Hypotrichia ID help

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D0c
Posts: 267
Joined: Mon Nov 30, 2020 9:13 pm
Location: England

Hypotrichia ID help

#1 Post by D0c » Thu May 06, 2021 6:16 pm

A couple of hypotrichia that I need help with.

After going through the images of hypotrichia species inside the Foissner and Berger book I think this might be a Histriculus vorax. The book states it appears broadly rounded and sometimes notched with caudal cirri the same length as the marginal cirri. Quite large about 150µm in length

Video 1 (100X) - https://www.flickr.com/photos/154534235 ... datetaken/


Once again looking through some web sites etc I think this maybe a Uroleptus, the posterior end is pointed or tail-like, and I'm not sure but I might be able to see the odd glance of two rows of midventral cirri. As for size I would say about 160µm. The video is a combination of 100 and 200X.

Video 2 (100/200X) - https://www.flickr.com/photos/154534235 ... datetaken/
Leitz SM-Lux

Bruce Taylor
Posts: 986
Joined: Fri Sep 04, 2015 11:34 am

Re: Hypotrichia ID help

#2 Post by Bruce Taylor » Thu May 06, 2021 7:42 pm

The first one is a rigid-bodied oxytrichid with a very large AZM, and very highly-developed frontal cirri. We can confidently put it in the subfamily Stylonychinae. Histriculus is in that subfamily, however that genus lacks caudal cirri, by definition, so your critter is not one of those. It looks a lot like something in the Stylonychia mytilus complex, but with under-developed caudal cirri (only one is prominent, and it is not particularly long). It might be a Stylonychia post-divider, or possibly a recently-excysted specimen whose caudal cirri are only partially regenerated. It could also be another stylonychine, such as Steinia (identifying that genus requires close focus on the peristome, which has a distinctive shape). I would look for more specimens in the same water. As always, it's easier and more reliable to identify a population than it is to identify a single specimen.

The second critter could be a chubby Uroleptus, but there are other things it could be. Having a bit of a tail is just not enough for a genus-level ID, unfortunately. We see this guy from the dorsal side, and I can't make out any midventral cirri (perhaps I'm just overlooking them?). Anyway, I can't help narrow this down below "hypotrich."

D0c
Posts: 267
Joined: Mon Nov 30, 2020 9:13 pm
Location: England

Re: Hypotrichia ID help

#3 Post by D0c » Thu May 06, 2021 7:53 pm

Very interesting reply it gives me some pointers to read up on. Thanks once again for all your in depth knowledge.
Leitz SM-Lux

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