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Water sample taken from the edge of a freshwater playa on 2024-01-28 using a turkey baster.
Length: 90 µm
Width: 45 µm
Trophi: 32 µm
Toes: 14 µm
Ratios: L/TL: 6.4

Two eyespots. Type C virgate trophi.

1. Dorsal view shows the two eyespots and trophus.
2. Lateral view showing toes.
3. Another lateral view.
4. Remainder of images show various views of the trophus.

From the tychoplankton, collected by net beside the bridge across the stream. The zooids are about 60-70 µm in diameter, and the open peristomial lip is about 100 µm wide. The stalks are 500-600 µm long, extended. Presumably V. campanula. One of the shots is of the cells stained with a fluorescent nucleic acid stain (not entirely specific to nucleic acids as you can see). The last gif is slowed 60 X, trying to capture the moment of contraction.

Habitat small, temporary, grassland pool.
Image 1 - female, ventral view with eggs and two attached spermatophores.
Image 2 - male, ventral view.
Image 3 - male 5th pair of legs, posterior view, showing i) inner and distal processes on left exopod 2 forming a pincer-like structure, ii) spiniform process on outer distal corner of right basis.
Image 4 - male right first antenna, showing short, curved, spinous process at distal end of antepenultimate segment.
Image 5 - female posterior dorsum showing elongate outer sensilla on metasomal wings.
Image 6 - female 5th pair of legs.

On a small piece of decayed vegetation from the marsh. The microscope field at 1000x is 200 µm wide, and this creature is larger than that when extended. The third gif is slo-mo so that you can almost catch a glimpse of the 'head'.

Lac Gilbert is a headwater lake in a valley, which protects it from the wind. It has a relatively deep hole (12 m) at one end that allows the bottom water to go anoxic over the course of the summer. The stability of the water column means that distinct bands of different communities develop in layers in the water, and also on the sediments. For instance, above the anaerobic zone that starts at 9 m depth, there is a band of Hydra on the sediments that feeds on migrating zooplankton.
The surface water is pristine and low in nutrients, so phytoplankton abundance is low, allowing light to penetrate deep into the lake. Photosynthetic pigments increase greatly in the anoxic layer, where large populations of anoxygenic photosynthetic bacteria appear. Just above the oxygen-free zone, the sediments develop a dense mat of spiral cyanobacteria, Arthrospira jenneri. Their identity is given away by the thickness of the filament relative to coil length. A. jenneri, like all cyanobacteria, is facultatively anaerobic. That means it can grow in a zone that is bathed in the nutrients released by anaerobic processes.
These are images from both the water column and the sediment mat. Some are transmitted light and some are by epifluorescence. Some are unstained and some are stained with a fluorescent dye (DAPI) that makes nucleic acids fluoresce light blue. Arthrospira is blue-green by transmitted light, and red by epifluorescence. The red of epifluorescence signals the presence of chlorophyll. Sediment samples will have bright yellow particles. These are granules of polyphosphate that are stored by bacteria and that glow yellow when stained by DAPI. The deep water column samples, without DAPI, contain cyanobacteria, and also photosythetic picoplankton (red dots) that are probably photosynthetic bacteria.
The filament labelled Oscillatoria in one of the photos is orange because it contains a fluorescent auxiliary pigment, phycoerythrin. It might be another member of the Oscillatoriales, maybe Planktothrix, but there is no large Planktothrix layer in the lake.

Aspidisca leptapsis Fresenius, 1865 from the coarse sand sulfidic intertidal benthos of marine estuary Acabonac Harbor at Louse Point launching ramp. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone camera cropping on Samsung Galaxy S9+.

The cells measure from 66-80 um in length. There are four dorsal ribs on the rigid pellicle. There is a prominent left peristomial spur adjacent to the posterior AZM and a smaller left lateral anterior spur. The posterior cell margin shows 3 or 4 subtle serrations or spurs. There are six transverse cirri with the rightmost one being split into two at the base. There are seven strong fronto-ventral cirri and a single weak one. These characters are congruent with the description of the species by Song and Wilbert (1).

From Song and Wilbert 1997:
"Size of our populations in vivo about 60-80x40-50 um, body elliptical with snout-shaped anterior end; broadest in or behind mid-body, right margin convex, left almost straight, anteriorly broadly rounded; dorso-ventrally highly flattened (ca. 1:2.5-3). Outline associated with indentation or protrusion of cell, one lateral spur subapically located, which is usually smaller than prostomial one even inconspicuous in some specimens. Additionally, several (4-6) posterior spurs on border of caudal portion, which make the cell usually rugged (q.v. Borror 1968; Dragesco 1960; Kahl 1932; Tuffrau 1964). Ventral surface generally flattened, on dorsal always 4 dominant ridges. Buccal area with 1 distinct thorn-like projection (prostomial spur) on left subcaudally, which covers the AZM2. Pellicle rigid. Cytoplasm hyaline. Contractile vacuole right of median, at level of adoral zone of membranelles. Macronucleus C-shaped, with many spherical nucleoli (ca. 1-2 um). Micronuclei several in number (usually 3-5), always located in depressions of macronucleus. Movement crawling on substrate, quite fast compared with other congeners. When disturbed, always attached to substrate firmly for quite a while. Ciliary pattern stable. Frontoventral cirri rather stiff and strong, cilia of 7 large ones about 12-15 um long; one small, satellite-like cirrus close to right-most (posteriormost) cirrus, which is easy to be overlooked (q.v. Agamaliev 1967). Transverse cirri usually strong, tightly arranged in oblique row, base of right-most cirrus always splitting (but mostly imperfectly) into closely spaced 2-3 ones or even more, which are in vivo clearly recognizable. Cilia of transverse cirri about 15-20 um long. Anterior portion of adoral zone (AZM1) containing 7-8 membranelles, located in deep concave. Posterior part (AZM2) significantly long, as usual beneath lid-like prostomial spur. Paroral membrane (PM) small, difficult to observe. Pharyngeal fibres curved anteriorly. Constant 4 dorsal kineties with tightly spaced basal body pairs. Very characteristically, both basal bodies ciliated with rossete-shaped granules at bases of cilia. Each kinety along dorsal ridge and generally extending from end to end of cell (yet 2 central rows may be slightly shortened at posterior end)" (1).

"As we observed both from newly collected samples and in culture, the dorsal ridges and spurs in caudal region, which form the rugged body outline, could vary from less to very conspicuous. Since those characters are so variable and depend so much on description of the observers, we appraise these as weak characters for species separation. Alike is the number of transverse cirri: since the left-most one is only partly divided (the bases are closely connected), the number of those cirri might depend in a large scale on the quality of impregnation. Due to these factors, we suggest that forms with 5-8 transverse cirri, with or without appearance rugged body outline but similar in all other morphological (in vivo and at infraciliature level), biological (habitat, behaviour) and morphometric features should be considered as the same species. Based on the reasons stated above, we synonymize with Aspidisca leptaspis the following species (see; Syn) simply because they show basically no differences but the number of transverse cirri and "absence" of spurs at caudal end of cell" (1).

The redescription of A. leptapsis by Li et al (2010) lists the following synonyms laid out by Song and Wilbert (1997): "Aspidisca leptaspis Fresenius, 1865 Syn. A. sedigita Quennerstedt, 1867; A. crenata Fabre-Domergue, 1885; A. sedigita sensu Dragesco, 1960; A. lyncaster sensu Tuffrau, 1964; A. baltica sensu Borror, 1968; A. psammobiotica Burkovsky, 1970; A. lyncaster sensu Fleury et al., 1968". They depict the subtle posterior serrations (also called spines- see figure from their paper included here) (2).

1. Morphological Investigations on Some Free Living Ciliates (Protozoa, Ciliophora) from China Sea with Description of a New Hypotrichous Genus, Hemigastrostyla nov. gen. Weibo Song, Norbert Wilbert. Archiv für Protistenkunde Volume 148, Issue 4, December 1997, Pages 413-444
2. Morphological Redescriptions of Aspidisca magna Kahl, 1932 and A. leptaspis Fresenius, 1865 (Ciliophora, Euplotida), with Notes on Ontogenesis in A. magna. Liqiong LI, Qianqian ZHANG, Khaled A. S. AL-RASHEID, Choon Bong KWON, Mann Kyoon SHIN. Acta Protozool. (2010) 49: 327–337

Mag. 100x (1-3), 400x (4-6)

• A pond-side water sample (retentate) was taken using a 10µ dip net to enrich for microorganisms. Air temp 58F.

Rotifer. Two thorn-like spines at the top of the foot. Long toes. Looks similar to Trichotria tetractis as seen here https://www.plingfactory.de/Science/Atlas/KennkartenTiere/Rotifers/01RotEng/source/Trichotria%20tetractis.html and as observed by @paul_norwood here on iNaturalist https://www.inaturalist.org/observations/95064795.
For a video of this speciment: https://youtu.be/pIN2rfAvreE.

Water sample taken from the edge of a stagnate freshwater playa on 2023-08-27 using a turkey baster.

Model for labels:
https://en.wikipedia.org/wiki/Stylonychia#/media/File:Stylonychia_mytilus.png

Thank you to Bruce Taylor for help with these labels.

Host was Mississippi Kite, Ictinia mississippiensis. Laemobothrion maximum is apparently a known ectoparasite of Ictinia mississippiensis. https://phthiraptera.myspecies.info/category/avian/aves/falconiformes/accipitridae/ictinia/ictinia-mississippiensis

This is my first time seeing bird lice in person and these look really interesting.

Big thanks to Melissa for saving these two individuals for me. Definitely something I never expected to have in my collection.

Metopus spiculatus from the sulfidic fine sand superficial intertidal benthos of marine estuary Acabonac Harbor. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone camera cropping on Samsung Galaxy S9+. The cell measures 84 um in length. The Latin adjective “spiculatus” refers to the distinctive, beak-like anterior protrusion which is present in this specimen. The needle-like intracytoplasmic structures were not visualized. Sample collected Jan 2023- organism observed 7-2-2023.

Marine form about 55–100 × 25–40 μm in vivo. Body shape oblong to ovoid. Preoral dome extremely compressed, distal end curved and tapered into a conspicuous beak-like structure. Posterior body tapered sharply into an about 25 μm long tail. Cell surface covered by a layer of rod-shaped ectosymbionts arranged perpendicularly except for most of the preoral dome and tail zone. Cytoplasm filled with needle-like intracytoplasmic structures, aggregate in the anterior part. Elongate ellipsoidal macronucleus centrally located below the preoral dome and spherical micronucleus. On average, 21 somatic kineites including 5 preoral dome kineties. Perizonal stripe rows 1 and 2 forming false kineties. The adoral zone consisted of about 20 membranelles, occupying about 30% of body length. Paroral membrane double-rowed with one about twice as long as the other. Sulfide-rich sediments in an intertidal zone in Liujiawan, Rizhao (119°26′, N35°17′), China.

M. spiculatus sp. n. can be distinguished from all other Metopus by the following characteristics: (i) marine habitat, (ii) rod-shaped ectosymbionts, (iii) a beak-like structure at the preoral dome end, (iv) a posterior body that tapers into a tail, (v) an in vivo size of 75–100 × 30–40 μm, (vi) 17–22 adoral membranelles and 19–25 somatic kineties, and (vii) needle-like intracytoplasmic structures. The new species resembles M. vestitus Kahl, 1932 (Figure 6G) in most features except the distinct beak-like preoral dome end (present vs. lacking). Similar to this new species, M. caudatus, Tropidoatractus acuminatus and Tropidoatractus spinosus are medium-sized, and have an oblong body and one acute tail, but all of them lack ectosymbionts, which are considered as an important feature for species identification (Esteban et al., 1995; Rotterová et al., 2018; Li et al., 2021a). In addition, M. rostratus Kahl, 1932 and Tropidoatractus levanderi Rotterová et al., 2018 also possess a beak-like preoral dome end, but both lack a long tail and conspicuous ectosymbionts as shown in our form (Kahl, 1932; Foissner, 2016a; Rotterová et al., 2018).

New Contribution to the Diversity of the Anaerobic Genus Metopus (Ciliophora, Armophorea), With Descriptions of Three New Marine Species
Wenbao Zhuang, Ran Li, Xiaochen Feng, Saleh A. Al-Farraj and Xiaozhong Hu. Front. Mar. Sci., 26 May 2022. Sec. Marine Evolutionary Biology, Biogeography and Species Diversity. Volume 9 - 2022 | https://doi.org/10.3389/fmars.2022.884834. https://www.frontiersin.org/articles/10.3389/fmars.2022.884834/full

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.

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.

Saprodinium dentatum from the decomposing leaf matter at the edge of my long-neglected garden pond imaged in Nomarski DIC using Olympus BH2 using SPlan 40x objective plus variable phone camera cropping on Samsung Galaxy S9+. The cell measures 66 um in length, body discoid, laterally compressed. Left side with 3 spines the 2 posterior-most two having ciliary rows. Right side with three smaller spines devoid of ciliary rows, the dorsal spine having ciliary row and the large ventral tooth. One macronucleus. Oral opening and adoral zone of membranelles the middle of the ventral side. Perizonal ciliary row very long on right side. Contractile vacuole below adorale zone of membranelles.

"Saprodinium dentatum is a highly asymmetrical cell with extremely reduced somatic ciliature and a number of site-specific spines. The cell shape resembles a laterally compressed helmet of a Roman soldier. The anterior and the dorsal edges of the cell are wedge-shaped, while the ventral and the posterior sides of the cell are wider. Both the length (measured from the anterior to the posterior pole) and depth (measured from the dorsal to the ventral side) of the cell are of about 60 um. Widest point, measured from the right lateral side to the left lateral side in the lower ventral area of the cell, is 15 um. The right side of the cell is dominated by the frontal band consisting of the ciliated anterior segments of five somatic kineties. The long axis of the frontal band is at a right angle to the anterior-posterior axis of the cell. The left side of the cell bears a long dorsal kinety to the left of the dorsal keel. Moreover, the left lateral view shows part of the oral ciliature that is hidden in a complex oral cavity. The oral apparatus lies near the left side of the cell where the body wall is thin and transport. The opening of the oral cavity to the outside is close to the prominent ventrocaudal spine that bears three caudal spine kineties.

The majority of the spines are located around the posterior end of the cell and therefore are called spines. Moreover, a so-called oral spine on the ventral ridge is just above the opening of the oral cavity (this "tooth" close to the mouth led to the name "tooth-mouthed" odontostomes (Corliss 1979), while the "comb-mouthed" ctenostomes had their name from the comb-like array of the adoral membranelles (Kahl 1932)). Finally, a frontal spine is a continuation of the dorsal keel; the dorsal keel is the anterior compressed part of the dorsal ridge. Living cells of S. dentatum are easily identified by their characteristic locomotion and transparency. Cells either swim in a jerky motion or creep with help from the frontal band cilia so that the right side of the cell is orientated toward the substratum. Closer light microscopical observations show that S. dentatum has usually 1-3 macronuclei (12 um in diameter) and one micronucleus (3 um in diameter) located in the posterior part of the cell. Because of the cell's transparency, eight adoral membranelles can be seen in the biggest part of the buccal cavity (actual complexity of the oral apparatus is only seen in electron micrographs). A conspicuous feature in the cell's anterior is an accumulation of strongly refractile spherical bodies called lithosomes (Andre & Faure-Fremiet 1967) because of their inorganic nature. Lithosomes consist of alternating electron-dense and electron-transparent concentric layers of unknown chemical composition; the bigger lithosomes may cause serious difficulties during thin sectioning. Saprodinium dentatum has no typical mitochondria. The cytoplasm is crowded with endobiontic bacteria; many of them seemingly undergoing cell division. Two bacteria of different size can be distinguished; the big ones look similar to the large Gram-negative bacteria found in the heterotrich ciliate Metopus striatus, and the small ones may correspond to the small-sized Gram-positive bacteria in the same ciliate" (1).

1. Hans-Gunther Schrenk and Christian F. Bardele; The Fine Structure of Saprodinium dentatum Lauterborn, 1908 as a Representative of the Odontostomatida (Ciliophora). J.Protozool. 38(3):278-293, 1991

A ciliated swarmer of the suctorian Sphaerophrya magna Maupas, 1881 in my long-neglected garden pond filled with rotting leaves. I previously showed the feeding behavior (https://www.inaturalist.org/observations/162692722). This swarmer measures 30 um in diameter and shows an actively cycling contractile vacuole and large central round macronucleus.

S. magna from this site measure from 37.5 to 50 um in diameter. Imaged in Nomarski DIC using Olympus BH2 under SPlan 40x objective plus variable phone cropping on Samsung Galaxy S9+.

Sphaerophrya magna Maupas, 1881 Spherical; numerous tentacles of different length; nucleus spheroid; standing fresh water with decaying vegetation. Measurements
About 50 um in diameter.