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Polysiphonia

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Polysiphonia
Polysiphonia urceolata
Polysiphonia urceolata
Scientific classification Edit this classification
Clade: Archaeplastida
Division: Rhodophyta
Class: Florideophyceae
Order: Ceramiales
Family: Rhodomelaceae
Genus: Polysiphonia
Greville, 1823

Polysiphonia is a genus of filamentous red algae with about 19 species on the coasts of the British Isles[1] and about 200 species worldwide,[2] including Crete in Greece, Antarctica and Greenland.[3][4] Its members are known by a number of common names.[note 1][3] It is in the order Ceramiales and family Rhodomelaceae.[5]

Description

Polysiphonia is a red alga, polysiphonous[1] and usually well branched, with some plants reaching a length of about 30 cm. They are attached by rhizoids or haptera[4] to a rocky surface or other alga. The thallus (tissue) consists of fine branched filaments each with a central axial filament supporting pericentral cells.[6] The number of these pericentral cells (4–24) is used in identification.[7][8][9] Polysiphonia elongata[10] shows a central axial cell with 4 periaxial cells with cortical cells growing over the outside on the older fronds.[1] Its cuticle contains bromine.[11]

Features used in identification include the number of pericentral cells, the cortication of main branches, constriction of young branches at their base, whether the branching dichotomous or spiral, and the width and length of thalli.

Distribution and ecology

Species have been recorded from Europe, Australia and New Zealand, North America and South America, islands in the Pacific Ocean, South Africa, southwest Asia, Japan, Greenland and Antarctica.[3]

The species are entirely marine, found growing on rock, other algae, mussels or limpets and artificial substrata etc. from mid-littoral to at least 27 m depth. Many species are abundant in rock pools.[1] Polysiphonia lanosa is commonly found growing on Ascophyllum nodosum.[12]

Reproduction and life cycle

The life-cycle of the red algae has three stages (triphasic). In Polysiphonia it consists of a sequence of a gametangial, carpospoangial and tetrasporangial phases.[13][14][page needed] Male (haploid) plants (the male gametophytes) produce spermatia and the female plants (the female gametophytes) produce the carpogonium (the haploid carpogonium) which remains attached to the parent female plant. After fertilization the diploid nucleus migrates and fuses with an auxiliary cell. A complex series of fusions and developments follow as the diploid zygote develops to become the carposporophyte, this is a separate phase of the life-cycle and is entirely parasitic on the female, it is surrounded by the haploid pericarp of the parent female plant. The diploid carpospores produced in the carposporangium when released are non-motile, they settle and grow to form filamentous diploid plants similar to the gametophyte. This diploid plant is the tetrasporophyte which when adult produced spores in fours after meiosis. These spores settle and grow to become the male and female plants thus completing the cycle.[7][page needed][15][page needed]

Species

Notes

  1. ^ Recorded common names are olann dhearg, craonach, cúnach triosgar, cluaisíní, mileara, millreacha, salata tou yialou (σαλάτα του γιαλού) and lobster horns.

References

  1. ^ a b c d Maggs, C.A. & Hommersand, M.H. (1993). Seaweeds of the British Isles. Volume 1: Rhodophyta. HMSO, London. ISBN 978-0-11-310045-3. OCLC 28928653.
  2. ^ Dickinson, C.I. 1963. British Seaweeds. The Kew Series
  3. ^ a b c Norris, R.E. & Guiry, M.D. (2006-03-15). "Polysiphonia Greville 1823: pl. 90". AlgaeBase.
  4. ^ a b Stegenga, H., Bolton,J.J. & Anderson,R.J. (1997). Seaweeds of the South African West Coast. Bolus Herbarium Number 18.{{cite book}}: CS1 maint: multiple names: authors list (link)
  5. ^ Abbott, I.A. & Hollenberg,G.J. (1976). Marine Algae of California. Stanford University Press, California. ISBN 978-0-8047-0867-8. OCLC 180623827.{{cite book}}: CS1 maint: multiple names: authors list (link)
  6. ^ Newton, L. 1931. A Handbook of the British Seaweeds. British Museum
  7. ^ a b van den Hoek, C., Mann,D.G. & Jahns,M.H. (1995). Algae: An Introduction to Phycology. Cambridge University Press, Cambridge. ISBN 978-0-521-30419-1. OCLC 28182088.{{cite book}}: CS1 maint: multiple names: authors list (link)
  8. ^ Parmentier,Jan (1999). "Polysiphonia, a red alga". Micscape Magazine.
  9. ^ von Sengbusch,Peter (2003-07-31). "Polysiphonia nigrescens". Botanik online. University of Hamburg. Archived from the original on 2007-05-01. Retrieved 2007-05-03.
  10. ^ Guiry,M.D. (2004-09-23). "Polysiphonia echinata Harvey". AlgaeBase.
  11. ^ Pedersén, M. E. E.; Roomans, G. M.; Hofsten, A. V. (1981). "Bromine in the Cuticle of Polysiphonia Nigrescens: Localization and Content". Journal of Phycology. 17: 105–108. doi:10.1111/j.0022-3646.1981.00105.x.
  12. ^ "Polysiphonia lanosa". Marine Life Information Network for Britain & Ireland. Archived from the original on 2010-02-06. Retrieved 2007-05-09.
  13. ^ Smith, G.M. 1955. Cryptogamic Botany Algae and Fungi. Volume 1. Second Edition. p.337
  14. ^ Dixon,P.D. (1973). Biology of Rhodophyta. Oliver & Boyd, Edinburgh. ISBN 978-0-05-002485-0. OCLC 944032.
  15. ^ Mondragon, J. & Mondragon, J. (2003). Seaweeds of the Pacific Coast. Sea Challengers, California. ISBN 978-0-930118-29-7. OCLC 50912900.
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