Taxonomische Studien über Cyanophyceen aus Oxydationsteichen

The Cyanophyta found in 8 oxydation ponds in the South of Sweden were analysed. Three species appeared regularly:Phormidium autumnale, Oscillatoria chalybea andO. tenuis. The last species was present in all of the ponds and often in very large quantities.Statistical measures were made of the trichom width, especially ofO. tenuis for which considerable variations were observed in a single sample. The largest differences in width varied from 3·5 to 10 μ. Nevertheless,O. tenuis must be considered as a good species. It is easy to identify and its microtaxa cannot statistically be held apart. Thevar. natans andtergestina should probably be considered as microtaxa and included in the main species. A smaller type from Humlebäcken (not from an oxydation pond) differs from the main species not only in the width of its cells, but also in other characteristics and could therefore be considered as a variety.