''Thaumatomastix'' is a protist genus of the order ''

Thaumatomonadida Thaumatomonadida is an order of flagellates A flagellate is a cell or organism with one or more whip-like appendages called flagellum, flagella. The word ''flagellate'' also describes a particular construction (or level of organization) c ...

'', within the phylum

Cercozoa 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 phylogeny, molecular phylogenies of rRNA and actin or Ubiqu ...

and the class

Imbricatea Imbricatea is a class of Rhizaria characterised by silica scales. It is sometimes described as "Imbricatea/Silicofilosea", due to the similarity of those two groupings. Imbricatea is divided into the Order (biology), orders Euglyphida and Thaumat ...

. Its species are aquatic, feeding on

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

and appearing in waters of a wide range of temperatures and

salinities Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal to ...

, and are 15-50 micrometers long. They can interchange between

flagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and the ...

d and amoeboid forms, and are notable for being covered in both spiny and flattened siliceous scales.

Etymology

The genus was named by Robert Lauterborn in 1899. '' Thauma'' in Greek can mean ‘miracle,’ ‘wonder,’ or ‘marvel,’ while ''

mastix ''Pistacia lentiscus'' (also lentisk or mastic) is a dioecious evergreen shrub or small tree of the genus ''Pistacia'' native to the Mediterranean Basin. It grows up to tall and is cultivated for its aromatic resin, mainly on the Greek isla ...

'' is a suffix (also Greek-derived) that can be used to mean ‘scourge’ or ‘whip,’ which may refer to the organism’s flagella.

History of knowledge

The genus was first identified in 1899 by Robert Lauterborn, a German

protozoologist Protistology is a scientific discipline devoted to the study of protists, a highly diverse group of eukaryotic organisms. All eukaryotes apart from animals, plants and fungi are considered protists. Its field of study therefore overlaps with the ...

. Since then several new species have been discovered within the genus. However, analyses of

ribosomal DNA The ribosomal DNA (rDNA) consists of a group of ribosomal RNA encoding genes and related regulatory elements, and is widespread in similar configuration in all domains of life. The ribosomal DNA encodes the non-coding ribosomal RNA, integral struc ...

have indicated that Thaumatomastix may in fact be a

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 ...

group, and have resulted in seven species (''T. formosa, T. fragilis, T. fusiformis, T. groenlandika, T. igloolica, T. spinosa,'' and ''T. splendida'') being reclassified under the genus ''Reckertia'' in 2011. It has also been recently suggested that the genus be split into three separate genera, with the others being ''Ovaloplaca'' and ''Thaumatospina.''

Habitat and ecology

''Thaumatomastix'' is found in marine and

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

environments, over a wide range of salinities and temperatures. Though organisms may be found amidst

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

, they most often occur in sediments. Comparison of their ribosomal DNA sequences with cloned partial sequences has indicated that they can survive in suboxic or even anoxic environments. ''Thaumatomastix'' are phagotrophs, with some known to feed on algae. Many species have been primarily observed via whole mounts rather than living samples, and much about their behavior in their natural environment remains unknown. In culture, they have been noted to thrive in samples where suspended sediment particles are allowed to settle.

Description

A typical organism of the genus ''Thaumatomastix'' is single-celled and

heterotroph A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...

ic, with a 15-50 micrometer body covered in siliceous scales and spines. The body scales can be triangular or elliptical plates, while the spines vary in length between species and are even bifurcated in the case of ''T. bipartita.'' The elliptical plates consist of two fused disks with a varying number of perforations, while the spines have three ridges and a collar-like structure near the proximal plate. Scales are produced by silica deposition

vesicles Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry), a supramolecular assembly of lipid molecules, like a cell membrane * Synaptic vesicle In a neuron, synaptic vesicles (or neurotransmitter vesicles) s ...

, which remain invaginated in or close to the cell’s

mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...

during their development. Once a scale is fully formed, its vesicle will move to the

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

to deposit it there. ''Thaumatomastix'' are biflagellate, with one

flagellum 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 ...

being longer than the cell itself, and move around by swimming or gliding. The two flagella emerge from a short furrow at the anterior end of the cell; the shorter one is armored by scales while the longer one is not. Though present in most species, flagella have not been observed in ''T. tauryanini'' as of 2012. In addition to a large anterior nucleus, ''Thaumatomastix'' possess one or more

vacuole A vacuole () is a membrane-bound organelle which is present in Plant cell, plant and Fungus, fungal Cell (biology), cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water ...

s. Cylindrical structures similar to

ejectosome An ejectosome is a cellular organelle responsible for ejecting their contents from the cell. Two unrelated types of ejectosomes are described in the literature: # Cryptomonads have two types of characteristic extrusomes known as ejectosomes. # In ...

s, contained within vesicles just below the plasma membrane, have also been observed in some species. ''Thaumatomastix'' can produce

pseudopodia 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 ...

from the ventral surface of their body in order to feed and will sometimes change from flagellated cells to amoeboid cells and back. As amoeboids, they possess branching pseudopodia which they can use to move across a substrate. Many of these characteristics are shared by the closely related genus ''Thaumatomonas.'' However, ''Thaumatomastix'' differs in that it has flagellar scales and a longer anterior flagellum. Genetic analysis suggests that ''Thaumatomastix'' is paraphyletic and may need to be divided into multiple genera. Those with oval-shaped plate scales (''Ovoplaca'') are closely related to another newly discovered genus, ''Scutellomonas'', which also has oval-shaped scales but does not have spines. This does not hold true for ''Thaumatomastix'' with triangular scales, and as a result there is currently some uncertainty as to which species still belong in the genus. Based on the new proposed phylogeny, ''Thaumatomastix'' itself would be reduced to contain only the three freshwater species with triangular scales, which are distinguished by a thicker cell boundary layer than their marine relatives.

List of species

Nine species are currently recognized in the genus ''Thaumatomastix'' as of 2012. *''

Thaumatomastix bipartita ''Thaumatomastix'' is a protist genus of the order ''Thaumatomonadida'', within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and salinities, and ar ...

'' Beech & Moestrup, 1986 *''

Thaumatomastix dybsoeana ''Thaumatomastix'' is a protist genus of the order ''Thaumatomonadida'', within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and salinities, and ar ...

'' Thomsen, Hällfors, Hällfors & Ikävalko, 1993 *''

Thaumatomastix patelliformis ''Thaumatomastix'' is a protist genus of the order ''Thaumatomonadida'', within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and salinities, and ar ...

'' (Takahashi & Hara) Beech & Moestrup, 1986 *''

Thaumatomastix punctata ''Thaumatomastix'' is a protist genus of the order ''Thaumatomonadida'', within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and salinities, and ar ...

'' Thomsen ex Vørs *''

Thaumatomastix sagittifera ''Thaumatomastix'' is a protist genus of the order ''Thaumatomonadida'', within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and salinities, and ar ...

'' (Conrad) Beech & Moestrup, 1986 *''

Thaumatomastix salina ''Thaumatomastix'' is a protist genus of the order ''Thaumatomonadida'', within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and salinities, and ar ...

'' (Birch-Andersen) Beech & Moestrup, 1986 *''

Thaumatomastix setifera ''Thaumatomastix'' is a protist genus of the order ''Thaumatomonadida'', within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and salinities, and ar ...

'' (Lauterborn) Lemmermann, 1908 *''

Thaumatomastix thomseni ''Thaumatomastix'' is a protist genus of the order ''Thaumatomonadida'', within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and Salinity, saliniti ...

'' Tong, 1997 *'' Thaumatomastix tripus'' (Takahashi & Hara) Beech & Moestrup, 1986

References

{{Taxonbar, from=Q7711446 Rhizaria genera