Identificaciones de peptolab

A predatory ciliate of the family Colpodidae that feeds on the ciliates Colpoda sp.

A sample was taken from the moss on the tree bark. The sample was stored at room temperature and observed one day after collection.

Video: https://youtu.be/S5B7_vhAbJQ

A water sample was taken from the shore of Srednerogatsky Pond. The air temperature was 14°C (57.2 °F). The sample was stored at room temperature and observed 10 days after collection.

Video: https://youtu.be/7Awc1MaxZm0

A ciliate with a curious flagellum-like process at its anterior. This structure is not a true flagellum. It does not move independently, but simply dangles from the ciliate's mouth as it swims around. Its purpose is not known. In other respects, Ileonema closely resembles Trachelophyllum. Like members of that genus it is enveloped by a coat of ornate epicortical scales, visible only in the scanning electron microscope. (See Foissner's monograph on Terrestrial and Semiterrestrial Ciliates from Venezuela and Galápagos, pp. 50ff)

Ileonema dispar is the type species of the genus, which was erected in 1884 by Alfred C. Stokes. In 1922, Penard described a similar species under the name I. simplex. I think there reason to believe that I. dispar and I. simplex are the same species, viewed in different conditions. Penard observed only one specimen, although he was able to watch it for a couple of hours. Stokes found I. dispar "in abundance", and describes it as having a variable shape: "Its changes of form are...quite constant as it rests among the algal threads and lengthens the entire body into a club-shaped creature searching for food, or contracts into an egg-shape with a short, narrow neck." However, he only illustrates one specimen (a rather pudgy one!), and it is this illustration that was reproduced in Kahl, with a short description (Kahl does not seem to have found the organism himself). Stokes also observed that his Ileonema is nearly identical in overall appearance to Trachelophyllum apiculatum: a telling comment, since the latter is usually quite slender, like Penard's simplex.

Stokes describes the "flagellum" as follows: "entire flagellum one-half the length of the body, the basal half thick, obliquely grooved and presenting a twisted or cord-like appearance, slightly tapering yet suddenly constricted at the beginning of the finely filamentous distal one-half."

The "flagella" of my critters are generally shaped much as Stokes describes: quite thick at the proximal end, finely filamentous at the distal. Seeing them at low magnification, it's easy to see how he might have misinterpreted the flagellum as being twisted, or ropelike. In my observations, the flagella of some individuals, at certain levels of illumination, appear to be quite uniform from base to tip.

The Ileonema in my population are also extremely contractile, ranging in shape from plumply ovoid to gracefully attenuated and vermiform. After they've eaten, they become almost unrecognizable!

A few more specimens of Ileonema dispar, the type species of the genus, which, as far as I know, has not been recorded since it was discovered by Stokes in 1884. It is differentiated from I. simplex by its flagellar process, which, in the species Stokes describes, is in two distinct parts, thick at the base and finely filamentous at the distal end (Stokes, 1884; Penard, 1922; Kahl, 1930). This is reflected in the name of the species, "dispar" (=unequal). Stokes also describes the species as having two contractile vacuoles in the posterior, an arrangement that would be extremely odd for a trachelophyllid ciliate. In several specimens, I observed some compartmentalization in the posterior vesicle, which could easily be read as two separate vacuoles adjacent to the "anal pore." See image #4.

The flagellar process is retractable, and its appearance is quite variable. The division of this organelle into two distinct parts--which I did not see in every specimen--strikes me as a weak character. As I noted in my previous observation, I think there is some reason to think that I. simplex should be considered a junior synonym of I. dispar (or possibly a variant, or sub-species).

I caught one in fission, and have included two images of the dividers.

I also watched an individual eating a huge clump of debris containing living and dead algae. This observation, and the contents of the cytoplasm in other individuals, lead me to think the critter lives by consuming small round green algae.

Mag. 400x
Euglenoid with grit/sand-covered body, and a cytostome surrounded by a flared collar with a distinct rim. It uses a single flagellum for locomotion. It feeds on detritus and small algae. In the linked video you will see the creature worm its way through a mound of detritus, https://youtu.be/PUfNi0aoE5U. There were instances when it appeared to be foraging/feeding; the flared anterior moving over a surface like a handheld vacuum. :o) A very similar creature (but only in swimming rather than feeding mode) was observed from a different, local water-body https://www.inaturalist.org/observations/107162369.

• A water sample was taken on 5/8/2023, from the shore of Lantern Hill Pond, using a 10µ dip net to enrich for microbes. Air temp. 73°F.

Mag. 400x
First image shows the 5/8/23 specimen in 2 focal planes. The slumped shoulders are closer to the base of the semi-cell rather than the apex. Interestingly, the shoulders are more pronounced in the lower semi-cell. In the second image, I compare the current specimen with 2 other similarly shaped specimens (from 4/20/23: https://www.inaturalist.org/observations/156155539, from 5/22/21: https://www.inaturalist.org/observations/80061147). I'm still struggling to determine the difference between E. humerosum as pictured here http://www.digicodes.info/Euastrum_humerosum.html#2013014002 and E. didelta as variously depicted here https://www.algaebase.org/search/images/detail/?img_id=25833 and http://www.biolib.de/migula/desmidiaceen/high/IMG_9444.html and https://www.mikro-foto.de/assets/images/3/Euastrum%20didelta%20cf-11c04b92.jpg. Consider image 2 a challenge: which is E. didelta and which is E. humerosum?

• A water sample was taken on 5/8/2023, from the shore of Lantern Hill Pond, using a 10µ dip net to enrich for microbes. Air temp. 73°F.

Mag. 100x (1), 400x (2, 3)
Large, wide Closterium; 460µ x 80µ; L/W= 5.75. Described as having an alate (winged) chloroplast; I assume the longitudinal ribs are the wings. In cross-section, the chloroplast would appear stellate (star-shaped), see https://planktonnet.awi.de/index.php?contenttype=image_details&itemid=61475#content. The chloroplast has many, radomly distributed pyrenoids. For additional reference images, see http://www.digicodes.info/Closterium_lunula.html#2011057002 and https://www.algaebase.org/search/images/detail/?img_id=34284 and https://www.desmids.nl/maand/english/closterium_lunula.html.

• A water sample was taken on 4/26/2023, from the shore of a Pine Swamp impoundment, using a 10µ dip net to enrich for microbes. Air temp. 58°F.

Water sample (freshwater) was taken on 2023-04-09 using a turkey baster.

These five images show what might be an Acineria feeding on a Rhynchomonas nasuta.

Here are some links to videos of more of the feeding process: https://youtu.be/4Mqo76Nd_Go
https://youtu.be/ePp3ZNQhevA
https://youtu.be/jr-OqmsKmyE

Magnification of photos: 200×, 200×, 200×, 200×, 200×, 400×, 400×, 400×, 400×, 400×, 400×
Habitat: water and organic matter floating, in a salt marsh. Salinity unknown, but probably brackish.
Photo taken with a Celestron PentaView Digital Microscope. According to their website, the FOV (i.e. the diagonal width) at 200× is 300 µm.
Really large for a flagellate: about 60 µm long!

Magnification of photos: 200×, 200×, 200×, 200×, 200×, 400×, 400×, 400×, 400×, 400×, 400×
Habitat: water and organic matter floating, in a salt marsh. Salinity unknown, but probably brackish.
Photo taken with a Celestron PentaView Digital Microscope. According to their website, the FOV (i.e. the diagonal width) at 200× is 300 µm.
Really large for a flagellate: about 60 µm long!

Same living cell, three focal planes. Left shows anterior cingulum and its flagellum, then central shows cingulum sulcus and nucleus with sausage-like chromosomes and right the sulcus and its flagellum. Nomarksi optics.