Goniomonas appears to be a primitive cryptomonad organism because it lacks chloroplasts, unlike other cryptomonads. It also lacks any other type of plastid or nucleomorph. In all cases, it appears transparent. That's why I liked drawing it: simple and easy to remember.
In the following illustrations, I've depicted the dorsal and lateral views of the organism. The illustrations are based on the following sources:
- "Chapter 18 - Cryptomonads". In: "Freshwater Algae of North America (Second Edition)". Brec L. Clay 2015.
- "Goniomonas truncata (Fresenius, 1858) Stein, 1878". Dr. Martin Kreutz. 2023 (Estimated with WebsiteAge).
Additionally, I needed to consult other sources of information for the writing of what is written in this entry, which are the following:
- "Cryptic Cryptophytes – revision of the genus Goniomonas". Maria Sachs, Frank Nitsche, Hartmut Arndt. 2025.
- "Heterotrophic flagellates (Amorpha and Diaphoretiches) in phytotelmata bromeliad (Bromeliaceae)". Poliana Maria Sachertt Mendes, Fernando Miranda Lansac-Tôha, Bianca Ramos Meira, Felipe Rafael Oliveira, Luiz Felipe Machado Velho, Fábio Amodêo Lansac-Tôha. 2019.
- "Morphology, Ultrastructure, and Small Subunit rDNA Phylogeny of the Marine Heterotrophic Flagellate Goniomonas aff. amphinema". Mercedes Martin-Cereceda, Emily C. Roberts, Emma C. Wootton, Elisa Bonaccorso, Patricia Dyal, Almudena Guinea, Dale Rogers, Chris J. Wrighte and Gianfranco Novarino. 2009.
- "Order Cryptomonadida". Paul Kugrens, Robert E. Lee and David R. A. Hill. In: J. J. Lee, G. F. Leedale & P. Bradbury (ed.), An Illustrated Guide to the Protozoa. 2nd ed. 2002. p. 1111–1125.
- "Ultrastructure and molecular phylogeny of the cryptomonad Goniomonas avonlea sp. nov.". Eunsoo Kim, John M Archibald. 2013.
I was seriously considering postponing writing this, but I really want to finish it and at least try to reach 10 protists and not feel like an empty shell. Let's look at the main image:
I've included two views: dorsal and lateral. I think the dorsal view is easier to understand than the ventral view; I believe the parts are clearer in the ventral view. I don't want it to be obvious that the main inspiration was Clay's diagrams (2015).
The flagella of Goniomonas truncata are of similar length, approximately half the length of the cell, and emerge from the dorsal side of the vestibule. Clay (2015) mentions, however, that one of these flagella has a row of "curved spines" (Kugrens et al. 2002 describe them as "recurved"), and a row of fine "non-tubular hairs" on both flagella. Indeed, that is how I have depicted them in the illustrations, although you may need to enlarge the images to see that detail.
In Clay's diagrams (2015, Figure 3A), it is represented with 8 ejectisomes, but Kreutz (2023) mentions that there are only 6, and according to the micrographs in that reference, there appear to be 4 ejectisomas larger than the other 2 (see Figures 4a and 4b of the reference), with the 4 facing ventrally and the other 2 facing dorsally. However, this is just my observation, and I don't know if it's a real anatomical feature, since I don't see that arrangement in Figures 2 and 3 of the same reference. I have represented it as mentioned in Kreutz (2023) and as visualized in Kreutz (2023, Figures 4a and 4b).
I think many agree that Goniomonas appears to be an ancestral cryptomonad organism and that's why it doesn't have chloroplasts or any other type of plastid. It has several food vacuoles, which form each time the organism ingests bacteria, so their number and size vary depending on the size and quantity of bacteria ingested. The nucleus is located dorsally in the center. And in Clay (2015), it is not represented with anything else, giving the appearance that it is actually simpler than other cryptomonads.
Of course, mitochondria, Golgi apparatus, rough and smooth endoplasmic reticulum were represented, but their shapes, sizes, and colors are merely speculative, and I assume they must exist because this organism is a eukaryote, and these organelles are technically present in "most eukaryotic cells." Ribosomes are also represented, in high concentration near the rough endoplasmic reticulum, and dispersed and a lighter purple hue (like small dots) throughout the cell.
However, Clay (2015) mentions that Goniomonas truncata only has one furrow and does not connect to any gullet as occurs in other cryptomonads. It also mentions that bacterial ingestion occurs through phagocytosis, via a structure known as an "infundibulum." Neither of these structures is depicted in Clay (2015).
The descriptions I found of the furrow and infundibulum are limited, mainly because I don't have enough visual references. But I did what I could. According to Kugrens et al. (2002), the furrow is ventral and connected to the vestibule. The furrow has a stoma on its posterior end (I understood this to mean "at the posterior end," and there is a reference to this in Cryptomonas tetrapyrenoidosa, see Kugrens et al. (2002), Figure 4). The infundibulum is described as being located "on the left side" of the cell. Kugrens et al. (2002), Figure 13, shows a micrograph of Goniomonas truncata that conveniently indicates the furrow and infundibulum.
Considering that the flagella are located on the dorsal side of the vestibule, then in that figure we are viewing the organism from the ventral side, and the furrow appears to be a large structure that runs along a good portion of the ventral area, I believe roughly halfway, although that is just a rough estimate. In Clay (2015), the diagrams also have an unnamed notch on the ventral side, which I suppose could represent the furrow. The infundibulum in Figure 13 appears as a hollow, which obviously extends deeper into the cell, but its length is not indicated.
Kim and Archibald (2013) mention that the infundibulum of G. truncata is "narrow and located near the anterior left corner," which is basically what I had already mentioned: that it is "located on the left side." I don't know how narrow it actually is; I have represented it as roughly the same width as the furrow, although shorter in length. In Martin-Cereceda et al. (2009), it's mentioned that the infundibulum of G. truncata could actually be interpreted as a cytopharynx, but in my representation, I call it an "infundibulum" anyway.
And what else can I say about this? Well, nothing more. The rest of the cell is occupied by food vacuoles. I could swear I've already mentioned that somewhere. I think I have nothing more to add. Oh yes, except that this was supposed to be published at Christmas, but I got delayed because I was terribly depressed to see that the furrow was ventral and not "dorsal" as I was originally representing it, and I had to redraw the diagrams and names again to make them match. That said, the part about the infundibulum and furrow is almost speculative, because I don't know their true morphology and size. It's there as a research reference for future projects.
Of course, Goniomonas truncata is transparent and doesn't have that many colors in real life. The ones shown here are for illustrative and educational purposes. I've tried to avoid using overly bright colors that might lead to misunderstandings. The images are free to use and are available on Wikimedia Commons. As always, the only requirement is that you credit me if you use, reference, or modify any of the images: DOTkamina 2025.
