Lobosa is a

taxonomic group In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

amoeba An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of Cell (biology), cell or unicellular organism with the ability to alter its shape, primarily by extending and ret ...

e in the phylum

Amoebozoa 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 and currently no longer supported classi ...

. Most lobosans possess broad, bluntly rounded

pseudopod A pseudopod or pseudopodium (plural: pseudopods or pseudopodia) is a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement. Filled with cytoplasm, pseudopodia primarily consist of actin filamen ...

s, although one genus in the group, the recently discovered ''Sapocribrum,'' has slender and threadlike (filose) pseudopodia. In current classification schemes, Lobosa is a

subphylum In zoological nomenclature, a subphylum is a taxonomic rank below the rank of phylum. The taxonomic rank of "subdivision (rank), subdivision" in fungi and plant taxonomy is equivalent to "subphylum" in zoological taxonomy. Some plant taxonomists ...

, composed mainly of amoebae that have lobose pseudopods but lack

cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...

flagella A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

Characteristics

The group was originally proposed in 1861 by William B. Carpenter, who created it as a taxonomic order containing the single family Amoebina. Carpenter's Lobosa consisted of amoeboid organisms whose

endoplasm Endoplasm generally refers to the inner (often granulated), dense part of a cell's cytoplasm. This is opposed to the ectoplasm which is the outer (non-granulated) layer of the cytoplasm, which is typically watery and immediately adjacent to the ...

(endosarc) flows into lobe-like "pseudopodian prolongations." This type of pseudopod, which was understood to be typical of the genus

Amoeba An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of Cell (biology), cell or unicellular organism with the ability to alter its shape, primarily by extending and ret ...

"and its allies," differed from the filose (thread-like) or reticulose (netlike) pseudopods of the

Foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and ot ...

. The name Lobosa was chosen for these amoebae "as expressing the lobe-like character of their pseudopodial extensions". As currently defined, the subphylum Lobosa includes both shelled (

testate Intestacy is the condition of the estate of a person who dies without having in force a valid will or other binding declaration. Alternatively this may also apply where a will or declaration has been made, but only applies to part of the estat ...

) and naked amoebae (gymnamoebae), but excludes some organisms traditionally regarded as "lobosean", such as ''

Pelomyxa ''Pelomyxa'' is a genus of giant flagellar amoebae, usually 500-800 μm but occasionally up to 5 mm in length, found in anaerobic or microaerobic bottom sediments of stagnant freshwater ponds or slow-moving streams.Chistyakova, L. V., and A. ...

'' and ''

Entamoeba ''Entamoeba'' is a genus of Amoebozoa found as internal parasites or commensals of animals. In 1875, Fedor Lösch described the first proven case of amoebic dysentery in St. Petersburg, Russia. He referred to the amoeba he observed microscopic ...

'' (Amoebozoa) and some

Heterolobosea The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages. Characteristics Most Percolozoa are found as bacterivores in soil, fresh water and occasionall ...

(

Excavata Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon. It contains a variety of free- ...

Phylogeny

The subphylum Lobosa is

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

, consisting of a

grade Grade most commonly refers to: * Grade (education), a measurement of a student's performance * Grade, the number of the year a student has reached in a given educational stage * Grade (slope), the steepness of a slope Grade or grading may also ref ...

of three clades:

Discosea 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 ...

Tubulinea The Tubulinea are a major grouping of Amoebozoa, including most of the more familiar amoebae genera like ''Amoeba'', '' Arcella'', ''Difflugia'' and '' Hartmannella''. Characteristics During locomotion most Tubulinea have a roughly cylindrical f ...

and

Cutosea 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. I ...

. The first two are part of a paraphyletic superclass

Glycopoda 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 and currently no longer supported classi ...

, while the latter constitutes the monophyletic superclass

Cutosa 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 and currently no longer supported classi ...

. The clade uniting

Conosa Conosa is a grouping of Amoebozoa. It is subdivided into three groups – Archamoebae, Variosea (paraphyletic) and Mycetozoa (polyphyletic). In some classifications, the mycetozoan Myxogastria and Dictyostelia are united in Macromycetozoa. ...

is named Tevosa, while the clade uniting

is named Evosea.

Gallery

File:Chaos_carolinense.jpg, '' Chaos carolinensis'' (

) File:Arcella sp.jpg, ''

Arcella ''Arcella'' is a genus of testate amoebae in the order Arcellinida, usually found in freshwaters and mosses, and rarely in soils. A key characteristic of ''Arcella'' is the circular test with a hole on its center from where finger-like pseudopod ...

'' sp. test (Tubulinea) File:Parasite140120-fig3 Acanthamoeba keratitis Figure 3B.png, ''

Acanthamoeba ''Acanthamoeba'' is a genus of amoeboid, amoebae that are commonly recovered from soil, fresh water, and other habitat (ecology), habitats. ''Acanthamoeba'' has two evolutive forms, the metabolically active trophozoite and a dormant, stress-resi ...

'' sp. (

) File: Thecamoeba striata001.JPG, ''

Thecamoeba ''Thecamoeba ''is a genus of Amoebozoa 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 tradition ...

'' sp. (Discosea)

References

External links

Amorphea subphyla {{Amoebozoa-stub fr:Rhizopoda