This post was originally going to be dedicated to another Cryptomonas species, specifically Cryptomonas marssonii, but I'm having some trouble representing the chloroplast (I think I'm going to have to rearrange layers or something, i'm about to get polymerized at this point with this shit).
So I started reviewing the taxonomy that includes the Cryptomonas genus and found that there are a ton of species and genera, some of them quite obscure. What if I tried to represent them?
And so begins the context for this genus, Protocryptomonas. It's considered a "rare" genus, but only because it lacks detail. No preserved specimens exist; all that remains are the illustrations and descriptions made by Skvortsov. Therefore, the genus is questionable, as to whether they are truly cryptomonads. The question, it seems to me, also lies in whether it's a true genus, or a form of a better-known species, but since only illustrations remain, not much can be determined. It amuses me that, despite everything, the genus and species were accepted taxonomically based solely on the images. You can read more about this in Bicudo (1989).
Friendly (abusive) reminder!: The illustrations are free to use under CC BY-SA 4.0, non-commercial, attribution required (DOTkamina 2026).
Taxonomically, Protocryptomonas is a genus that, along with others (including Cryptomonas, of course), belongs to the family Cryptomonadaceae. I don't have much more to add there, so what follows is a copy-paste of other descriptions of Cryptomonas species: family Cryptomonadaceae is included in 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 Protocryptomonas is another distant relative of plant ancestors.
I should mention that my references for the text and images are:
- "A Companion to the Identification of Cryptomonad Flagellates (Cryptophyceae = Cryptomonadea)". Gianfranco Novarino. 2003. Hydrobiologia 502(1):225-270. DOI: 10.1023/B:HYDR.0000004284.12535.25
- "Algae Novae et Minus Cognitae Chinae Boreali-Orientalis 2. Flagellatae Prope Oppidum Mukden in Anno 1957 Collectarum". B. V. Skvortzov. 1960. Bulletin of Botanical Research. 1-8 pp.
- "Protocryptomonas Skvortsov ex C.E.M.Bicudo, 1989". AlgaeBase (formerly "E.A. Molinari Novoa in Guiry, M.D. & Guiry, G.M"). 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.
- "Validation of the generic name Protocryptomonas (Cryptophyceae: Cryptomonadaceae)". Carlos E. de M. Bicudo. 1989. TAXON. Vol. 38, Issue 1. 82-83 pp. https://doi.org/10.2307/1220898
Well then, to begin discussing this species, let's start with some general information about the genus. I have based myself on the most current description which is the one in AlgaeBase 2023, and it continues like this: "Free-swimming, biflagellate, dorsiventrally asymmetric monads; with a firm, smooth, hyaline periplast; elliptic or obovate with rounded ends; non-metabolic; flagella unequal, subapically inserted, one twice the cell length, the other one and one-half times the cell length; chloroplasts absent; with five to ten spherical starch grains; a single contractile vacuole near the flagellar bases; A little known freshwater genus recorded only from cold water ponds, impure ditch water and standing water near Harbin, northern Manchuria, China".
Some of these general characteristics are those I have represented for M. mukdenensis Skvortsov ex C.E.M.Bicudo 1989, which is the type species for Protocryptomonas. The central nucleus is visible (I have decided not to depict a nucleolus, as I don't know if one exists or should exist), as is the contractile vacuole near the "flagellar bases" (this leads me to believe it's near the basal bodies, which anchor the flagella to the cytoplasm, but I haven't depicted them). Bicudo (1989) mentions that there are "two contractile vacuoles," although the original descriptions by Skvortzov (1960) only mention one, and AlgaeBase also mentions one, so I'll conclude that there is only one contractile vacuole.
However, in Skvortzov (1960), the descriptions are in Latin and Chinese XDDD. But roughly translated by machine (thanks a lot, Google Translate!), it says the following about Protocryptomonas mukdenensis: oblong or ovate cell shape, 13 to 15 µm long, 7 to 9 µm wide.
Two flagella at the anterior end, the primary one twice as long as the cell, and the secondary one almost the same length as the cell. That's how I've represented them, with the secondary flagellum as if it were "ventral" to the primary one. This arrangement isn't mentioned anywhere; it's an inference derived from how I've been representing the flagella in the Cryptomonas illustrations (the ventral flagellum is shorter, and the dorsal one is longer).
So that's where the analogy comes in. According to Clay (2015), the vestibulum exists in all cryptomonads, and that would also include Protocryptomonas, but there's no actual data or evidence for that, so the vestibulum is highly speculative, which is why it's marked with a question mark and the text is transparent. The same applies to the reticulated mitochondrion, the endoplasmic reticulum, and the Golgi apparatus. These structures should be present in most eukaryotes, but I'm not sure if they exist in Protocryptomonas, given the shapes and sizes I've used to represent them. That's why they're speculative and presented in transparent text. If anything is more relevant, I'd say the reticulated mitochondrion, as Clay (2015) suggests that cryptomonads have this form. However, it's still entirely speculative for Protocryptomonas because there's no direct ultrastructural evidence.
In the general description for Protocryptomonas, AlgaeBase (2023) mentions 5 to 10 spherical starch grains (the organism lacks chloroplasts, and in my opinion, any other type of plastid). But for P. mukdenensis specifically, Skvortzov (1960) mentions that "Cellula oblonga vel ovata; granula amylaceae magna singula," or in Chinese if you prefer: "細胞長橢圓形或卵形；澱粉粒大，單一," which apparently means that the cells have large, individual starch granules. I assume that each cell has a single starch granule, which, according to the same article, is half the size of the cell and has the same width as the cell.
... So it's a huge thing, and it can't mean that each cell has "a few individual granules" because the cell would be too swollen and would have to be larger. Either that, or I simply don't know Latin or Chinese, which is true. So if you're reading this and think I'm misinterpreting everything, let me know in the comments here or on the Wikimedia discussion! Or something like that; sooner or later I'll see it and might correct it.
So, the conclusion is that I've represented P. mukdenensis with only one large starch granule. Since the image is designed as if viewed ventrally, the nucleus is dorsal and the starch grain is "ventral," as if it were covering the nucleus. Actually, this is just an assumption; I'm not saying it necessarily applies to all of them. It's something I inherited from how I've represented Cryptomonas species, with the chloroplasts "covering" the nucleus, which is "behind," although what actually happens is that the chloroplasts "envelop" the nucleus like a sandwich. Protocryptomonas doesn't have chloroplasts—uhm, did I already mention it doesn't have chloroplasts?
And well, I suppose that's all I had to explain about this organism. It lacks other structures present in Cryptomonas or other genera. It does not have ejectisomes or a furrow/gullet system. More details providing context for Protocryptomonas are supposed to be found in this reference: Castro, A. A. J. d., C. E. d. M. Bicudo & D. d. C. Bicudo, 1991. Cryptogamos do Parque Estadual das Fontes do Ipiranga, SaoPaulo, SP. Algas, 2: Cryptophyceae. Hoehnea 18: 87–106. But unfortunately, I have not been able to access that reference.
What do you do in these situations?
Well. Open Roblox.
