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Description of Volvulina

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Colonies ellipsoidal to more or less spherical, composed of 16 (sometimes 8, rarely 4 or 32) cells, all of same size, arranged in alternating tiers of 4 cells each, embedded in the periphery of a common gelatinous matrix; colonial boundary smooth, part of it penetrating between cells into central region of colony forming individual sheaths around cells; cells mostly separated from each other by spaces; cells lenticular to hemispherical (in young colonies more spherical), if compressed roughly tetragonal in surface view; 2 equal flagella; chloroplast cup-shaped, somewhat striated on surface; pyrenoid present or lacking; eyespot present, largest in anterior cells and progressively smaller or absent in posterior cells; nucleus central; 2 or more contractile vacuoles; asexual reproduction by formation of 8- or 16-celled plakea which inverts to form a spheroidal daughter colony; sexual reproduction isogamous, heterothallic; freshwater, of scattered distribution, especially in pools and ponds, sometimes appearing in cultures from dried soil samples.
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Volvulina

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Volvulina is a genus of colonial green algae in the family Volvocaceae.[1] The colony (coenobium) is broadly ellipsoidal or spherical and consists of a fixed number of cells, usually 16 in mature individuals (rarely 4, 8 or 32). The cells are located at periphery of the coenobium and separated from each other by being embedded in a swollen sack. The cell body is lens-shaped or half spherical when mature with two flagella. The chloroplast is dish- or bowl-shaped. Pyrenoids may be present or absent, the stigma large. The nucleus is centrally located and there may be 4 to 8 contractile vacuoles. Sexual reproduction is by isogamy.[2]

References

  1. ^ See the NCBI webpage on Volvulina. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information. Retrieved 2007-03-19..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""'"'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
  2. ^ Protist Images: Volvulina.

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Volvulina: Brief Summary

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Volvulina is a genus of colonial green algae in the family Volvocaceae. The colony (coenobium) is broadly ellipsoidal or spherical and consists of a fixed number of cells, usually 16 in mature individuals (rarely 4, 8 or 32). The cells are located at periphery of the coenobium and separated from each other by being embedded in a swollen sack. The cell body is lens-shaped or half spherical when mature with two flagella. The chloroplast is dish- or bowl-shaped. Pyrenoids may be present or absent, the stigma large. The nucleus is centrally located and there may be 4 to 8 contractile vacuoles. Sexual reproduction is by isogamy.

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