Lobosa is a

taxonomic group In biology, a taxon (back-formation from ''taxonomy''; : 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 name and ...

amoeba An amoeba (; less commonly spelled ameba or amœba; : amoebas (less commonly, amebas) or amoebae (amebae) ), often called an amoeboid, is a type of Cell (biology), cell or unicellular organism with the ability to alter its shape, primarily by ...

e in the phylum

Amoebozoa Amoebozoa is a major Taxonomy (biology), taxonomic group containing about 2,400 described species of Amoeba, amoeboid protists, often possessing blunt, fingerlike, Pseudopod#Morphology, lobose pseudopods and tubular mitochondrial cristae. In trad ...

. Most lobosans possess broad, bluntly rounded

pseudopod A pseudopod or pseudopodium (: 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 filaments and ...

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 (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike proj ...

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

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, also known as entoplasm, generally refers to the inner (often granulated), dense part of a cell's cytoplasm. This is opposed to the ectoplasm (cell biology), ectoplasm which is the outer (non-granulated) layer of the cytoplasm, which ...

(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; : amoebas (less commonly, amebas) or amoebae (amebae) ), often called an amoeboid, is a type of Cell (biology), cell or unicellular organism with the ability to alter its shape, primarily by ...

"and its allies," differed from the

filose Cercozoa (now synonymised with Filosa) 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. ...

(thread-like) or reticulose (netlike) pseudopods of the

Foraminifera Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...

. 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 a legally valid will, resulting in the distribution of their estate under statutory intestacy laws rather than by their expressed wishes. Alternatively this may also apply ...

) 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 ''

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 microscopica ...

'' (Amoebozoa) and some

Heterolobosea Heterolobosea are a class of Percolozoa. The only member of this class that is infectious to humans is '' Naegleria fowleri'', the causative agent of the often fatal disease amoebic meningitis. Typically, their life cycle alternates between fl ...

(

Excavata Excavata is an obsolete, extensive and diverse paraphyletic group of unicellular Eukaryota. The group was first suggested by Simpson and Patterson in 1999 and the name latinized and assigned a rank by Thomas Cavalier-Smith in 2002. It contains ...

Phylogeny

The subphylum Lobosa is

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

, consisting of a

grade Grade most commonly refers to: * Grading in education, a measurement of a student's performance by educational assessment (e.g. A, pass, etc.) * A designation for students, classes and curricula indicating the number of the year a student has reach ...

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 cylindrica ...

and

Cutosea 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 membr ...

. 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 classification schemes, Amoebozoa is usu ...

, while the latter constitutes the monophyletic superclass

Cutosa 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 membr ...

. The clade uniting

Conosa Conosa is a grouping of Amoebozoa. It is subdivided into three groups: Archamoeba, Variosea and Mycetozoa. In some classifications, the mycetozoan Myxogastria and Dictyostelia are united in Macromycetozoa (= Eumycetozoa). Conosa includes t ...

is named Tevosa, while the clade uniting

is named

Evosea 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 unicel ...

Gallery

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

) File:Arcella sp.jpg, '' Arcella'' 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. The genus ''Acanthamoeba'' has two stages in its life cycle, the metabolically active trophozoite stage a ...

'' sp. (

) File: Thecamoeba striata001.JPG, ''

Thecamoeba ''Thecamoeba ''is a genus of Amoebozoa Amoebozoa is a major Taxonomy (biology), taxonomic group containing about 2,400 described species of Amoeba, amoeboid protists, often possessing blunt, fingerlike, Pseudopod#Morphology, lobose pseudopods ...

'' sp. (Discosea)

References

External links

{{Authority control Amorphea subphyla