Cryptomonas obovata Skuja 1948... and notes on Cryptomonas morphs

Well, I don't expect to have much to say about this one, to be honest, except that I've noticed some details that were perhaps missing from the other Cryptomonas curvata illustration I published back in 2025. Damn, that year sounds so far away, and it's already February 2026. When will it be Christmas again?

The following illustrations depict Cryptomonas obovata Skuja 1948, as the name is recorded on AlgaeBase. I have shown it in ventral view. The images 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.

There are two main sources I used as a basis for creating the illustration of this organism:

• "Cryptomonas obovata Skuja, 1948". Martin Kreutz, 2021. Real Micro Life.
• "Chapter 18 - Cryptomonads". Brec L. Clay, 2015. Freshwater Algae of North America (Second Edition). Academic Press.

Btw, that chapter of "Cryptomonads" is even haunting my dreams. Clay, Lee, Hill, Andersen, Kugrens etc., seem to be the experts on cryptomonad algae; they've been researching these organisms since the past century (That's an exaggeration, but... well, you know what I mean). It would fill me with uncertainty, humility, joy, and a touch of fear if they were to see the images I create.

For the design of the flagella, I relied on this article: "Ultrastructural variations in cryptomonad flagella", by Paul Kugrens, Robert E. Lee, Robert A. Andersen, 1987. The design of the mitochondrion is speculative, but it is based on what is said in Santore and Greenwood (1977). I will explain it later.

Cryptomonas obovata follows a similar anatomical scheme to that of Cryptomonas curvata, which I illustrated earlier. The first noticeable difference is in its shape: Cryptomonas curvata could be oval-shaped but slightly more elongated than C. obovata, in addition to having a slight curve at its posterior end.

The second difference, and the one I find most unnerving, is the absence of pyrenoids. Instead, it has numerous starch granules distributed throughout the cell, although Kreutz (2021) mentions that these are located "beneath the chloroplasts." In microscopic photographs (see Kreutz (2021): Figures 1 to 4), these starch granules are clearly visible in both ventral and dorsal views. In my representation, I have chosen to depict them as being beneath the chloroplasts—in other words, "covered" or "hidden" by them. But you should consider that in real life, this property wouldn't be so obvious. Let's not forget that C. obovata has two chloroplasts.

There's another important aspect I should mention: some species within the genus Cryptomonas, according to Clay (2015), can have two distinct morphotypes in their life cycles: the cryptomorph and the campylomorph. I'd say this is a bit poorly worded, because at first glance it implies that it occurs "in all Cryptomonas species," but a quick review of the article by Hoef-Emden and Melkonian (2003) shows that this isn't always the case. Some species do indeed exhibit both morphotypes (cryptomorph or campylomorph), while other species only express one of the two (or, based on current research, it's assumed that only one morphotype occurs in these species because the other simply hasn't been found or observed).

So, briefly, using Clay's (2015) description: the cryptomorph consists of cells that are more or less rounded or oval in shape. These cells are protected by the periplast (a structure that performs a function similar to that of the cell wall in plant cells). The periplast has two layers: the inner periplast component (which in the cryptomorph consists of rounded or oval plates), and the surface periplast component (which in the cryptomorph is made of a thin layer of fibrils).

In the cryptomorph, the plastidial complex (the set of cellular plastids) is generally made up of two chloroplasts, with two pyrenoids not traversed by thylakoids, and two nucleomorphs, one between the nucleus and the pyrenoids. The furrow of the cryptomorph is "complex," possessing a stoma.

The campylomorph was considered for some time to be such a distinct morph that individuals with this morph were considered species in different genera of Cryptomonas. Formally, Campylomonas and Chilomonas. Now that it's known that the forms of both genera are actually the campylomorph, an alternative to the cryptomorph of Cryptomonas, they are considered synonymous where applicable.

But let's see: using again Clay (2015): the campylomorph is first different from the cryptomorph by having a more "sigmoid" cell shape; I would describe it, in simple terms, as a somewhat oval, flattened cell shape with varying degrees of elongation and curvature. More importantly, the periplast may be composed solely of the inner periplast component, simply a layer without shaped plates. The surface periplast component may be absent, but if present, it would be made of fibrillar material or heptagonal "scales."

The campylomorph generally has the same plastidial complex structure as the cryptomorph. The most noticeable difference is seen in the furrow, which lacks a stoma. In addition, it also has a scalariform furrow plate, a structure similar to the furrow plate that, in the campilomorph, resembles a ladder. In the cryptomorph, this furrow plate is only fibrous. I haven't depicted the furrow plate in the illustrations of this species. Finally, the vestibulum in the campylomorph also has a "vestibular ligule," a kind of extension that covers a small portion of the vestibule.

My state right now.

But anyway, those would be the main differences between the cryptomorph and the campylomorph of a Cryptomonas species. Now, in which species exactly, and in which ones only a single morph has been observed... hell, who knows?

According to the article by Hoef-Emden and Melkonian (2003), and comparing it with the information in Clay (2015), the cryptomonad species in which only the cryptomorph was found are: C. ovata, C. obovata (the species I illustrated in this post), C. phaseolus, C. tetrapyrenoidosa, and C. erosa. Clay (2015) also mentions C. ozolinii Skuja 1939 as a cryptomorph, but Hoef-Emden and Melkonian (2003) already indicate that it is actually a synonym of C. pyrenoidifera Geitler 1922 emend. Hoef-Emden and Melkonian (in Hoef-Emden and Melkonian (2003), this synonym is written simply as "C. ozolini Skuja"). C. pyrenoidifera exhibits both morphs, cryptomorph and campylomorph.

Similarly, considering Hoef-Emden and Melkonian (2003) and Clay (2015), the species where, conversely, only the campylomorph was found are: C. platyuris and C. marssonii. Clay (2015) also mentions C. rostratiformis Skuja (omitting the "1950"), which would actually be a synonym of C. curvata Ehrenberg 1832. I had illustrated C. curvata as campylomorphic, but according to Hoef-Emden and Melkonian (2003), it also has the cryptomorph.

There is a problem with C. reflexa. First, it should be noted that Clay (2015) mentions C. reflexa Marsson (syn. Campylomonas reflexa Hill). In AlgaeBase, the closest taxon to the one mentioned is C. reflexa (M.Marsson) Skuja 1939, but I'm not certain. Hoef-Emden and Melkonian (2003) mention C. reflexa Skuja (1939), which may in fact be the same as C. reflexa (M.Marsson) Skuja 1939 in AlgaeBase (they also appear in the same original publication). In any case, Hoef-Emden and Melkonian (2003) indicate C. reflexa as another synonym of C. curvata, and therefore, it would have both cryptomorph and campylomorph. C. reflexa has about five names in AlgaeBase, and all of them are in an "unstable" state, meaning they are not fully accepted.

C. marssonii Skuja 1948 does have only a campylomorph (or rather, only that morph has been found), according to Hoef-Emden and Melkonian (2003). The problem is that this name is currently being debated...

But anyway. I think that covers the important points regarding the morphs.

Returning to Cryptomonas obovata, it's established that it only has the cryptomorph. Based on the general characteristics of the cryptomorph, I have represented its furrow with a stoma. The vestibule lacks a vestibular ligule. There are two nucleomorphs, one on each side of the nucleus.

The main difference from the general scheme of the cryptomorph is that C. obovata does not have pyrenoids; instead, it has those starch granules I mentioned earlier. The ejectisomes "envelop" the entire gullet. This is something that also occurs in other Cryptomonas species. I mention this because in the illustration of C. curvata I did some time ago, I didn't depict the ejectisomes surrounding the entire gullet. Why? For better visibility... I suppose. The contractile vacuole is located behind the chloroplasts and near the anterior region, according to what I see in Kreutz (2021). I haven't represented the periplast and its components.

I have drawn the endoplasmic reticulum, Golgi apparatus, and the single reticulated mitochondrion. The shapes of these structures are 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.

Finally, the flagella of C. obovata are of type 1 flagella according to Kugrens et al. (1987): 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!

I could swear there was more to say, but the truth is I went off for a while to... I don't know, do something, the thing is I don't remember anymore. I hope I've covered everything.

Oh right, I almost forgot... the maupas bodies! Those two funny things way behind the chloroplasts and starch granules. C. obovata only has two maupas bodies. I don't know if you know this, but all the colors in these drawings are merely schematic and for educational purposes, and don't necessarily correspond to what you can see in real life. However, according to the images in Kreutz (2021), maupas bodies can be seen under a microscope as two shiny structures. What are they for? .... HAH, who knows?