Neocercomonas

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Neocercomonas
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Phylum: Cercozoa
Class: Sarcomonadea
Order: Cercomonadida
Family: Cercomonadidae
Genus: Neocercomonas
Ekelund, Fredslund & Daugbjerg 2004
Type species
Neocercomonas jutlandica Ekelund, Fredslund & Daugbjerg 2004

Neocercomonas is a protist genus of the order Cercomonadida. It consists of single-celled bacteriophagous organisms that usually live on or nearby terrestrial plants, both above and belowground. [1] Species are biflagellate and may grow up to 60 micrometers long, with a trailing tail-like mass of protoplasm at their posterior end and a pair of roots connecting their posterior flagellum to the cytoskeleton. [2]

Contents

Etymology

The genus was named by Ekelund et al. in 2004. [3] The first three letters of the genus name are directly lifted from the Greek neo , meaning 'new', whereas the second part refers to the closely related genus Cercomonas, from which Neocercomonas was originally distinguished when the former was discovered not to be a monophyletic group. Hence, Neocercomonas can be interpreted as 'new Cercomonas'. Higher classifications such as the phylum Cercozoa and the order Cercomonadida also bear similar names, though Cercomonas was identified first (in 1841).

History of knowledge

The genus was discovered in 2004 by Flemming Ekelund, Niels Daugbjerg, and Line Fredslund, whose phylogenetic analysis of rDNA sequences led them to conclude that the genus Cercomonas should be separated into two taxa, with the new one being named Neocercomonas. [3] In 2006 Karpov et al. determined that there was insufficient evidence for its status as a separate genus and reclassified it as part of Cercomonas, but study of differences in microtubule nucleation by Karpov and Cavalier-Smith in 2012 re-established it as a genus, and more recent genetic analysis seems to support Neocercomonas being a monophyletic group. [2]

Habitat and ecology

Organisms belonging to this genus occur in terrestrial systems, most often in forested, agricultural, or otherwise plant-rich areas. Some may be found aboveground on leaf surfaces, while others live amongst soil particles. In the former case, their ability to quickly reproduce while resisting desiccation is key to their ability to survive in an exposed environment. [1]

Description

Morphologically, Neocercomonas is similar to the genus Cercomonas, though genetic analysis has indicated that they are separate taxa. Cells are 13-60 micrometers long, feed on bacteria, and are usually flattened in shape. They have a ragged 'tail' formed from the protoplasm at their posterior end, as well as two flagella near the front end of the cell, each being around one and a half times the cell's length. The anterior flagellum beats rapidly in front of the cell to propel its movement; the posterior flagellum remains attached to both the body and the substrate to provide stability while the organism glides. Two cytoskeletal 'roots' are attached to different points along the posterior flagellum's length, adding further support. [2]

After having settled on a substrate for some time, Neocercomonas may also deploy pseudopodia from the posterior end of the cell. The anterior flagellum will continue to move after pseudopodia have been extended, though usually in a more erratic manner. [3]

Within the cell there is an anterior nucleus, accompanied by numerous contractile vacuoles spread throughout the cell. The cytoplasm tends to be filled with small granules, some of which are refractive, making it difficult to observe the organelles. As part of their life cycle, cells may form round cysts 5-13 micrometers in diameter. [3]

Some species (N. dactyloptera and N. braziliensis) have been noted as having a particularly strong anterior cytoskeleton, though it is unknown whether this is the case for all Neocercomona species. The species Neocercomonas grandis is the largest known member of the order Cercomonadida. [2]

List of species [2]

Related Research Articles

<span class="mw-page-title-main">Cercozoa</span> Group of single-celled organisms

Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead united by molecular phylogenies of rRNA and actin or polyubiquitin. They were the first major eukaryotic group to be recognized mainly through molecular phylogenies. They are the natural predators of many species of bacteria. They are closely related to the phylum Retaria, comprising amoeboids that usually have complex shells, and together form a supergroup called Rhizaria.

<span class="mw-page-title-main">Cercomonad</span> Order of single-celled organisms

Cercomonads are small amoeboflagellates, widespread in aqueous habitats and common in soils.

<span class="mw-page-title-main">Monadofilosa</span> Group of protists

Monadofilosa is a grouping of Cercozoa. These organisms are single-celled amoeboid protists.

<span class="mw-page-title-main">Thecofilosea</span> Class of single-celled organisms

Thecofilosea is a class of unicellular testate amoebae belonging to the phylum Cercozoa. They are amoeboflagellates, organisms with flagella and pseudopodia, distinguished from other cercozoa by their scale-lacking test composed of organic material. They are closely related to the Imbricatea, a group of testate amoebae with tests composed of inorganic silica scales.

<span class="mw-page-title-main">Sarcomonadea</span> Class of flagellate protists

The sarcomonads or class Sarcomonadea are a group of amoeboid biciliate protists in the phylum Cercozoa. They are characterized by a propensity to move through gliding on their posterior cilium or through filopodia, a lack of scales or external theca, a soft cell surface without obvious cortical filamentous or membranous skeleton, two cilia without scales or hairs, tubular mitochondrial cristae, near-spherical extrusomes, and a microbody attached to the nucleus.

Paracercomonas is a genus of rhizaria.

Proleptomonas is a genus of coprophilic protists, containing the single species Proleptomonas faecicola. It belongs to the phylum Cercozoa, although it was previously considered the only free-living kinetoplastid. It is the only member of family Proleptomonadidae.

<i>Amastigomonas</i> Genus of protozoa with two flagella

Amastigomonas is a genus of protists belonging to a lineage of biciliated zooflagellates known as Apusomonadida. It was first described in 1931 by Henri de Saedeleer. The current use of Amastigomonas is as a descriptive archetype, with no phylogenetic or taxonomic implications. The term "Amastigomonas-like" is used to refer to all apusomonads that lack the 'derived' characteristics of Apusomonas.

<span class="mw-page-title-main">Apusomonadidae</span> Group of microorganisms with two flagella

The apusomonads are a group of protozoan zooflagellates that glide on surfaces, and mostly consume prokaryotes. They are of particular evolutionary interest because they appear to be the sister group to the Opisthokonts, the clade that includes both animals and fungi. Together with the Breviatea, these form the Obazoa clade.

<i>Thaumatomastix</i> Genus of single-celled organisms

Thaumatomastix is a protist genus of the order Thaumatomonadida, within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and salinities, and are 15-50 micrometers long. They can interchange between flagellated and amoeboid forms, and are notable for being covered in both spiny and flattened siliceous scales.

<i>Katabia</i> Genus of heterotrophic protists

Katabia is a genus of soil-dwelling heterotrophic flagellate cercozoans containing the single species Katabia gromovi, and the only member of family Katabiidae.

Ancoracysta is a genus of eukaryotic microbes containing the species Ancoracysta twista, a predatory protist that appears to be related to Haptista.

The paracercomonads are a group of cercozoan protists. Taxonomically, they comprise the family Paracercomonadidae, order Paracercomonadida and subclass Paracercomonada. Due to their morphological similarities to the cercomonads, members of this family were grouped with Cercomonas and similar taxa from the beginning. However, their similarities are due to convergent evolution.

<span class="mw-page-title-main">Ventrifilosa</span> Superclass of protists

Ventrifilosa is a highly diverse group of phagotrophic protists that glide through their flagella and emit filose pseudopods from their ventral side for feeding. Because of their mixture of amoeba and flagellate characteristics, they are amoeboflagellates. Members of this group are the Imbricatea, Sarcomonadea and Thecofilosea.

Minimassisteria is a marine bacterivorous genus of protists with only one species, M. diva, that presents three different lifestyle forms. It has a widespread geographic distribution. It is an amoeboflagellate most closely related to Massisteria, and together comprise the family Massisteriidae.

<span class="mw-page-title-main">Glissomonadida</span> Order of protists

The glissomonads are a group of bacterivorous gliding flagellated protists that compose the order Glissomonadida, in the amoeboflagellate phylum Cercozoa. They comprise a vast, largely undescribed diversity of soil and freshwater organisms. They are the sister group to cercomonads; the two orders form a solid clade of gliding soil-dwelling flagellates called Pediglissa.

Pediglissa is a subclass of phagotrophic protists that inhabit soil or freshwater habitats. They were defined in 2018 according to phylogenetic analyses that showed a clade containing the orders Cercomonadida and Glissomonadida. They're the sister group of Paracercomonadida.

<span class="mw-page-title-main">Viridiraptoridae</span> Family of predatorial protists

Viridiraptoridae, previously known as clade X, is a clade of heterotrophic protists in the phylum Cercozoa. They're a family of glissomonads, a group containing a vast, mostly undescribed diversity of soil and freshwater organisms.

Aurigamonas is a genus of predatory protists of an unusual cell structure, with two flagella and numerous haptopodia. It is a monotypic genus containing the single species Aurigamonas solis. It is the only genus of the family Aurigamonadidae.

Helkesida is a group of microscopic protists belonging to the supergroup Rhizaria, both discovered through molecular phylogenetic analyses. It contains amoeboid flagellates with two flagella. They are either free-living, mostly on fecal matter, or live inside the gut of animals. Among these amoebae, one lineage has independently evolved aggregative multicellularity similarly to slime moulds.

References

  1. 1 2 Flues, Sebastian; Blokker, Malte; Dumack, Kenneth; Bonkowski, Michael (2018). "Diversity of Cercomonad Species in the Phyllosphere and Rhizosphere of Different Plant Species with a Description of Neocercomonas epiphylla (Cercozoa, Rhizaria) a Leaf-Associated Protist". Journal of Eukaryotic Microbiology. 65 (5): 587–599. doi:10.1111/jeu.12503. ISSN   1550-7408. PMID   29377417. S2CID   46862258.
  2. 1 2 3 4 5 Cavalier-Smith, Thomas; Karpov, Sergey A. (2012-01-01). "Paracercomonas Kinetid Ultrastructure, Origins of the Body Plan of Cercomonadida, and Cytoskeleton Evolution in Cercozoa". Protist. 163 (1): 47–75. doi:10.1016/j.protis.2011.06.004. ISSN   1434-4610. PMID   21839678.
  3. 1 2 3 4 Ekelund, Flemming; Daugbjerg, Niels; Fredslund, Line (2004-08-30). "Phylogeny of Heteromita, Cercomonas and Thaumatomonas based on SSU rDNA sequences, including the description of Neocercomonas jutlandica sp. nov., gen. nov". European Journal of Protistology. 40 (2): 119–135. doi:10.1016/j.ejop.2003.12.002. ISSN   0932-4739.