Kentomonas sorsogonicus Votypka et Lukes 2014

A strangely named organism, one of those I like to choose for the morbid fascination of illustrating the unknown. Kentomonas sorsogonicus isn't in AlgaeBase, so I based its taxonomy on that of NCBI Taxonomy.

The organism belongs to the subfamily Strigomonadinae, family Trypanosomatidae, order Trypanosomatida. That alone is enough to tell you that Kentomonas is related to the legendary Trypanosoma (sleeping sickness) and Leishmania. In this order, no one is spared: all its members are parasites. Trypanosomatids have several characteristics, among which I can highlight the kinetoplast (an organelle with a dense granule of kDNA located within the mitochondria, and usually associated with the basal bodies of the flagella), and the presence of glycosomes, which store glycolytic enzymes for glycolysis (Michels et al. 2006).

The order Trypanosomatida is included in the subclass Metakinetoplastina, along with the other orders Eubodonida, Neobodonida, and Parabodonida. These other orders are very diverse in their organisms, a few being parasitic and most free-living. In fact, I illustrated a species of Neobodonida, Klosteria bodomorphis, some time ago.

The subclass Metakinetoplastina is included in the class Kinetoplastea, and this in the phylum Euglenozoa, which makes Kentomonas distantly related to more "innocent" organisms like Euglena or Diplonema. Euglenozoa is included in the clade Discoba (which includes the other phyla Heterolobosea, Jakobea (which includes the last species I illustrated, Andalucia godoyi), and Tsukubea), and finally in the domain Eukaryota.

Anyway, the main source that I have used to create the illustrations, and the information written here, was "Kentomonas gen. n., a New Genus of Endosymbiont-containing Trypanosomatids of Strigomonadinae subfam. n." (2014), by Jan Votýpka, Alexei Yu Kostygov, Natalya Kraeva, Anastasiia Grybchuk-Ieremenko, Martina Tesařová, Danyil Grybchuk, Julius Lukeš and Vyacheslav Yurchenko. Protist, Vol. 165, Issue 6. 825-838 pp.

Another source was: "Farming, slaving and enslavement: histories of endosymbioses during kinetoplastid evolution", (2018), by Jane Harmer, Vyacheslav Yurchenko, Anna Nenarokova, Julius Lukeš and Michael L. Gingerby. Parasitology, 145, 1311–1323. https://doi.org/10.1017/S0031182018000781 

A peaceful screamer reminder: the following illustrations are free to use and are also available on Wikimedia Commons. Of course, commercial use of these images is not permitted, nor is their use without proper attribution. "DOTkamina (2026)" is sufficient.

Kentomonas sorsogonicus was found infecting the hindgut of a female Sarcophaga fly (species undetermined), which was captured near Donsol, Sorsogon, in the Philippines. Its cellular form is called a "choanomastigote": an oval or rounded shape with a ring-like structure at its anterior end from which the flagellum protrudes. I have indicated this ring in the illustration. In Kentomonas sorsogonicus, the choanomastigote is more elongated, giving it a "barleycorn" appearance. You, as a likely native English speaker, will know what a "barleycorn" is because either I'm searching incorrectly, or I'm getting seeds I've never seen before.

Another unsettling thing is that the "choanomastigote" has the kinetoplast anterior to the nucleus (watch this image). I thought I'd messed up because I depicted the kinetoplast posterior to the nucleus in my illustration, near the basal body. However, in K. sorsogonicus, the kinetoplast doesn't appear to be fixed; its position varies depending on the individual, being posterior, anterior, or lateral to the nucleus, or wherever you like. But that's perfect for me because I didn't have to correct anything, haha.

Speaking of the flagellar pocket, it seems to be incredibly long and occupy a large part of the cell, as can be seen in Votýpka et al. (2014): Figure 2B, reaching the area where the nucleus and the endosymbiont are located (in the posterior region). Logically, "beneath" the flagellar pocket (which, remember, is an invagination that envelops the flagellar axoneme) is the basal body, whose size I don't know, so I've represented it with a "normal" size for me, but it's up to you to judge.

Flagellar axoneme

The axoneme is 9+2, the standard microtubular structure of eukaryotic flagella (9 peripheral microtubular doublets surrounding two central microtubular singlets). This axoneme, when enveloped by the plasma membrane, is what is called the "flagellum." Since the flagellar pocket is an invagination, its interior is technically lined by the plasma membrane. The flagellum, therefore, originates from inside the cell, emerges through the ring, and widens as it does so. The flagellum has a paraflagellar rod, a protein structure that supports the flagellum. In other trypanosomatids, this rod is well-developed, but in K. sorsogonicus and other species of the subfamily Strigomonadinae, it is inconspicuous (rudimentary or almost nonexistent). I have depicted the paraflagellar rod along a section of the first part of the flagellum as it emerges from the ring. I don't know if it will be a fragmented structure, if it's shorter, or if it occupies the entire flagellum.

The flagellar pocket is an invagination shaped like a round-bottomed bottle with a neck (like a Florence flask). This means that near the anterior part of the cell, where it opens with the ring, it's narrower, and the plasma membrane that acts as its inner "wall" is closer to the plasma membrane that surrounds the axoneme (that is, the flagellum). It's in this area of ​​contact that we find the desmosomes, two or three rows of them that attach the flagellum to the membrane of the flagellar pocket.

K. sorsogonicus, cell anatomy

Transversal section of the flagellar pocket in the anterior zone, with the desmosomes.

The organism has an oval-shaped nucleus, which, according to Votýpka et al. (2014): Figure 2B, appears to be located at the posterior of the cell, with the endosymbiont even further posterior. This endosymbiont is a β-proteobacterium, known as Candidatus Kinetoplastibacterium sorsogonicusi Yurchenko et Kostygov sp. n. This symbiont is typically surrounded by glycosomes, which is why I have depicted them in greater numbers around the symbiont.

The kinetoplast is cylindrical and has a loose network of kDNA fibrils. The kinetoplast is located within the mitochondrion, which, as in other species, is single and reticulated. In K. sorsogonicus, the mitochondrion is so reticulated that it extends close to the plasma membrane, pushing it outward like longitudinal horizontal varices, forming the longitudinal ridges visible on the cell's exterior. The mitochondria are rich in tubular cristae.

SEM external appearance.

The endoplasmic reticulum appears to be a structure as branched as the mitochondria, distributed throughout the cell, or at least that's what has been observed in other trypanosomatids (Sandes and Queiroz de Figueiredo 2022). In the case of K. sorsogonicus, its actual appearance is not described; I have depicted it as much less extended, almost near the nucleus. This shape and size are speculative, and it could actually be more widespread throughout the cell. The shape of the Golgi apparatus is also speculative.

In addition to the main image, I have also drawn the organism's external appearance as it would be seen under a scanning electron microscope (SEM), where the ring and, above all, the mitochondrial ridges are visible. I have also drawn the cross-section of the flagellum's axoneme with the paraflagellar rod; the cross-section of the anterior region of the cell where the flagellar pocket is narrow and in contact with the flagellum via desmosomes (in the main image, I have depicted two rows of desmosomes that are not very noticeable; in the cross-section, the desmosomes are more visible, but only one row is shown); and the cross-section of a posterior region of the cell, where the nucleus, the posteriorly widened portion of the flagellar pocket, the flagellum's axoneme within the flagellar pocket, and the mitochondrion are visible. In the cross-section, the mitochondrion appear as a cluster of individual, round mitochondria. I hope I have pointed out the branches near the surface that form the ridges, giving, in this cross-section, a wavy cell surface.

And now...

some non-labeled icons

That's all I had to say about this organism.

Klosteria bodomorphis Mylnikov & Nikolaev 2003

Klosteria bodomorphis is a free-living protist belonging to the Neobodonidae family, which, as I'll explain later, is related to dangerous kinetoplastid organisms... well, it's not that surprising, but still.

These drawings are free to use and you probably found them on Wikimedia Commons. They are licensed under CC BY-SA 4.0 Attribution-ShareAlike 4.0 International. Free use for non-commercial purposes. You also have to give credit every time you use an image. "DOTkamina 2026" is fine, I think.

Sources: formally just one: "The taxonomic position of Klosteria bodomorphis gen. and sp. nov. (Kinetoplastida) based on ultrastructure and SSU rRNA gene sequence analysis" by Sergey I. Nikolaev, Alexander P. Mylnikov, Cedric Berney, Jose Fahrni, Nikolai Petrov and Jan Pawlowski, Protistology 3 (2), 126-135 (2003)... or simply Nikolaev et al. (2003). It's literally the article where this species is described. Although, to be honest, it was a bit complicated because there were strange concepts I didn't quite understand. That's why I also consulted this book chapter on kinetoplastid microanatomy: "Kinetoplastea" by Gibson, W. (2016).

So... Klosteria bodomorphis belongs to the family Neobodonidae, order Neobodonida, subclass Metakinetoplastina, in the class Kinetoplastea. I don't know what is more unnerving: that Kinetoplastea is included in the phylum Euglenozoa (meaning they are distantly related to the famous microalgae Euglena), or that along with Neobodonida, which includes free-living species that eat bacteria, it encompasses other clades where the titans, the horror of many, reside, such as Trypanosoma and Leishmania (in the order Trypanosomatida).

But with Klosteria bodomorphis, you have nothing to worry about. This is a free-living organism that was isolated from samples taken from the Baltic Sea shoreline, near the town of Kloster, Germany, in December 1994. It's an organism that feeds on bacteria—which ones? I don't know. In the illustration, I depict a specimen of Aerobacter (Klebsiella) aerogenes as prey, and within its food vacuoles, I have drawn amorphous pinkish blobs representing partially digested bacteria of that species. The reason for choosing this specific species is that Nikolaev et al. (2003) used this bacterium as a food source in laboratory culture. However, it is unknown exactly which bacterial species or clades it might consume in nature.

But focusing on its anatomy, I'll begin by saying that it has two heterodynamic flagella: the anterior one measures 12 µm and the posterior one 17 µm. At the end of each flagellum are short, tapering tips known as acronemes. The anterior flagellum is covered with mastigonemes measuring 2 to 2.5 µm. Both flagella are covered by a layer of condensed glycocalyx, but I haven't depicted that.

You already know the typical flagellar configuration: 9+2 (nine doublets of microtubules surrounding two central single microtubules), enclosed by the plasma membrane. More generally, flagella "emerge" from the cytoplasm. In Klosteria bodomorphis, the flagella emerge from a kind of "depression" on the cell surface, surrounding the lower portions of the external flagella. This "depression" is known as a "flagellar pocket," which is shallow and located subapically. According to Nikolaev et al. (2003), flagellar pockets containing four flagella have been found... which is quite disturbing.

Equally disturbing is the microtubule system identified using electron microscopy, which I have represented more accurately based on the text by Gibson (2016). First, it's worth noting that the flagella, or rather, the 9+2 configuration, originate from the basal bodies. The basal bodies are also anchored by flagellar roots (abbreviated "fr" in the image). Hell yeah, fr!

The flagellar root of the anterior flagellum (that is, the one that originates from the basal body of the previous flagellum) is made of 2 to 3 microtubules and then gives rise to the dorsal submembrane band (simply called the "dorsal band"), which is made of at least 25 microtubules. This band, according to Gibson (2016), extends along the entire dorsal side of the cell.

Simultaneously, the flagellar root of the posterior flagellum emerges from the basal body of the posterior flagellum. This root is composed of six microtubules and extends posteriorly (presumably towards the ventral side of the cell) to form the ventral submembrane band (or simply the "ventral band"), composed of 27 microtubules, which runs along the entire ventral side of the cell.

Between the basal bodies are two microtubules that connect them, which I have labeled as the "fibrillar connection" in the illustration. Another interesting microtubular structure is the so-called "MTR band" (microtubular reinforced band), composed of four to five microtubules. It originates at the surface of the flagellar pocket and extends to the cytopharynx, where it is supplemented by additional microtubules. I have depicted two additional microtubules in the illustration, but Nikolaev et al. (2003) do not specify the actual number. I chose that number because I think I see two more than the 5 of MTR (I hope there are 5) in Illustration 16, but in Illustrations 14 and 15 I think I see more... so I don't know xd.

The shapes of the bands are purely illustrative, but their placement is based verbatim on Nikolaev et al. (2003), and primarily visually on Gibson (2016) Figure 3, and Frolov et al. 2021.

The organism has a cytostome (the "mouth" through which food, bacteria, enters), which is essentially the opening through which food enters. This opening connects to the rest of the invagination, the cytopharynx, a tunnel-like structure measuring 1.8 to 2.3 µm. The lower part of the cytopharynx is surrounded by vesicles. This can be called the "cytostome-cytopharynx complex," and it is simply a very complex cellular feature for phagocytosis, since it is in the cytopharynx that food is packaged into food vacuoles. These vacuoles are directed toward the hind part of the cell (the posterior part).

The organism also has a Golgi apparatus, which is located near the basal bodies. The shape of the Golgi apparatus in the illustration is more schematic than realistic. The nucleus with nucleolus, obviously (although I haven't depicted the nucleolus in this image), "lies at the level of the bottom of the flagellar pocket and at the end of the cytopharynx," according to Nikolaev et al. (2003). They also say that the nucleus is vesicular. I don't know exactly what that means; in (cancer) cytology, it refers to cells with loosely packed chromatin, which under the microscope appear to have nothing inside... but I don't know. In my illustration, you'll see that the nucleus has some dark ornaments in the center and others surrounding it. You can assume the one in the center is the nucleolus. This decision was based on Nikolaev et al. (2003): Figure 17. Around the nucleus is the endoplasmic reticulum, both smooth and rough, and its shapes and existence are speculative (I assume they must exist because they are common in all eukaryotic cells).

The mitochondrion have an almost speculative shape. As can be seen in Nikolaev et al. (2003): Figure 18, appears to extend across a significant portion of the cell. The authors debate whether it is truly a single structure or if it might be more branched. I have chosen to depict it as slightly branched. The authors describe the mitochondria as having discoid cristae. The cristae are invaginations of the inner mitochondrial membrane, and their discoid form refers to the fact that these invaginations are shaped like discs with small "peduncles" (pedicellate, see Pánek et al. (2020): Figures 2A and 2F) when the section is longitudinal, and like sausages or cylindrical "bacilli" when the section is transverse. I have represented them almost as if they were seen in transverse section and pedicellate, in the mitochondrion of my illustration.

Now, I mentioned earlier that Klosteria bodomorphis belongs to the large order Kinetoplastea, and you'll read that the most important characteristic of this group is the kinetoplast, a mass of DNA arranged in maxicircles and minicircles (Wang et al. 2025), located within the mitochondria in a specific region, usually near the basal bodies. But this isn't a mandatory feature for all kinetoplastids; it's actually a structure that is repeated in some, and especially studied in species that are parasitic to humans. For other kinetoplastid species, we can speak of "kinetoplasty," a term that encompasses other forms of organization of kinetoplastid DNA (kDNA).

One such form is pankinetoplasty, described as bundles of kDNA isotropically distributed throughout part or all of the mitochondrial lumen (Gibson 2016: Figure 1i)... think of it as more or less elongated groups of kDNA that are present throughout, or almost throughout, the interior of the mitochondrion. In cell biology, "isotropic" refers to the fact that, in any part of a structure, the properties (I suppose physical, shape, optical, chemical, or whatever) will be more or less similar (New World Encyclopedia n.d.).

According to Nikolaev et al. (2003), Klosteria bodomorphis has little DNA within the mitochondrion that can be interpreted as kDNA, and if so, the most appropriate classification would be pankinetoplasty. The reason they give is that the kDNA fibers do not occupy a very prominent space within the mitochondria. The pankinetoplast (and any other type of kinetoplast, really) should appear as dark spots or aggregates within the mitochondria under an electron microscope. I only manage to observe this more or less in Nikolaev et al. (2003): Figures 16 and 18. I imagine these small spots are slightly darker than the cristae... I have represented the supposed "pankinetoplast" of K. bodomorphis as more or less elongated spots, somewhat distributed throughout the mitochondrion... but it is possible that in reality they are even smaller, more insignificant, less observable or noteworthy spots.

Finally, storage substance granules measuring 0.10 to 0.35 µm in diameter have also been observed in Klosteria bodomorphis. These, along with symbiotic bacteria, one of the most cursed aspects of the organism, measure 0.3 to 0.6 µm in diameter. The authors noted cell division in some of these bacteria, and I have indeed depicted such bacterial division in my illustration.

However, this isn't the end. I've forgotten about the trichocysts. In Klosteria bodomorphis, these are elongated and cylindrical. Length: 1.2 to 1.9 µm, diameter: 0.15 µm, with an internal rod of 0.6 to 0.77 µm, which I've represented as a darker area within the trichocysts. Nikolaev et al. (2003) mention that they are located near the ventral side of the flagellar pocket. I suppose I've erred here because I've depicted them more dorsally, near the ventral band. In fact, this is clearer in the image attached next to the main one, titled "Close-up of the flagellar zone," (the image above, without labels) which is entirely inspired by Nikolaev et al. (2003): Figure 13. So... feel free to discuss whatever you like in the comments. I'd be happy to see corrections and possible improvements. My hand hurts right now, and I have a trip planned where I'll be dragging myself along to see if my final project makes any progress, so lol.

There are 8 to 9 trichocysts arranged in a row, also known as extrusomes. This group is known as a "trichocyst battery." In the main image, only two trichocysts are visible, but that doesn't mean there are only two... they're assumed to be viewed from the side, and those two are "covering" the others.

I guess that's all I have to say. I wasn't expecting to do this illustration, because the organism seemed strange to me. I don't even know how I came across this organism; I think I was reading about trichocysts for a previous illustration. I don't know, I just got a sudden urge and said, "Let's do it, or I'll die." Or maybe it was out of pride. Or perhaps it was out of morbid curiosity to see if I'll finally reach 100 illustrations, or even 20. That number 20 looks pretty promising.