See text Cryptomonas is the name-giving genus of the Cryptomonads established by German biologist Christian Gottfried Ehrenberg in 1831.

[1] The algae are common in freshwater habitats and brackish water worldwide and often form blooms in greater depths of lakes.

[3] The plastid genome contains 118 kilobase pairs and is a result of one endosymbiosis event of ancient red alga.

[1] Cryptomonas cells are fairly large; they average about 40 micrometers in size and often take the shape of an oval or ovoid.

[2] In a secondary endosymbiosis event, the phagotrophic ancestor of the Cryptomonas presumably captured a red alga and reduced it to a complex plastid with four envelope membranes.

[9] The phycoerythrin was translocated into the thylakoid lumen with its chromophore composition altered; subsequently, phycobiliproteins with at least seven different absorption spectra evolved.

[4] Cryptomonas is distinguished by the purple phycoerythrin 566 as an accessory pigment, which gives the organisms a brownish color in appearance.

[4] In Proteomonas, another genus of Cryptophyceae, the two morphs revealed large differences in cell size which apparently led to its discovery and subsequent recognition.

For example, a furrow plate (extending posteriorly along one side of the ventral furrow-gullet complex) has been described as “scalariform” in Campylomonas yet “fibrous” in Cryptomonas.

[2] However, during later research, more evidence of both molecular phylogeny and morphology has been found to support the claim that the three genera should be considered one single dimorphic genus.

[4] To evaluate the taxonomic significance of the type of periplast and other characters previously used to distinguish genera and species, molecular phylogenetic analyses have been used to study two nuclear ribosomal DNA regions (ITS2, partial LSU rDNA) and a nucleomorph ribosomal gene (SSU rDNA).