Lobosa

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Lobosa
Amoeba proteus with many pseudopodia.jpg
Amoeba proteus (Tubulinea)
Scientific classification OOjs UI icon edit-ltr.svg
(disputed)
Domain: Eukaryota
Phylum: Amoebozoa
Subphylum: Lobosa
Carpenter, 1861, em. Cavalier-Smith, 2009
Groups included
Cladistically included but traditionally excluded taxa

Lobosa is a taxonomic group of amoebae in the phylum Amoebozoa. Most lobosans possess broad, bluntly rounded pseudopods, although one genus in the group, the recently discovered Sapocribrum, has slender and threadlike (filose) pseudopodia. [1] In current classification schemes, Lobosa is a subphylum, composed mainly of amoebae that have lobose pseudopods but lack cilia or flagella. [2] [3]

Contents

Characteristics

The group was originally proposed in 1861 by William B. Carpenter, who created it as a taxonomic order containing the single family Amoebina. [4] Carpenter's Lobosa consisted of amoeboid organisms whose endoplasm (endosarc) flows into lobe-like "pseudopodian prolongations." This type of pseudopod, which was understood to be typical of the genus Amoeba "and its allies," differed from the filose (thread-like) or reticulose (netlike) pseudopods of the Foraminifera. The name Lobosa was chosen for these amoebae "as expressing the lobe-like character of their pseudopodial extensions". [5]

As currently defined, the subphylum Lobosa includes both shelled (testate) and naked amoebae (gymnamoebae), but excludes some organisms traditionally regarded as "lobosean", such as Pelomyxa and Entamoeba (Amoebozoa) and some Heterolobosea (Excavata).

Phylogeny

The subphylum Lobosa is paraphyletic, consisting of a grade of three clades: Discosea, Tubulinea and Cutosea. The first two are part of a paraphyletic superclass Glycopoda, while the latter constitutes the monophyletic superclass Cutosa. The clade uniting Tubulinea + Cutosea + Conosa is named Tevosa, while the clade uniting Cutosa + Conosa is named Evosea. [6]

Amoebozoa

Opisthokonta

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">Amoebozoa</span> Phylum of protozoans

Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. In traditional classification schemes, Amoebozoa is usually ranked as a phylum within either the kingdom Protista or the kingdom Protozoa. In the classification favored by the International Society of Protistologists, it is retained as an unranked "supergroup" within Eukaryota. Molecular genetic analysis supports Amoebozoa as a monophyletic clade. Modern studies of eukaryotic phylogenetic trees identify it as the sister group to Opisthokonta, another major clade which contains both fungi and animals as well as several other clades comprising some 300 species of unicellular eukaryotes. Amoebozoa and Opisthokonta are sometimes grouped together in a high-level taxon, variously named Unikonta, Amorphea or Opimoda.

<span class="mw-page-title-main">Amorphea</span> Group including fungi, animals and various protozoa

Amorphea is a taxonomic supergroup that includes the basal Amoebozoa and Obazoa. That latter contains the Opisthokonta, which includes the Fungi, Animals and the Choanomonada, or Choanoflagellates. The taxonomic affinities of the members of this clade were originally described and proposed by Thomas Cavalier-Smith in 2002.

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

The tectofilosids are a group of filose amoebae with shells. These are composed of organic materials and sometimes collected debris, in contrast to the euglyphids, which produce shells from siliceous scales. The shell usually has a single opening, but in Amphitrema and a few other genera it has two on opposite ends. The cell itself occupies most of the shell. They are most often found on marsh plants such as Sphagnum.

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

The Amoebidae are a family of Amoebozoa, including naked amoebae that produce multiple pseudopodia of indeterminate length. These are roughly cylindrical with granular endoplasm and no subpseudopodia, as found in other members of the class Tubulinea. During locomotion one pseudopod typically becomes dominant and the others are retracted as the body flows into it. In some cases the cell moves by "walking", with relatively permanent pseudopodia serving as limbs.

<span class="mw-page-title-main">Tubulinea</span> Class of protozoans

The Tubulinea are a major grouping of Amoebozoa, including most of the more familiar amoebae genera like Amoeba, Arcella, Difflugia and Hartmannella.

<span class="mw-page-title-main">Discosea</span> Class of amoebae

Discosea is a class of Amoebozoa, consisting of naked amoebae with a flattened, discoid body shape. Members of the group do not produce tubular or subcylindrical pseudopodia, like amoebae of the class Tubulinea. When a discosean is in motion, a transparent layer called hyaloplasm forms at the leading edge of the cell. In some discoseans, short "subpseudopodia" may be extended from this hyaloplasm, but the granular contents of the cell do not flow into these, as in true pseudopodia. Discosean amoebae lack hard shells, but some, like Cochliopodium and Korotnevella secrete intricate organic scales which may cover the upper (dorsal) surface of the cell. No species have flagella or flagellated stages of life.

<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">Eumycetozoa</span> Taxonomic group of slime molds

Eumycetozoa, or true slime molds, is a diverse group of protists that behave as slime molds and develop fruiting bodies, either as sorocarps or as sporocarps. It is a monophyletic group or clade within the phylum Amoebozoa that contains the myxogastrids, dictyostelids and protosporangiids.

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

Acanthamoebidae is a family of single-celled eukaryotes within the group Amoebozoa.

<span class="mw-page-title-main">Conosa</span> Phylum of protozoans

Conosa is a grouping of Amoebozoa. It is subdivided into three groups: Archamoeba, Variosea and Mycetozoa.

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

Testate amoebae are a polyphyletic group of unicellular amoeboid protists, which differ from naked amoebae in the presence of a test that partially encloses the cell, with an aperture from which the pseudopodia emerge, that provides the amoeba with shelter from predators and environmental conditions.

<i>Trichosphaerium</i> Genus of amoebae

Trichosphaerium is a genus of amoebozoan protists that present extraordinary morphological transformations, both in size and shape, during their life cycle. They can present a test that may or may not be covered in spicules. They are related to the family Microcoryciidae, which contains other amoebae with tests, within the clade Corycidia of the phylum Amoebozoa.

<span class="mw-page-title-main">Amoeba</span> Cellular body type

An amoeba, often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopods. Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.

<span class="mw-page-title-main">Varisulca</span> Proposed phylum of protists

Varisulca was a proposed basal Podiate taxon. It encompassed several lineages of heterotrophic protists, most notably the ancyromonads (planomonads), collodictyonids (diphylleids), rigifilids and mantamonadids. Recent evidence suggests that the latter three are closely related to each other, forming a clade called CRuMs, but that this is unlikely to be specifically related to ancyromonads.

<span class="mw-page-title-main">Flabellinia</span> Subclass of protozoans

The Flabellinia are a subclass of Amoebozoa. During locomotion the cells are flattened and have a clear layer called hyaloplasm along the front margin. Some form slender subpseudopodia projecting outward from the hyaloplasm, but the cell mass does not flow into these as in true pseudopodia, and advances without a definite central axis as in the Tubulinea. They also lack distinctive features like shells and flagella, and are united mainly by evidence from molecular trees.

Cutosea is a small group of marine amoeboid protists proposed in 2016. It is a monotypic class of Amoebozoa containing the order Squamocutida. Cutosean organisms are characterized by a cell coat of microscales separated from the cell membrane. Four genera, Armaparvus, Idionectes, Sapocribrum and Squamamoeba, belong to this group, distributed in three families.

<span class="mw-page-title-main">Cryptodifflugiidae</span> Family of testate amoebae

Cryptodifflugiidae is a family of arcellinid testate amoebae.

<span class="mw-page-title-main">Evosea</span> Group of amoebae

Evosea is a diverse clade of amoeboid protists discovered through molecular analyses. Along with Tubulinea and Discosea, Evosea is one of the three major groups within Amoebozoa, an important clade of eukaryotic organisms. It contains unicellular organisms that display a wide variety of life cycles and cell shapes, including amoebae, flagellates and different kinds of slime molds.

<span class="mw-page-title-main">Amoeboflagellate</span> Cellular body type

An amoeboflagellate is any eukaryotic organism capable of behaving as an amoeba and as a flagellate at some point during their life cycle. Amoeboflagellates present both pseudopodia and at least one flagellum, often simultaneously.

References

  1. Cavalier-Smith, Thomas; Chao, Ema E.; Lewis, Rhodri (2016). "187-gene phylogeny of protozoan phylum Amoebozoa reveals a new class (Cutosea) of deep-branching, ultrastructurally unique, enveloped marine Lobosa and clarifies amoeba evolution". Molecular Phylogenetics and Evolution. 99: 275–296. doi: 10.1016/j.ympev.2016.03.023 . PMID   27001604.
  2. Smirnov, Alexey V. (2011). "A Revised Classification of Naked Lobose Amoebae (Amoebozoa: Lobosa)" (PDF). Protist. 162 (4): 545–570. doi:10.1016/j.protis.2011.04.004. PMID   21798804. Archived from the original (PDF) on 2016-03-04.
  3. Cavalier-Smith, Thomas (2009-02-01). "Megaphylogeny, cell body plans, adaptive zones: causes and timing of eukaryote basal radiations". The Journal of Eukaryotic Microbiology. 56 (1): 26–33. doi: 10.1111/j.1550-7408.2008.00373.x . ISSN   1550-7408. PMID   19340985.
  4. Carpenter, William Benjamin (1861). "On the systematic arrangement of the Rhizopoda". Natural History Review (Dublin and London). 1 (4).
  5. Carpenter, William Benjamin (1862). Introduction to the Study of the Foraminifera. Ray Society. pp. 16–28.
  6. Kang, Seungho; Tice, Alexander K; Spiegel, Frederick W; Silberman, Jeffrey D; Pánek, Tomáš; Čepička, Ivan; Kostka, Martin; Kosakyan, Anush; Alcântara, Daniel M C; Roger, Andrew J; Shadwick, Lora L; Smirnov, Alexey; Kudryavtsev, Alexander; Lahr, Daniel J G; Brown, Matthew W (September 2017). "Between a Pod and a Hard Test: The Deep Evolution of Amoebae". Molecular Biology and Evolution. 34 (9): 2258–2270. doi:10.1093/molbev/msx162. PMC   5850466 . PMID   28505375.