Merismopedia
| Generic name: MERISMOPEDIA Meyen, 1839. N. Syst. Pflanzen-Physiol. 3: 440. | ||||||||||
| Synonyms: AGMENELLUM Brébisson, 1839. Mem. Soc. Acad. Sci., Arts, Bell.-Lett. Falaise, 1839: 2.[ Druet & Daily, 1956; de Brebisson, Mém. Soc. Acad. Sci., Art. & Belles-Lettres Falaise 1839: p. 2 of reprint. 1839. | ||||||||||
| Diagnosis: | ||||||||||
| Type species: Merismopedia punctata Meyen 1939. [Druet & Daily, 1956; Type species: Trochiscia quadruplicata Menegh.] | ||||||||||
| Descriptions: Komárek & Anagnostidis (1998): Colonies microscopic, rarely (in large species) macroscopic, free-living, tabular, with one layer of densely or loosely arranged cells in the plane of the colony square or rectangular, later sometimes with irregular outline, flat or wavy; large colonies sometimes contorted or composed of several subcolonies. Colonies consist of few to very many (in several species over 4000) cells; cells arranged in perpendicular rows, distant or close together. Colonial mucilaginous envelopes colourless, structureless, hyaline, fine, usually with indistinct narrow or wide margin; cells sometimes with individual gelatinous envelopes (in several species facultatively so). Cells spherical or widely elliptical (when they are elongate or oval, the longer axis lies in the plane of the colony), after division hemispherical, with homogeneous, pale or bright blue-green or reddish (violet, pink) content; in a few species in central parts of cells appear refractive bodies or aerotopes. The parietal arrangement of thylakoids was found in all up to now studied members of Merismopedia. Komárek (1992): Unicellular - colonial; colonies free floating, microscopic, rarely (in several “large” species) macroscopically visible, usually table-like, flat or slightly waved, with cells situated in one plane, in rows more or less perpendicular one to another (sometimes two or four cells more or less in duplets or quadriplets), squared or rectangular when young, in later stages sometimes irregular or composed from smaller, clustered, table-like colonies; colonies with 4-16, but in several species up to several hundreds of cells (up to 4000); mucilaginous envelope of colonies colour less, usually homogeneous, fine, diffluent at the margin, rarely limited, in few species with ferric precipitations; around cells sometimes own, colourless mucilaginous envelopes. Cells spherical or widely oval (before division), after division hemispherical, with homogeneous content, sometimes finely granular or with visible chromatoplasma, in several planktic species one or more: aerotopes in a cell. Geitler (1932): Kolonien tafelförmig, durch regelmäßig abwechselnde Teilungen nach zwei aufeinander senkrecht stehenden Raumrichtungen gebildet, meist, namentlich in der Jugend, eben und quadratisch oder rechteckig, oft im Alter gefaltet oder mehr oder weniger kugelig zusammengerollt und mit einspringenden rechten Winkeln, immer aus einer einzigen Zellage bestehend, in der Regel freischwimmend. Zellen kugelig oder ellipsoidisch bis zylindrisch (im letzteren Fall steht die lange Achse senkrecht zur Ebene der Kolonie), oft in Vierergruppen, mit oder ohne Spezialhüllen, in gemeinsamer Gallerte. |
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| Genotype differences, molecular data: | ||||||||||
| Reproduction strategies, life cycles, cell division: Komárek & Anagnostidis (1998): Cell division (binary fission) into two equal daughter cells, in two planes perpen- dicularly to one another and to the plane of the colony in successive generations; cells do not change their alignment after division (reason for regular perpendicular , rows of cells) and reach the original size before next division. Reproduction by disintegration of colonies. Komárek (1992): Cell division in two planes in successive generations, perpendicular one to another and to the plane of a flat colony. Daughter cells shift slightly one from another, but they remain in perpendicular rows in a colony. Reproduction by the disintegration of colonies. |
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| Ultrastructure: | ||||||||||
| Taxonomic position, higher hierarchy: Cyanophyceae, Chroococcales, Merismopediaceae, Merismopedioideae Notes to taxonomy, misinterpretations: Komárek & Anagnostidis (1998): Small-celled Merismopedia species with reddish cell content can be easily misidentified as Thiopedia (Rhodobacteria). - Palinska & al. (1996) isolated from a salinic microbial mats in Norderney Island (Germany) five strains, which corresponded morphologically to three species, M. elegans, M. glauca and M. punctata. They proved the evolutionary relationship to Synechocystis (one strain) and the genotype similarity of all other studied strains by the 16S rDNA sequencing. The stability of different phenotypes, ecotypes, and variability of various species need the further study and confirmation. The identity of, e.g., very variable M. glauca from saline biotopes (sensu Palinska & al. 1996) and M. glauca from acidic peaty waters should be also revised. |
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| Ecology, ecophysiology, ecological significance: Komárek (1992): Free floating in water or in metaphyton, detritus, among water plants, usually in submerged biotopes with numerous water vegetation. Several small species are planktic, several live in halophilic biotopes (sea shores, salinic swamps) or in thermal springs. Distribution allover the world, but several species have clearly ecologically and geographically limited areas of distribution. To this genus belongs evidently also "Low GC-cluster of Synechocystis", defined by Waterbury (1989; freshwater, with facultative gliding motility, forming flat sheets, photoautotroph, facultatively containing phycoerythrins in cells). |
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| Physiology and biochemistry: |
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| Distribution, endemism, problematic citations: |
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| Reference strain: |
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| Infrageneric scheme, species concept: |
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| List of species: Merismopedia aeruginea Brébisson in Kützing sensu Frémy 1930 Merismopedia affixa Richter 1895 Merismopedia africana Komárek et Cronberg 2001 Merismopedia angularis Thompson 1938 Merismopedia arctica (Kosinskaja) Komárek et Anagnostidis 1995 Merismopedia cantonensis Chu 1987 Merismopedia convoluta Brébisson in Kützing 1849 [syn.: M. willei Gardner 1927; Pseudoholopedia convoluta (Brébisson) Elenkin 1938 pro typo] Merismopedia danubiana Hortobagyi 1974 Merismopedia duplex Playfair 1918 [syn.: M. cyanea Playfair 1918; M. distans Fedorov 1969; M. distans Messikomer 1971] Merismopedia elegans A. Braun in Kützing Merismopedia ferrophila Hindák 1982 Merismopedia gardnerii (Collins) Setchell in Gardner 1906 Merismopedia glauca (Ehrenberg) Kützing 1845 [syn.: M. aeruginea Brébisson in Kützing 1849; M. nova Wood 1872; Agmenellum thermale sensu auct.] Merismopedia hyalina (Ehrenberg) Kützing 1845 Merismopedia insignis Škorbatov 1923 Merismopedia jeanelii Bachmann 1938 Merismopedia litoralis (Oersted) Rabenhorst 1865 [syn.: M. massartii Kufferath 1942] Merismopedia marssonii Lemmermann 1900 Merismopedia mediterranea Nägeli 1849 Merismopedia minima Beck 1897 Merismopedia minutissima Joosten 2006 Merismopedia messikommeri Joosten 2006 Merismopedia punctata Meyen 1839 [syn.: M. kuetzingii Nägeli 1849; M. haumanii Kufferath 1942; Agmenellum quadruplicatum sensu auct. after Drouet et Daily 1956 pp.] Merismopedia regularis Komárek et Cronberg 2001 Merismopedia remota Hirose et Chung in Chung 1970 Merismopedia revoluta Askenasy1894 Merismopedia sinica Ley 1947 Merismopedia smithii De Toni 1939 [syn.: M. major (G.M. Smith) Geitler 1925] Merismopedia sparsa Komárek et Cronberg 2001 Merismopedia sphagnicola Joosten 2006 Merismopedia tenuissima Lemmermann 1898 Merismopedia thermalis Kützing 1843 [syn.: Agmenellum thermale (Kützing) Drouet et Daily 1956 pro typo] Merismopedia trolleri Bachmann 1920 Merosmopedia vangoorii Joosten 2006 Merismopedia warmingiana Lagerheim 1883 Unclear taxa: |
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| Keys: | ||||||||||
| List of stains: | ||||||||||
Drawings: Komárek 1992
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