Rigifilida is a clade of non-

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...

phagotroph 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 ca ...

eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

s. It consists of two genera: ''

Micronuclearia ''Micronuclearia'' is a genus of free-living protozoa. While originally thought to be a nucleariid Nucleariida is a group of amoebae with filose pseudopods, known mostly from soils and freshwater. They are distinguished from the superficially ...

'' and '' Rigifila''.

Characteristics

Cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...

of rigifilids are covered with either a single or a double-layered submembrane pellicular lamina that makes them rigid in consistence. Slender branching

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 ...

emanate from a ventral aperture of the

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

and are employed to collect

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 ...

upon which they feed and to attach the organism to the substratum. Around this aperture, the pellicle is reflexed around forming a peristomial collar. Other notable features are flat and irregular shaped mitocondrial cristae, a single dorsal

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucle ...

and the lack of

centriole In cell biology a centriole is a cylindrical organelle composed mainly of a protein called tubulin. Centrioles are found in most eukaryotic cells, but are not present in conifers (Pinophyta), flowering plants (angiosperms) and most fungi, and a ...

s and

cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...

Phylogeny

Taxonomy

Rigifilida is currently placed in

CRuMs CRuMs is a proposed clade of microbial eukaryotes, whose name is an acronym of the following constituent groups: i) collodictyonids also known as diphylleids, ii) rigifilids and iii) mantamonadids as sister of the Amorphea. It more or less s ...

. *Order Rigifilida Cavalier-Smith 2012 icronucleariida Cavalier-Smith 2008** Family Rigifilidae Yabuki & Cavalier-Smith 2012 *** Genus '' Rigifila'' Yabuki & Cavalier-Smith 2012 **** Species '' Rigifila ramosa'' Yabuki & Cavalier-Smith 2012 ** Family Micronucleariidae Cavalier-Smith 2008 *** Genus ''

'' Mikrjukov & Mylnikov 2001 **** Species '' Micronuclearia podoventralis'' Mikrjukov & Mylnikov 2001

References

{{Taxonbar, from=Q16989278 Podiata orders