These are usually distinctive, being broad (approximately 20µm or 28µm diameter respectively) filaments, with twin stellate chloroplasts, dark green under the microscope but the mass of filaments appearing almost brown to the naked eye.
Cell diameter is reported to be an unreliable taxonomic feature in this genus (Miller and Hoshaw, 1974).
A morphological variant was rarely encountered in samples from Loch Ard and other areas, in which the chloroplast is a parietal ribbon or band, the full length of the cell, but filling approximately 50% of the circumference so that it appears similar to Mougeotia or Ulothrix spp. That it was actuallyZygnema was revealed when a filament was discovered which had normal Zygnema morphology at one end but the aberrant form at the other. There were no pyrenoids visible in the aberrant chloroplast.
These are usually distinctive, being broad (approximately 20µm or 28µm diameter respectively) filaments, with twin stellate chloroplasts, dark green under the microscope but the mass of filaments appearing almost brown to the naked eye.
Cell diameter is reported to be an unreliable taxonomic feature in this genus (Miller and Hoshaw, 1974).
A morphological variant was rarely encountered in samples from Loch Ard and other areas, in which the chloroplast is a parietal ribbon or band, the full length of the cell, but filling approximately 50% of the circumference so that it appears similar to Mougeotia or Ulothrix spp. That it was actuallyZygnema was revealed when a filament was discovered which had normal Zygnema morphology at one end but the aberrant form at the other. There were no pyrenoids visible in the aberrant chloroplast.
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