Hymenostome

Hymenostomes
Tetrahymena thermophila
Scientific classification
Domain:
Eukaryota
(unranked):
SAR
(unranked):
Phylum:
Ciliophora
Class:
Order:
Hymenostomatida

Delage & Hérouard 1896
Typical families

Suborder Tetrahymenina
    Curimostomatidae
    Tetrahymenidae
    Turaniellidae
    Glaucomidae
Suborder Ophryoglenina
    Ichthyopthiriidae
    Ophryoglenidae
Suborder Peniculina

The hymenostomes are an order of ciliate protozoa. Most are free-living in freshwater, such as the commonly studied genus Tetrahymena, but some are parasitic on fish or aquatic invertebrates. Among these is the important species Ichthyophthirius multifiliis, a common cause of death in aquaria and fish farms.

The hymenostomes are fairly typical members of the Oligohymenophorea. Their body cilia are mostly uniform, sometimes with a few long caudal cilia, and arise from monokinetids or from dikinetids at the anterior. The oral cilia are in general distinctly tetrahymenal, with three membranelles and a paroral membrane, which corresponds only to the middle segment of the tripartite membranes found in certain scuticociliates. Mouth formation during cell division usually begins next to a postoral kinety.

The hymenostomes were first defined by Delage & Hérouard in 1896. Initially the scuticociliates and peniculids were included, then later treated as separate orders of a subclass Hymenostomatia, to which the astomes are sometimes added. More recently each of these groups tends to be treated as a separate subclass.[1]

References

  1. John O Corliss (2016-04-20). The Ciliated Protozoa: Characterization, Classification and Guide to the Literature. Pergamon. pp. 112–124. ISBN 9781483154176. Retrieved 17 January 2018.


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