''Colpodella'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

alveolate The alveolates (meaning "pitted like a honeycomb") are a group of protists, considered a major clade and Biological classification, superphylum within Eukarya. They are currently grouped with the stramenopiles and Rhizaria among the protists with ...

s comprising 5

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, and two further possible species: They share all the

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

of apicomplexans, but are free-living, rather than parasitic. Many members of this genus were previously assigned to a different genus - '' Spiromonas''. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''

Colpodella pugnax ''Colpodella'' is a genus of alveolates comprising 5 species, and two further possible species: They share all the synapomorphies of apicomplexans, but are free-living, rather than parasitic. Many members of this genus were previously assigned t ...

'' Cienkowski 1865.

Description

These are small (< 20

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

in diameter) flagellated protists. The life cycle of consists of two main stages:

flagellated 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 ...

trophozoites and

cysts A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...

, which are the reproductive stage in the life cycle. Morphologically the trophozoites of ''Colpodella'' are similar to ''

Perkinsus ''Perkinsus'' is a genus of alveolates in the phylum Perkinsozoa. The genus was erected in 1978 to better treat its type species, ''Perkinsus marinus'', known formerly as ''Dermocystidium marinum''. These are parasitic protozoans that infect mol ...

zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or mo ...

s, although the two taxa are not specifically related. The motile stages of both genera have a pair of anterior orthogonal

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 ...

, vesicular mitochondrial cristae, inner alveolar membranes and micropores. Both ''Colpodella'' and ''Perkinsus'' species have open sided truncated conoids (sometimes called pseudoconoids),

rhoptries A rhoptry is a specialized secretory organelle. They are club-shaped organelles connected by thin necks to the extreme apical pole of the parasite. These organelles, like micronemes, are characteristic of the motile stages of Apicomplexa protoz ...

that occupy the length of the cell and smaller micronemes. Both the rhoptries and micronemes arise at the anterior portion of the cell. A three-layered pellicle lies beneath the

plasma membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (t ...

and is otherwise composed of the alveolar membranes and widely separated

microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 an ...

s that arise subapically. Some species have extrusive organelles ( trichocysts). Unlike ''Perkinsus'', ''Colpodella'' are free-living and are voracious predators of other free-living

protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...

s. Most species apparently penetrate through the cell membrane and consume the prey's cytoplasm - this mode of feeding is known as myzocytosis. While feeding the predator attaches its anterior portion - the rostrum - to the prey. The rostrum contains the pseudoconoid, which transforms into a ring of

s encircling the attachment zone. The cytoplasm of the prey is then drawn into a large posterior food

vacuole A vacuole () is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic mo ...

. Following feeding cells lose their flagella, become spherical, encyst and divide (i.e. reproduce). The

are simple spheres. The food vacuole appears as a large central

in the cyst; as division progresses the remnant vacuole material is reduced to a residual body. Typically Colpodella divides into four daughter cells (sometimes just two). This is in contrast to true Apicomplexa and ''Perkinsus'', which typically produce many more daughter cells during reproduction - ''Perkinsus'' species can produce up to 32 cells, for example, while ''Toxoplasma'' produces 128. The daughter cells grow flagella, the cyst wall ruptures, and the cells swim away, leaving the residual body behind. A possible sexual process has been observed in at least two species.

Taxonomy

This family appears to be a sister clade to the Apicomplexa. Their life style may be representative of the free living ancestors of the Apicomplexa. One significant difference is that this genus, like the

Perkinsea Perkinsea is a class of alveolates. Taxonomy '' Perkinsus'' is a genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological c ...

, have an open sided conoid (pseudoconoid) while the Apicomplexa which possess a conoid (the

Conoidasida Conoidasida is a class of parasitic alveolates in the phylum Apicomplexa. The class was defined in 1988 by Levine and contains two subclasses – the coccidia and the gregarines. All members of this class have a complete, hollow, truncated c ...

) have a closed conoid. Another genus in this family is ''

Acrocoelus ''Acrocoelus'' is a genus of alveolates. History This genus was named in 1999 by Fernández ''et al''.Fernández I, Pardos F, Benito J, Arroyo NL (1999) ''Acrocoelus glossobalani'' ''gen''. ''nov''. ''et sp''. ''nov''., a protistan flagellate ...

''. Species currently within genus: * '' Colpodella edax'' (Klebs 1892) Simpson & Patterson 1996 * '' Colpodella pseudoedax'' Mylnikov & Mylnikov 2007 * ''

'' Cienkowsky 1865 non Simpson & Patterson 1996 * '' Colpodella angusta'' (Dujardin 1841) Simpson & Patterson 1996 'Dingensia angusta'' (Dujardin 1841) Patterson & Zoelffel 1991">Dingensia_angusta.html" ;"title="'Dingensia angusta">'Dingensia angusta'' (Dujardin 1841) Patterson & Zoelffel 1991 Species transferred to other genera: * ''Colpodella gonderi'' (Foissner & Foissner 1984) Simpson & Patterson 1996 as ''Microvorax gonderi'' (Foissner & Foissner 1984) Cavalier-Smith 2017 * ''Colpodella perforans'' (Hollande 1938) Patterson & Zölffel 1991 as ''Chilovora perforans'' (Hollande 1938) Cavalier-Smith & Chao 2004 * ''Colpodella pontica'' Mylnikov 2000 as ''

Voromonas pontica ''Voromonas'' is a genus of predatory Alveolata, alveolates. The genus and species were described by Mylnikov in 2000. It was originally described as ''Colpodella pontica'' but was later renamed by Thomas Cavalier-Smith, Cavalier-Smith and Chao ...

'' (Mylnikov 2000) Cavalier-Smith & Chao 2004 * ''Colpodella pugnax'' Simpson & Patterson 1996 non Cienkowsky 1865 as '' Algovora pugnax'' (Simpson & Patterson 1996) Cavalier-Smith & Chao 2004 * ''Colpodella tetrahymenae'' Cavalier-Smith 2004 as '' Microvorax tetrahymenae'' (Cavalier-Smith & Chao 2004) Cavalier-Smith 2017 * ''Colpodella turpis'' Simpson & Patterson 1996 as '' Algovora turpis'' (Simpson & Patterson 1996) Cavalier-Smith & Chao 2004 * ''Colpodella unguis'' Patterson & Simpson 1996 as '' Colpovora unguis'' (Patterson & Simpson 1996) Cavalier-Smith 2017 * ''Colpodella vorax'' (Kent, 1880) Simpson & Patterson, 1996 as '' Dinomonas vorax'' Kent 1880

Clinical

These organisms are not normally considered to be human pathogens. However, a report of an infection of the

erythrocyte Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

s in a Chinese woman with a deficiency of

natural killer cell Natural killer cells, also known as NK cells or large granular lymphocytes (LGL), are a type of cytotoxic lymphocyte critical to the innate immune system that belong to the rapidly expanding family of known innate lymphoid cells (ILC) and repres ...

s has been reported.Yuan CL, Keeling PJ, Krause PJ, Horak A, Bent S, Rollend L, Hua XG (2012) ''Colpodella'' spp.-like parasite infection in woman, China. Emerg Infect Dis 18(1):125-127 doi: 10.3201/eid1801.110716

References

External links

* {{Taxonbar, from=Q5149298 Apicomplexa genera