Pinnularia and a Achnanthidiun I think?

[molehill]

I found these two diatoms, a Pinnularia and a Achnanthidiun ( I may well be wrong) in the storm water pond in the park I live next to.
The final image is a focus stack of ten images processed with combineZP. The background has been smoothed to remove distractions



Meiji Techno MT5000L microscope, S Apo 40x 0.82 objective. 2.5x relay lens
Canon 40D 100ASA 1/15 sec

molehill

[75RR]

Very nice! Love the overall whiteness
Is that Brightfield?
If my thumb is working well that looks like a 200µm diatom?

P.S. Just got my plastic ruler out: 205µm! Never seen one that large.

[exmarine]

Great photo's with this black and white its easy to identify the species, and I think the Pinnularia is
P. abaujensis because the end nodules are open and the raphe in the centre nodule comes to a point..

As for the smaller diatom on the right I have to disagree (unless it is only particular to the USA). Do you know the species? The genera is as you put it Achnanthidiun but what's the species? Again I can not find that Genera.

As I can only find Achnanthidium (Round et al(1990)) it depends on which author has written about the individual diatom. The taxonomic work on diatoms is a bloody mess.

We will get there Ihave no doubt.

All the best.

[zzffnn]

Very sharp!

[rnabholz]

Beautiful shot of an excellent specimen.

Well done!

Rod

[vasselle]

Bonjour
Très belle image
Cordialement seb

[KurtM]

I agree, a very nice image! Really makes me think about getting more aggressive with image stacking, and cleaning up artifacts and distractions in post processing. In other words, it makes me want to imitate you, how's that for flattery?

As for the smaller diatom, wonder if we're seeing valve, or girdle view? I'm thinking the latter.

[billben74]

No idea about the ids.
Damn fine photo tho'

[exmarine]

Kurt my man,[As for the smaller diatom, wonder if we're seeing valve, or girdle view? I'm thinking the latter/quote]
If it were seen in the girdle view we would not be able to see the markings on the valve, and it would appear a lot thinner. Also you would not be able to see the outline shape of the diatom it would appear as two straight edges, with possible girdle bands showing. Its not very often we see diatoms in the girdle view but when we do there is no way for identification.

With reference to black and white photo's for positive I.D. against darkfield the darkfield does show a pattern of sorts on the valve but it does not show the difference in striae, it could be tube-like, alveoli, coarsely spaced, densely spaced, lineolae, puncta, parallel ect. We can see the apex and the distal raphe ending (or polar), and the central area on the diatom, so therefore we must be seeing it in valve view.
Hope that helps to clear up any misunderstanding, keep your great photo's coming they are a pleasure to study.

AS with all you diatom maniac's we are all learning as we progress through these pages, so keep the photo's rolling in.

All the best to you all.

[molehill]

Thanks zzffnn, Rod,Vasselle, KurtM, billben74 for your kind remarks. 75RR yes it is brightfield
exmarine thank you for your efforts in trying to ID the smaller specimen. I have also been trawling the NZ diatom data bases,
but no success yet. I found quite a few large diatoms in this water sample.

molehill

[KurtM]

Gentlemen: please see the exciting conclusion to this thread and see what you think...?

viewtopic.php?f=6&t=3359

[gekko]

Beautiful photo, as always.

[molehill]

Thank you gekko