Acropisthium mutabile Perty, 1852 from the decomposing bottom leaf matter at the edge bottom of my long-neglected freshwater garden pond. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone camera cropping on Samsung Galaxy S9+. The cells measure 56 um in length and have an ellipsoid cell body circular in cross section with shallow ridges. The posterior end is tapered and ends in a sharp point. The cytostome is apical and slightly raised above the surface and the cytopharynx is supported by a basket of trichites. There is a single round midposterior macronucleus and a terminal contractile vacuole. It swims with a side to side motion. Thanks to Dr. Martin Kreutz for identifying my observation.

"The phylogenetic affinity of the genus Acropisthium has been rather unstable, assigned to the family Didiniidae by Corliss (1979), then to the family Trachelophyllidae (Foissner 1984), and then to its current position as the nominotypical genus of the family Acropisthiidae in the suborder Acropisthiina (Foissner and Foissner, 1988)" (1). Like the study of Chi et al 2022 Acropisthium mutabile from my local pond population "was found in the company of typical sapropelobionts (e.g., Metopus spp., odontostomes, Tropidoatractus spp., and Urostomides spp) indicating that it is, at least facultatively, microaerophilic" (1). Chi et al 2022 found prokaryotic ectosymbiosis in Acropisthium mutabile (1).

"Acropisthium mutabile Perty, 1852 The Value of work by Perty,(1852), Eberhard (1858, 1862), Bütschli (1887-89), Shewiakoff (1889), Rimsky-Korsakov (1897), KahI (1926) and Bohatier et al. (1973) and my own observations were convincing me that KahI (1930-35) rightly accepted only one species in this genus. Poorly nourished individuals are beet-shaped, well-fed teardrop. The 45-63 pm large animals are very voracious; often one finds 10 food vacuoles with Chilomonas sp. Contractile vacuole and cytopyge open at the suhterminal (Fig. 2)" (2).

"Body shape ovoid to cylindrical, with pointed posterior region and short anterior snout-like process. Oral aperture apical on domed snout, cytopharynx armed with trichites. There is a ciliary band around the shoulder where the snout joins the body which is composed of about 20 short rows of cilia. The body behind the ciliary band is uniformly ciliated by about 20 longitudinal kineties which are usually well spaced, however the anterior half of three of the kineties are closely packed and these bear short clavate bristles representing the dorsal brush. Macronucleus spherical in posterior half body. Contractile vacuole posterior. Single-species genus" (3).

1. Taxonomy and molecular phylogeny of two poorly known ciliate genera, Balantidion and Acropisthium (Protista: Ciliophora: Litostomatea), including a new species of Balantidion. Yong Chi, Yujie Liu, Honggang Ma, Ya Wang, Ran Liu, Saleh A. Al-Farraj, Weibo Song, William A. Bourland. European Journal of Protistology 85 (2022) 125906. https://www.researchgate.net/publication/359845376
2. FOISSNER W. (1979): Taxonomic studies on the ciliates of the Grossglockner area (Hohe Tauern, Austria). III. Families Tracheliidae, Didiniidae, Nassulopsidae and Orthodonellidae. – Acta Protozool., 18: 417–428
3. From NIES Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)
4. Foissner, W., 1984. Infraciliatur, silberliniensystem und biometrie einiger neuer und wenig bekannter terrestrischer, limnischer und mariner ciliaten (Protozoa: Ciliophora) aus den klassen Kinetofragminophora, Colpodea und Polyhymenophora. Stapfia 12, 1–165.

Lagynus elegans from decomposing leaf debris in my long-neglected freshewater garden pond. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone camera cropping on Samsung Galaxy S9+. I have found this organism before in my pond, this is the best imaging I have achieved. The cell measures 112 um in maximal length but throughout the time I observed it, it contracted its neck shortening the cell to as little as 90 um. This is considerably smaller than the specimens of Dr. Martin Kreutz length 130–200 µm, width 40–60 µm (1). Also, Foissner writes: "Size in vivo about 130-200 x 40-60 pm, contracted cells 60-100 pm long.: (2). The posterior body when I first encountered the ciliate was almost cylindrical without the tapering posterior but it soon assumed the more amphora-like shape and became more or less plump in association with the contractile vacuole systole and diastole. Foissner explains this thus: "Contracted and irritated specimens drastically change shape: the plasma migrates from the back to the middle, which swells spherically; the rear end will wrinkled, flat and transparent" (2).

We can see the 5 annular furrows of the "stepped neck". I also was able to visualize the longitudinal furrows of the body of which Dr. Kreutz writes: " The longitudinal furrows of the pellicle is not mentioned by either Kahl or Foissner, although I was able to detect it in all specimens in my population" (1). This is the first time I have demonstrated this structural feature. This is a very well fed individual with its cytoplasm filled with refractile globules obscuring the macronucleus. I have subsequently added more individuals in which the elongate bean-shaped macronucleus with closely applied compact rounded micronucleus are visible. Many individuals are markedly contracted.

From (3):
Lagynus elegans (Engelmann, 1862) Quennerstedt, 1867 or Quennerstedt, 1867 (ref. ID; 3540) reported author and year? (ref. ID; 191, 1629)

Lagynus elegans observed "in vivo" is an elongate ciliate dark in color, with an amphora-like shape. The cytoplasm, of blackish color, appears full of refringent granules. The main part of the cell is cylindrical and wider than the rest of the body. In the anterior region, four or five step-like formations end in a retractable neck at the tip of which a tuft of cilia originates. The posterior part of the ciliate is narrower and flattened, and has in the interior a large contractile vacuole. The macronucleus is usually reniform, even though it sometimes appears oval. It is located in the middle region of the ciliate. Beside it is a small elongated micronucleus which is, sometimes, placed in the central concavity of the macronucleus. Nematodesmal crown: Finally, on the most apical zone of the cell, and surrounding the cytostome, there is a crown of strongly argentophilic nematodesmata. These nematodesmata, as they appear in our preparations, seem to be united to each other by an argentophilic fibrillar structure. In addition, numerous extrusomes are found between the circumoral infraciliature and the nematodesmata.

1. https://realmicrolife.com/lagynus-elegans/
2. FOISSNER W., BERGER H., BLATTERER H. & KOHMANN F. (1995): Taxonomic and Ecological Revision of the Ciliates of the Saprobia System – Volume IV: Gymnostomatea, Loxodes, Suctoria. – Information reports from Bayer. State Office for Water Management, 1: 1–540.
3. https://www.nies.go.jp/chiiki1/protoz/morpho/ciliopho/lagynus.htm#Lagynus%20elegans

Atopodinium fibulatum from my long- neglected garden pond filled with decomposing leaves. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40 objective plus variable phone camera cropping on Samsung Galaxy S9+. Thanks to Dr. Martin Kreutz for identifying my observation.

The discoid cell body measures 56 um in diameter and is laterally compressed. There are two round macronuclei. There is a short frontal tooth, and a ventral tooth above the azm. My population differs from that of others in that there are two macronuclei, however other odontostomatida are known to have variable macronuclear numbers as well. Also, the terminal posterior spine that points dorsally is quite high up close to the posterior aspect of the dorsal keel. There are some large rod-like symbiotic bacteria visible when the focus is perfect.

From Dr. Martin Kreutz https://realmicrolife.com/atopodinium-fibulatum/ : "cell 40 – 60 µm long; body discoid, laterally compressed with flat left and convex right side; one ventral spine (above the adoral zone of membranelles); four posterior spines; anterior extension of the dorsal keel in a tooth-like spine;
short perizonal row of cilia and
short terminal row of cilia on left side; one spherical macronucleus with one adjacent micronucleus
contractile vacuole in posterior third". "Very characteristic in this species is a ventral spine over the adoral zone and a terminal spine pointing to the dorsal side".

From Colin R. Curds, Michael A. Gates and David McL. Roberts "British and other freshwater ciliated protozoa Part II Ciliophora: Oligohymenophora and Polyhymenophora" Cambridge University Press, 1983 (ref. ID; 2014) via NIES: Body discoid, laterally compressed with flat left and convex right sides and covered in pellicular armour with 4 posterior spines and 1 short spine-like anterior extension of the dorsal keel. In addition there is distinct tooth-like spine above the AZM which is characteristics of all odontostomes. Somatic cilia greatly reduced and exist only as a single row in the terminal region. Perizonal complex short, consisting of 5 upper single rows and 2 lower double rows. Single macronucleus and adjacent micronucleus. Sapropelic. Most easily confused with Saprodinium in which there are cilia in both anterior and posterior regions of the body. Single species genus.

A water sample was collected from the shore of Srednerogatsky Pond. The air temperature was 14°C (57.2 °F). The sample was kept at room temperature until it was assayed 7 days later.

Video: https://youtu.be/BHVl8E9kaJ4

Paramecium caudatum from the decomposing leaf debris in my long-neglected freshwater garden pond. Imaged in Nomarski DIC on Olympus BH2 using SPlan 20x and 40x objectives plus variable phone camera cropping on Samsung Galaxy S9+. The population ranges from 187-225 um in length. The cells are cigar-shaped with the posterior end bluntly pointed and with a group of slightly longer cilia compared to the otherwise uniform ciliation. Early microscopists likened its shape to that of a slipper, and commonly referred to it as the "slipper animalcule." The oral groove/ vestibulum is long and slightly oblique; buccal cavity with one endoral membrane and 2 peniculi. There is a single large ellipsoid macronucleus and 1 round compact micronucleus. " Using light microscopy, however, it is possible to discriminate only the Mi type of P. caudatum from the nucleus of other two species. P. caudatum always has the Mi with the so-called “cap”, a space without chromatin at the nuclear pole" (1). Two contractile vacuoles, each with radial canals, are present at the aboral surface which serve to excrete excess water taken up from the outside, regulating the water contents of the body. Radially distributed "collecting canals" give the contractile vacuoles a distinctive star-like shape. The cell is enclosed by a cellular envelope (cortex) densely studded with spindle-shaped extrusomes called trichocysts.

Discussion adapted from: https://en.wikipedia.org/wiki/Paramecium_caudatum
P. caudatum feed on bacteria and small eukaryotic cells, such as yeast and flagellate algae. the accumulated food particles, at the posterior end of the cytopharynx, are directed by the long cilia into the rounded, ball-like mass in the endoplasm called food vacuole. The food vacuoles are circulated by the streaming movement of the endoplasm which is called cyclosis. In hypotonic conditions (freshwater), the cell absorbs water by osmosis. It regulates osmotic pressure with the help of bladder-like contractile vacuoles, gathering internal water through its star-shaped radial canals and expelling the excess through the plasma membrane. When moving through the water, they follow a spiral path while rotating on the long axis.

Paramecium have two types of nuclei, a large macronucleus and a varying numbers of smaller micronuclei depending on the species. P. caudatum has 1 compact round macronucleus. The macronucleus controls somatic gene expression and the micronucleus controls reproduction. Like all ciliates, Paramecia reproduce asexually, by binary fission. During reproduction, the macronucleus splits by a type of amitosis, and the micronuclei undergo mitosis. The cell then divides transversally, and each new cell obtains a copy of the micronucleus and the macronucleus. Fission may occur as part of the normal vegetative cell cycle. Under certain conditions, it may be preceded by self-fertilization (autogamy), or it may follow conugation, a sexual phenomenon in which Paramecia of compatible mating types fuse temporarily and exchange genetic material. During conjugation, the micronuclei of each conjugant divide by meiosis and the haploid gametes pass from one cell to the other. The gametes of each organism then fuse to form diploid micronuclei. The old macronuclei are destroyed, and new ones are developed from the new micronuclei. Without the rejuvenating effects of autogamy or conjugation a Paramecium ages and dies. Only opposite mating types, or genetically compatible organisms, can unite in conjugation.

I observed a Paramecium in the early mid stages of transverse fission with formation of two oral anlagen and a beginning constriction of the cortex dividing into two cells.

1. Paramecium genus: biodiversity, some morphological features and the key to the main morphospecies
   discrimination. Sergei I. Fokin. Protistology 6 (4), 227–235 (2010/11)
   https://www.researchgate.net/publication/285129115

Lembadion bullinum (Müller, 1786) Perty, 1849 from the decomposing leaf debris in my long-neglected freshwater garden pond imaged in Nomarski DIC on Olynmpus BH2 using SPlan 40x objective plus variable phone camera cropping on Samsung Galaxy S9+.

The cells of this population range from 92-103 um in length which is larger than the size described for the similar species L. lucens (range 45-80 um) (1,2). The tuft of caudal cilia and the pellicle rowed meridionally with rectangularly meshed parallel lines are both present in L. bullinum and L. lucens. However, L. bullinum is much larger than L. lucens (about 120–200 μm × 70– 120 μm and usually 140 μm in length in vivo vs. 45–75 um). Additionally, L. bullinum has a more elongated body shape described as shittle-shaped vs. ovoid to elliptical in L. lucens. L. bullinum possesses more somatic kineties, 50–60 with dikinetids anteriorly versus 25–35, with monokinetids at both ends in L.lucens. Lembadion bullinum also has more and longer caudal cilia than L. lucens (about 17 kinetids of caudal cilia arranged into two rows with cilia that are 40–50 μm long vs. seven to 10 kinetids in two rows, and cilia about 20–30 μm in length) (Maskell 1887, Dragesco and Dragesco-Kernéis 1986, Guinea et al. 1990, Foissner et al. 1994). Since I can find no reports of L. lucens reaching 100 um in length and inview of the elongate body shape in my population where I can sometimes count in excess of 10 caudal cilia, this is L. bullinum (1).

"The family Lembadionidae Jankowski in Corliss, 1979 is a monotypic taxon including only the genus Lembadion Perty, 1849. This genus can be characterized by following features: small to medium sizes; ovoid cell shape; holotrichous somatic ciliation; large oral region composed of one long polykinetid, two paroral kineties, and three argentophilic line (Lynn, 2008). Above all, the large oral structure makes this genus easy to be recognized from other ciliates. Presently, more than 20 species have been described but only five valid species are known in the genus Lembadion: L. bullinum Perty, 1849; L. lucens (Maskell, 1887) Kahl, 1931; L. magnum (Stokes, 1887) Kahl, 1931; L. conchoides Fauré-Fremiet, 1924; L. gabonensis Dragesco, 1965"(2).

"Body size about 110-130×60-73 μm in vivo; length about 1.8 times of width. Body shape more or less ovoid, inflexible, ventral surface flat to slightly concave, dorsal surface convex and rough, slightly asymmetric at anterior end (Fig. 3A, F, G). Cytoplasm colorless with several food vacuoles. One spherical contractile vacuole placed dorsally in subequatorial region of cell, with one long collecting canal connected to excretory pore. One excretory pore placed near proximal end of undulating membranes on ventral side. Cortical granules difficult to find in whole cell. One bean- or kidney-shaped macronucleus, about 40 μm in vivo, positioned posterior end of cell. One globular or ellipsoid micronucleus about 4 μm long in vivo, close to macronucleus Locomotion by swimming with rotation around longitudinal axis, occasionally gliding on substrate" (2).

"Oral aperture occupying almost four-fifths on ventral side, composed of long adoral membranes, undulating membranes, and argyrophilic fibrils. Buccal cavity surrounded by long adoral membranes on left margin, undulating membranes on right margin. Adoral membranes beginning at anterior end of cell, expending to posterior region of cell. Undulating membranes placed closely along right side of buccal cavity. Outer undulating or paroral membrane reaching near proximal end of adoral membranes, while inner undulating or endoral membrane not to proximal end of buccal cavity. Longitudinal argyrophilic fibril lines present between adoral membranes and undulating membranes. Somatic kineties 48-55 in number, consisted of dikinetids, occasionally, monokinetid, forming posterior sutures on ventral side. 10-16 caudal cilia in two short transverse lines consisted of monokinetids . Pellicle rowed meridionally with rectangularly meshed parallel lines in posterior portion about 84% of cell, and these lines extended to anterior portion about 16 % of cell without rectangular meshes" (2).

1. Morphological Redescription and SSU rDNA-based Phylogeny of Two Freshwater Ciliates, Uronema nigricans and Lembadion lucens (Ciliophora, Oligohymenophorea), with Discussion on the Taxonomic Status of Uronemita sinensis Mingjian LIU, Lifang LI, Zhishuai QU, Xiaotian LUO, Saleh A. AL-FARRAJ, Xiaofeng LIN, Xiaozhong HU. Acta Protozool. (2017) 56: 17–37
2. Three Freshwater Lembadion Ciliates (Peniculida, Lembadionidae) Newly Reported from Korea. Sung Hoon Kim, Jae Sool Yoon, Seong Myeong Yoon, Mann Kyoon Shin. Anim. Syst. Evol. Divers. Vol. 33, No. 4: 246-255, October 2017

Urostomides campanula (Kahl, 1932) comb. nov. (original combination Metopus campanula Kahl, 1932) from the decomposing leaves at the edge of my long-negelkected freshwater garden pond imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone camera cropping on Sasmsung Galaxy S9+. The cells measure 37.5 um in length and show the peculiar side to side motion when swimming. With this and with its obpyriform to campanulate shape, the posterior body taking the form of an inverted truncate cone, and the “crown” kinety comprised of closely spaced inclined dikinetids that give rise to membranelle-like adherent syncilia, and the horizontal azm, this matches the description and depictions provided by Bourland et al 2017 (1). Strangely, the tuft of caudal cilia in this example is reduced to a single long cilium.

Bourland et al 2017 "provide morphologic and molecular characterization of seven taxa from the poorly-known resurrected genus Urostomides obtained in the course of broad geographic sampling. Foissner (2016) established the family Apometopidae to include Apometopus (a junior synonym of Urostomides) and Cirranter Jankowski, 1964. These two genera differ from all other metopid genera in having a four-rowed perizonal ciliary stripe, the only currently recognizable morphologic synapomorphy for the family. The members of Urostomides show remarkable morphologic diversity. The genus has a broad geographic distribution, occurring on six continents. Urostomides species form a strongly supported clade in phylogenetic analyses" (1).

"Description of Idaho strain ACAMTR. Size in vivo 33–46 × 29–40 um in vivo. Shape broadly obpyriform to campanulate. Length:width ratio including preoral dome 1.1:1 on average. Preoral dome more or less symmetric, hemispherical to broadly conical, occupies about 70% of body length. Body posterior to preoral dome broad, truncate inverted cone. Macronucleus globular, in preoral dome, occupies about 30% of body length in protargol preparations; chromatin finely granular, sparse scattered 1 um-sized nucleoli in protargol preparations. Micronucleus about 3 um in length, ellipsoidal, usually adjacent to macronucleus but in separate envelope. Extrusomes prominent, ellipsoidal to short blunt rods, about 2–3 um long, seen as refractive peripheral fringe in vivo, explode to form mucus coat around distressed cells. Contractile vacuole terminal, excretory pore and cytopyge not observed. Cortex flexible, prominent kinetal furrows in preoral dome, cortical granules absent. Cytoplasm colorless to faintly brownish in vivo, many food vacuoles. Swims at moderate pace with distinctive side-to-side twitching movement while rotating on long axis" (1).

"On average 13 (range 11–15) somatic kineties about 6 um apart in the posterior body portion; invariably five more widely spaced dome kineties. Cilia of preoral dome kineties often form syncilia, dome kinety 3 thigmotactically specialized, cilia about 20 um long, adhere to form sagittal pseudomembrane. Nonmotile caudal cilia grouped in eccentric tuft at right margin of posterior end, about 30 um long. Adoral zone comprises 33 membranelles on average (range 26–36), begins on ventral surface and ends at same level on right margin (i.e. horizontally oriented, makes about 270◦ turn around long axis), proximal end not enclosed in buccal cavity. Paroral membrane stichomonad, originates in, but and protrudes only slightly from, buccal cavity at posterior end of adoral zone. Cytopharyngeal fibers inconspicuous, curve anteriorly from cytostome into preoral dome" (1).

While the original combination for U. campanula is Metopus campanula Kahl 1932, U. campanula actually more closely resembles another form shown and discussed together by Kahl 1932 -Trochella mobilis, 40 um, page 424 fig 9. Trochella mobilis is closer in size and shape and shows the characteristic dome kinety syncilia membrane which Kahl described as "flame like". I provide a copy of the illustrations from Kahl 1932.

1. Morphologic and molecular characterization of seven species of the remarkably diverse and widely distributed metopid genus Urostomides Jankowski, 1964 (Armophorea, Ciliophora). William Bourland, Johana Rotterová, Ivan Čepička. European Journal of Protistology Volume 61, Part A, October 2017, Pages 194-232

Brachonella contorta from a four month old sample taken in August 2022 from the northernmost edge benthos of a spring-fed freshwater coastal pond in the Atlantic Double Dune Reserve. The sampling site is 250 meters from the edge of the Atlantic Ocean. They measure up to 123 um in length.

"Brachonella contorta (Levander, 1894) Jankowski, 1964 (original combination Metopus contortus Levander, 1894) Improved diagnosis based on our populations and the original description (Levander 1894): Body size about 70 − 126 × 42 − 106 um in vivo. Body bullet-shaped, massive conical preoral dome nearly obscures short bluntly truncate postoral part. Dorsoventral flattening of preoral dome rather variable. Cytostome markedly displaced posteriorly. Dense brownish-black cytoplasmic granule aggregate at the anterior end of preoral dome invariably present. Macronucleus globular, in anterior body half. Usually about 55 ciliary rows, about 22 of which are preoral dome kineties abutting to form apical suture in ventral view. Elongated evenly distributed cilia encircle posterior end. Perizonal ciliary stripe invariably comprises five rows, never arranged in false kineties, same length as adoral zone proximally, slightly longer distally. Paroral stichomonad. Adoral zone makes 360◦ spiral around long axis, usually comprises about 60 membranelles" (1).

1. William Bourland, Johana Rotterová, Ivan Čepička. Redescription and molecular phylogeny of the type species for two main metopid genera, Metopus es (Müller, 1776) Lauterborn, 1916 and Brachonella contorta (Levander, 1894) Jankowski, 1964 (Metopida, Ciliophora), based on broad geographic sampling. Eur. J. Protistol. (2016), http://dx.doi.org/10.1016/j.ejop.2016.11.002

Colpidium singulare Vuxanovici, 1961 from the rotting leaf debris of my long-neglected freshwater garden pond imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone camera cropping on Samsung Galaxy S9+. The following features make the species identification of Colpidium singulare doubtless: Macronucleus long, band-shaped, anteriorly bipartite; body length ca. 80 pm; about 45 kineties. Note the contractile vacuole subequatorially, in vivo 10 pm in diameter which I was fortunate in one screen capture to capture during diastole where there is a conspicuous rosette of smaller vacuoles ('Nebenblasen' ; Gelei, 1939).

"Colpidium singulare Vuxanovici, 196l 196l Colpidium singulare n. sp. - Vuxanovici, Studii Cerc. Biol. (Biol. Anim.), v. 13,, p.453, Pl. II, fig 9. Description Body size 76 um, shape similar to C. colpoda. 22-24 ciliary rows on one side of the body. Macronucleus long, band shaped, anteriorly bipartite. Endoplasm hyaline, containing algae, darkly granulated. Occurrence. Observed by Vuxanovici in high numbers in stale cultures with decaying plants from Lake Tei (Roumania) in October 1959. Remarks. The characteristic form of the macronucleus requires a consideration of C. singulare as a distinct species. The bipartition of the macronucleus, however, is very uncommon for tetrahymenids and suggests that this species belongs to another group of ciliates. Another possibility is that the smaller macronuclear segment represents the micronucleus which is not mentioned by Vuxanovici ( 1961)" (1).

1. Taxonomy and ecology of some ciliates (Protozoa, Ciliophora) of the saprobic system. III. Revision of the genera Colpidium and, Dexiostoma, and establishment of a new genus, Paracolpidium nov. gen. B. Ganner & W. Foissner. Hydrobiologia 182: l8l-218, 1989.

Urostomides bacillatus (Levander, 1894) comb. nov. (original combination Metopus bacillatus Levander, 1894) from rotting leaf debris my long-neglected freshwater garden pond. Imaged in Nomarski DIC using Olympus BH2 under SPlan 40x objective plus variable phone cropping on Samsung Galaxy S9 +.

In 2017, Bourland et al (1) redescribed six metopid species having four-rowed perizonal ciliary stripes that were previously classified within Metopus and Brachonella and, after analyzing their morphology and 18S rRNA gene sequences, transferred them to Urostomides Jankowski, 1964, a poorly characterized genus until now in family Apometopidae.

"Improved diagnosis based on population ABACBLUFF, original description (Levander 1894),and redescription by Kahl (1932): Body size about 65–100 × 45–65 m in vivo, obpyriform, broadly ellipsoidal in cross-section. Preoral dome broadly rounded, wider than posterior body portion, slightly overhangs left margin. Posterior body obconical, more or less triangular in cross-section, posterior end rounded to obliquely truncate and not tail-like, with elongated caudal cilia. Right margin slightly concave, left margin slightly convex. Macronucleus 15–27 m in length, globular to reniform, located in anterior half of body. Micronucleus ellipsoidal, relatively large, about 6 m long in vivo. Contractile vacuole subterminal, excretory pore not observed, may empty via cytopyge. Cytopyge subterminal, on ventral surface. Extrusomes narrowly ellipsoidal to oblong, 2–3 m long,colorless in vivo but form distinct refractive peripheral fringe in vivo. Cortex slightly flexible, kinetal furrows conspicuous in dome, very shallow in posterior body, cortical granules absent. Cytoplasm colorless, contains scattered refractive 2 m diameter globules, anterior granule aggregate absent. Food vacuoles up to 20 m diameter. Swims at moderate pace, rotates on long axis. Twenty-three somatic kineties on average (range 21–25)" (1).

"About 15 kineties converge at posterior body end, posterior-most dikinetids usually bear about 12 elongated caudal cilia, invariably eight widely-spaced dome kineties, none obviously specialized. Perizonal stripe, same length as adoral zone posteriorly, slightly longer anteriorly, rows 1–3 equidistant, separated from row 4 by gap, Adoral zone steeply oblique,makes <180◦turn around long axis, comprises about 42 membranelles (range 32–47), begins at right margin of ventral surface, extends obliquely about 20 m more anteriorly to left side of dorsal surface (i.e. makes <180◦turn around long axis). Paroral membrane originates in and protrudes only slightly from buccal cavity, extends to undersurface of preoral dome" (1).

1. William Bourland, Johana Rotterová, Ivan Čepička. Morphologic and molecular characterization of seven species of the remarkably diverse and widely distributed metopid genus Urostomides Jankowski,1964 (Armophorea, Ciliophora). European Journal of Protistology 61 (2017) 194–232