| Vannellidae | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Phylum: | Amoebozoa |
| Class: | Discosea |
| Subclass: | Flabellinia |
| Order: | Vannellida Smirnov et al., 2005 |
| Family: | Vannellidae Bovee, 1970 |
| Genera | |
The Vannellidae are a family of Amoebozoa, which are found in soil, fresh- and salt water. [1] [2] The most common genus is Vannella.
Vannellidae tend to be flattened and fan-shaped during motion, although some are long and narrow, and have a prominent clear margin at the anterior. [3] In most amoebae, the endoplasm glides forward through the center of the cell, but vannellids undergo a sort of rolling motion with the outer membrane sliding around like a tank tread. These amoebae are usually 10-40 μm in size, but some are smaller or larger.
Vannellidae are surrounded by an outer covering called the glycocalyx, which is generally 10-20 nm across, though the thickness varies among species. In some species, a layer of hair-like filaments called glycostyles protrudes from the glycocalyx. [2]
Vannellidae simplex full mitochondrial genome sequence shows significant difference from its close relative Neoparamoeba pemaquidensis. Similarities are limited to family or genera levels with too much diversity to see commonalities amongst clades beyond the genera level. [4]
Currently, there is an investigation into Vanellidae focused on parasitization. Vanellidae can be found within the gills of freshwater rainbow trouts. These infections pose significant problems for farming rainbow trouts. Current treatments being investigated include chemical and some vegetable compounds. As of 2020, these findings are still being worked on in vitro with hopes of doing in vivo experiments to alleviate the issues. [5]
While not directly pathogenic to humans, free living amoebas, such as Vannellidae, can be the host of pathogenic microorganisms. [6] Due to their ability to transmit other pathogens, clinical identification is encouraged.
Issues in classification for Vannellidae arise from the genus classification level. Morphological data being used for classification has found conflict with genetic information. Genetic sequencing of multiple vannellid amoebas has shown a mix of morphological characteristics. As of 2007, there were 40 species Vannellidae identified through genetic sequencing. Molecular phylogenies include Vannellidae in the class Flabellinia as a sister group to the others, which have subpseudopodia. In 2007, the taxonomy of Vannella expanded to include Platyamoeba. Previously, Vannella was separated based on the presence of glycostyles in the cell surface. Through genetic verification, Vanella and Platyamoeba are shown to not be genetically distinct. [7]
Cercozoa 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. They were the first major eukaryotic group to be recognized mainly through molecular phylogenies. They are the natural predators of many species of bacteria. They are closely related to the phylum Retaria, comprising amoeboids that usually have complex shells, and together form a supergroup called Rhizaria.
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 usually ranked as a phylum within either the kingdom Protista or the kingdom Protozoa. In the classification favored by the International Society of Protistologists, it is retained as an unranked "supergroup" within Eukaryota. Molecular genetic analysis supports Amoebozoa as a monophyletic clade. Modern studies of eukaryotic phylogenetic trees identify it as the sister group to Opisthokonta, another major clade which contains both fungi and animals as well as several other clades comprising some 300 species of unicellular eukaryotes. Amoebozoa and Opisthokonta are sometimes grouped together in a high-level taxon, variously named Unikonta, Amorphea or Opimoda.
The Rhizaria are a diverse and species-rich supergroup of mostly unicellular eukaryotes. Except for the Chlorarachniophytes and three species in the genus Paulinella in the phylum Cercozoa, they are all non-photosynthethic, but many foraminifera and radiolaria have a symbiotic relationship with unicellular algae. A multicellular form, Guttulinopsis vulgaris, a cellular slime mold, has been described. This group was used by Cavalier-Smith in 2002, although the term "Rhizaria" had been long used for clades within the currently recognized taxon. Being described mainly from rDNA sequences, they vary considerably in form, having no clear morphological distinctive characters (synapomorphies), but for the most part they are amoeboids with filose, reticulose, or microtubule-supported pseudopods. In the absence of an apomorphy, the group is ill-defined, and its composition has been very fluid. Some Rhizaria possess mineral exoskeletons, which are in different clades within Rhizaria made out of opal, celestite, or calcite. Certain species can attain sizes of more than a centimeter with some species being able to form cylindrical colonies approximately 1 cm in diameter and greater than 1 m in length. They feed by capturing and engulfing prey with the extensions of their pseudopodia; forms that are symbiotic with unicellular algae contribute significantly to the total primary production of the ocean.
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. In current classification schemes, Lobosa is a subphylum, composed mainly of amoebae that have lobose pseudopods but lack cilia or flagella.
The Apusozoa are a paraphyletic phylum of flagellate eukaryotes. They are usually around 5–20 μm in size, and occur in soils and aquatic habitats, where they feed on bacteria. They are grouped together based on the presence of an organic shell or theca under the dorsal surface of the cell.
The Tubulinea are a major grouping of Amoebozoa, including most of the more familiar amoebae genera like Amoeba, Arcella, Difflugia and Hartmannella.
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 transparent layer called hyaloplasm forms at the leading edge of the cell. In some discoseans, short "subpseudopodia" may be extended from this hyaloplasm, but the granular contents of the cell do not flow into these, as in true pseudopodia. Discosean amoebae lack hard shells, but some, like Cochliopodium and Korotnevella secrete intricate organic scales which may cover the upper (dorsal) surface of the cell. No species have flagella or flagellated stages of life.
Eumycetozoa, or true slime molds, is a diverse group of protists that behave as slime molds and develop fruiting bodies, either as sorocarps or as sporocarps. It is a monophyletic group or clade within the phylum Amoebozoa that contains the myxogastrids, dictyostelids and protosporangiids.
Himatismenida is an Amoebozoa order, in the class Discosea, along with Glycostylida and Dermamoebida. It contains species such as Cochliopodium gallicum.
Leptomyxida is an order of Amoebozoa.
Dactylopodida is an Amoebozoa grouping.
Hartmannella is a genus of Amoebozoa.
Leptomyxa is a free-living genus of lobose naked multinucleate amoebae in the order Leptomyxida that inhabits freshwater, soil and mosses. It is very closely related to the genus Rhizamoeba, and some species have been moved between the two genera due to molecular data.
Rhizamoeba is a small genus of free-living marine naked lobose amoebae in the monotypic family Rhizamoebidae in the order Leptomyxida. It is most closely related to Leptomyxa and Flabellula, and some species have been moved to Leptomyxa due to molecular data.
Mayorella is a genus of small amoeboid protists in the phylum Amoebozoa. The genus consists of amoebae that exhibit pseudopodia and feed on a variety of organisms through phagocytosis, making them an important group in microbial ecology across most environments worldwide. Mayorella species have been found in soil, freshwater and marine environments.
Trichosphaerium is a genus of amoebozoan protists that present extraordinary morphological transformations, both in size and shape, during their life cycle. They can present a test that may or may not be covered in spicules. They are related to the family Microcoryciidae, which contains other amoebae with tests, within the clade Corycidia of the phylum Amoebozoa.
The sarcomonads or class Sarcomonadea are a group of amoeboid biciliate protists in the phylum Cercozoa. They are characterized by a propensity to move through gliding on their posterior cilium or through filopodia, a lack of scales or external theca, a soft cell surface without obvious cortical filamentous or membranous skeleton, two cilia without scales or hairs, tubular mitochondrial cristae, near-spherical extrusomes, and a microbody attached to the nucleus.
The vampyrellids, colloquially known as vampire amoebae, are a group of free-living predatory amoebae classified as part of the lineage Endomyxa. They are distinguished from other groups of amoebae by their irregular cell shape with propensity to fuse and split like plasmodial organisms, and their life cycle with a digestive cyst stage that digests the gathered food. They appear worldwide in marine, brackish, freshwater and soil habitats. They are important predators of an enormous variety of microscopic organisms, from algae to fungi and animals. They are also known as aconchulinid amoebae.
The Flabellinia are a subclass of Amoebozoa. During locomotion the cells are flattened and have a clear layer called hyaloplasm along the front margin. Some form slender subpseudopodia projecting outward from the hyaloplasm, but the cell mass does not flow into these as in true pseudopodia, and advances without a definite central axis as in the Tubulinea. They also lack distinctive features like shells and flagella, and are united mainly by evidence from molecular trees.
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 membrane. Three genera, Armaparvus, Sapocribrum and Squamamoeba, belong to this group, distributed in two families.
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| Tubulinea |
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| Evosea | |||||||||||||||||||||||||||
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