{{Short description|Genus of algae}} {{Automatic taxobox | image = Pterosperma dictyon as Pterosphaera dictyon, cropped.jpg | image_caption = ''Trochiscia dictyon'' | taxon = Trochiscia | authority = Kützing | subdivision_ranks = Species | subdivision = * ''Trochiscia hystrix'' }}
'''''Trochiscia''''' is a genus of green algae in the family Oocystaceae. It is found in the plankton of freshwater habitats. The name ''Trochiscia'' was used in 1834 by Friedrich Traugott Kützing.<ref name=AlgaeBase>{{AlgaeBase genus|name=Trochiscia|id=43293|access-date=2025-02-09}}</ref>
==Description== ''Trochiscia'' consists of solitary, spherical cells up to 50 μm in diameter. The cell walls are thick, and are variously sculptured with spines, ribs, reticulations, and or projections. Cells are uninucleate (one nucleus). The single chloroplast is variable in morphology, and may be stellate and axial or parietal, and may have or lack a pyrenoid. Asexual reproduction occurs by the formation of autospores or zoospores; sexual reproduction has not been observed.<ref name=AlgaeBase/>
Species of ''Trochiscia'' are distinguished based on details of cell morphology, particularly the sculpturing of the cell wall.<ref name=AlgaeBase/>
==Taxonomy== The taxonomy of ''Trochiscia'' is very unclear and in need of revision. The name ''Trochiscia'' was described twice by Kützing. His first description was in 1834, referring to a broad assemblage of green algae (including desmids) and diatoms). The second description was in 1845, he had defined the genus for single, spherical to ellipsoidal cells which were polygonal or covered with spines or tubercles. This definition is approximately the current circumscription of ''Trochiscia''.
Because the current naming of ''Trochiscia'' is predated by one in 1834, ''Trochiscia'' is a later homonym and needs to be replaced according to the rules of botanical nomenclature. Currently, some of the species in ''Trochiscia'' were transferred to ''Glochiococcus''. However, most names within ''Trochiscia'' are poorly known and their true affinities are unknown.<ref name=Silva>{{cite journal|title=Taxonomic and nomenclatural status of ''Trochiscia'' Kützing and ''Trochiscia moniliformis'' Montagne|last1=Silva|first1=P.C.|date=1996|journal= Cryptogamie. Algologie|volume=17|issue=2|pages=69–75|doi=10.5962/p.309436 |bibcode=1996CrypA..17...69S |url=https://www.biodiversitylibrary.org/part/309436}}</ref> In particular, many species of ''Trochiscia'' are likely to represent zygospores or aplanospores of other algae.<ref name=AlgaeBase/>
The species ''Trochiscia hystrix'' forms a previously-unknown lineage in the class Chlorophyceae, along with ''Golenkinia'' and ''Treubaria'', but the relationships also need to be investigated further.<ref name=Bicudo_and_Menezes2006>{{cite book | title= Gêneros de Algas de Águas Continentais do Brasil: chave para identificação e descrições | edition=2 | year=2006 | first1=Carlos E. M. |last1=Bicudo | first2=Mariângela | last2= Menezes | publisher= RiMa Editora | pages=508 | isbn= 857656064X }}</ref>
==References== {{Reflist|1}}
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Category:Trebouxiophyceae genera Category:Freshwater algae Category:Oocystaceae