153,622 species and infraspecific names are in the database, 20,981 images, 59,421 bibliographic items, 412,629 distributional records.

Mychonastes P.D.Simpson & S.D.Van Valkenburg, 1978

Classification:
Empire Eukaryota
Kingdom Plantae
Subkingdom Viridiplantae
Infrakingdom Chlorophyta infrakingdom
Phylum Chlorophyta
Subphylum Chlorophytina
Class Chlorophyceae
Order Sphaeropleales
Family Mychonastaceae

Holotype species: Mychonastes ruminatus P.D.Simpson & S.D.Van Valkenburg

Original publication and holotype designation: Simpson, P.D. & Van Valkenburg, S.D. (1978). The ultrastructure of Mychonastes ruminatus gen. et sp. nov., a new member of the Chlorophyceae isolated from brackish water.. British Phycological Journal 13(2): 117-130.

Taxonomic status: currently recognized as a distinct genus.

Most recent taxonomic treatment adopted: Tsarenko, P.M. (2011). Chlorococcales. In: Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Volume 3: Chlorophyta. (Tsarenko, P.M., Wasser, S.P. & Nevo, E. Eds), pp. 232-264. Ruggell: A.R.A. Gantner Verlag K.-G..

Taxonomic notes
According to Krienitz et al. (2011), the species of Mychonastes form a monophyletic clade within the Sphaeropleales sensu lato. The Dictyosphaerium-like taxa of Mychonastes form a monophyletic clade in the Chlorophyceae. Other species of Dictyosphaerium, including the type (D. ehrenbergianum belong to the Chlorellales (Trebouxiophyceae). - (1 Mar 2011) - Wendy Guiry

According to Hanagata (1998), the subfamily Scotiellocystoideae should be removed from the Chlorellaceae. His study suggests that only the genus Mychonastes should still remain in this subfamily. He notes, however, that the type speciesM. ruminatuswould have to be examined to establish the phylogenetic position of Mychonastes, but the type culture is missing. - (10 Aug 2011) - Wendy Guiry

Description: Cells solitary or in groups rarely more than 4. Cells spherical or slightly ovate, 1-10 µm or up to 30 µm diameter. Cell walls with irregular arrangement of ridges only visible with electron microscopy; one species with 1-2 dark brown spots of iron encrustation. Cells uninucleate; chloroplast single and parietal, up to 4 prior to spore production; pyrenoids absent. Asexual reproduction by autospores, 2 or 4 or up to 64 formed per cell; released by rupture of parental cell walls; residues of cell walls remaining in cultures. Flagellated stages and sexual reproduction unknown. Mychonastes planktonic with M. ruminatus in brackish water; known only from Chesapeake Bay, Maryland; found throughout the year but a dominant during August, September. In culture growth at 1- 30 0/00 with cell size decreasing with increasing salinity; growth decreasing below 10 0/00 and above 20 0/00. Other species reported from Europe, occurring in freshwater (M. homosphaera) or isolated from soil (M. zofingiensis). 18S rRNA analysis of chlorococcalean algae by Wilcox and others (1992) suggest that M. homosphaera (as C. minutissima) closer to Nanochlorum, than Chlorella. Taxonomic position complicated by absence of cultured strain of type species. Further study required to define monophyletic nature of genus and its affinities. Genus distinguished from Chlorella based on cell wall features and absence of pyrenoid, although pyrenoid present or absent in Chlorella depending on generic concepts. Genus variously assigned to Oocystaceae or subfamily Scotiellocystoideae of Tetraedronaceae (or Chlorellaceae). Species distinguished based on cell size, number of autospores, chloroplast morphology and habitat. Chemotaxonomy of pigments supports recognition of genus. Cells solitary or in groups rarely more than 4. Cells spherical or slightly ovate, 1-10 µm or up to 30 µm diameter. Cell walls with irregular arrangement of ridges only visible with electron microscopy; one species with 1-2 dark brown spots of iron encrustation. Cells uninucleate; chloroplast single and parietal, up to 4 prior to spore production; pyrenoids absent. Asexual reproduction by autospores, 2 or 4 or up to 64 formed per cell; released by rupture of parental cell walls; residues of cell walls remaining in cultures. Flagellated stages and sexual reproduction unknown. Mychonastes planktonic with M. ruminatus in brackish water; known only from Chesapeake Bay, Maryland; found throughout the year but a dominant during August, September. In culture growth at 1- 30 0/00 with cell size decreasing with increasing salinity; growth decreasing below 10 0/00 and above 20 0/00. Other species reported from Europe, occurring in freshwater (M. homosphaera) or isolated from soil (M. zofingiensis). 18S rRNA analysis of chlorococcalean algae by Wilcox and others (1992) suggest that M. homosphaera (as C. minutissima) closer to Nanochlorum, than Chlorella. Taxonomic position complicated by absence of cultured strain of type species. Further study required to define monophyletic nature of genus and its affinities. Genus distinguished from Chlorella based on cell wall features and absence of pyrenoid, although pyrenoid present or absent in Chlorella depending on generic concepts. Genus variously assigned to Oocystaceae or subfamily Scotiellocystoideae of Tetraedronaceae (or Chlorellaceae). Species distinguished based on cell size, number of autospores, chloroplast morphology and habitat. Chemotaxonomy of pigments supports recognition of genus. Emended by Krienitz, C. Bock, Dadheech & Proschild (2011: 99).

Information contributed by: T. Kalina & D. Garbary. The most recent alteration to this page was made on 25 Mar 2014 by M.D. Guiry.

Numbers of names and species: There are 21 species names in the database at present, of which 20 have been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..

Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):

Click here to also show infraspecific names in the list below.

References
Hanagata, N. (1998). Phylogeny of the subfamily Scotiellocystoideae (Chlorophyceae, Chlorophyta) and related taxa inferred from 18S ribosomal RNAgene sequence data. Journal of Phycology 34: 1049-1054, 2 figs.

Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.

Contributors
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

Created: 16 April 2003 by M.D. Guiry

Verified by: 26 January 2012 by M.D. Guiry

Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=45862

Citing AlgaeBase
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 20 November 2018.

SITE © 1996 - 2018 M.D. Guiry. All rights reserved.

Website Design : 249 Design Studio