''Minimassisteria'' is a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

bacterivorous A bacterivore is an organism which obtains energy and nutrients primarily or entirely from the consumption of bacteria. The term is most commonly used to describe free-living, heterotrophic, microscopic organisms such as nematodes as well as many s ...

genus of

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 with only one species, ''M. diva'', that presents three different lifestyle forms. It has a widespread geographic distribution. It is an amoeboflagellate most closely related to ''

Massisteria ''Massisteria'' is a genus of Cercozoa. They are naked 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 sha ...

'', and together comprise the family

Massisteriidae Massisteriidae is a family of granofilosean protists within the phylum Cercozoa. Taxonomy Massisteriidae contains two genera: *''Massisteria ''Massisteria'' is a genus of Cercozoa. They are naked protist A protist () is any eukaryotic or ...

Morphology and behavior

''Minimassisteria'' are trimorphic (i.e. with three forms)

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 ...

amoeboflagellates with two

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 ...

. Their life cycle has a trophic phase that feeds by non-

anastomosing An anastomosis (, plural anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal ...

filose

pseudopodia A pseudopod or pseudopodium (plural: 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 filament ...

(i.e.

filopodia Filopodia (singular filopodium) are slender cytoplasmic projections that extend beyond the leading edge of lamellipodia in migrating cells. Within the lamellipodium, actin ribs are known as ''microspikes'', and when they extend beyond the lame ...

) that bear evident granules along their length. There is a distinct swimming form and, unlike its closest relative ''

'', a crawling form with a thicker non-granular anterior filopodia used for traction. *Feeding form. These cells, known as trophonts, have a flattened cell body attached to the substrate, measuring 2.3 to 5.0 μm in diameter. Between 1 and 15 delicately thin filopodia radiate from the cell body up to 52 μm in length, with up to 11 granules each, probably

extrusome Extrusomes are membrane-bound structures in some eukaryotes which, under certain conditions, discharge their contents outside the cell. There are a variety of different types, probably not homologous, and serving various functions. Notable extru ...

s. The cells are found aggregated over the substrate, where attached cells multiply by fission. *Swimming form. The attached cells can change into sausage-shaped swimming cells, more slender than the trophonts, measuring 2 to 4.5 μm in size. They have one anterior and one trailing

flagellum 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 ...

, each around 4 μm long, and can move relatively fast. Within a few minutes, swimming stages may attach to the substrate to reform as trophonts; if so, flagella are partly reabsorbed and therefore appear shorter than in swimming stages (less than 2 μm), are immotile and hard to see. This phase is still

phagotrophic Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is c ...

and capable of capturing

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

. *Crawling form. There is one major pseudopodium, thicker and shorter than in trophonts, with invisible granules. There is also a posterior flagellum that trails behind. Typically there are other thick pseudopods on either side of the cell.

Etymology

The genus name references the small size, as well as its similarity to ''

''. The species

epithet An epithet (, ), also byname, is a descriptive term (word or phrase) known for accompanying or occurring in place of a name and having entered common usage. It has various shades of meaning when applied to seemingly real or fictitious people, di ...

references the deep-sea expedition DIVA, during which the

type strain The International Code of Nomenclature of Prokaryotes (ICNP) formerly the International Code of Nomenclature of Bacteria (ICNB) or Bacteriological Code (BC) governs the scientific names for Bacteria and Archaea.P. H. A. Sneath, 2003. A short histor ...

of ''M. diva'' was collected, at a depth of 5036 meters in the

Northern Cape The Northern Cape is the largest and most sparsely populated province of South Africa. It was created in 1994 when the Cape Province was split up. Its capital is Kimberley. It includes the Kalahari Gemsbok National Park, part of the Kgalagadi T ...

abyssal plain.

References

External links

{{Taxonbar, from=Q25366060 Cercozoa genera