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Frontonia

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Frontonia
Frontonia sp., specimen is digesting cyanobacteria, the mouth (cytostome) is at the bottom right.
Scientific classification
Domain:
Eukaryota
(unranked):
SAR
(unranked):
Alveolata
Phylum:
Ciliophora
Subphylum:
Intramacronucleata
Class:
Oligohymenophorea
Order:
Peniculida
Family:
Frontoniidae
Genus:
Frontonia

Ehrenberg, 1838

Frontonia is a genus of free-living unicellular ciliate protists, belonging to the order Peniculida. As Peniculids, the Frontonia are closely related to members of the genus Paramecium. However, whereas Paramecia are mainly bacterivores, Frontonia are capable of ingesting large prey such as diatoms, filamentous algae, testate amoebas,[1] and even, in some circumstances, members of their own species.[2] In bacteria-rich saprobic conditions, Frontonia leucas can live as a facultative bacterivore.[3]

Frontonia are widely dispersed, and members of the genus can be found in marine and freshwater environments on every continent.[4][5]

Appearance and characteristics

Frontonia leucas, by V. Schewiakoff, 1889
Frontonia sp.

Frontonia species vary in length from 50 to 600 micrometres.[6] Cell bodies are typically ovoid or elongate, and somewhat flattened from back to front. They are flexible, uniformly ciliated, and usually surrounded by trichocysts. The small oral aperture is pear-shaped, and located in the anterior half of the cell.[7] Along the left side of the opening there are three membranelles, and the right has a single paroral membrane. The mouth is supported by inconspicuous microtubular rods (nematodesmata),[8] and may expand during feeding to as much as two-thirds of the cell's length.[9]

The cytoplasm of some species, such as Frontonia atra and Frontonia acuminata, can be darkly pigmented.

Classification

The genus Frontonia, created by C. G. Ehrenberg in 1838, includes some thirty named and described species.[10]

In 2008, analysis of small subunit rRNA gene sequences confirmed the close relationship of several members of the genus: Frontonia leucas, F. vernalis, F. tchibisovae, F. lynni. However, Frontonia didieri was found to be related more closely to a species from another genus, Apofrontonia dohrni. This result calls into question the monophyly of the genus Frontonia, and also casts doubt on the morphological criteria used to distinguish Apofrontonia from it.[11]

  • Frontonia leucas ingesting a diatom
  • Frontonia atra has symbiotic bacteria in its cytoplasm
  • Frontonia leucas, radiating canals around contractile vacuole
  • Frontonia vernalis carries symbiotic algae in its cytoplasm

List of accepted species names

References

  1. ^ Dias, Roberto and D'Agosto, Marta. 2006. "Feeding Behavior of Frontonia leucas (Ehrenberg)." Revista Brasiliera de Zoologia 23 (3): 758-763
  2. ^ Devi, R. Vimala. 2007. "Cannibalism in Frontonia leucas Ehr." JEM 11 (3): 304-307
  3. ^ Dias 2006
  4. ^ Petz, Wolfgang et al. 2007. "Ciliate biogeography in Antarctic and Arctic freshwater ecosystems: endemism or global distribution of species?" FEMS Microbiology Ecology 59 (2): 396-408
  5. ^ "Long, Hongan et al. 2008. "Taxonomic studies on three marine species of Frontonia from northern China." Zootaxa 1687:35-50" (PDF). Archived from the original (PDF) on 2012-04-25. Retrieved 2011-10-08.
  6. ^ Patterson, D.J. Free-Living Freshwater Protozoa: A Colour Guide. Manson, 1992,1996. p. 133. ISBN 1-874545-40-5
  7. ^ Carey, Philip G., Marine interstitial ciliates: an illustrated key. Chapman and Hall, 1992, ISBN 978-0-412-40610-2 p. 129
  8. ^ Gil, Rosario. 1984. Cortical Fine Structure of Frontonia Leucas. Transactions of the American Microscopical Society. 100(4):373-83. https://www.jstor.org/pss/3226150
  9. ^ Goldsmith, WM. (1922) The process of ingestion in the ciliate, Frontonia. Journal of Experimental Zoology 36(3):331-52.
  10. ^ Long et al. (2005). Frontonia lynni Archived 2012-04-25 at the Wayback Machine n. sp., a new marine ciliate (Protozoa, Ciliophora, Hymenostomatida) from Qingdao, China. Zootaxa 1003:57-64.
  11. ^ Gao et al. (2008). Reconsideration of the Phylogenetic Position of Frontonia-related Peniculia (Ciliophora, Protozoa) Inferred from the Small Subunit Ribosomal RNA Gene Sequences. Acta Protozool. 47:47-54.
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