Was on my last sample trip last Sunday and took some water out of the ditch, near to my favorite lake. And this is what I found:
Size 38×48 µm.
Lots of them. Seems to be the home of Staurastrum sexcostatum Brébisson ex Ralfs 1848. According to Coesel & Meesters (2007) it particularly occurs in ephemeral pools. Might well be, that this ditch gets dry in the summer. In the Netherlands it’s rare, Coesel and Meesters state. The same thing is told us by John and Williamson (2009) and they are referring to West of Ireland. Lenzenweger (1997) let’s us know that this species has been but rarely found in the Alps of Austria. He seems to have seen slightly smaller cells than the others, by the way. Ralfs stated in his book The British Desmidieae in 1848, that this species was very rare, whereas West, West & Carter (1923) 75 years later do mention quite a few places, where it has been found. Finland was not mentioned here, though.
But it is here. Tikkanen (1986) does not mention it, but it’s on the official phytoplankton list maintained by the Finnish Environmental Administration. It’s not yet on the Finnish Phytoplankton net guide, but it probably will be, soon.
Coesel, Peter F.M. & Meesters, Koos (J.) 2007. Desmids of the Lowlands. Mesotaeniaceae and Desmidiaceae of the European Lowlands. KNNV, Zeist.
John, D.M. & Williamson D.B. 2009. A practical guide to the Desmids of the West of Ireland. MRI.
Lenzenweger R. (1997) Desmidiaceenflora von Österreich.
Teil 2. Bibliotheca Phycologica, Vol. 102.
J. Cramer, Berlin & Stuttgart.
Tikkanen, Toini 1986. Kasviplanktonopas. Suomen Luonnonsuojeluliiton tuki Oy. Helsinki.