Dear Rinaldi:

You have a little piece of information.

You need to see raw material of each specimen in girdle view and in valvar view.

Additionally, you need to oxidize the organic matter and mount the material in Naphrax for seeing in light microscopy.

When you determine the material based on LM analysis, it could be necessary to mount it in stubs for seeing specimens with scanning electron microscopy.

I recommend you two texts:

Hasle & Syvertsen (1996) Marine Diatoms. In: Tomas (ed.) Identifiying marine phytoplakton. Academic Press,

Round, F.E., R. Crawford & D.G. Mann. 1990. The Diatoms. Morphology and Biology of the Genera. Cambridge University Press, London.

The first one for seeing the criterion used in determination of genera, it would be useful for you as a metodological text, not for determining your material because this book is about  phytoplankton not on benthic flora.

Round is a very good manual about morphology of taxa of diatoms.

When you determine your material at genus level you can search in google scholar, scopus, researchgate, etc. papers about species of this genus. Based on this literature you could determine your taxa.

All the best.

Eugenia

Dear Rinaldi,

Difficult to identify by these light microscope images. You need to remove the pigments by treating your specimens with  hydrogen peroxide or acid treatment to clear the frustules.

Good luck,  Sumera

Dear Eugenia and Sumera,

Thanks for the inputs. I forgot to mention that I am only going to ID them down to big groups (e.g. genus). I am not recording what kind of species I found, I just want to find out diversity index based on the genus of phytoplankton I found.

Do you reckon you recognize them down to their genus? I have another picture from oil immersion lens (x100). I appreciate the help, thanks again.

Looks like the first long one is the tintinnid lorica, the others phots are pennate diatoms. You need to use books like those one recommended above to confirm what is it and go to the right genus. Good luck

@Isabel I also first thought it was a cilliate but then it also kind of resembles Climacosphenia sp. (attached). I will have to revisit my samples and check its girdle, if any. I've got some books for reference, thanks. Marine Benthic Diatoms in China (Jin et. al, 1985) has been especially useful.

http://img.algaebase.org/images/8CCBD7A40f6231E1ADHNq34105E7/r97sP1dWJZCc.jpg

Yes, you are right, it really looks like Climacosphenia sp. Good luck.

Dear Rinaldi:

Your last picture probably is a species of Amphora or Halamphora.

I do not agree in determining your first picture as Climacosphenia because there is not evidence of the characteristic septa. Compare with the picture from Algaebase and see pictures in Round et al. (1990).

You need to analyze the generic features in detail for determining genera. 

Regards.

Eugenia