On auxospore formation inCaloneis and the nature ofAmphiraphia (Bacillariophyta) |
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Authors: | David G Mann |
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Institution: | (1) Botany Department, University of Edinburgh, The King's Buildings, Mayfield Road, EH9 3JH Edinburgh, UK |
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Abstract: | Amphiraphia
Chen & Zhu, together with theAmphiraphiaceae andAmphiraphidales, should be abandoned, sinceAmphiraphia cells are the heterovalvar initial cells ofCaloneis. WhenCaloneis reproduces sexually two cells pair and become surrounded by a two-layered capsule of mucilage. Each cell produces two gametes and these become rearranged within the gametangial frustule before plasmogamy. The gametes are amoeboid and fusion is isogamous. Following plasmogamy the zygote contracts, becomes ellipsoidal, and lays down a primary perizonial band. This is a complete, wide hoop, while subsequent perizonial bands are narrow and open. |
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Keywords: | Diatoms Amphiraphia Amphiraphidales Caloneis Auxospore formation initial cell structure perizonium structure sexual reproduction |
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