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Rhoicosphema
Rhoicosphema species are asymmetrical over both axes. In valve view they look similar to Gomphonema; one pole is slightly wider than the other, giving it a club-like appearance. However, Rhoicosphema also often have a "pseudoseptum," a false ending to the cell's tips. Additionally, each of its two valves has a different raphe system: one valve has a full, long raphe system, and the other only has a short raphe system near the foot of the valve. In girdle view the two genera also differ: while both genera have a wedge shape, Rhoicosphema cells have a bend at the middle of the valve while Gomphonema remain straight.
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Rhoicosphema are epiphytes, attaching at their narrower tip to the stalks of plants and other algae.
R. abbreviata
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Cells are 10-55 µm in length, 4-8 µm in width.
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Rows of striae are 15-20 per 10 µm.
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In valve view, cells have pseudoseptae on both poles. The true ends are blunt and rounded.
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In valve view, central area is oval shaped.
For more information, visit diatoms.org here.
A8m1 Rhoicosphema abbreviata_edited
A1m1 Rhoicosphenia abbreviata(_), Gomphonema_edited
R. stoermeri
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Cells are 25-84 µm in length, 6-9 µm in width.
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Rows of striae per 10 µm are 11-13 near the center, and 14-16 near the tips.
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In valve view, cells are elongated and thin.
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Raphe are spaced farther apart, and each has its own small unornamented space near the raphe head which connects at the center.
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Pseudoseptum are present but less prominent.
For more information, visit diatoms.org here.
A3m1 Rhoicosphenia Stoermeri_edited
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