Help with IDs for three ciliates

billporter1456 · Post by **billporter1456** » Wed Apr 23, 2014 6:17 pm

I was just relaxing with my scope this afternoon and saw three ciliates I’d seen before, but I didn’t have an ID for any of the three. I should have done some research, but then I thought that there are members of this forum who actually enjoy providing what Charles G. calls a “fun” ID for critters. By “fun,” I mean that I certainly don’t expect a definitive and certain ID, just a good, educated guess. Here the three critters, each with its own short video.

Carlos has already made a couple of excellent suggestions.

https://www.youtube.com/watch?v=3bmMf6uFFL4

https://www.youtube.com/watch?v=FMl188m11WQ

https://www.youtube.com/watch?v=2OIcAamkTmc

carlos.uruguay · Post by **carlos.uruguay** » Wed Apr 23, 2014 8:41 pm

Very nice videos.
Thank you Bill.
Now I risk the three approximate ID
Unknown1 Perhaps Frontonia
Unknown2 a Hypotrichida, without certainty perhaps Oxytricha
Unknown3 Perhaps Chilodonella
carlos

Olympusman · Post by **Olympusman** » Thu Apr 24, 2014 2:15 pm

I agree with Carlos that #3 is Chilodonella

Bruce Taylor · Post by **Bruce Taylor** » Thu Apr 24, 2014 4:52 pm

Hi Bill. As Carlos says, the first guy is a big Frontonia, unmistakeably. Some would go so far as to call it F. leucas, but who believes in species anymore?

The most we can say about the second one is that it is a flexible stichotrichian (a hypotrich, in the loose sense of the word). To identify these guys properly, you have to get a good look at patterns in the cilia, particularly on the ventral surface. No fair trying to leapfrog over that step and identify the critter by its approximate shape and behaviour.

The third is probably a member of the family Chilodonellidae, but if we are being scrupulous we ought to go up one level and just call it a Chlamdydodontid. We don't see enough here to identify it to genus level. For instance, to distinguish between Trithigmostoma and Chilodenella you need to determine whether it has a bald spot on its belly.

And Pseudochilodonopsis has a series of short kineties on the suture line (where the somatic kineties meet, between the mouth and rostrum), etc.

billporter1456 · Post by **billporter1456** » Thu Apr 24, 2014 7:30 pm

Since everyone seems to agree that #1 is a Frontonia, that's what I will call it in the description under the video. In fact, now that I know what it is, I will probably make a slightly longer video featuring this organism.

For #2, I see no problem in taking what Bruce said to put under the video. Namely, "a flexible stichotrichian."

After seeing the comments by Carlos and Olympusman about #3, I looked at several videos and became convinced that you were both correct. But I must consider Bruce's advice as well. Just to be safe, I'll say that it looks like a Chilodonella to me and several others, but I can at least say that it is, "a Chlamdydodontid."

Thanks to the three of you for your help!

carlos.uruguay · Post by **carlos.uruguay** » Thu Apr 24, 2014 9:13 pm

Hi Bill.
With respect to Unknown3 I think that you might do a video to more increase to seek the characteristics that Bruce explained
Regards
carlos
Pd. Thanks Bruce for your always valuable explanation

Protos · Post by **Protos** » Fri Apr 25, 2014 2:41 am

I agree with everyone regarding Frontonia and The chilodonella like ciliate.
My guess for the Hypotrich one is Tachysoma based on shape, vacuole location and flexibility. That said I would love see more details on Cirri for further confirmation.

Bruce Taylor · Post by **Bruce Taylor** » Fri Apr 25, 2014 6:57 am

Hi Protos.

This is a pretty instructive example of the difficulties caused by trying identify hypotrichs on the basis of their approximate appearance.

The drawing above (originally from Wang & Nie, Report on the rare and new species of fresh-water infusoria, 1935) shows Tachysoma pellionellum. It's a common species, known under a variety of names (T. pellionella, Oxytricha pellionella, etc.) This particular image of the critter kind of looks like our guy...bulgy in the middle, skinnier at the ends. However, here is the same species as drawn (more authoritatively) by Foissner:

As it happens, Tachysoma pellionellum (like most of its congeners) is a very small creature...usually between 65 and 85 µm! The guy in Bill's video is perhaps three times longer than that (bigger than the Paramecia around him). Bill's guy also seems to lack those very prominent marginal setae (though it's hard even to be sure about that), and we don't see any characters that are specific to Tachysoma.

The characters we do see (location of vacuole, overall flexibility and shape) are all very weak, and do not get us below the subclass level. Yes, this could be an unusually big Tachysoma (T. chilensis is about 200 µm, which is at least in the ballpark), or some other Oxytrichid w/ 18 cirri on its tummy. But it could also be a Urostylid (which is a little like saying, "It could be a tiger, or it could also be a zebra"). Without seeing the defining traits, we're just guessing.

Protos · Post by **Protos** » Fri Apr 25, 2014 9:05 am

Bruce Taylor wrote:Hi Protos. This is a pretty instructive example of the difficulties caused by trying identify hypotrichs on the basis of their approximate appearance.

The drawing above (originally from Wang & Nie, Report on the rare and new species of fresh-water infusoria, 1935) shows Tachysoma pellionellum. It's a common species, known under a variety of names (T. pellionella, Oxytricha pellionella, etc.) This particular image of the critter kind of looks like our guy...bulgy in the middle, skinnier at the ends. However, here is the same species as drawn (more authoritatively) by Foissner:

As it happens, Tachysoma pellionellum (like most of its congeners) is a very small creature...usually between 65 and 85 µm! The guy in Bill's video is perhaps three times longer than that (bigger than the Paramecia around him). Bill's guy also seems to lack those very prominent marginal setae (though it's hard even to be sure about that), and we don't see any characters that are specific to Tachysoma.

The characters we do see (location of vacuole, overall flexibility and shape) are all very weak, and do not get us below the subclass level. Yes, this could be an unusually big Tachysoma (T. chilensis is about 200 µm, which is at least in the ballpark), or some other Oxytrichid w/ 18 cirri on its tummy. But it could also be a Urostylid (which is a little like saying, "It could be a tiger, or it could also be a zebra"). Without seeing the defining traits, we're just guessing.

Can't agree more ! Cirri location rules !
Reminds me I should get back to my protargol

billporter1456 · Post by **billporter1456** » Fri Apr 25, 2014 11:30 am

I tried to get a bit better images of this protist. I'm not at all sure that the video shows structure well enough for a better guess at identifying the organism, but I'll upload it tonight and post a link tomorrow.

billporter1456 · Post by **billporter1456** » Sat Apr 26, 2014 10:31 am

In case anyone is still interested in the ID of Unknown #2, I did another video featuring this critter. Every one of these I've seen is about the same size, always a bit larger than the largest Paramecium. I happened to catch one expelling something and started the video with that. It's about a 2 minute watch. https://www.youtube.com/watch?v=6DqWUWbHTCo

Bruce Taylor · Post by **Bruce Taylor** » Sat Apr 26, 2014 11:29 am

Well, it has caudal cirri, which rules out a few critters (including Tachysoma). It still doesn't get us below subclass Stichotrichia, though.

When you get one of these guys under slight compression like this, that's the best time to observe the ventral cirri. You need to focus specifically on the pellicle, and forget about keeping the rest of the organism in focus. You'll have to play with diaphragm & illumination (a wide open diaphragm often helps, especially if you are viewing on screen and can boost contrast through software settings).

Rather than waiting for evaporation to cause coverslip compression, you might want to go straight to the endgame. First, select an individual specimen with a micropipette (a glass pasteur pipette, drawn thin on a gas flame) and put it, in its teeny drop, on a slide. Then put a dab of vaseline on each corner of the coverslip and drop it over the specimen. Lightly tapping the coverslip with a needle or pencil increases compression. If you're careful, and your specimen is not too fragile, you can pin your critter in place without exploding it.

Then, start counting cirri and recording their positions, and get on with the (sometimes futile!

) process of keying it out to genus level.

Or, you could just decide that "hypotrich" and "stichotrichian" are perfectly dignified and accurate identifications.

billporter1456 · Post by **billporter1456** » Sat Apr 26, 2014 1:18 pm

Bruce Taylor wrote:Well, it has caudal cirri, which rules out a few critters (including Tachysoma). It still doesn't get us below subclass Stichotrichia, though.

When you get one of these guys under slight compression like this, that's the best time to observe the ventral cirri. You need to focus specifically on the pellicle, and forget about keeping the rest of the organism in focus. You'll have to play with diaphragm & illumination (a wide open diaphragm often helps, especially if you are viewing on screen and can boost contrast through software settings).

Rather than waiting for evaporation to cause coverslip compression, you might want to go straight to the endgame. First, select an individual specimen with a micropipette (a glass pasteur pipette, drawn thin on a gas flame) and put it, in its teeny drop, on a slide. Then put a dab of vaseline on each corner of the coverslip and drop it over the specimen. Lightly tapping the coverslip with a needle or pencil increases compression. If you're careful, and your specimen is not too fragile, you can pin your critter in place without exploding it.

Then, start counting cirri and recording their positions, and get on with the (sometimes futile! ) process of keying it out to genus level.

Or, you could just decide that "hypotrich" and "stichotrichian" are perfectly dignified and accurate identifications.

Bruce, thank you for taking the time to make such a detailed and informative reply! My main motivation for identifying any microorganism is to avoid giving incorrect information in the little videos I make. Even when I make a video with the intention of it being humorous, I don't want it to have misleading or wrong information.

I find myself more interested in the behavior of the organisms than their taxonomy, but, of course, I need to be aware of at least a bit of taxonomy to avoid ascribing a particular behavior to the wrong organism. I don't want to title a video, "Rotifer eats Stentor" when it was a Stentor eating a Rotifer.

So, all of this being said, I have decided that, " 'hypotrich' and 'stichotrichian' are perfectly dignified and accurate identifications."

I'll try to not make a pest of myself asking for IDs, but don't be surprised if I try to take advantage of the members of this forum from time to time by seeking their help in making an identification.

Bruce Taylor · Post by **Bruce Taylor** » Sat Apr 26, 2014 3:06 pm

I look forward to seeing what turns up in your sample jar.

I do share your interest in watching behaviour...I think doing taxonomy has improved my observational skills, overall. I think of it as an exercise in "honest seeing."

Re. the cirri you need to notice to identify these troublesome hypotrichs...here's one I recorded in January with the various hairy bits labeled: https://www.youtube.com/watch?v=BGDQxaRy5FM

Help with IDs for three ciliates

Help with IDs for three ciliates

ID

Thanks for your help!

I made another video of "Unknown #2"

As promised, here's another look at Unknown #2