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 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.
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.
The raphidophytes, formally known as Raphidophycidae or Raphidophyceae, are a small group of eukaryotic algae that includes both marine and freshwater species. All raphidophytes are unicellular, with large cells, but no cell walls. Raphidophytes possess a pair of flagella, organised such that both originate from the same invagination. One flagellum points forwards, and is covered in hair-like mastigonemes, while the other points backwards across the cell surface, lying within a ventral groove. Raphidophytes contain numerous ellipsoid chloroplasts, which contain chlorophylls a, c1 and c2. They also make use of accessory pigments including β-carotene and diadinoxanthin. Unlike other heterokontophytes, raphidophytes do not possess the photoreceptive organelle typical of this group.
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.
Phaeothamniophycidae is a subclass of heterokont algae. It contains two orders, Phaeothamniales and Pleurochloridellales, and consists of species separated from Chrysophyceae.
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.
Opalozoa is a subphylum of heterotrophic protists of the phylum Bigyra, and is the sister group to Sagenista. Opalozoans are non-photosynthetic heterokonts that are ancestrally phagotrophic but many times have evolved to be osmotrophic saprotrophs in the gut of vertebrate animals.
Kiitoksia is a genus of aquatic protist. The taxonomic position of the genus is still uncertain and it has not found a robust location in any subgroup.
Rigifila is a genus of free-living single-celled eukaryotes, or protists, containing the sole species Rigifila ramosa. It is classified within the monotypic family Rigifilidae. Along with Micronucleariidae, it is a member of Rigifilida, an order of basal eukaryotes within the CRuMs clade. It differs from Micronuclearia by having two proteic layers surrounding their cytoplasm instead of a single one, and having more irregular mitochondrial cristae, among other morphological differences.
Platysulcus is an eukaryotic microorganism that was recently discovered to be the earliest diverging lineage of the Heterokont phylogenetic tree. It is the only member of the family Platysulcidae, order Platysulcida and class Platysulcea, of uncertain taxonomic position within the phylum Bigyra. It contains the only species P. tardus.
Raphidomonadea is a class of Stramenopiles containing both photosynthetic and phagotrophic protists. The phagotrophic groups are known as Raphopoda, and comprise actinophryid heliozoa and the marine genus Commation. The photosynthetic groups are known as the raphidophyte algae. Their relationship was elucidated through phylogenetic analyses.
Wobblata is a paraphyletic grouping of all placidozoans except Opalinata. It unites the classes Placididea, Nanomonadea and Opalomonadea.
Gyrista is a phylum of heterokont protists containing three diverse groups: the mostly photosynthetic Ochrophyta, the parasitic Pseudofungi, and the recently described group of nanoflagellates known as Bigyromonada. Members of this phylum are characterized by the presence of a helix or a double helix/ring system in the ciliary transition region.
Heliorapha is a genus of heliozoan protists, amoeboid eukaryotes with stiff axopodia radiating from their cells. It contains one species, Heliorapha azurina. It is classified within a monotypic family Helioraphidae inside the actinophryids, a group of heliozoa that belong to the Ochrophyta along with other protists such as diatoms and brown algae.
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.
Commation eposianum 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.
Raphopoda is a grouping of heterotrophic protists. It contains the heterotroph organisms within class Raphidomonadea, classified as two orders: Commatiida, comprised by the sole genus of flagellates Commation, and Actinophryida, an order of heliozoa, amoebae with stiff specialized pseudopodia called axopodia.
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.
