Pedinellales is a group of single-celled algae found in both marine environments and freshwater. These are found in both freshwater and marine environments, and most genera are sessile, attached by posterior stalks. The flagellum is at the anterior of the cell, and the tentacles surround it, often capturing small prey drawn in by its current. The colored genera are '' Pedinella'', '' Apedinella'', '' Pseudopedinella'', and '' Mesopedinella''. Several more genera have lost their chloroplasts and feed entirely by

phagocytosis Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is ...

. These are '' Parapedinella'', '' Actinomonas'', and '' Pteridomonas''. It also appears that certain

heliozoa 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 f ...

are actually derived pedinellids. ''Ciliophrys'' alternates between a mobile flagellate stage and a heliozoan feeding stage, where the body is contracted with extended axopods all over its surface, and the flagellum is curled up into a tight figure eight. The

actinophryid 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 a ...

s, ''Actinophrys'' and ''Actinosphaerium'', exist only in a heliozoan form with no flagellum and with more elaborate bundles of microtubules supporting their axopods. Their inclusion was argued by Mikrjukov and Patterson, who coined the term actinodine to refer specifically to this extended group. Pedinellids were classified as

ns by some authors. The colored pedinellids were originally treated as a family of

golden algae The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer to a single species, '' Prymnesium parvum'', whic ...

in the order Ochromonadales, promoted to an order Pedinellales by Zimmerman in 1984. Their relationship to the silicoflagellates became apparent some time later, and Patterson defined this rankless group for the two in 1994. Moestrup treated it as the class Dictyochophyceae, previously restricted to the silicoflagellates, while Cavalier-Smith defined a new class Actinochrysophyceae for them.

Taxonomy

Taxonomy provided by AlgaeBase. * Family Cyrtophoraceae Pascher 1911 ** Genus '' Cyrtophorana'' Strand 1929 ** Genus '' Palatinella'' Lauterborn 1906 * Family Pedinellaceae Pascher 1910 ctinomonadaceae Kent 1880; Ciliophryidae Poche 1913; Pedinellidae Cavalier-Smith 1986 stat. nov. 1995; Pseudopedinellaceae** Genus '' Actinomonas'' Kent 1880 ** Genus '' Apedinella'' Throndsen 1971 ** Genus '' Ciliophrys'' Cienkowski 1876 ** Genus '' Helicopedinella'' Sekiguchi et al. 2003 ** Genus '' Mesopedinella'' Daugbjerg 1996 ** Genus '' Parapedinella'' Pedersen, Beech & Thomsen 1986 ** Genus '' Pedinella'' Wyssotzki 1887 non Dahl 1909 ** Genus '' Pseudopedinella'' Carter 1937 ** Genus '' Pteridomonas'' Penard 1889

References

{{Taxonbar, from=Q7159272 Heterokont orders Dictyochophyceae