Dictyosphaerium
| Dictyosphaerium | |
|---|---|
| |
Scientific classification 
| |
| (unranked): | Viridiplantae |
| Division: | Chlorophyta |
| Class: | Trebouxiophyceae |
| Order: | Chlorellales |
| Family: | Chlorellaceae |
| Genus: | Dictyosphaerium Nägeli, 1849 |
| Type species | |
| Dictyosphaerium chlorelloides | |
| Species[1] | |
Dictyosphaerium is a genus of green algae, in the family Chlorellaceae.[1] It occurs in freshwater habitats around the world and is planktonic.[1][2]
Description[edit]
Dictyosphaerium consists of irregular colonies of 4 to 64 cells in a common mucilaginous envelope 10–100 μm wide. Cells are roughly spherical to ellipsoidal, 1-10 μm in diameter, with one nucleus and a single pyrenoid-containing chloroplast. Cells are attached to the end of thin stalks; the stalks emerge from the center of the colony and continuously branch out.[1] These stalks are formed from the remnants of the mother cell wall.[2]
Dictyosphaerium cells reproduce asexually by autospores. Two or four autospores are produced per sporangium; after release, the mother cell wall gelatinizes and develops into a thin strand, which are connected to the newly released cells.[2]
Taxonomy[edit]
Dictyosphaerium has traditionally been classified in its own family, Dictyosphaeriaceae,[3] or as part of the family Botryococcaceae, characterized by cells connected by gelatinous stalks or strands of mucilage.[4] However, molecular phylogenetic studies have demonstrated that Dictyosphaerium is closely related to the unicellular genus Chlorella, and is now currently placed in the family Chlorellaceae.[1]
Additionally, the morphotype of Dictyosphaerium (consisting of branching strands of mucilage connecting cells) is known to be polyphyletic, having evolved multiple times. Therefore, this morphotype can now be found in many new genera. For example, the genus Mucidosphaerium differs from Dictyosphaerium sensu stricto in having spherical cells, as opposed to Dictyosphaerium with oval cells.[5] The genus Mychonastes (including the former genus Pseudodictyosphaerium) differs in having chloroplasts without pyrenoids, and more irregular mucilaginous strands.[6]
Other similar genera include Compactochlorella, Kalenjinia, Marasphaerium, Masaia,[2] Hindakia, Heynigia,[7] and Xerochlorella.[8] These genera appear to be more or less cryptic, being reliably differentiated only by DNA barcoding.[9] Their biogeographical patterns remain unclear.[10]
References[edit]
- ^ a b c d e Guiry, M.D.; Guiry, G.M. "Dictyosphaerium". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.
- ^ a b c d Bicudo, Carlos E. M.; Menezes, Mariângela (2006). Gêneros de Algas de Águas Continentais do Brasil: chave para identificação e descrições (2 ed.). RiMa Editora. p. 508. ISBN 857656064X.
- ^ Hindák, F. (1978). "New taxa and reclassifications in the Chlorococcales (Chlorophyceae)". Preslia. 50: 97–109.
- ^ Komárek, J.; Fott, B. (1983). Chlorophyceae (Grünalgen), Ordnung Chlorococcales. Das Phytoplankton des Süßwassers (in German). E. Schweizerbart'sche Verlagsbuchhandlung. p. 1044.
- ^ Bock, Christina; Pröschold, Thomas; Krienitz, Lothar (2011). "Updating the Genus Dictyosphaerium and Description of Mucidosphaerium gen. nov. (Trebouxiophyceae) Based on Morphological and Molecular Data". Journal of Phycology. 47 (3): 638–652. Bibcode:2011JPcgy..47..638B. doi:10.1111/j.1529-8817.2011.00989.x. PMID 27021993. S2CID 26144724.
- ^ Krienitz, L.; Bock, C.; Dadheech, P. K.; Pröschold, T. (2011). "Taxonomic reassessment of the genus Mychonastes (Chlorophyceae, Chlorophyta) including the description of eight new species". Phycologia. 50 (1): 89–106. Bibcode:2011Phyco..50...89K. doi:10.2216/10-15.1. S2CID 86110297.
- ^ Bock, Christina; Pröschold, Thomas; Krienitz, Lothar (2010). "Two new Dictyosphaerium-morphotype lineages of the Chlorellaceae (Trebouxiophyceae): Heynigia gen. nov. and Hindakia gen. nov". European Journal of Phycology. 45 (3): 267–277. Bibcode:2010EJPhy..45..267B. doi:10.1080/09670262.2010.487920. S2CID 85093080.
- ^ Mikhailyuk, Tatiana; Holzinger, Andreas; Tsarenko, Petro; Glaser, Karin; Demchenko, Eduard; Karsten, Ulf (2020). "Dictyosphaerium-like morphotype in terrestrial algae: What is Xerochlorella (Trebouxiophyceae, Chlorophyta)". Journal of Phycology. 56 (3): 671–686. Bibcode:2020JPcgy..56..671M. doi:10.1111/jpy.12974. PMC 7317402. PMID 31994728.
- ^ Krienitz, Lothar; Bock, Christina; Kotut, Kiplagat; Pröschold, Thomas (2012). "Genotypic diversity of Dictyosphaerium-morphospecies (Chlorellaceae, Trebouxiophyceae) in African inland waters, including the description of four new genera". Fottea. 12 (2): 231–253. doi:10.5507/fot.2012.017.
- ^ Song, Huiyin; Wang, Qinghua; Liu, Xudong; Hu, Yuxin; Long, Jijian; Liu, Guoxiang; Hu, Zhengyu (2018). "Phylogenic Diversity and Taxonomic Problems of the Dictyosphaerium Morphotype within the Parachlorella Clade (Chlorellaceae, Trebouxiophyceae)". Journal of Eukaryotic Microbiology. 65 (3): 382–391. doi:10.1111/jeu.12482. PMID 29080384. S2CID 19043002.