The actinophryids are an order of heliozoa, a polyphyletic array of stramenopiles, having a close relationship with pedinellids and Ciliophrys. They are common in fresh water and occasionally found in marine and soil habitats. Actinophryids are unicellular and roughly spherical in shape, with many axopodia that radiate outward from the cell body. Axopodia are a type of pseudopodia that are supported by hundreds of microtubules arranged in interlocking spirals and forming a needle-like internal structure or axoneme. Small granules, extrusomes, that lie under the membrane of the body and axopodia capture flagellates, ciliates and small metazoa that make contact with the arms.
A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word flagellate also describes a particular construction characteristic of many prokaryotes and eukaryotes and their means of motion. The term presently does not imply any specific relationship or classification of the organisms that possess flagella. However, the term "flagellate" is included in other terms which are more formally characterized.
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.
Pedinellales 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.
Heliozoa, commonly known as sun-animalcules, are microbial eukaryotes (protists) with stiff arms (axopodia) radiating from their spherical bodies, which are responsible for their common name. The axopodia are microtubule-supported projections from the amoeboid cell body, and are variously used for capturing food, sensation, movement, and attachment. They are similar to Radiolaria, but they are distinguished from them by lacking central capsules and other complex skeletal elements, although some produce simple scales and spines. They may be found in both freshwater and marine environments.
Actinophrys is a genus of heliozoa, amoeboid unicellular organisms with many axopodial filaments that radiate out of their cell. It contains one of the most common heliozoan species, Actinophrys sol. It is classified within the monotypic family Actinophryidae.
Stephanopogon is a genus of flagellated marine protist that superficially resembles a ciliate.
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.
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.
Actinosphaerium is a genus of heliozoa, amoeboid unicellular organisms with many axopodial filaments that radiate out of their cell. It is classified within the monotypic family Actinosphaeriidae and suborder Actinosphaerina. Species of Actinophrys are distinguished by their large number of nuclei in each cell. Their axopodia sometimes terminate on the surface of nuclei. Vacuoles are abundant in the periphery of the cytoplasm.
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.
Mantamonads are a group of free-living heterotrophic flagellates that move primarily by gliding on surfaces. They are classified as one genus Mantamonas in the monotypic family Mantamonadidae, order Mantamonadida and class Glissodiscea. Previously, they were classified in Apusozoa as sister of the Apusmonadida on the basis of rRNA analyses. However, mantamonads are currently placed in CRuMs on the basis of phylogenomic analyses that identify their closest relatives as the Diphylleida and Rigifilida.
Ultrastructural identity is a concept in biology. It asserts that evolutionary lineages of eukaryotes in general and protists in particular can be distinguished by complements and arrangements of cellular organelles. These ultrastructural components can be visualized by electron microscopy.
Tetrahelia is a genus of four-ciliated protists belonging to the Endohelea, a group of heterotrophic eukaryotes previously considered heliozoa. It is the only genus in the family Tetraheliidae and order Axomonadida. It is a monotypic genus, containing the sole species Tetrahelia pterbica, previously classified as Tetradimorpha.
Commation is a genus of marine heterotrophic protists closely related to the actinophryids. It contains two species, Commation cryoporinum and Commation eposianum, discovered in antarctic waters and described in 1993. Currently, the genus is classified within a monotypic family Commatiidae and order Commatiida. Along with the photosynthetic raphidophytes, these organisms compose the class of stramenopiles known as Raphidomonadea.
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.
Urceolus is a genus of heterotrophic flagellates belonging to the Euglenozoa, a phylum of single-celled eukaryotes or protists. Described by Russian biologist Konstantin Mereschkowsky in 1877, its type species is Urceolus alenizini. Species of this genus are characterized by deformable flask-shaped cells that exhibit at least one flagellum that is active at the tip, arising from a neck-like structure that also hosts the feeding apparatus. They are found in a variety of water body sediments across the globe. According to evolutionary studies, Urceolus belongs to a group of Euglenozoa known as peranemids, closely related to the euglenophyte algae.
