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 alveolates are a group of protists, considered a major clade and superphylum within Eukarya. They are currently grouped with the stramenopiles and Rhizaria among the protists with tubulocristate mitochondria into the SAR supergroup.
The cryptomonads are a group of algae, most of which have plastids. They are traditionally considered a division of algae among phycologists, under the name of Cryptophyta. 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. Some may exhibit mixotrophy. They are classified as clade Cryptomonada, which is divided into two classes: heterotrophic Goniomonadea and phototrophic Cryptophyceae. The two groups are united under three shared morphological characteristics: presence of a periplast, ejectisomes with secondary scroll, and mitochondrial cristae with flat tubules. Genetic studies as early as 1994 also supported the hypothesis that Goniomonas was sister to Cryptophyceae. A study in 2018 found strong evidence that the common ancestor of Cryptomonada was an autotrophic protist.
Pedinellales (ICN) or Pedinellida (ICZN) is a group of single-celled algae found in both marine environments and freshwater.
The axodines are a group of unicellular stramenopiles that includes silicoflagellate and rhizochromulinid algae, actinomonad heterotrophic flagellates and actinophryid heliozoa. Alternative classifications treat the dictyochophytes as heterokont algae, or as Chrysophyceae. Other overlapping taxonomic concepts include the Actinochrysophyceae, Actinochrysea or Dictyochophyceae sensu lato. The grouping was proposed on the basis of ultrastructural similarities, and is consistent with subsequent molecular comparisons.
The chlorarachniophytes are a small group of exclusively marine algae widely distributed in tropical and temperate waters. They are typically mixotrophic, ingesting bacteria and smaller protists as well as conducting photosynthesis. Normally they have the form of small amoebae, with branching cytoplasmic extensions that capture prey and connect the cells together, forming a net. They may also form flagellate zoospores, which characteristically have a single subapical flagellum that spirals backwards around the cell body, and walled coccoid cells.
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.
Labyrinthulomycetes (ICBN) or Labyrinthulea (ICZN) is a class of protists that produce a network of filaments or tubes, which serve as tracks for the cells to glide along and absorb nutrients for them. The two main groups are the labyrinthulids and thraustochytrids. They are mostly marine, commonly found as parasites on algae and seagrasses or as decomposers on dead plant material. They also include some parasites of marine invertebrates and mixotrophic species that live in a symbiotic relationship with zoochlorella.
Cercomonads are small amoeboflagellates, widespread in aqueous habitats and common in soils.
Ochrophytes, also known as heterokontophytes or stramenochromes, are a group of algae. They are the photosynthetic stramenopiles, a group of eukaryotes, organisms with a cell nucleus, characterized by the presence of two unequal flagella, one of which has tripartite hairs called mastigonemes. In particular, they are characterized by photosynthetic organelles or plastids enclosed by four membranes, with membrane-bound compartments called thylakoids organized in piles of three, chlorophyll a and c as their photosynthetic pigments, and additional pigments such as β-carotene and xanthophylls. Ochrophytes are one of the most diverse lineages of eukaryotes, containing ecologically important algae such as brown algae and diatoms. They are classified either as phylum Ochrophyta or Heterokontophyta, or as subphylum Ochrophytina within phylum Gyrista. Their plastids are of red algal origin.
Bigyra is a phylum of microscopic eukaryotes that are found at the base of the Stramenopiles clade. It includes three well-known heterotrophic groups Bicosoecida, Opalinata and Labyrinthulomycetes, as well as several small clades initially discovered through environmental DNA samples: Nanomonadea, Placididea, Opalomonadea and Eogyrea. The classification of Bigyra has changed several times since its origin, and its monophyly remains unresolved.
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 kathablepharids are a group of heterotrophic flagellates (Protists) the first species of which was described by Skuja in 1939 as Kathablepharis phoenikoston. His spelling was challenged because of non-compliance with botanical nomenclatural conditions, hence the alternative spelling Katablepharis. As the organism was heterotrophic and usually regarded as 'protozoan', and to favour stability, Skuja's original spelling has largely prevailed. With an anterior pocket and ejectisomes, the kathablepharids were thought initially to be cryptomonads. There were a variety of differences with Cryptomonas and other typical cryptomonads = cryptophytes, such as the thickness, length, and beat pattern of the flagella, their phagotrophic habitat, differences in the ejectisomes, and various features of their ultrastructure. The distinctive characteristics of the group were established from electron microscopical studies by Clay and Kugrens and Vørs. More recently they have been tentatively grouped with the chromalveolates, or distantly with the cryptophytes.
Telonema is a genus of single-celled organisms.
Perkinsids are single-celled protists that live as intracellular parasites of a variety of other organisms. They are classified as the class Perkinsea within the monotypic phylum Perkinsozoa. It is part of the eukaryotic supergroup Alveolata, along with dinoflagellates, their closest relatives, and another parasitic group known as Apicomplexa. Perkinsids are found in aquatic environments, as parasites of dinoflagellates and various animals.
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.
Picophagea, also known as Synchromophyceae, is a class of photosynthetic stramenopiles. The chloroplast of the Synchromophyceae are surrounded by two membranes and arranged in a way where they share the outer pair of membranes. The entire chloroplast complex is surrounded by an additional two outer membranes.
The cortical alveolum is a cellular organelle consisting of a vesicle located under the cytoplasmic membrane, to which they give support. The term "corticate" comes from an evolutionary hypothesis about the common origin of kingdoms Plantae and Chromista, because both kingdoms have cortical alveoli in at least one phylum. At least three protist lineages exhibit these structures: Telonemia, Alveolata and Glaucophyta.
Commation cryoporinum is a species of heterotrophic protists discovered in 1993 in Antarctic waters. It is one of two species in the Commatiida, an order of stramenopiles closely related to actinophryids, a group of heliozoan protists, and to raphidophytes, a group of algae.
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.
