Cryptomonas curvata = Campylomonas rostratiformis

The first time I drew this organism, I thought I was drawing a rare species. Then I carefully read the synonymy history, and no, what I thought was Campylomonas rostratiformis is now Cryptomonas curvata. I'm well aware of the tensions in the taxonomic world and how they fight over authorship. Sometimes that makes me distrustful. The scientific world can be cruel at times.

Anyway, I'll include below the list of all the synonyms registered for Cryptomonas curvata in AlgaeBase. Curiously, "Campylomonas rostratiformis" isn't listed. That's how it was proposed by Clay in 2015. Later, when I tried to find reference micrographs for the species, only "Cryptomonas curvata" appeared, and that's when I discovered that the current taxonomic decision (at least as of the date of this post, December 14, 2025) is to maintain that name, as a species belonging to Cryptomonas.

I based this drawing on the following articles and sources. Additionally, I obtained the text information in this blog from the first three sources:

• "Chapter 18 - Cryptomonads". In: "Freshwater Algae of North America (Second Edition)". Brec L. Clay 2015.
• "An ultrastructural survey of cryptomonad periplasts using quick-freezing freeze fracture techniques". Paul Kugrens and Robert E. Lee, 1987.
• "Ultrastructural variations in cryptomonad flagella". Paul Kugrens, Robert E. Lee, Robert A. Andersen. 1987.
• "Light microscopical observations of the sigmoid species of the genus Cryptomonas Ehrenberg (Cryptophyceae) and their eventual pyrenoids". Pavel Javornický. 2014.
• "The phytoplankton community (except Bacillariophyceae) of Lake Abant (Bolu, Turkey)". Abuzer Çelekli, Olcay Obali, Okan Külköylüoğlu. 2007.
• "Cryptomonas rostratiformis". Protist Information Server.
• "Cryptomonas". PhycoKey. University of New Hampshire.

Ah, and the synonims list (.づ◡﹏◡)づ, according to AlgaeBase:

Homotypic synonym:

• Cryptomonas ovata var. curvata (Ehrenberg) Lemmermann 1903

Heterotypic synonyms

• Cryptomonas rostrata O.V.Troitzkaja 1922
• Cryptomonas rostrata Skuja 1948
• Cryptomonas rostratiformis Skuja 1950
• Cryptomonas lilloensis W.Conrad & H.Kufferath 1954.

And don't forget about Campylomonas rostratiformis. I saw that name first in Clay (2015), but it's termed as "Campylomonas rostratiformis Hill 1991" in Çelekli et al. 2007.

The main (full) image of Cryptomonas curvata.

Clay (2015) mentions that it is the largest cryptomonad species, with the following dimensions: 45 to 80 µm long, 16 to 40 µm wide, and 14 to 24 µm deep. He mentions that the posterior part of the Cryptomonas curvata cell (which he refers to as Campylomonas rostratiformis in the article, page 837) is slightly curved, and this is very evident in his illustration of the organism (Figure 7B). However, in the micrographs, I don't see it as so evident, nor can I discern this curvature (Figures 8A-B and 9B). The micrograph on AlgaeBase does show this curvature of the posterior region. Nevertheless, I have included this characteristic in the main drawing (ventral view).

Cryptomonas belongs to the family Cryptomonadaceae, which is part of the superclass Cryptomonada, within the phylum Cryptista, clade Pancryptista, which in turn is part of the CAM clade. The CAM clade encompasses not only Pancryptista but also Archaeplastida, the group that includes algae related to and ancestors of plants.

Anyway, in the main image, I've shown the ventral view of the organism, and below it on the left, the anterior view. On the right, there's a simplified recreation of what the organism would look like unsectioned, as if viewed under SEM. Please note that all colors used here are for illustrative and educational purposes only and may not necessarily correspond to the actual colors. However, Cryptomonas curvata is an alga that naturally appears reddish-brown due to its chloroplasts. According to Protist Information Server, the color range varies from green, through turquoise/blue-green, to brown, and even rarely red.

                                             

Cryptomonas curvata, ventral view illustration.

What can I say about this organism? Let's start with the ventral view: the most ventral part would be the vestibule, which connects to a gullet (a "digestive system," although it's an organelle; remember, it's just a single cell). The vestibule has a slit that faces downwards (towards the posterior region), known as the "furrow." The furrow is oriented slightly to the left. "Hey DOTkamina, but in the drawing it's oriented to the right." Yes, that's because the furrow faces to the left if you were viewing the cell dorsally. In ventral view, it will point to the other side (the left). I don't know why they always describe how it looks in dorsal orientation if the illustrations are ventral. It's confusing.

Slightly parallel and adjacent to both sides of the gullet are two large, reddish-brown chloroplasts. The chloroplasts occupy almost the entire length of the organism. According to Javornický (2014), these chloroplasts may sometimes be joined by a narrow dorsal isthmus. He also mentions that "6 pyrenoids should be typical for the species." Clay (2015) only states that there are "several" pyrenoids. I depicted 6 pyrenoids, 3 for each chloroplast. Of course, each pyrenoid is encased in a starchy sheath, presumably made of granules.

Among other features, the chloroplasts enclose a nucleus with a nucleolus at the rear of the cell (I'm not sure why I mention this; most nuclei in eukaryotic cells have a nucleolus). Around the nucleus, I have depicted the rough endoplasmic reticulum (with dots representing ribosomes. It's assumed they are more concentrated there, but are also distributed throughout the cell), and the smooth endoplasmic reticulum. I have also depicted the Golgi apparatus and a few mitochondria. The shape, number, and size of these structures are purely speculative, and I have done so to emphasize the eukaryotic nature of the organism. It is known that these structures "should" exist.

                                                              

I will briefly mention the presence of a single contractile vacuole in the anterior portion. 

With that said, let's move on to the last interesting part of Cryptomonas curvata (Campylomonas rostratiformis): the flagella. Two are identified: one short and one long. According to Kugrens et al. (1987) (Figures 9 to 11), both flagella have a single row of mastigonemes, but the structure varies. In the long flagellum, each mastigoneme has only one terminal filament. In the short flagellum, on the other hand, there are two terminal filaments, one shorter than the other. Additionally, at the end of the long flagellum, there appear to be "terminal hairs" (I represented 4, as indicated in Figure 19D of Kugrens et al. (1987)), but I'm not sure if there are actually exactly 4. According to the authors, this flagellar morphology is called "Cryptomonad-type 4 flagella," and it is also observed in Cryptomonas platyuris, C. marssonii, C. olozini, and Chilomonas paramecium. One troubling point to mention is that in that article, this flagellar morphology does seem to correspond to C. curvata, and "Cryptomonas rostratiformis" is mentioned as another species. As you know, it is currently considered yet another synonym of C. curvata.

There is no micrograph of the organism's cross-section. No, the illustration of the "anterior view," or "top view" for better understanding (as if you were looking at the "head" of the cell from above), is not a cross-section as such. In it, I represent the vestibule (omitting the two flagella, I only show two white dots that would be the "bases" of both flagella). Below the vestibule would be the gullet surrounded by ejectisomes. Incidentally, in the main illustration in ventral view, I represent the gullet surrounded by a single apparent row of ejectisomes, but in reality, there would be more rows covering the entire gullet. This is how it is represented in the drawings in Javornický (2014) (Figures 1 to 9). You can also see the anterior ends of both chloroplasts, and part of the nucleus, as well as the contractile vacuole and the furrow.

                                           

Finally, in the last illustration, the one of the whole, unsectioned cell, I know I said it's inspired by what you'd see in SEM (the reference is Figure 9B from Clay (2015)), but there are some creative choices. The existence of two shades of gray isn't natural; I actually did that to distinguish the two halves of the cell, especially so you can see the arrangement of the vestibule. The flagella should appear equally gray, not with those blue tones. That was to distinguish them better.

You know what annoys me about writing this post? I don't know why Blogger has been acting up; it won't let me post the images correctly, and they keep shifting around. I thought letting it sit would do the trick, but it's still the same.

I think that's all I have to say in this post. Of course, you can use any of these images freely; you know they're hosted on Wikimedia Commons. The only requirement is that you credit the author, for example, "DOTkamina 2025". 

That's all.