., Kim, W., Wright, A.-D. G., Krawczyk, C. & Lynn, D. H.(2000). Phylogenetic position of the ciliates Phacodinium (order Phacodiniida) and Protocruzia (subclass Protocruziidia) and systematics of the spirotrich ciliates examined by small subunit ribosomal RNA gene sequences. Eur J Protistol 36, 293–302.[CrossRef] [Google Scholar]
  34. Sikes, D. S. & Lewis, P. O.(2001).pauprat. A tool to implement parsimony and likelihood ratchet searches using PAUP*. Distributed by the authors. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA.
  35. Small, E. B. & Lynn, D. H.(1985). Phylum Ciliophora. In An Illustrated Guide to the Protozoa, pp. 393–575. Edited by J. J. Lee, S. H. Hutner & E. C. Bovee. Lawrence, KS: Society of Protozoologists.
  36. Sogin, M. L. & Elwood, H. J.(1986). Primary structure of the Paramecium tetraurelia small-subunit rRNA coding region: phylogenetic relationships within the Ciliophora. J Mol Evol 23, 53–60.[CrossRef] [Google Scholar]
  37. Song, W. & Packroff, G.(1993). Beitrag zur Morphogenese des marinen Ciliaten Diophrys scutum (Dujardin, 1841). Zool Jahrb Abt Anat Ontogenie Tiere 123, 85–95 (in German). [Google Scholar]
  38. Song, W. & Wilbert, N.(1997). Morphological studies on some free living ciliates (Ciliophora: Heterotrichida, Hypotrichida) from marine biotopes in Qingdao, China, with descriptions of three new species: Holosticha warreni nov. spec., Tachysoma ovata nov. spec. and T. dragescoi nov. spec. Eur J Protistol 33, 48–62.[CrossRef] [Google Scholar]
  39. Song, W., Wilbert, N., Chen, Z. & Shi, X.(2004). Considerations on the systematic position of Uronychia and related euplotids based on the data of ontogeny and 18S rRNA gene sequence analyses, with morphogenetic redescription of Uronychia setigera Calkins, 1902 (Ciliophora, Euplotida). Acta Protozool 43, 313–328. [Google Scholar]
  40. Stoeck, T., Foissner, W. & Lynn, D. H.(2007). Small subunit rRNA phylogenies suggest that Epalxella antiquorum (Penard, 1922) Corliss, 1960 (Ciliophora, Odontostomatida) is a member of the Plagiopylea. J Eukaryot Microbiol 54, 436–442.[CrossRef] [Google Scholar]
  41. Swofford, D. L.(2002).paup*. Phylogenetic Analysis using Parsimony (* and other methods). Sunderland, MA: Sinauer.
  42. Thompson, J. D., Higgins, D. G. & Gibson, T. J.(1994).clustalw: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucleic Acids Res 22, 4673–4680.[CrossRef] [Google Scholar]
  43. Villeneuve-Brachon, S.(1940). Recherches sur les ciliés hétérotriches, cinétome, argyrome, myonèmes formes nouvelles ou peu connues. Arch Zool Exp Gen 82, 1–180 (in French). [Google Scholar]
  44. Vos, R. A.(2003). Accelerated likelihood surface exploration: the likelihood ratchet. Syst Biol 52, 368–373. [Google Scholar]
  45. Wicklow, B. J.(1982). The Discocephalina (n. subord.): ultrastructure, morphogenesis and evolutionary implications of a group of endemic interstitial hypotrichs (Ciliophora, Protozoa). Protistologica 18, 299–330. [Google Scholar]

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error