''Mychonastes'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

, specifically of the

Chlorophyceae The Chlorophyceae, also known as chlorophycean algae, are one of the classes of green algae, within the phylum Chlorophyta. They are a large assemblage of mostly freshwater and terrestrial organisms; many members are important primary producers i ...

. It is the sole genus of the family Mychonastaceae. Species of ''Mychonastes'' are found in

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

of freshwater or brackish waters, or found in soil. It is a very common genus, and is often dominant.

Description

''Mychonastes'' consists of solitary cells of groups of a few cells (rarely more than four). Cells are spherical or slightly ovate, uninucleate (with one

nucleus Nucleus (: nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucleu ...

) and a single parietal

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

without any

pyrenoid Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...

s. The

cell wall A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, ...

is covered in an irregular network of ridges, only visible in (scanning electron microscopy). Cells are sometimes connected together by irregular, mucilaginous strands. These mucilaginous strands are formed from the mother cell wall after autospore release. ''Mychonastes'' reproduces asexually via

autospore Autospores are a type of spores that are produced by algae to enable asexual reproduction and spread. They are non-motile and non-Flagellated cell, flagellated Aplanospore, aplanospores that are generated within a parent cell and have the same sha ...

s. Usually 2 or 4 (sometimes up to 64) are produced per cell. They are released through a tear in the cell wall. Species are differentiated from each other by the shape of the cells and their attachment to the strands, cell size, strand morphology, and colony characteristics. However, some species are cryptic and can only be distinguished through

DNA barcoding DNA barcoding is a method of species identification using a short section of DNA from a specific gene or genes. The premise of DNA barcoding is that by comparison with a reference library of such DNA sections (also called " sequences"), an indiv ...

. Additionally, the genus itself is difficult to distinguish from other single small-celled genera such as '' Choricystis'', '' Meyerella'' and ''

Nannochloris ''Nannochloris'' is a genus of green algae in the family Chlorellaceae. It is found in freshwater habitats. ''Nannochloris'' consists of very small cells less than 4.5 μm in diameter. The cells are solitary or paired, subspherical to subcylind ...

''; therefore, molecular data appear to be the only reliable way to identify species of ''Mychonastes''.

Taxonomy

In 2011, Krienitz ''et al.'' proposed that ''Pseudodictyosphaerium'' be combined with ''Mychonastes'' into a single genus; since the latter genus was published earlier in 1978, its name has priority, therefore making ''Pseudodictyosphaerium'' a synonym of ''Mychonastes''. ''Pseudodictyosphaerium'' was differentiated from ''Mychonastes'' in having colonies of cells. However, most strains can form both single cells and colonies, prompting the merger of the two genera.

Species

*'' M. afer'' Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. anomalus'' (Korshikov) Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. botrytella'' (Komárek & Perman) Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. densus'' (Hindák) Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. desiccatus'' S.W.Brown, 1988 *'' M. elegans'' (Bachmann) Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. fluviatilis'' (Hindák) Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. hindakii'' Martynenko, E.Gusev, D.Kapustin & M.Kulikovskiy 2022 *'' M. homosphaera'' (Skuja) Kalina & Puncochárová, 1987 *'' M. huancayensis'' Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. jurisii'' (Hindák) Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. lacunaris'' (Hindák) Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. minusculus'' (Hindák) Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. ovahimbae'' Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. pushpae'' Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. pusillus'' Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. racemosus'' Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. rotundus'' Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. ruminatus'' P.D.Simpson & S.D.Van Valkenburg, 1978 *'' M. scoticus'' (Hindák) Krienitz, C.Bock, Dadheech & Proschold, 2011 *'' M. timauensis'' Krienitz, C.Bock, Dadheech & Proschold, 2011 * '' M. sp. 5C3'' * '' M. sp. 2C1'' * '' M. sp. 6A3'' * '' M. sp. 5C5'' * '' M. sp. AN 2/29-3'' * '' M. sp. AS 7-9'' * '' M. sp. JL 1/12-12'' * '' M. sp. Tow 6/3 P-1w'' * '' M. sp. YHL/S/PLANKTON10''

Genome

The whole genome of ''Mychonastes homosphaera'' has been sequenced. Among species in the order Sphaeropleales that have been sequenced, it has the most compact, with a nuclear genome of 24.23 kB. Harboring 6,649 protein-coding genes, the genome is heavily streamlined. ''Mychonastes'' appears to be adapted for rapidly changing freshwater environments such as varying light conditions, nutrient concentrations, and temperatures.

References

External links

AlgaTerra database

Index Nominum Genericorum
{{Taxonbar, from=Q6946939 Sphaeropleales genera Freshwater algae