A new BIG critter (maybe Climacostomum?)

[NachoBen]

I have been shifting from one species to another and beyond, to no avail.

This critter is big, but to my understanding not as big as Bursaria truncatella, an organism I have observed many times. As size does matter, I have ruled out Bursaria even though it has a vermiform nucleus, like my critter. Moreover, Bursaria lacks the "membranelle" that can be seen in my second video.

Video 1: An overview.


Video 2: Details of the "foamy" citoplasm and membranelle (?).


Anyway, my search has explored unknown fields of Bursaridium (oval nucleus), Linostoma (big membranes), Phascolodon (oral basket) and even the rarely seen Bursellopsis (no membranelles). My critter seems to sport a vermiform nucleus, so it could be a form of Climacostomum without zoochlorellae (sorry if this is a nonsense ).

I have some darkfield footage, just in case.

I hope someone can help me.

Thank you very much!

[Bruce Taylor]

To me, it looks like a very squashed heterotrich, but I don't see anything to suggest it is Climacostumum. It would not be unusual to find Climacostomum without algal endosymbionts (I see them quite often), but members of that genus always have a prominent vacuole in the posterior, with collecting canals. I don't see any sign of that structure, here, and I don't see any sign of the cytopharynx either. This could be a compressed/deformed Stentor (they can look quite strange, when smushed!).

By the way, Bursaria truncatella is not as big as it used to be! The genus has recently been revised, and the enormous Bursaria cultivated and sold by Carolina Biological as B. truncatella has been identified as a distinct species, now called B. americanum. Several other species have been added to the genus, which now has eight members. B. truncatella is still pretty big, but much smaller than americanum and some others. See: https://www.researchgate.net/profile/He ... ted-by.pdf

[NachoBen]

I am sorry I have to disagree this time, Bruce.

It doesn't look to me like Stentor at all. There is no Stentor in the samples I have extracted from that site (some cow footprints, by the way!). I have seen many Stentor specimens in recent months and I know how they contract and change shape (beautifully indeed!).

I admit that my bug is somewhat compressed, but I have observed some others in other drops with plenty of water (not smushed) and they are almost the same. Furthermore, it can be seen that it moves freely. Last but not the least, if it were Stentor, I think you could see the membranes that encircle the peristomal cap. It must be some other Heterotrich, but which one?

You are right: it is not Climacostumum (not cytopharynx, not big CV). I am glad to know that there can be specimens without algal endosymbionts.

Very, very interesting your information and comments about Bursaria, one of my favourites.

I will continue searching and upload new videos (I hope more conclusive ones!).

THANK YOU AGAIN, BRUCE.

[Bruce Taylor]

Hmmm...assuming this is not from a marine sample, there aren't too many other heterotrich candidates. Linostomella (previously known as Linostoma) is too small. I suppose Condylostomides could be a contender.

It could be I'm misinterpreting the footage, of course. Heterotrichs typically have clearly visible longitudinal kineties (often with associated cortical granules), and this ciliate doesn't show that. So maybe one of the smaller Bursaria species, after all?

[NachoBen]

You are right, my critter could be Condylostomides (a genus I did not know). But I have to do some Google research about Bursaria.

Too bad that my unknown critter has not shown up in later samples!

Thank you very much indeed.

[NachoBen]

Here you are a new critter with a high resemblance to others we have talked about in previous posts.



Perhaps Bursaridium. Anyway, I have not met neither Bursaridium nor this one before.

Thank you for any help.

[Bruce Taylor]

This one is Paracondylostoma.

[NachoBen]

Wow! Right on target!

Thank you very much!