Sigmoid diatoms

[gpmatthews]

Both samples collected today from Warnham Mill Pond, Horsham, UK.

Microscope: Zeiss Standard GFL
Objective: Leitz x40 NPL Fluotar ICT
Ocular: Olympus P15
Substage: Leitz ICT

Top image is for those that like their diatoms live.

Lower image for interest, showing just over half of one frustule of a long thin sigmoid diatom.

I am not well up on diatom identification, so any info greatly welcome.

[Ken Ramos]

Ah, I just finished viewing your heliozoan. A very nice set of images here also. Yes, I too like my diatoms fresh and alive. I find them to be more interesting like that. That is also an interesting round structure in the center of the first diatom. Any idea as to what that is or is it just the design of the frustule?

[bernhardinho]

Hi Graham,

very nice pics there. The upper one is quite certain a Gyrosigma ( I hope, Dominique will confirm that) The round structure in the middle is the nucleus. The second one can only be guessed, it does remind me of Nitzschia acicularis.


Bernhard

[Ken Ramos]

Bernhard replied:

The round structure in the middle is the nucleus.

For some reason I didn't occur to me that they had one. Why didn't I think of that.

[Gyrosigma]

Hello everybody,

bernhardinho is right... I think about Gyrosigma littorale for the alive one but I am not sure for the frustule.... Nitzschia must be smaller and have no raphee in the midle area, I think about Pleurosigma macrum.

best regards

Dominique