Editing Gymnosphaerid

{{Short description|Group of protists}}
{{Automatic taxobox
| name = Gymnosphaerids
| taxon = Gymnosphaeridae
| authority = (Poche, 1913)
| subdivision_ranks = Species
| subdivision = 
* ?''[[Actinolophus]]''
* ?''[[Wagnerella]]''
* ''[[Actinocoryne]]''
* ''[[Gymnosphaera]]''
* ''[[Hedraiophrys]]''
| synonyms = 
* Axoplasthelida <small>Febvre-Chevalier, 1984</small>
* Axoplastheliales
* Gymnidae
* Hedraiophryidae
* Wagnerellidae <small>Poche 1913</small>
}}
The '''gymnosphaerids''' (or '''Gymnosphaerida''')<ref name="pmid15148395">{{cite journal  |vauthors=Nikolaev SI, Berney C, Fahrni JF, etal |title=The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=101 |issue=21 |pages=8066–71 |date=May 2004 |pmid=15148395 |pmc=419558 |doi=10.1073/pnas.0308602101 |doi-access=free }}</ref> are a small group of [[heliozoa]]n protists found in marine environments.  They tend to be roughly spherical with radially directed [[pseudopod|axopods]], supported by [[microtubule]]s in a triangular-hexagonal array arising from an amorphous central [[Granule (cell biology)|granule]].

==Genera==
There are only three genera, each with a single species: ''Gymnosphaera albida'', ''Hedraiophrys hovassei'', and ''Actinocoryne contractilis''.

*''Gymnosphaera albida'' is free-living, usually benthic in shallow water.  The cells are round and naked, around 70-100 μm in diameter, and resemble the unrelated ''[[actinophryid|Actinosphaerium]]''.  The outer cytoplasm, or ectoplasm, forms a distinct layer containing large vesicles.
*''Hedraiophrys hovassei'' is larger and lives attached to [[alga]]e and other objects.  The cells have a conical base, and are covered with long siliceous spicules.  The ectoplasm is distinct and frothy, and typically contains bacterial and algal [[endosymbiont]]s.
*''Actinocoryne contractilis'' is benthic.  When feeding, it has a [[multinucleate]] base and a contractile stalk up to 150 μm in length, supporting a relatively small [[uninucleate]] head, where the central granule and axopods are located.  In order to move, it collapses the stalk and head into an amoeboid form which is capable of migration.<ref>{{cite journal|title=Preliminary study of the motility processes in the stalked heliozoan ''Actinocoryne contractilis'' |author=Febvre-Chevalier C |journal=Biosystems |volume=14 |issue=3–4 |date=1981 |pages=337–343 |pmid=7337812 |doi=10.1016/0303-2647(81)90040-X}}</ref> Reproduction is either by budding off the head or fragmentation of the headless form, producing small free-living cells similar to ''Gymnosphaera'', which then attach themselves and regrow the stalk and base.

==Classification==
Gymnosphaerids were originally considered [[centrohelid]]s, which also have microtubules in a triangular-hexagonal array, but are set apart from the others by the structure of the central granule and the [[mitochondrion|mitochondria]], which have tubular [[crista]]e.  The two groups have been treated as separate orders (Axoplasthelida and Centroplasthelida) in a common class, but this has lost support.  Instead the gymnosphaerids may be allied with the [[desmothoracid]]s, and on account of this have been placed in the [[Cercozoa]], but this is somewhat tentative.

* Order '''Gymnosphaerida''' <small>Poche 1913 emend. Mikrjukov 2000</small><ref>{{cite web| last1=Zicha | last2=Hrb | last3=Maňas |last4=Novák |title = Systema Naturae 2000 / Classification, Species Gymnophrys cometa | year=1999 | publisher =BioLib | url=https://www.biolib.cz/en/taxon/id497139/ | access-date = 9 November 2016}}</ref>
** Family '''Gymnosphaeridae''' <small>Poche 1913</small>
*** Genus ?''[[Actinolophus]]'' <small>Schultze 1874</small>
**** Species ''[[Actinolophus pedunculatus]]'' <small>Schulze 1874</small>
*** Genus ?''[[Wagnerella]]'' <small>Mereschkowsky 1878</small>
**** Species ''[[Wagnerella borealis]]'' <small>Mereschkowsky 1878</small>
*** Genus ''[[Gymnosphaera]]'' <small>Sassaki 1894 non BIume 1828</small>
**** Species ''[[Gymnosphaera albida]]'' <small>Sassaki 1894</small>
*** Genus ''[[Hedraiophrys]]'' <small>Febvre-Chevalier & Febvre 2005</small>
**** Species ''[[Hedraiophrys hovassei]]'' <small>Febvre-Chevalier & Febvre 2005</small>
*** Genus ''[[Actinocoryne]]'' <small>Febvre-Chevalier 1980</small>
**** Species ''[[Actinocoryne contractilis]]'' <small>Febvre-Chevalier 1980</small>

==References==
{{Wikispecies|Gymnosphaerida}}
{{Reflist}}

{{Rhizaria}}
{{Taxonbar|from=Q575077}}

[[Category:Amoeboids]]
[[Category:Filosa]]


{{Cercozoa-stub}}