Lobosa is a taxonomic group of amoebae 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 pseudopods, although one genus in the group, the recently discovered ''Sapocribrum,'' has slender and threadlike (filose) pseudopodia. In current classification schemes, Lobosa is a subphylum, 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 (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 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 (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) 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 ( Excavata).

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 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 for ...

and

Cutosea Lobosa is a Taxon, taxonomic group of amoebae in the phylum Amoebozoa. Most lobosans possess broad, bluntly rounded Pseudopodia, pseudopods, although one genus in the group, the recently discovered ''Sapocribrum,'' has slender and threadlike (fi ...

. The first two are part of a paraphyletic superclass Glycopoda, while the latter constitutes the monophyletic superclass Cutosa. 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 Cutosa +

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'' sp. (

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

References

External links

Amorphea subphyla {{Amoebozoa-stub fr:Rhizopoda