| Corbistoma | |
|---|---|
| Movement of a Picomonas judraskeda cell | |
Scientific classification  | |
| Domain: | Eukaryota |
| Clade: | Diaphoretickes |
| Phylum: | Cryptista |
| Clade: | Corbistoma Cavalier-Smith and Chao, 2015 |
| Classes | |
Corbistoma is a proposed clade within the Cryptista which includes the Picobiliphytes and Telonemidae. [1]
Chromista is a proposed but polyphyletic biological kingdom, refined from the Chromalveolata, consisting of single-celled and multicellular eukaryotic species that share similar features in their photosynthetic organelles (plastids). It includes all eukaryotes whose plastids contain chlorophyll c and are surrounded by four membranes. If the ancestor already possessed chloroplasts derived by endosymbiosis from red algae, all non-photosynthetic Chromista have secondarily lost the ability to photosynthesise. Its members might have arisen independently as separate evolutionary groups from the last eukaryotic common ancestor.
Amorphea is a taxonomic supergroup that includes the basal Amoebozoa and Obazoa. That latter contains the Opisthokonta, which includes the Fungi, Animals and the Choanomonada, or Choanoflagellates. The taxonomic affinities of the members of this clade were originally described and proposed by Thomas Cavalier-Smith in 2002.
A bikont is any of the eukaryotic organisms classified in the group Bikonta. Many single-celled and multi-celled organisms are members of the group, and these, as well as the presumed ancestor, have two flagella.
Chromalveolata was a eukaryote supergroup present in a major classification of 2005, then regarded as one of the six major groups within the eukaryotes. It was a refinement of the kingdom Chromista, first proposed by Thomas Cavalier-Smith in 1981. Chromalveolata was proposed to represent the organisms descended from a single secondary endosymbiosis involving a red alga and a bikont. The plastids in these organisms are those that contain chlorophyll c.
The Archaeplastida are a major group of eukaryotes, comprising the photoautotrophic red algae (Rhodophyta), green algae, land plants, and the minor group glaucophytes. It also includes the non-photosynthetic lineage Rhodelphidia, a predatorial (eukaryotrophic) flagellate that is sister to the Rhodophyta, and probably the microscopic picozoans. The Archaeplastida have chloroplasts that are surrounded by two membranes, suggesting that they were acquired directly through a single endosymbiosis event by phagocytosis of a cyanobacterium. All other groups which have chloroplasts, besides the amoeboid genus Paulinella, have chloroplasts surrounded by three or four membranes, suggesting they were acquired secondarily from red or green algae. Unlike red and green algae, glaucophytes have never been involved in secondary endosymbiosis events.
The cryptophyceae are a class of algae, most of which have plastids. About 220 species are known, and they are common in freshwater, and also occur in marine and brackish habitats. Each cell is around 10–50 μm in size and flattened in shape, with an anterior groove or pocket. At the edge of the pocket there are typically two slightly unequal flagella.
Telonemia is a phylum of microscopic eukaryotes. They are unicellular free-living flagellates with a unique combination of cell structures, including a highly complex cytoskeleton unseen in other eukaryotes. They present characteristics similar to their sister group, the SAR supergroup, such as cortical alveoli, tripartite mastigonemes and filopodia. Together, the two lineages compose the TSAR clade. They are classified in three genera and seven species, although numerous undescribed lineages are known. They are detected in all marine and freshwater environments, where they prey on bacteria and small phytoplankton through phagotrophy.
Corticata, in the classification of eukaryotes, is a clade suggested by Thomas Cavalier-Smith to encompass the eukaryote supergroups of the following two groups:
The cryptomonads-haptophytes assemblage is a proposed but disputed monophyletic grouping of unicellular eukaryotes that are not included in the SAR supergroup. Several alternative names have been used for the group, including Hacrobia ; CCTH ; and "Eukaryomonadae".
The katablepharids, a group of heterotrophic flagellates, have been considered as part of the Cryptista since katablepharids were described in 1939. Although they differ from other cryptophytes and have even been proposed to be alveolates, early 21st century research suggests they are related to cryptophytes.
Picozoa, Picobiliphyta, Picobiliphytes, or Biliphytes are protists of a phylum of marine unicellular heterotrophic eukaryotes with a size of less than about 3 micrometers. They were formerly treated as eukaryotic algae and the smallest member of photosynthetic picoplankton before it was discovered they do not perform photosynthesis. The first species identified therein is Picomonas judraskeda. They probably belong in the Archaeplastida as sister of the Rhodophyta.
Cryptista is a clade of alga-like eukaryotes. It is most likely related to Archaeplastida which includes plants and many algae, within the larger group Diaphoretickes.
Haptista is a proposed group of protists made up of centrohelids and haptophytes. Phylogenomic studies indicate that Haptista, together with Ancoracysta twista, forms a sister clade to the SAR+Telonemia supergroup, but it may also be sister to the Cryptista (+Archaeplastida). It is thus one of the earliest diverging Diaphoretickes.
Endohelea is a proposed clade of eukaryotes that are related to Archaeplastida and the SAR supergroup. They used to be considered heliozoans, but phylogenetically they belong to a group of microorganisms known as Cryptista.
Palpitea is a proposed clade of eukaryotes that are related to Archaeplastida and the SAR supergroup.
Corbihelia is a proposed phylum of eukaryotes.
Microheliella is a monotypic genus of protists containing the sole species M. maris, first described in 2012. It has a variety of unusual morphological characteristics which make its broader classification difficult. These include a centrosome with two concentric granular shells and axopodia much simpler in structure than in visually similar protists.
Rappephyceae, or Rappemonads, are a small family of protists first described in 2011, of uncertain phylogenic affinity. It has been discussed as a possible member of a larger clade Haptophyta. This newly identified taxonomic class of phytoplankton are named after a professor from the Hawai’i institute of marine biology, known as Michael Rappé. Rappé discovered these phytoplankton in the Atlantic Ocean and published his findings on their DNA in 1998. Current research has shown that these organisms provide an immense amount of nutritional organic molecules, such as oxygen, for other organisms using biochemical processes like photosynthesis and carbon fixation.
The cortical alveolum is a cellular organelle consisting of a vesicle located under the cytoplasmic membrane, to which they give support. They have been defined as membrane sacs that strengthen the cellular cortex through the firm fixation to the underlying membrane and microtubules. They typically form a continuous layer that acts as a flexible film, although they can also constitute a semi-rigid structure or the scales of a theca.
Eolouka is a paraphyletic phylum of protists localized in the clade Discoba. It contains two lineages: Jakobea and Tsukubea, the last containing only one genus, Tsukubamonas.
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