Is this the flagellate Petalomonas?

[macnmotion]

Is this the flagellate Petalomonas?

[Bruce Taylor]

We see an ovoid heterotrophic euglenoid with a strongly ribbed pellicle, but I can't make out an ingestion apparatus or any flagella. I don't see how we can rule out a strongly ribbed biflagellate, like certain species of Ploeotia and Entosiphon. Is there a particular species of Petalomonas you had in mind?

[macnmotion]

At various frames in the videos, when I look frame by frame, a flagellum comes into focus. I'll grab a screenshot when home. I was hoping to ID to at least the genus level for the BioBlitz project but I had thought I probably don't have enough detail. I had thought the ribs, along with the barrel shape (not flat) might be enough. I'll scan for frames with better detail and post anything I find here. Thanks Bruce.

[macnmotion]

We see an ovoid heterotrophic euglenoid with a strongly ribbed pellicle, but I can't make out an ingestion apparatus or any flagella. I don't see how we can rule out a strongly ribbed biflagellate, like certain species of Ploetia and Entosiphon. Is there a particular species of Petalomonas you had in mind?

Hi again Bruce. I've slowed down a couple short clips to 10% speed and zoomed in (at the expense of resolution), but it's pretty clear that there are 2 short flagella. Does this help?

[Bruce Taylor]

If there are 2 flagella it rules out Petalomonas, which has just one. I think the length of the flagella is indeterminable, because depth of field is limited. I believe this is probably a ploeotid of some kind (e.g. Lentomonas corrugata, Ploeotia, Olkasia). However, I don't have much experience with heterotrophic euglenids (and even less with marine flagellates!). A more knowledgeable person might recognize this at a glance.

A paper on ploeotids, with some nice photos: https://pubmed.ncbi.nlm.nih.gov/31102975/

[macnmotion]

Ok thanks. Brought down by the old double flagella!