Lobosa is a taxonomic group of

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 or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudop ...

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 c ...

. 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 filament ...

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" in fungi and plant taxonomy is equivalent to "subphylum" in zoological taxonomy. Some plant taxonomists have also used th ...

, 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 proje ...

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 fro ...

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 or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudop ...

"and its allies," differed from the

filose Filose can refer to a few things: *Filose, describing members of the Filosa subphylum of Cercozoa Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead ...

(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 for catching food and other uses; and commonly ...

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

'' (Amoebozoa) and some Heterolobosea ( Excavata).

Phylogeny

The subphylum Lobosa is

paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...

, 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.

Gallery

File:Chaos_carolinense.jpg, '' Chaos carolinensis'' ( Tubulinea) File:Arcella sp.jpg, '' Arcella'' sp. test (Tubulinea) File:Parasite140120-fig3 Acanthamoeba keratitis Figure 3B.png, ''

Acanthamoeba ''Acanthamoeba'' is a genus of amoebae that are commonly recovered from soil, fresh water, and other habitats. ''Acanthamoeba'' has two evolutive forms, the metabolically active trophozoite and a dormant, stress-resistant cyst. Trophozoites are ...

'' sp. ( Discosea) File: Thecamoeba striata001.JPG, '' Thecamoeba'' sp. (Discosea)

References

External links

Amorphea subphyla {{Amoebozoa-stub fr:Rhizopoda