Do you have LM pic of species?. 

Galovic, It is not distinguishable under LM  because it is 5 microns

I saw, it is a small species, but you can still gat a nice picture at 100 or even at 63 objectives. It depends on type of microscope with specifications (filters, phase contrast...). 

Best wishes,

Ines

Dear Biszel:

I think that it could be a nanoplaktonic marine species of Thalassiosira, it shows a central fultoportulae, a marginal ring of fultoportulae and probably a rimoportulae at 5 more or less, on valve surface near the ring of fultoportulae.

You need internal view of this taxon and more morphological information.

Good luck with the search of more material.

Regards.

Eugenia

Eugenia, thank you for your suggestion