Plagiophrys armatus?

fpelectronica · Post by **fpelectronica** » Thu Dec 01, 2011 11:55 am

Hello
For Id
http://youtu.be/gSUhbIrI-pc
Francisco

Chris_M · Post by **Chris_M** » Thu Dec 01, 2011 1:01 pm

Great! I've never seen that.

Mitch640 · Post by **Mitch640** » Thu Dec 01, 2011 1:28 pm

Oh Wow, it's a testate amoeba. I thought at first it was a ciliate eating some kind of squashed bug. I wondered why it was moving so slow.

Ferry · Post by **Ferry** » Thu Dec 01, 2011 3:43 pm

Congratulations! I also have never seen this one, maybe a look-a-like (www.arcella.nl/plagiophrys-armatus) which I temporarely gave this name and from the time when there were no digital cameras. But yours is definitely a Plagiophrys species and probably P. armatus. Do you also have photographs?

Cyclops · Post by **Cyclops** » Thu Dec 01, 2011 4:20 pm

Fabulous!! Now what is the long thin line travelling left to right at the top-bacteria chain?

Bruce Taylor · Post by **Bruce Taylor** » Thu Dec 01, 2011 8:51 pm

Ferry wrote:But yours is definitely a Plagiophrys species and probably P. armatus. Do you also have photographs?

Who described Plagiophrys armatus? My internet searches all lead to your (excellent) site!

Being somewhat inexperienced at identifying amoeboids, I'd have assumed this was one of the "hairy / spiny" euglyphids...Euglypha strigosa, ciliata, compressa, etc. Or maybe, Placocista spinosa.

Interesting video, in any case.

I've only run across one Plagiophrys...and mine was a smooth type, with a rather assymmetrical test: https://www.youtube.com/watch?v=snH1JXwZLRM

Mitch640 · Post by **Mitch640** » Fri Dec 02, 2011 1:09 am

Bruce, that is Ferry's excellent amoeba site. I use it all the time.

Cactusdave · Post by **Cactusdave** » Fri Dec 02, 2011 1:16 am

An excellent video in its own right, irrespective of the unusual an intriguing nature of the subject. Some detail of camera and microscope would be interesting.

RogelioMoreno · Post by **RogelioMoreno** » Fri Dec 02, 2011 4:49 am

Francisco,

Interesting video and specimen!

Rogelio

Bruce Taylor · Post by **Bruce Taylor** » Fri Dec 02, 2011 7:29 am

Mitch640 wrote:Bruce, that is Ferry's excellent amoeba site. I use it all the time.

Yes, it's a wonderful site.

Reading Ferry's post more carefully, I see he means that P. armatus is his own name for a possibly-undescribed species. Most interesting!

Ferry · Post by **Ferry** » Sun Dec 04, 2011 5:28 am

Bruce, Plagiophrys armatus was originally described by Lauterborn (1901), and later by Penard (1902) as Pamphagus armatus. Probably the same amoeba was described by Cash, Wailes and Hopkinson in 1915 with the name Lecythium spinosum.
The problem is that those old descriptions are inadequate. See the description of Penard (translated from French): 'Body has the shape of a pocket. Membranous test with curved spines all over its surface. 45-70 um' So, that's all, without any picture...
Wailes (1915) description: 'Test membranous, ovoid or pyriform, unsymmetrically compressed, furnished with short curved spines; aperture sub-terminal, oblique; nucleus granular, placed posteriorly; plasma filling the test, pseudopodia numerous, simple or branched. 45-70 um.' and at least with some pictures.

Your smooth Plagiophrys is Plagiophrys scutiformis. Scutiformis means: shaped like a shield (of a knight).

Bruce Taylor · Post by **Bruce Taylor** » Sun Dec 04, 2011 8:50 am

Ferry wrote:Your smooth Plagiophrys is Plagiophrys scutiformis. Scutiformis means: shaped like a shield (of a knight).

Thank you so much! I'm delighted to have species-level ID for that guy. I've been trying to be careful about names, because a misidentified organism on YouTube can lead other amateurs astray. (I've been fooled more than once by sloppy identifications, and have no doubt misled others. )

When looking for Plagiophrys armatus I ran across Lauterborn's Pamphagus, but was confused by it, because Pamphagus (which I've never run across) was described as having a soft test. Being unfamiliar with the genus, I imagined to be more like that of a Thecamoeba.

I'm familiar with the difficulties that can be caused by inadequate and overlapping descriptions of "historic" amoeboids (many of which were assigned to a species on the basis of a single sighting). I recently struggled to untangle the bizarre career of Chaos chaos/C. Proteus/Pelomyxa carolinensis/C. carolinensis for the Wikipedia entry on the genus Chaos...a very messy -- you might even say chaotic! -- business.

Rarely-seen organisms like Pamphagus/Lecythium/Plagiophrys (if indeed they're one creature) seem to be a particularly fertile breeding ground for synonymy. I've noticed that amateurs like me have a tendency to resurrect cast-off synonyms and names of taxonomical ill-repute.

That may be because the internet has made older materials, like the works of Leidy, Stein, Kahl, Saville-Kent, freely available, while the latest work is often sequestered behind a pay-wall. Well, I guess it will all change anyway in the next few years, as the molecular data rolls in.

Thanks again, Ferry. You can bet I'll look more closely (and turn on the camera!) the next time I see something that looks like a hairy Euglyphid.

fpelectronica · Post by **fpelectronica** » Sun Dec 04, 2011 9:37 am

Thanks for your comments
Ferry, I have no pictures but I can Get original video screen capture
Cyclops Yes, it is a bacteria, possibly Spirillum
Bruce actually, there is almost no information online about P. armatus
Cactusdave I use a Nikon Fluophot microscope and a camera cctv Panasonic
Francisco

Bruce Taylor · Post by **Bruce Taylor** » Sun Dec 04, 2011 9:49 am

fpelectronica wrote: Bruce actually, there is almost no information online about P. armatus

That is because Ferry himself created Plagiophrys armatus. If you search for the synonyms "Pamphagus armatus Lauterborn" and "Lecythium spinosum" you will find more.

Bruce Taylor · Post by **Bruce Taylor** » Sun Dec 04, 2011 10:45 am

Ferry wrote:The problem is that those old descriptions are inadequate. See the description of Penard (translated from French): 'Body has the shape of a pocket. Membranous test with curved spines all over its surface. 45-70 um' So, that's all, without any picture... .

I had a look at Penard's Faune rhizopodique du bassin du Léman (1902) and was pleased to see that he did supply a very small (and easily overlooked!) picture of Pamphagus armatus on p. 573:

He regarded Lauterborn's Pamphagus as a synonym of an organism he's previously described as Trinema spinosum (see his self-correction on p. 578)

Downloadable .pdf of Penard's text: http://www.archive.org/details/faunerhizopodiqu00pena

Edit to add:

Here's an illustration of Lecythium spinosum (=Trinema spinosum, Pamphagus armatus and Plagiophrys armatus) from Plate L in vol III of Cash, Wailes & Hopkinson, British Freshwater Rhizopoda and Heliozoa:

Downloadable .pdf here: http://www.archive.org/details/britishfreshwate03cash