Thecamonadinae

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Thecamonadinae
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Class: Thecomonadea
Order: Apusomonadida
Family: Apusomonadidae
Subfamily: Thecamonadinae
Larsen & Patterson, 1990 [1] stat. nov. Heiss et al., 2015 [2]
Type genus
Thecamonas
Larsen & Patterson, 1990 [1]
Genera
Synonyms
Thecamonadidae
Larsen & Patterson, 1990 [1]

Thecamonadinae is a subfamily of heterotrophic protists. It is a monophyletic group, or clade, of apusomonads, a group of protozoa with two flagella closely related to the eukaryotic supergroup Opisthokonta. The subfamily contains two genera Chelonemonas and Thecamonas , which are found in marine habitats. [2] [3]

Contents

Morphology

Thecamonadinae are unicellular eukaryotes, exhibiting cells smaller than 10 μm, and an " Amastigomonas -type" cell body shape: plastic, oval to oblong, with a prominent proboscis that measures around ¼ of the cell body length. They have a rigid "tusk" of between 200 and 250 nm in diameter, that arises to the right of the anterior flagellum and extends around 0.5–1.0 μm. This tusk can be visible under optimal conditions of light microscopy. Aside from the flagella, they often present thin pseudopodia trailing behind the moving cell. [2]

Systematics

History of taxonomy

Thecamonadinae was initially a family-level taxon, Thecamonadidae, described in 1990 by Jacob Larsen and David J. Patterson. At the time, it was composed exclusively of the genus Thecamonas , described by the same authors. Members of this family were characterized by a mobile anterior "snout" (or "tusk"), which is superficially resembling of the flagellate Rhynchomonas . However, their ultrastructure resembled Apusomonas in the pliable dorsal theca. [1] Posterior phylogenetic analyses showed that this family branched within Apusomonadidae, and the taxon fell out of use. [4] In 2015, Aaron A. Heiss and collaborators co-opted this taxon as a subfamily within Apusomonadidae to designate the clade uniting Chelonemonas and Thecamonas . This clade is supported by multiple phylogenetic analyses and accepted as a valid taxon. [2]

Classification

As of 2022, the subfamily contains two genera, Chelonemonas and Thecamonas , and a total of 7 species.

  • T. filosa Larsen & Patterson, 1990 [1]
    = Amastigomonas filosa(Larsen & Patterson, 1990) Molina & Nerad, 1991
  • T. muscula (Mylnikov, 1999) Cavalier-Smith, 2010 [4]
    = Amastigomonas musculaMylnikov, 1999
  • T. mutabilis (Griessmann, 1913) Larsen & Patterson, 1990 [3]
    = Rhynchomonas mutabilisGriessmann 1913
    = Amastigomonas mutabilis(Griessmann, 1913) Patterson & Zölffel, 1993
  • T. trahens Larsen & Patterson, 1990 [3]
    = Amastigomonas trahens(Larsen & Patterson, 1990) Molina & Nerad, 1991

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<span class="mw-page-title-main">Opisthokont</span> Group of eukaryotes which includes animals and fungi, among other groups

The opisthokonts are a broad group of eukaryotes, including both the animal and fungus kingdoms. The opisthokonts, previously called the "Fungi/Metazoa group", are generally recognized as a clade. Opisthokonts together with Apusomonadida and Breviata comprise the larger clade Obazoa.

<span class="mw-page-title-main">Apusozoa</span> Phylum of micro-organisms

The Apusozoa are a paraphyletic phylum of flagellate eukaryotes. They are usually around 5–20 μm in size, and occur in soils and aquatic habitats, where they feed on bacteria. They are grouped together based on the presence of an organic shell or theca under the dorsal surface of the cell.

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<span class="mw-page-title-main">Jakobid</span>

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<span class="mw-page-title-main">Diplonemidae</span> Family of protozoans

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Chelonemonas is a genus of heterotrophic protists. They are unicellular eukaryotes with two flagella, characterized by the presence of a honeycomb or turtle shell pattern on the dorsal surface of their cells that is visible under electron microscopy. They belong to the Apusomonadida, a clade of flagellates related to the opisthokonts, the group containing animals, fungi and their closest protist relatives.

<span class="mw-page-title-main">Colponemid</span> Group of predatorial flagellates

Colponemids are free-living alveolates, unicellular flagellates related to dinoflagellates, apicomplexans and ciliates. They are predators of other small eukaryotes, found in freshwater, marine and soil environments. They do not form a solid clade, but a sparse group of deep-branching alveolate lineages.

<span class="mw-page-title-main">Chrompodellid</span> Clade of alveolates

Chrompodellids are a clade of single-celled protists belonging to the Alveolata supergroup. It comprises two different polyphyletic groups of flagellates: the colpodellids, phagotrophic predators, and the chromerids, photosynthetic algae that live as symbionts of corals. These groups were independently discovered and described, but molecular phylogenetic analyses demonstrated that they are intermingled in a clade that is the closest relative to Apicomplexa, and they became collectively known as chrompodellids. Due to the history of their research, they are variously known in biological classification as Chromerida or Colpodellida (ICZN)/Colpodellales (ICN).

References

  1. 1 2 3 4 5 6 Larsen, Jacob; Patterson, David J. (1990). "Some flagellates (Protista) from tropical marine sediments". Journal of Natural History. 24 (4): 801–937. Bibcode:1990JNatH..24..801L. doi:10.1080/00222939000770571.
  2. 1 2 3 4 5 6 7 Heiss, Aaron A.; Lee, Won J.; Ishida, Ken-ichiro; Simpson, Alastair G. B. (2015). "Cultivation and Characterisation of New Species of Apusomonads (the Sister Group to Opisthokonts), Including Close Relatives of Thecamonas (Chelonemonas n. gen.)". Journal of Eukaryotic Microbiology. 62 (5): 637–649. doi:10.1111/jeu.12220. PMID   25912654.
  3. 1 2 3 4 Torruella G, Galindo LJ, Moreira D, Ciobanu M, Heiss AA, Yubuki N, et al. (November 2022). "Expanding the molecular and morphological diversity of Apusomonadida, a deep-branching group of gliding bacterivorous protists". Journal of Eukaryotic Microbiology. 70 (2): e12956. doi:10.1111/jeu.12956. hdl: 2117/404026 . PMID   36453005.
  4. 1 2 Cavalier-Smith, Thomas; Chao, Ema E. (October 2010). "Phylogeny and evolution of Apusomonadida (Protozoa: Apusozoa): new genera and species". Protist . 161 (4): 549–576. doi:10.1016/j.protis.2010.04.002. PMID   20537943.