''Barthelona'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Adhesive#Anaerobic, Anaerobic ad ...

protist A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancest ...

s. They are basal

eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

s closely related to skoliomonads, within the

phylum In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below Kingdom (biology), kingdom and above Class (biology), class. Traditionally, in botany the term division (taxonomy), division has been used instead ...

Metamonada. It is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus containing the sole species ''Barthelona vulgaris''. Members of this genus are informally known as barthelonids.

Description

Barthelonids are

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 ...

unicellular A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...

s (a type of

) that use

flagella 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 ...

for movement. Their cells measure 6–8 μm in length, and are oval on the dorsal side and flattened on the ventral side. Each cell has two flagella inserted sub-apically and laterally, at an angle of 60° from each other. The anterior flagellum is 1–2 times the cell length, while the posterior flagellum is 3–5 times as large as the cell body, and is slightly acronematic. The nucleus is located in the anterior end of the cell. The cytoplasm usually contains refractile granules. Barthelonids are free-living solitary

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 ...

s. They swim or, more rarely, glide slowly. When stationary, they still beat their flagella with a gentle undulation.

Taxonomy

The

''Barthelona'' was described by protistologists Catherine Bernard, Alastair G.B. Simpson, and David J. Patterson. They isolated flagellates from sediments of Quibray Bay,

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

in the spring of 1996. After observing the microorganisms, the authors assigned them to a new species ''Barthelona vulgaris'' and published the description in 2000. Since the identification of ''B. vulgaris'' was purely based on observations under

light microscopy Microscopy is the technical field of using microscopes to view subjects too small to be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, el ...

, it was treated as a morphospecies. This morphospecies was later identified at other geographical locations, but it was never genetically sequenced, and consequently its evolutionary position remained uncertain. In 2020, five strains of ''Barthelona'' were isolated and genetically sequenced in order to reveal their phylogenetic position. They form a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

informally known as "barthelonids", resolved as the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to the

Fornicata Trichozoa is a group of excavates. "Fornicata" is a similar grouping, but it excludes Parabasalia.Tree

Description

Taxonomy

References

Citations

Cited literature