Pedinellales

{{Short description|Order of single-celled organisms}} {{Automatic taxobox | image = Pteridomonas danica diversity-15-00044-ag.png | image_caption = Light micrograph of ''Pteridomonas danica'' | taxon = Actinomonadaceae | authority = Kent 1880 | parent_authority = Zimmermann, Moestrup & Hallfors 1985 | subdivision_ranks = Genera | subdivision = * ''Actinomonas'' * ''Apedinella'' * ''Cyrtophora'' * ''Helicopedinella'' * ''Mesopedinella'' * ''Palatinella'' * ''Parapedinella'' * ''Pedinella'' * ''Pseudopedinella'' * ''Pteridomonas'' | synonyms = {{Collapsible list | expand = | framestyle = | titlestyle = font-size:100% | title = As class | liststyle = | hlist = | bullets = | Pedinellea (ICZN) {{au|Cavalier-Smith, 1986}} | Pedinellophyceae (ICN) {{au|Cavalier-Smith, 1986}} }} {{Collapsible list | expand = | framestyle = | titlestyle = font-size:100% | title = As subclass | liststyle = | hlist = | bullets = | Pedinellidae {{au|Cavalier-Smith, 1995}} }} {{Collapsible list | expand = | framestyle = | titlestyle = font-size:100% | title = As order | liststyle = | hlist = | bullets = | Ciliophryida (ICZN) {{small|Febvre-Chevalier 1985}} | Ciliophryales (ICN) Cavalier-Smith, 1995 }} {{Collapsible list | expand = | framestyle = | titlestyle = font-size:100% | title = As suborder | liststyle = | hlist = | bullets = | Actinomonadineae Cavalier-Smith 2006<ref name="Cavalier-Smith 2006">{{cite Q|Q28303534}}</ref> | Ciliophryineae Febvre-Chevalier ex Cavalier-Smith, 2006<ref name="Cavalier-Smith 2006"/> }} {{Collapsible list | expand = | framestyle = | titlestyle = font-size:100% | title = As family | liststyle = | hlist = | bullets = | Apedinellaceae {{small|Cavalier-Smith, 1995}}<ref name="Cavalier-Smith 1995"/> | Cyrtophoraceae Pascher, 1911 | Pedinellidae (ICZN) {{au|Pascher, 1910}} | Pedinellaceae (ICN) {{small|Pascher, 1910 orthog. emend. Cavalier-Sith, 1995}}<ref name="Cavalier-Smith 1995"/> | Ciliophryidae (ICZN) {{au|Poche, 1913}} | Ciliophryaceae (ICN) {{au|Poche, 1913 orthog. emend. Cavalier-Smith, 1995}}<ref name="Cavalier-Smith 1995"/> }} }}

'''Pedinellales''' (ICN) or '''Pedinellida''' (ICZN) is a group of single-celled algae found in both marine environments and freshwater.<ref>{{cite book|title=Phycology |author=Lee RE |edition=5 |isbn=978-1-107-55565-5 |publisher=Cambridge University Press |chapter=Heterokontophyta - Dictyochochyceae |chapter-url=https://books.google.com/books?id=mgZNDwAAQBAJ&q=Pedinellales&pg=PA345 |access-date=28 August 2018 |pages=345|date=March 2018}}</ref>

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. These are ''Parapedinella'', ''Actinomonas'', and ''Pteridomonas''.

It also appears that certain heliozoa 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 actinophryids, ''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 heliozoans by some authors. The colored pedinellids were originally treated as a family of golden algae 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.

==Systematics==

=== Taxonomic history ===

Pedinellids have been known since the 19th century, but were classified as either algae or heliozoan protozoa due to the absence of chloroplasts in some species.<ref name="heliozoan interrelationships">{{cite Q|Q125959734}}</ref> Before the taxonomic revisions that took place in the late 20th century, pedinellids were treated as a single family '''Pedinellaceae''', described in 1910 by Pascher. Some authors classified pedinellids within the order Ochromonadales, together with a variety of unrelated heterokonts such as Synuraceae and Bicosoecaceae, as part of the class Chrysophyceae or golden algae.<ref>{{cite book|page=116|first1=Tyge|last1=Christensen|date=1980|publisher=AiO Tryk as|publication-place=Odense|url=https://archive.org/details/algaetaxonomicsu0000chri/page/116|url-access=registration|title=Algae: a taxonomic survey|volume=1}}</ref> In 1985, phycologists Birthe Zimmermann, Øjvind Moestrup and Guy Hällfors classified them as an independent order, '''Pedinellales'''.<ref name="Zimmermann 1985">{{cite journal|last1=Zimmermann|first1=B.|last2=Moestrup|first2=Ø.|last3=Hällfors|first3=G.|date=1985|title=Chrysophyte or heliozoon: ultrastructural studies on a cultured species of ''Pseudopedinella'' (Pedinellales ord. nov.), with comments on species taxonomy|journal=Protistologica|volume=20|pages=591–612}}</ref> The same year, John J. Lee and coauthors segregated the phagotrophic (i.e. without chloroplasts) pedinellids as a different order '''Ciliophryida''' under the polyphyletic class Heliozoea. Other authors, such as Thomas Cavalier-Smith, went a step further and proposed treating pedinellids as a separate class, under the name of '''Pedinellea''' (spelt '''Pedinellophyceae''' under botanical nomenclature).<ref name="Moestrup 1995">{{cite book|title=Chrysophyte algae: ecology, phylogeny, and development|pages=75–92|url=https://archive.org/details/chrysophytealgae0000unse/page/78|url-access=registration|date=1995|first1=Øjvind|last1=Moestrup|author1-link=Øjvind Moestrup|chapter=Current status of chrysophyte 'splinter groups': synurophytes, pedinellids, silicoflagellates|editor-first1=Craig D.|editor-last1=Sandgren|editor-first2=John P.|editor-last2=Smol|editor-first3=Jørgen|editor-last3=Kristiansen|publisher=Cambridge University Press|isbn=0-521-46260-6}}</ref>

In 1995, Charles J. O'Kelly and Daniel E. Wujek classified the Dictyochophyceae in three orders: Rhizochromulinales (containing the sole genus ''Rhizochromulina''), Pedinellales (containing all pedinellids) and Dictyochales (silicoflagellates), separating them from golden algae.<ref name="O'Kelly 1995">{{cite book|title=Chrysophyte algae: ecology, phylogeny, and development|pages=361–372|url=https://archive.org/details/chrysophytealgae0000unse/page/361|url-access=registration|date=1995|first1=Charles J.|last1=O'Kelly|first2=Daniel E.|last2=Wujek|chapter=Staus of the Chrysamoebales (Chrysophyceae): observations on ''Chrysamoeba pyrenoidifera'', ''Rhizochromulina marina'' and ''Lagynion delicatum''|editor-first1=Craig D.|editor-last1=Sandgren|editor-first2=John P.|editor-last2=Smol|editor-first3=Jørgen|editor-last3=Kristiansen|publisher=Cambridge University Press|isbn=0-521-46260-6}}</ref> Simultaneously, Cavalier-Smith proposed a slightly different classification where he created a new class Actinochrysea to embrace these three groups, avoiding the usage of Dictyochophyceae as a name. He considered pedinellids as subclass '''Pedinellidae''', with two orders: Pedinellales (with chloroplasts), containing the families Pedinellaceae and Apedinellaceae; and Ciliophryales (without chloroplasts), containing Actinomonadaceae and Ciliophryaceae. The remaining two groups, Rhizochromulinales and Dictyochales, were transferred to a separate subclass Dictyochidae.<ref name="Cavalier-Smith 1995"/> The next year, Cavalier-Smith and Ema E. Chao recognized that the chloroplast losses were polyphyletic, and the family Actinomonadaceae was transferred to Pedinellales on the basis of a molecular phylogenetic analysis.<ref name="Cavalier-Smith 2016">{{cite journal|title=18S rRNA sequence of ''Heterosigma carterae'' (Raphidophyceae), and the phylogeny of heterokont algae (Ochrophyta)|journal=Phycologia|first1=T.|last1=Cavalier-Smith|first2=E.E.|last2=Chao|volume=35|issue=6|pages=500–510|doi=10.2216/i0031-8884-35-6-500.1|date=1996}}</ref>

In 2006, Cavalier-Smith once again rearranged the classification. He lowered Actinochrysea to a subclass Actinochrysia within a new class Hypogyristea, which also included pelagophytes as subclass Pelagophycia. He lumped together all pedinellid genera in the family Actinomonadaceae and new suborder Actinomonadineae, with the exception of ''Ciliophrys'', which he included with the non-pedinellid ''Rhizochromulina'' in two families of a new suborder Ciliophryineae.<ref name="Cavalier-Smith 2006"/> He maintained this classification in later years.<ref name="Incisomonas marina"/> In 2018, he finally recognized class Dictyochophyceae, and created the subclass Pedinellia or Pedinellophycidae (equivalent to his earlier Actinochrysea/Actinochrysia) to lump together pedinellids and silicoflagellates. Pelagophytes remained under the subclass Pelagophycidae, and two genera of more uncertain placement under a third subclass Sulcophycidae: ''Olisthodiscus'' and ''Sulcochrysis''.<ref name="8phyla">{{cite Q|Q47194626}}</ref>

Cavalier-Smith's taxonomic scheme is not accepted by the scientific community. Instead, Moestrup's 1995 classification is more commonly supported, where pedinellids are all contained in the order Pedinellales, rendering Ciliophryales a junior synonym. They are considered part of Dictyochophyceae, along with orders Dictyochales (silicoflagellates), Rhizochromulinales (''Rhizochromulina''),<ref name="Preisig 1999">{{cite book|last1=Preisig|first1=Hans R.|date=1999|chapter=Systematics and Evolution of the Algae: Phylogenetic Relationships of Taxa Within the Different Groups of Algae|editor-first1=K.|editor-last1=Esser|editor-first2=J.W.|editor-last2=Kadereit|editor-first3=U.|editor-last3=Lüttge|editor-first4=M.|editor-last4=Runge|title=Progress in Botany|volume=60|publisher=Springer|publication-place=Berlin|doi=10.1007/978-3-642-59940-8_14|pages=369–412}}</ref> and a more recent fourth order Florenciellales.<ref name="Verrucophora farcimen">{{cite journal|title=''Verrucophora farcimen'' gen. et sp. nov. (Dictyochophyceae, Heterokonta)—a bloom-forming ichthyotoxic flagellate form the Skagerrak, Norway|first1=Bente|last1=Edvardsen|first2=Wenche|last2=Eikrem|journal=Journal of Phycology|volume=43|pages=1054–1070|date=2007|doi=10.1111/j.1529-8817.2007.00390.x|hdl=10852/11590|hdl-access=free}}</ref> In addition, pelagophytes are rejected as members of Dictyochophyceae, and instead form an independent class Pelagophyceae.<ref name="Adl 2019">{{cite Q|Q57086550}}</ref> Within pedinellids, there have been several attempts to establish different families according to morphological data such as the presence or absence of stalks and chloroplasts. However, molecular analyses do not support these internal divisions.<ref name="Preisig 1999"/> Consequently, all pedinellids have been grouped into a single family, '''Actinomonadaceae''', which has taxonomic preference due to being the earliest described, and all other proposed families (Pedinellaceae, Apedinellaceae, etc.) have become junior synonyms.<ref name="IGP Silicoflagellata">{{cite book | chapter = Class Silicoflagellata Lemmermann, 1901 | first1 = Øjvind | last1 = Moestrup | first2 = Charles J. | last2 = O'Kelly | title = An Illustrated Guide to the Protozoa | edition = 2nd | editor-first1 = John J. | editor-last1 = Lee | editor-first2 = Gordon F. | editor-last2 = Leedale | editor-first3 = Phyllis | editor-last3 = Bradbury | publisher = Society of Protozoologists | publication-place = Lawrence, Kansas | date = 2000 | url = https://protistologists.org/publications/illustrated-guide-to-the-protozoa/ | volume = II | pages = 775–782 | chapter-url = https://protistologists.org/wp-content/uploads/2023/07/17SILICOFLAGELLATA.pdf}}</ref> {| class="wikitable mw-collapsible" style="background-color: white;" |+History of pedinellid classification ! colspan="3" |Cavalier-Smith (1995)<ref name="Cavalier-Smith 1995"/> ! colspan="3" |Cavalier-Smith (2006)<ref name="Cavalier-Smith 2006"/> ! colspan="2" |Present<ref name="Moestrup 1995"/><ref name="Sekiguchi-2003"/><ref>{{cite journal|last1=Safonov|first1=Pavel|last2=Berdieva|first2=Mariia|last3=Nassonova|first3=Elena|last4=Skarlato|first4=Sergei|last5=Pozdnyakov|first5=Ilya|title=The first arctic strain of ''Rhizochromulina'': Morphology, ultrastructure, and position in the evolutionary tree of the order Rhizochromulinales (Heterokontophyta, Dictyochophyceae)|journal=European Journal of Protistology|volume=92|date=2024|doi=10.1016/j.ejop.2023.126050|article-number=126050|url=https://linkinghub.elsevier.com/retrieve/pii/S0932473923000950|url-access=subscription}}</ref> !Includes |- | style="border-spacing: 1px; border: 1px solid white; background-color:#ffef91" rowspan="6" |Pedinellidae | rowspan="3" style="border-spacing: 1px; border: 1px solid white; background-color:#fff5b8" |Pedinellales | rowspan="2" style="border-spacing: 1px; border: 1px solid white; background-color:#faffdb" |Pedinellaceae | rowspan="7" style="border-spacing: 1px; border: 1px solid white; background-color:#ffef91" |Pedinellales | rowspan="5" style="border-spacing: 1px; border: 1px solid white; background-color:#fff5b8" |Actinomonadineae | rowspan="5" style="border-spacing: 1px; border: 1px solid white; background-color:#faffdb" |Actinomonadaceae | rowspan="5" style="border-spacing: 1px; border: 1px solid white; background-color:#ffef91" |Pedinellales | rowspan="5" style="border-spacing: 1px; border: 1px solid white; background-color:#faffdb" |Actinomonadaceae |''Pedinella'' |- |''Pseudopedinella'' |- |style="border-spacing: 1px; border: 1px solid white; background-color:#faffdb"|Apedinellaceae |''Apedinella'' |- | rowspan="3" style="border-spacing: 1px; border: 1px solid white; background-color:#ecffb8" |Ciliophryales | rowspan="2" style="border-spacing: 1px; border: 1px solid white; background-color:#f4ffdb" |Actinomonadaceae |''Actinomonas'' |- |''Pteridomonas'' |- | style="border-spacing: 1px; border: 1px solid white; background-color:#f4ffdb" | Ciliophryaceae | rowspan="2" style="border-spacing: 1px; border: 1px solid white; background-color:#ecffb8" |Ciliophryineae |style="border-spacing: 1px; border: 1px solid white; background-color:#f4ffdb"|Ciliophryaceae | colspan="2" rowspan="2" style="border-spacing: 1px; border: 1px solid white; background-color:#f7f7f7" |excluded |''Ciliophrys'' |- | colspan="3" style="border-spacing: 1px; border: 1px solid white; background-color:#f7f7f7" |excluded |style="border-spacing: 1px; border: 1px solid white; background-color:#f4ffdb"|Rhizochromulinaceae |''Rhizochromulina'' |}

=== Classification ===

Pedinellids currently sum the following genera:<ref name="Sekiguchi-2003">{{cite journal|last1=Sekiguchi|first1=Hiroshi|last2=Kawachi|first2=Masanobu|last3=Nakayama|first3=Takeshi|last4=Inouye|first4=Isao|title=A taxonomic re-evaluation of the Pedinellales (Dictyochophyceae), based on morphological, behavioural and molecular data|journal=Phycologia|volume=42|issue=2|date=2003|issn=0031-8884|doi=10.2216/i0031-8884-42-2-165.1|pages=165–182|url=https://www.tandfonline.com/doi/full/10.2216/i0031-8884-42-2-165.1|url-access=subscription}}</ref><ref name="Moestrup 1995"/><ref name="Incisomonas marina">{{Cite journal| last1=Cavalier-Smith | first1=Thomas | last2=Scoble | first2=Josephine Margaret |title=Phylogeny of Heterokonta: ''Incisomonas marina'', a uniciliate gliding opalozoan related to ''Solenicola'' (Nanomonadea), and evidence that Actinophryida evolved from raphidophytes | journal=European Journal of Protistology | date=2013 | volume=49 | issue= 3| pages=328–353 | doi= 10.1016/j.ejop.2012.09.002| pmid= 23219323}}</ref>

* ''Actinomonas'' Kent 1880 * ''Apedinella'' Throndsen 1971 * ''Cyrtophora'' Strand 1929 * ''Helicopedinella'' Sekiguchi et al. 2003 * ''Mesopedinella'' Daugbjerg 1996 * ''Palatinella'' Lauterborn 1906 * ''Parapedinella'' Pedersen, Beech & Thomsen 1986 * ''Pedinella'' Wyssotzki 1887 non Dahl 1909 * ''Pseudopedinella'' Carter 1937 * ''Pteridomonas'' Penard 1889

==References== {{Reflist|30em|refs= <ref name="Cavalier-Smith 1995">{{cite journal|journal = Archiv für Protistenkunde | vauthors = Cavalier-Smith T, Chao EE, ((Allsopp MTEP))|title=Ribosomal RNA Evidence for Chloroplast Loss within Heterokonta: Pedinellid Relationships and a Revised Classification of Ochristan Algae|volume=145|pages=209–220|issue=3–4|date=1995|doi=10.1016/S0003-9365(11)80316-7}}</ref> }} == External links== * {{Wikispecies-inline}} * {{Commons-inline}} {{Heterokont}} {{Taxonbar|from=Q7159272}} {{Authority control}}

Category:Ochrophyte orders Category:Dictyochophyceae Category:Taxa described in 1880