Diatoms: Sturtiella elegans (and two friends)

[Beatsy]

Good morning all

I found an open strew of Oamaru forms under my microscope. It was very dusty and must of been there for 2-3 years. It had already been picked over but there were still things to be found. I selected a few forms and put them in a "photographic mount" (quickly placed, not accurately arranged).

I was pleased to find Sturtiella elegans, a genus I've not found before (on the left in the pic).

This is a hard crop as there were several less interesting forms in the mount too. A stack of 100 images shot with a 40x/0.75 objective under brightfield illumination.

Cheers
Beats

[Päule Heck]

Hallo Beats,
a nice picture of three fossil Oamaru-diatoms. I risk a determination of the second and the third diatom:
In the middle: Actinoptychus maculatus, and the other is certainly a Mastagloia splendida. 
Regards
Päule   

[Beatsy]

Hi Päule,

I logged in to name the other two forms after finding them in your excellent Oamaru Diatoms book. I thank you *again* for your help! 😀

M. splendida was easy to find. I wasn't so sure about A. maculatus though. The large clear patches at the ends of the alternate "spokes" look quite different to other images I found (except on Nigel Charles' Oamaru Diatoms site). It seems a very variable species though, so A. maculatus it is.

Cheers
Beats

[anne]

Hi Steve,
 wonderful, crisp sharp and contrast. A perfect example for using more brigthfield.
lg
anne

[Beatsy]

Thanks Anne,

Brightfield is my favourite for diatom photography. I admit it needs help from high RI mountant, Capture One, Affinity Photo and Topaz Photo AI though - but what doesn't these days? 😁

I shot another version at 100x/1.4. The three forms only just fit the field of view. It's also a colour image but far less pretty and doesn't show much new detail. Actinoptychus came out nice though. The rimportulae are easier to see and I like the way the "lenses" on the near-side magnify the sieve plates beneath.

Cheers
Beats

PS. You may need to right-click and "open in new tab" to zoom in and see the details mentioned above.

[Lupus]

Hello Steve,

It's also a colour image but far less pretty and doesn't show much new detail.

I think that the image with the 100x/1.4 is much better in resolution, also the object structure is clearer with less artefacts - especially Actinoptychus or the edge of Mastagloia. I have copied the two versions next to each other for a better comparison.

Hubert

[Beatsy]

Thanks Hubert,

The 100/1.4 certainly has more resolution, as you'd expect. I should have said that the higher resolution picture doesn't show "any new features" instead of "much new detail" (which implies resolution).

Bad choice of words on my part - sorry.

Cheers
Beats

[Beatsy]

Argh. Thanks again Hubert - I just realised I uploaded the wrong 100x pic. That one was inadvertently stacked with scaling and x/y shifts turned on. I turn those off for micro stacks - but had been doing something else and forgot to set then back to zero.

No scale bar or names on this one - I wanted to get it uploaded quickly...