Anisonemidae

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Anisonemidae
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Domain: Eukaryota
Phylum: Euglenozoa
Class: Euglenida
Order: Anisonemida
Cavalier-Smith, 2016 [1]
Family: Anisonemidae
Saville Kent, 1880 [2]

Anisonemidae is a small family of euglenid algae, with two accepted genera. It is the only family in the order Anisonemida. [1]

Contents

Description

The family consists of single-celled organisms with a larger posterior flagellum by means of which they are able to glide. They are phagotrophic, meaning that they feed by engulfing particles of food, and are non-photosynthetic. [1]

Taxonomy

The family was established by William Saville-Kent in a work published in 1880–1881. [2] [3] Saville-Kent used a much wider circumscription than more recent sources. [3] Historically, phagotrophic euglenids have been treated as animals, and named under the International Code of Zoological Nomenclature, [1] hence the family name ending "-idae".

Genera

As of May 2023, two genera are accepted: [1]

A third genus, Heteronema Dujardin, 1841, is listed by some sources. [2] The status of the genus is unclear; it appears to be polyphyletic, with some species falling into the order Peranemida and others in Anisonemida. Many of its species have been transferred into Teloprocta , which is placed in Peranemida. [1]

Related Research Articles

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<i>Phacus</i> Genus of algae

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<i>Peranema</i>

Peranema is a genus of free-living phagotrophic euglenids. There are more than 20 nominal species, varying in size between 8 and 200 micrometers. Peranema cells are gliding flagellates found in freshwater lakes, ponds and ditches, and are often abundant at the bottom of stagnant pools rich in decaying organic material. Although they belong to the class Euglenoidea, and are morphologically similar to the green Euglena, Peranema have no chloroplasts, and do not conduct autotrophy. Instead, they capture live prey, such as yeast, bacteria and other flagellates, consuming them with the help of a rigid feeding apparatus called a "rod-organ." Unlike the green euglenids, they lack both an eyespot (stigma), and the paraflagellar body (photoreceptor) that is normally coupled with that organelle. However, while Peranema lack a localized photoreceptor, they do possess the light-sensitive protein rhodopsin, and respond to changes in light with a characteristic "curling behaviour."

Neobodo are diverse protists belonging to the eukaryotic supergroup Excavata. They are Kinetoplastids in the subclass Bodonidae. They are small, free-living, heterotrophic flagellates with two flagella of unequal length used to create a propulsive current for feeding. As members of Kinetoplastids, they have an evident kinetoplast There was much confusion and debate within the class Kinetoplastid and subclass Bodonidae regarding the classification of the organism, but finally the new genera Neobodo was proposed by Keith Vickerman. Although they are one of the most common flagellates found in freshwater, they are also able to tolerate saltwater Their ability to alternate between both marine and freshwater environments in many parts of the world give them a “cosmopolitan” character. Due to their relatively microscopic size ranging between 4-12 microns, they are further distinguished as heterotrophic nanoflagellates. This small size ratio limits them as bacterivores that swim around feeding on bacteria attached to surfaces or in aggregates.

Petalomonas is a genus of phagotrophic, flagellated euglenoids. Phagotrophic euglenoids are one of the most important forms of flagellates in benthic aquatic systems, playing an important role in microbial food webs. The traits that distinguish this particular genus are highly variable, especially at higher taxa. However, general characteristics such as a rigid cell shape and single emergent flagellum can describe the species among this genus.

Heteronema is a genus of phagotrophic, flagellated euglenoids that are most widely distributed in fresh water environments. This genus consists of two very distinguishable morphogroups that are phylogenetically closely related. These morphogroups are deciphered based on shape, locomotion and other ultrastructural traits. However, this genus does impose taxonomic problems due to the varying historical descriptions of Heteronema species and its similarity to the genus Paranema. The species H. exaratum, was the first heteronemid with a skidding motion to be sequenced, which led to the discovery that it was not closely related to H. scaphrum, contrary to what was previously assumed, but instead to a sister group of primary osmotrophs. This suggests that skidding heteronemids can also be distinguished phylogenetically, being more closely related to Anisoma, Dinema and Aphageae, than to other species within Heteronema.

Postgaardia is a proposed basal clade of flagellate Euglenozoa, following Thomas Cavalier-Smith. As of April 2023, the Interim Register of Marine and Nonmarine Genera treats the group as a subphylum. A 2021 review of Euglenozoa places Cavalier-Smith's proposed members of Postgaardia in the class Symbiontida. As Euglenozoans may be basal eukaryotes, the Postgaardia may be key to studying the evolution of Eukaryotes, including the incorporation of eukaryotic traits such as the incorporation of alphaproteobacterial mitochondrial endosymbionts.

Dinema, synonym Dinematomonas, is a genus of flagellated algae in the phylum Euglenozoa.

References

  1. 1 2 3 4 5 6 Kostygov, Alexei Y.; Karnkowska, Anna; Votýpka, Jan; Tashyreva, Daria; Maciszewski, Kacper; Yurchenko, Vyacheslav & Lukeš, Julius (2021), "Euglenozoa: taxonomy, diversity and ecology, symbioses and viruses", Open Biology, 11 (3): 200407, doi:10.1098/rsob.200407, PMC   8061765 , PMID   33715388
  2. 1 2 3 Anisonemidae Saville Kent, 1880 . Retrieved through: Interim Register of Marine and Nonmarine Genera  on 2023-05-21.
  3. 1 2 Saville-Kent, William (1880–1881), "Fam. VIII. Anisonemidae, S.K.", A manual of the infusoria, including a description of all known flagellate, ciliate, and tentaculiferous protozoa, British and foreign and an account of the organization and affinities of the sponges, vol. 1, London: David Bogue, pp. 429–438, OCLC   2378093 , retrieved 2023-05-21