Cryptomonas tetrapyrenoidosa Skuja 1948

I consider this illustration special because my main source for drawing Cryptomonas species is usually the illustrations already in Clay (2015); you can see that my inspiration clearly comes from there. But there isn't a previous illustration of this species, only micrographs that don't provide much information. You could say this is one of my first Cryptomonas illustrations that "almost came from nowhere," except for the text and the limited photographic information available. Yes, this is a paragraph where I declare that I'm proud of what I'm doing.

The illustrations are free to use under CC BY-SA 4.0, non-commercial, attribution required (DOTkamina 2026).

This species belongs to the family Cryptomonadaceae, order Cryptomonadales, class Cryptophyceae (commonly called "cryptomonad algae"). You know where this is going: cryptomonad algae are then included in the subphylum Rollomonadia, phylum Cryptista, subkingdom Hacrobia, kingdom Chromista. 

The kingdom Chromista is related to the clade Archaeplastida, which includes algae that are relatives and ancestors of plants. You might also encounter another classification, where the phylum Cryptista is included in the clade Pancryptista, which is related to Archaplastida, and both form the large CAM clade. But that's not really important; the point is that Cryptomonas tetrapyrenoidosa is another distant relative of plant ancestors.

The information written here, as well as the illustrations themselves, were based on the following sources:

• "CCAP 979/26. Cryptomonas tetrapyrenoidosa". CCAP s.f. Culture Collection of Algae and Protozoa.
• "Chapter 18 - Cryptomonads". Brec L. Clay, 2015. Freshwater Algae of North America (Second Edition). Academic Press.
• "Cryptomonas tetrapyrenoidosa". Protist Information Server 2018.
• "Cryptomonas tetrapyrenoidosa Skuja 1948". M. D. Guiry in AlgaeBase. 2022.
• "Taxonomy and phylogeny of the genus Cryptomonas (Cryptophyceae, Cryptophyta) from Korea". Bomi Choi, Misun Son, Jong In Kim, Woongghi Shin. Algae, 28(4): 307-330. 2013. DOI: 10.4490/algae.2013.28.4.307

I drew this organism because it had a very long name. Which also gives many clues about its appearance: it has four pyrenoids, two in each chloroplast. Unfortunately, this isn't always the case; the number of pyrenoids can range from 6 to 7. It also has starch grains throughout the cell. By the way, C. tetrapyrenoidosa has two chloroplasts.

Dimensions: according to Clay (2015): 20–60 µm long, 10–27 µm wide, 5–17 µm deep. According to Protist Information Server (2018): 16–25 µm long, 8–13 µm wide, 7–12 µm thick. According to Choi et al. (2013): 16–22 µm long. Hmm, several dimensions to consider.

The name in Choi et al. (2013) should be noted that refers to Cryptomonas tetrapyrenoidosa (Skuja) Hoef-Emden et Melkonian 2003, a name whose equivalence to C. tetrapyrenoidosa Skuja, 1948, the species I have represented here, is uncertain.

According to Protist Information Server (2018), the species has two refractile bodies in the cell center. I am unsure if this term is equivalent to "maupas bodies," as they are technically the same in behavior: two structures found in several species (not only Cryptomonas, but also Chilomonas) that reflect light, hence their white and shiny appearance. However, I have decided to retain the term "refractile bodies" because, let's be honest, I am not an expert on this either. In Clay (2015) Figure 6G, two white oval-shaped circles can be seen in the cell center, which I consider micrographic visual evidence of these structures.

In Clay (2015) Figure 9A, there is an electron micrograph of the cell exterior of C. tetrapyrenoidosa which, thankfully, provides sufficient visual information about the shape of the vestibulum, the flagellar insertion, and the stoma location within the furrow. I have attempted to represent it somewhere between reality (that Figure 9A) and a more "simplified" way within the context of my illustration. I hope this is clear. In the illustration, I refer to the thin black line ending at the stoma as the "furrow," but the rest of the groove (dark gray) surrounding that black line would also be part of the "furrow." My intention was to depict the furrow as a groove-like structure with depth. I don't think I achieved that goal very well, to be honest.

Of course, there is a gullet, which has ejectisomes surrounding it. I don't know the exact arrangement, but I decided to use three rows of ejectisomes because that seems to be "the standard" in Cryptomonas species, according to the Protist Information Server (2018). But assume there can be more. Hey, while I'm at it, did you notice I used a different brush for the ejectisomes? IbisPaint has a special brush that you can temporarily unlock by watching an ad, and it draws like 3D beads. I thought it wouldn't look good, but I already tried it on the Cryptomonas erosa illustration and it turned out great, so I think I'll keep using it for a while longer.

The color is almost speculative, since in the Protist Information Server (2018) the cells appear bright green, but I've illustrated some Cryptomonas species before (not that many, but you get the idea) and they're always around a brownish color, so that's the color I decided to use for this illustration. They're also represented that way in CCAP (n.d.).

Regarding the flagella, their dimensions are almost speculative; I drew them by roughly estimating their size relative to the cell size in Clay (2015) Figure 9A. This time, unlike other species I have already illustrated, I am certain of the arrangement and shape of the mastigonemes on the flagella, since Kugrens et al. (1987) directly mentions that C. tetrapyrenoidosa has type I flagella. And this consists of: the long (dorsal) flagellum has two opposing rows of mastigonemes, each with a single terminal filament. The short (ventral) flagellum also has a single row of mastigonemes, each with two terminal filaments of different lengths. Additionally, there are approximately three terminal hairs at the end of the dorsal flagellum.

Both the mastigonemes and the additional filaments and hairs can only be seen with an electron microscope. Don't expect to see them with a light microscope. Even the flagella are sometimes difficult to see with a light microscope. I almost forgot: both flagella are located on the right side of the vestibule. That's from a dorsal view. In a ventral view, they appear to be on the left, but that's just an illusion!

Additionally, according to Clay (2015), Cryptomonas species generally have two nucleomorphs between the nucleus and the pyrenoids. Unfortunately, C. erosa does not have pyrenoids, so I have drawn the nucleomorphs above the nucleus. The nucleomorphs in this illustration are therefore speculative.

The shapes of the single reticulated mitochondrion, Golgi apparatus and endoplasmic reticulum are also speculative. In the case of the mitochondrion, it's a predicted reticulated shape based on what Santore and Greenwood (1977) explains, where it's mentioned that Cryptomonas has a single mitochondrion with numerous branches distributed throughout the cell, concentrated in areas like the gullet. It's assumed that these mitochondrial branches should have different thicknesses in various sections, but in my drawing, the width of these branches is almost uniform.

Will there be rule 34 of my OC?

I should be doing other things right now. Especially since I also have to study some user guides for special cameras. Because, as I mentioned in a previous post, next week I'll be going on a trip that could lead to my first real job. I'm excited about that, as well as about reaching 20 illustrations. I need to hurry and upload these files online and keep expanding my reach.

Cryptomonas erosa Ehrenberg 1832

And what better way to do it than with this song playing in the background?

(ﾟo´(┗┐ヽ(╰ , ╯ )ﾉ

Illustration 17 in the series. I finished it yesterday, April 8th. The illustrations are free to use under CC BY-SA 4.0, non-commercial, attribution required (DOTkamina 2026).

I was in an art course that had some interesting promises, but I didn't have the time. Nah, it actually bored me. I say that even though I'm not exactly the best person to claim I know anything about art, because it's clear I'm terrible at choosing colors, and I think there's a way I could improve my illustrations. Honestly, I didn't have the time, and I had to travel far away, and besides, I have more important projects to attend to. Did you know that probably? No, that most likely, sometime next week, I'll be heading off to what looks like my first paid job. I won't give any more details except that it involves invertebrates, but I'm excited about what it might mean.

Anyway, in this post, I'm going to talk about Cryptomonas erosa. I'm too lazy to explain the Taxonomy again, so I'll just copy and paste from someone else. I'll probably do the same to save myself some mental effort. This species belongs to the family Cryptomonadaceae, order Cryptomonadales, class Cryptophyceae (commonly called "cryptomonad algae"). You know where this is going: cryptomonad algae are then included in the subphylum Rollomonadia, phylum Cryptista, subkingdom Hacrobia, kingdom Chromista. 

The kingdom Chromista is related to the clade Archaeplastida, which includes algae that are relatives and ancestors of plants. You might also encounter another classification, where the phylum Cryptista is included in the clade Pancryptista, which is related to Archaplastida, and both form the large CAM clade. But that's not really important; the point is that Cryptomonas erosa is another distant relative of plant ancestors.

The information written here, as well as the illustrations themselves, were based on the following sources:

• "Chapter 18 - Cryptomonads". Brec L. Clay, 2015. Freshwater Algae of North America (Second Edition). Academic Press.
• "Cryptomonas erosa Ehrenberg, 1831". Martin Kreutz. Real Micro Life, 2021.
• "Cryptomonas erosa Ehrenberg 1832". M. D. Guiry in AlgaeBase. 2022.
• "Cryptomonas erosa/ovata/phaseolus". Part of; Steckbriefe der Phytoplankton-Indikatortaxa. Kasten J., Kusber W.-H., Riedmüller U., Tworeck A., Oschwald L. & Mischke U. Berlin: Botanic Garden and Botanical Museum Berlin, Freie Universität Berlin. –  177 pp., ISBN 978-3-946292-28-9, https://doi.org/10.3372/spi.01. 2018.

The cells are oval or slightly elliptical, 13 to 45 µm long and 6 to 26 µm wide. They have two chloroplasts without pyrenoids, like Cryptomonas phaseolus, but the difference in that respect is the cell size. More important is the color: the chloroplasts in Cryptomonas erosa range from brown to yellowish to greenish. I have chosen to represent it as an intermediate point between brown and yellowish (with a small green base, although I don't think it's very noticeable).

Another characteristic is that the dorsal side is significantly convex, while the ventral side is only slightly convex, or even flat. In the micrographs by Kreutz (2021), I don't see a large convexity (outward curvature) on the dorsal side, but it does appear to be more curved than the ventral side.

Another difference from C. phaseolus is that C. erosa has maupas bodies.

The contractile vacuole is located anteriorly, next to the flagellar insertion point. From a ventral view, it would appear to the right of the flagellar region. Dorsally, it would appear on the left side.

In C. erosa, the gullet is covered with ejectisomes (which shouldn't be surprising if you know about Cryptomonas species), and it extends up to half the length of the cell. It doesn't go beyond that half. The gullet connects to the outside through the vestibulum. The starch grains are distributed throughout the cell and have polygonal or oval shapes.  Since it has the cryptomorph shape, I have represented the furrow as a complex one (with the presence of a stoma). You can find out more about this in the post on Cryptomonas obovata.

Kreutz (2021) mentions that the flagella are the same length, but both there and in Clay (2015) Figure 5D, they are depicted as unequal. I have decided to represent them as very similar in size, such that the dorsal flagellum is slightly longer.

The flagella of C. erosa are represented as if they had type 1 flagella according to Kugrens et al. (1987). This decision is speculative. I haven't found any information on what they actually look like; I assume they correspond to type 1, because it's the most common type (or the one that should be the most common) according to Kugrens et al. (1987). In this type 1 flagella, the long (dorsal) flagellum has two opposing rows of mastigonemes, each with a single terminal filament. The short (ventral) flagellum also has a single row of mastigonemes, each with two terminal filaments of different lengths. Additionally, there are approximately three terminal hairs at the end of the dorsal flagellum.

Both the mastigonemes and the additional filaments and hairs can only be seen with an electron microscope. Don't expect to see them with a light microscope. Even the flagella are sometimes difficult to see with a light microscope. I almost forgot: both flagella are located on the right side of the vestibule. That's from a dorsal view. In a ventral view, they appear to be on the left, but that's just an illusion!

Additionally, according to Clay (2015), Cryptomonas species generally have two nucleomorphs between the nucleus and the pyrenoids. Unfortunately, C. erosa does not have pyrenoids, so I have drawn the nucleomorphs above the nucleus. The nucleomorphs in this illustration are therefore speculative.

The shapes of the single reticulated mitochondrion, Golgi apparatus and endoplasmic reticulum are also speculative. In the case of the mitochondrion, it's a predicted reticulated shape based on what Santore and Greenwood (1977) explains, where it's mentioned that Cryptomonas has a single mitochondrion with numerous branches distributed throughout the cell, concentrated in areas like the gullet. It's assumed that these mitochondrial branches should have different thicknesses in various sections, but in my drawing, the width of these branches is almost uniform.

I want to remind you that this mini visualization of the ventral view of C. erosa is simplified, indicating the parts most potentially visible under an optical microscope.

I think that's all I had to say about this organism. I have another illustration pending upload, which I'll also post about. I'm excited because I'm about to reach my goal of 20 illustrations. I don't want to think too much about having to do 100 because I feel like it will discourage me. Fortunately, things in my life have improved slightly.