Pedinellales is a group of single-celled
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
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
''Pedinella'' is a genus of small, unicellular planktonic or attached, flagellated heterokonts first described in 1888 by A. V. Vysotskij. The genus is monospecific, and the single species is ''Pedinella hexacostata'' Vysotskij. ''Pedinella'' ha ...
'', ''
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
''Parapedinella'' is a genus of heterokont
Heterokonts are a group of protists (formally referred to as Heterokonta, Heterokontae or Heterokontophyta). The group is a major line of eukaryotes. Most are algae, ranging from the giant multicel ...
'', ''
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
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 ...
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 Kent 1880; Ciliophryidae Poche 1913; Pedinellidae Cavalier-Smith 1986 stat. nov. 1995; Pseudopedinellaceae">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
''Parapedinella'' is a genus of heterokont
Heterokonts are a group of protists (formally referred to as Heterokonta, Heterokontae or Heterokontophyta). The group is a major line of eukaryotes. Most are algae, ranging from the giant multicel ...
''
Pedersen, Beech & Thomsen 1986
** Genus ''
Pedinella
''Pedinella'' is a genus of small, unicellular planktonic or attached, flagellated heterokonts first described in 1888 by A. V. Vysotskij. The genus is monospecific, and the single species is ''Pedinella hexacostata'' Vysotskij. ''Pedinella'' ha ...
''
Wyssotzki 1887 non Dahl 1909
** Genus ''
Pseudopedinella''
Carter 1937
** Genus ''
Pteridomonas''
Penard 1889
References
{{Taxonbar, from=Q7159272
Heterokont orders
Dictyochophyceae