''Stephanopogon'' is a genus of flagellated marine

protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...

that superficially resembles a ciliate.

Characteristics

''Stephanopogon'' closely resembles certain

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a differen ...

s and was originally classified with them (, but is now considered related to heterolobosean flagellates. The cell is somewhat flattened, with multiple smooth flagella arranged in rows running from the front to the back, and has an anterior mouth supported by rods. They feed on

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

, diatoms, and other smaller organisms. There are 2-16 nuclei, but they are not differentiated into

macronuclei A macronucleus (formerly also meganucleus) is the larger type of nucleus in ciliates. Macronuclei are polyploid and undergo direct division without mitosis. It controls the non-reproductive cell functions, such as metabolism. During conjugation, t ...

and

micronuclei Micronucleus is the name given to the small nucleus that forms whenever a chromosome or a fragment of a chromosome is not incorporated into one of the daughter nuclei during cell division. It usually is a sign of genotoxic events and chromosomal i ...

as occurs in ciliates. They have a cosmopolitan distribution. Prot euglenozoa stephanopogon apogon L eel pond mass

Classification

Because

nuclear dimorphism Nuclear dimorphism is a term referred to the special characteristic of having two different kinds of nuclei in a cell. There are many differences between the types of nuclei. This feature is observed in protozoan ciliates, like ''Tetrahymena'', an ...

is absent, ''Stephanopogon'' had been regarded as an evolutionary intermediate between the ciliates and other protozoa, and possibly an ancestor of the animals as well. Corliss and Lipscomb showed that it is not cytologically similar to

ciliates The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different ...

, lacking their complex pellicle and infraciliature. Further electron microscopical studies added details to the understanding of the cytological organization of ''Stephanopogon''. Yubuki and Leander demonstrated that ''Stephanopogon'' is closely related to ''Percolomonas'' within the Heterolobosea. The bases of the flagella in both genera are attached to an electron dense cytoskeletal material, but it has been argued that this is not an apomorphy of the clade It has recently been included as a heterolosean in the

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

Percolatea Percolatea are a class of excavates in the phylum Percolozoa. See also * Percolozoa The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages. Cha ...

, along with ''

Percolomonas ''Percolomonas'' is a genus of free-living flagellate Heteroloboseans, forming a clade with ''Stephanopogon''. The genus includes six described species (see infobox). However, ''P. cosmopolitus'' is likely a species complex containing multiple c ...

''. The genus contains 7 species: ''S. apogon'' Borror, 1965, ''S. colpoda'' Entz, 1884, ''S. mesnili'' Lwoff, 1923, ''S. minuta'' Lei et al., 1999, ''S. mobilensis'' Jones et Owen, 1974, ''S. paramesnili'' Lei et al., 1999 and ''S. pattersoni'' Lee et al., 2014 Lee, W. J. 2019. Small free-living heterotrophic flagellates from marine intertidal sediments of the Sydney region, Australia. Acta Protozoologica: 58 167-189. Prot stephie stephanopogon apogon L dp

References

External links

Tree of Life: Stephanopogon
{{Taxonbar, from=Q293160 Flagellates Percolozoa Excavata genera