It is there. In different Finnish waters, this tiny little thing.
Hegewald, Padisák, and Friedl (2007) found that this little thing differed markedly from other look-a-like algae and give a firm description of the differences in their article. A new family – Loboceae E. Hegewald – and a new genus – Pseudoteraëdriella Hegewald – was established in the Class Eustigmatophyceae Hibberd – and look: Pseudotetraëdriella kamillae Hegewald & Padisák had found it’s place in the taxonomic tree.
One might easily overlook it. Or mix it with Tetraëdron minimum or Tetraëdriella jovetii, but it is different. First of all, it’s very small – only 3-7 µm. Secondly it only has one (or two in older cells) chloroplast. It has no pyrenoid and the cell wall is smooth.
The green algae Tetraëdron minimum, on the other hand is, first of all, very green and it does have a pyrenoid. The size is about the same. Skuja (1948) has a nice drawing of Tetraëdron minimum var. tetralobulatum from Uppland, Sweden, which resembles our Pseudotetraëdriella kamillae quite a lot, but again – that pyrenoid.
Hindák (1980) describes even a smaller Tetraëdron, only 2-4 µm, which he calls mediocris, found in a fishpond near the beautiful city of Bratislava. This one still has the pyrenoid and it’s much more tetrahedrical than our little P. kamillae. Not that I would have seen Tetraëdron mediocris alive and kicking – or even lugolised- no, not here in Finland.
Pseudotetraëdriella kamillae has lobes, but they are not as much twisted as in Tetraëdriella jovetii, a yellow-green (Xanhtophyceae) algae, size 10-12 µm, with 5-9 chloroplasts, no pyrenoid and a smooth cell wall.
Look now how very different they are:
For further study:
Hegewald, E., Padisák, J. & Friedl, T. (2007): Pseudotetraëdriella kamillae: taxonomy and ecology of a new member of the algal class Eustigmatophyceae (Stramenopiles). – Hydrobiologia 586: 107-116.
Hindák, F. (1980): Studies on the chlorococcal algae (Chlorophyceae). II. – In:Ruzicka, M. (red.). Biologické Práce 26 (6). VEDA Vydavatelstvo Slovenskej Akadémie Vied / VEDA Publishing House of the Slovak Academy of Sciences, Bratislava, 195 + (1) pp., incl. 73 pls.
Komárek, J. & Fott, B. (1983): Chlorophyceae (Grünalgen). Ordnung: Chlorococcales. – In: G. Huber-Pestalozzi (†). Das Phytoplankton des Süßwassers. Systematik und Biologie. 7. Teil, 1. Hälfte. In: Elster, H.-J. & Ohle, W. (red.). Die Binnengewässer. Einzeldarstellungen aus der Limnologie und ihren Nachbargebieten. Band XVI. E. Schweizerbart’sche Verlagsbuchhandlung (Nägele u. Obermiller), Stuttgart. X + 1044 pp., incl. 253 pls. ISBN 3-510-40023-2.
Skuja, A. (1948). Taxonomie des Phytoplanktons einiger Seen in Uppland, Schweden. Symbolae Botanicae Upsalienses 9(3): 1-399.