Home / Diatoms / Pennate / Colonies / Araphes / Thalassionema
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Name derivation:
Classification:
Thalassionema Grunow ex Mereschkowsky 1902; 11 of 19 species descriptions are currently accepted taxonomically (Guiry and Guiry 2013). Order Thalassionematales; Family Thalassionemataceae
Morphology:
Emended Description (Hallegraeff 1986): Long (10-400 µm) needle-shaped frustules, united into stellate or zig-zag colonies. Valves furnished with uniquely structured marginal areolae, appearing as a row of open depressions along each edge of the valve face. Areolae with deep-set small internal opening (foramen), surmounted externally by simple or triradiate cross bars. Axial area (pseudoraphe) and girdle bands without areolation. Internally each valve pole carries a simple slit-like labiate process, corresponding to a small external opening in the valve face.
Similar genera:
Superficially the colonies are similar to Asterionella (when star-shaped with cells attached at the center of the colony) or Tabellaria (when cells are attached in a zig-zag pattern in the colony).
Habitat:
Marine plankton, widespread.
References:
Guiry, M.D. and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 01 August 2013. Hallegraeff, G.M. 1986. Taxonomy and morphology of the marine plankton diatoms Thalassionema and Thalassiothrix. Diatom Research, Bristol, England 1(1):75.