Cryptomonas phaseolus Skuja 1948

And well, this would be the third Cryptomonas species I've illustrated. I don't know whether to celebrate it as some kind of major event, but oh well. Actually, I'm writing this paragraph while watching an episode of standard Roncom, and I don't think I'll write any more. The goal is simply to get this post started.

Well, I think I've finally decided to write a little. In this post, I'll talk about Cryptomonas phaseolus. It's a species whose specific epithet makes me laugh; it's like they're talking about beans. 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 phaseolus 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/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.
• "Cryptomonas phaseolus 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 hope I don't take too long with this species. 

According to Clay (2015), it is the smallest Cryptomonas species, measuring 8 to 13 µm in length and 5 to 8 µm in diameter. It has an ellipsoidal shape in lateral view and an oval shape in cross-section. The anterior end has a rounded protrusion just above the flagellar insertion site, while the posterior end is slightly narrower. Oh, and it has two chloroplasts without pyrenoids. Graphically, as shown in Clay (2015) Figure 5C, it has several starch grains distributed throughout the cell. Classic cryptomonad structures are also present, such as the gullet covered with ejectisomes and the furrow. Since it has the cryptomonad morph, I have represented the furrow as a complex (with the presence of a stoma). You can find out more about this in the post on Cryptomonas obovata.

That is all the formal information available about the species. The shapes of the single reticulated mitochondrion, Golgi apparatus, endoplasmic reticulum, contractile vacuole, mastgigonemes/terminal hairs and nucleomorphs are purely 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.

The flagella of C. phaseolus are represented as if they had type 1 flagella according to Kugrens et al. (1987). This decision is equally speculative, and it doesn't so much affect the flagella as the nature of the mastigonemes. 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!

Regarding the two nucleomorphs, apparently, according to Clay (2015), Cryptomonas species generally have two nucleomorphs between the nucleus and the pyrenoids. Unfortunately, C. phaseolus does not have pyrenoids, so I have drawn the nucleomorphs above the nucleus.

Cryptomonas phaseolus (Skuja) Hoef-Emden 2007.

Now, next to the main image, there is another ventral view that represents, in a very simplified way, a strange strain I found in the article by Choi et al. (2013) (Figures 11 G and H): Cryptomonas phaseolus (Skuja) Hoef-Emden 2007. I already checked it on AlgaeBase and it's not listed there as a synonym of Cryptomonas phaseolus Skuja 1948. The morphology is identical to that of C. phaseolus Skuja 1948, except that C. phaseolus (Skuja) Hoef-Emden 2007 does have one pyrenoid per chloroplast (there are two chloroplasts, so there are two pyrenoids). Could it be a synonym of another species that has nothing to do with C. phaseolus Skuja 1948? Who knows? But if you find out anything, let me know in the comments. 

Yes, that uncertainty is why I haven't decided to make a version indicating the parts only for that strain, taxon, or whatever it's called... I was just too lazy, really. Maybe I'll make a version in the future, but don't count on me too much.

I think that's all I have to say. I have to write for the other species. See you.