Nice testate amoebe, but which one?

[janvangastel]

I found a testate amoebe with very clear pseudopodia, but I can't find out what it is. I hope someone knows.

[75RR]

Good catch.

I take it you looked here: https://www.arcella.nl/lobose-testate-amoebae/

I find it takes quite a lot of experience and reading to ID most amoebae, which is why I am not very good at it :)

One needs to know what to look for to enable an ID and then try to capture those areas in the images/video

[janvangastel]

Yes, I looked there. And I also searched my book 'Das leben im Wassertropfen' and a .pdf file I found on the internet. It's very difficult. I hoped to find some information about the shape of the pseudopodia, but I didn't find that.

[Bruce Taylor]

The pseudopods are lobose (tubular, blunt at the tips), not filose (threadlike), so we know this is in the supergroup Amoebozoa and not Rhizaria. Shelled amoebozoans are confined to the order Arcellinida, so that is easy. The shell is agglutinate (composed partly of found particles), so we can put it in the clade Glutinoconcha (where most arcellinids fall anyway). We don't see the shape of the shell very clearly, and have no view of the aperture (the opening from which the pseudostomes emerge). That makes identification to genus difficult. There are many shelled amoebae with rounded agglutinate shells (Netzelia,, Cyclopyxis, certain Difflugia, etc.), so I would simply call it an "arcellinid".

[janvangastel]

Thank you Bruce.

[deBult]

Bruce, also thank you from this beginner.

The step by step reasoning to come to a high level determination is really helpful.

[Rossf]

75RR thanks for posting that website all just for amoebae enthusiasts -it’s a permanent widget on my phone now-some wonderful photos of some really ornate testate amoebae forms-also makes me realise I’ve been missing a lot of testates in soil samples cos I didn’t realise what they were....they seem very shy-I’ve only seen pseudopodia poking out once or twice.
Regards ross