| Barthelona | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Phylum: | Metamonada |
| Genus: | Barthelona Bernard, Simpson & Patterson, 2000 [1] |
| Species: | B. vulgaris |
| Binomial name | |
| Barthelona vulgaris Bernard, Simpson & Patterson, 2000 | |
Barthelona is a genus of anaerobic protists. They are basal eukaryotes closely related to skoliomonads, within the phylum Metamonada. It is a monotypic genus containing the sole species Barthelona vulgaris. Members of this genus are informally known as barthelonids.
Barthelonids are flagellates, unicellular protists (a type of eukaryote) that use flagella 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. [1]
Barthelonids are free-living solitary heterotrophs. They swim or, more rarely, glide slowly. When stationary, they still beat their flagella with a gentle undulation. [1]
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| Cladogram of skoliomonads based on a SSU rRNA phylogeny published in 2024. [2] |
The genus Barthelona was described by protistologists Catherine Bernard, Alastair G.B. Simpson, and David J. Patterson. They isolated flagellates from sediments of Quibray Bay, Australia 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. [1] Since the identification of B. vulgaris was purely based on observations under light microscopy, 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 informally known as "barthelonids", resolved as the sister group to the Fornicata within the phylum Metamonada. [3]
The Stramenopiles, also called Heterokonts, are a clade of organisms distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, and in some they have been secondarily lost. Stramenopiles represent one of the three major clades in the SAR supergroup, along with Alveolata and Rhizaria.
The metamonads are a large group of flagellate amitochondriate microscopic eukaryotes. Their composition is not entirely settled, but they include the retortamonads, diplomonads, and possibly the parabasalids and oxymonads as well. These four groups are all anaerobic, occurring mostly as symbiotes or parasites of animals, as is the case with Giardia lamblia which causes diarrhea in mammals.
Hemimastigophora is a group of single-celled eukaryotic organisms including the Spironematellidae, first identified in 1988, and the Paramastigidae. Over the next 30 years, different authors proposed placing these organisms in various branches of the eukaryotes. In 2018 Lax et al. reported the first genetic information for Spironemidae, and suggest that they are from an ancient lineage of eukaryotes which constitute a separate clade from all other eukaryotic kingdoms. It may be related to the Telonemia.
Telonemia is a phylum of microscopic eukaryotes commonly known as telonemids. They are unicellular free-living flagellates with a unique combination of cell structures, including a highly complex cytoskeleton unseen in other eukaryotes.
Malawimonadidae is a family of unicellular eukaryotes of outsize importance in understanding eukaryote phylogeny.
Carpediemonas is genus of Metamonada, and belongs to the group Excavata. This organism is a unicellular flagellated eukaryote that was first discovered in substrate samples from the Great Barrier Reef. Carpediemonas can be found in anaerobic intertidal sediment, where it feeds on bacteria. A feature of this species is the presence of a feeding groove, a characteristic of the excavates. Like most other metamonads, Carpediemonas does not rely on an aerobic mitochondrion to produce energy. Instead, it contains hydrogenosomes that are used to produce ATP. This organism has two flagella: a posterior one used for feeding on the substrate, and an anterior one that moves in a slower sweeping motion. Carpediemonas is assigned to the fornicates, where similar Carpediemonas-like organisms are used in researching the evolution within excavates. Although Carpediemonas is a member of the metamonads, it is unusual in the sense that it is free-living and has three basal bodies.
Trimastix is a genus of excavate protists, the sole occupant of the order Trimastigida. Trimastix are bacterivorous, free living and anaerobic. It was first observed in 1881 by William Kent. There are few known species, and the genus's role in the ecosystem is largely unknown. However, it is known that they generally live in marine environments within the tissues of decaying organisms to maintain an anoxic environment. Much interest in this group is related to its close association with other members of Preaxostyla. These organisms do not have classical mitochondria, and as such, much of the research involving these microbes is aimed at investigating the evolution of mitochondria.
Malawimonas is genus of unicellular, heterotrophic flagellates with uncertain phylogenetic affinities. They have variably being assigned to Excavata and Loukozoa. Recent studies suggest they may be closely related to the Podiata.
Jakobids are an order of free-living, heterotrophic, flagellar eukaryotes in the supergroup Excavata. They are small, and can be found in aerobic and anaerobic environments. The order Jakobida, believed to be monophyletic, consists of only twenty species at present, and was classified as a group in 1993. There is ongoing research into the mitochondrial genomes of jakobids, which are unusually large and bacteria-like, evidence that jakobids may be important to the evolutionary history of eukaryotes.
The apusomonads are a group of protozoan zooflagellates that glide on surfaces, and mostly consume prokaryotes. They are of particular evolutionary interest because they appear to be the sister group to the Opisthokonts, the clade that includes both animals and fungi. Together with the Breviatea, these form the Obazoa clade.
The kathablepharids or katablepharids are a group of heterotrophic flagellates closely related to cryptomonads. First described by Heinrich Leonhards Skuja in 1939, kathablepharids were named after the genus Kathablepharis. This genus is corrected to Katablepharis under botanical nomenclature, but the original spelling is maintained under zoological nomenclature. They are single-celled protists with two anteriorly directed flagella, an anterior cytostome for ingesting eukaryotic prey, and a sheath that covers the cell membrane. They have extrusomes known as ejectisomes, as well as tubular mitochondrial cristae.
Phycophthorum is a monotypic genus of protists that parasitize diatoms, containing the sole species Phycophthorum isakeiti. It was discovered in 2020 in the coastal waters of Norway, as parasites of diatoms belonging to the genus Pleurosigma.
Thecamonadinae is a subfamily of heterotrophic protists. It is a monophyletic group, or clade, of apusomonads, a group of protozoa with two flagella closely related to the eukaryotic supergroup Opisthokonta. The subfamily contains two genera Chelonemonas and Thecamonas, which are found in marine habitats.
Colponemids are free-living alveolates, unicellular flagellates related to dinoflagellates, apicomplexans and ciliates. They are predators of other small eukaryotes, found in freshwater, marine and soil environments. They do not form a solid clade, but a sparse group of deep-branching alveolate lineages.
Paratrimastix pyriformis is a species of free-living (non-parasitic) anaerobic freshwater bacteriovorous flagellated protists formerly known as Trimastix pyriformis and Tetramitus pyriformis.
Ploeotia is a genus of heterotrophic flagellates belonging to the Euglenida, a diverse group of flagellated protists in the phylum Euglenozoa. Species of Ploeotia are composed of rigid cells exhibiting two flagella. The genus was described by Félix Dujardin in 1841.
The peranemids are a group of phagotrophic flagellates, single-celled eukaryotes or protists. They belong to the Euglenida, a diverse lineage of flagellates that contains the closely related euglenophyte algae. Like these algae, peranemids have flexible cells capable of deformation or metaboly, and have one or two flagella in the anterior region of the cell. They are classified as family Peranemidae (ICZN) or Peranemataceae (ICBN) within the monotypic order Peranemida (ICZN) or Peranematales (ICBN).
Anisonemia is a clade of single-celled protists belonging to the phylum Euglenozoa, relatives of the Euglenophyceae algae. They are flagellates, with two flagella for locomotion. Anisonemia includes various phagotrophic species and a group of primary osmotrophic protists known as Aphagea.
Neometanema is a genus of phagotrophic flagellates belonging to the Euglenida, a diverse group of flagellates in the phylum Euglenozoa. It is the sole genus within the monotypic family Neometanemidae and suborder Metanemina. It composes the order Natomonadida together with a closely related clade of osmotrophs known as Aphagea.
Skoliomonas is a genus of anaerobic protists closely related to barthelonids, a small group of basal eukaryotes within the phylum Metamonada. It is a monotypic genus containing the sole species Skoliomonas litria. Members of this genus are informally named skoliomonads. They are found inhabiting hypersaline alkaline lakes in Tanzania and North America.