''Mychonastes'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( Embryophytes) have emerged deep in the Charophyte alg ...

, specifically of the

Chlorophyceae The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b. The chloroplast A chlorop ...

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

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cr ...

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 Nucl ...

) and a single parietal

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it ...

without any

pyrenoid Pyrenoids are sub-cellular 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. Annu. Rev. Plant Bio ...

s. The

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mec ...

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 autospores. 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 Cryptic may refer to: In science: * Cryptic species complex, a group of species that are very difficult to distinguish from one another * Crypsis, the ability of animals to blend in to avoid observation * Cryptic era, earliest period of the Earth ...

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 indi ...

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

Choricystis ''Choricystis'' is a genus of green algae in the class Trebouxiophyceae, considered a characteristic picophytoplankton in freshwater ecosystems. ''Choricystis'', especially the type species ', has been proposed as an effective source of fatty ac ...

'', '' Meyerella'' and '' Nannochloris''; 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