Some diatoms from Oamaru with 450nm light

Images made through a microscope. All subject types.

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jmc
Posts: 233
Joined: Fri Apr 17, 2020 3:14 am

Some diatoms from Oamaru with 450nm light

Post by jmc »

Here's a few of the images I've have been working on recently. Diatoms from Oamaru sites from a range of slides. Olympus BHB microscope, using 450nm light. Details below each image. Naming based on the slide label and to the best of my ability. Reduced in resolution for sharing here.

2023-12-17-03.01.34 ZS retPM mod lab Porodiscus hirsutus 1000.jpg
Porodiscus hirsutus. 63x Leitz Pl Apo NA 1.40 objective.

2023-12-12-09.18.45 ZS retPM mod lab 1000.jpg
I think the label is wrong on this, and it could be Thalassiosira leptopus. 20x Nikon Plan Apo NA 0.65 objective.

2023-12-12-02.45.07 ZS retPM mod lab 1000.jpg
Dictyoneis marginata var. janischii. 63x Leitz Pl Apo NA 1.40 objective.

2023-12-12-10.31.23 ZS retPMmod lab 1000.jpg
Most likely Pinnularia lobata. 63x Leitz Pl Apo NA 1.40 objective.

2023-12-05-11.26.56 ZS retPMmod lab 1000.jpg
Auliscus tripinnatus. 40x Leitz Pl Apo NA 1.00 objective.

2023-12-04-06.12.05 ZS retPM mod lab 1000.jpg
I think this is Glyphodiscus strigillatus. 63x Leitz Pl Apo NA 1.40 objective.
Jonathan Crowther

Beatsy
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Location: Malvern, UK

Re: Some diatoms from Oamaru with 450nm light

Post by Beatsy »

Great set and an interesting variety of forms.

Those Glyphodiscus sp. are generally quite rare in (most) Oamaru material. Often tiny and easy to miss too. Nice find.

Cheers

jmc
Posts: 233
Joined: Fri Apr 17, 2020 3:14 am

Re: Some diatoms from Oamaru with 450nm light

Post by jmc »

One from a strew slide from Allan's Farm, prepared by Bernard Hartley. Brightwellia coronata. Almost complete - this is about as complete a one as I have seen in the slides I've got, usually it is just fragments. Olympus BHB microscope using 450nm light. 63x Leitz Pl Apo NA 1.40 objective with oil immersion. Olympus Aplanat Achromat condenser, oil immersion, slightly oblique. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 29 images stacked in Zerene (Pmax). Reduced in resolution for sharing here, as the original is about 4600 pixels across.
2024-02-09-08.47.44 ZS PMax mod2 lab 1000.jpg
Below shows the wider strew with a 10x objective.
DSC_9812 10x mod 1000.jpg
Jonathan Crowther

Beatsy
Posts: 2095
Joined: Fri Jul 05, 2013 3:10 am
Location: Malvern, UK

Re: Some diatoms from Oamaru with 450nm light

Post by Beatsy »

Nicely done Jonathan.

I cleaned a bit of diatomite from Allan's farm a few weeks ago and have been sporadically searching strews and picking out forms since. I must have seen hundreds of B. coronata (B for broken) but none even close to being as complete as yours. About 3/4s complete is the best I've seen. It does seem to be a particularly accident-prone species.

The central ring is often intact but the perimeter is always "chewed away". Although this is a sample with a high proportion of broken forms among all species, I'm beginning to wonder if the cleaning might be responsible. Having said that, I've found several perfect forms too (except B. coronata) so it could just be a natural phenomenon - e.g. broken during deposition or by geological compression etc.

I still have some of the raw diatomite left though, so I'll try a more careful clean (somehow) once I've searched all of this current batch...

Cheers
Beats

jmc
Posts: 233
Joined: Fri Apr 17, 2020 3:14 am

Re: Some diatoms from Oamaru with 450nm light

Post by jmc »

Thanks Beats. Yes, I've seen plenty of broken ones, often as you mentioned with the central ring intact. This was the most intact one on this slide, and of the other few Allan's Farm strew slides I've got. It's a beautiful form, and I was really happy (and surprised) when it appeared as I was scanning through the slide.
Jonathan Crowther

Smokedaddy
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Re: Some diatoms from Oamaru with 450nm light

Post by Smokedaddy »

Very nice.

hkv
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Location: Sweden

Re: Some diatoms from Oamaru with 450nm light

Post by hkv »

Very nice set!
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