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Welcome to cryptomonads.org, the cryptomonad website



This is an independent, self-funded website providing scientific information on cryptomonad flagellate protists (Cryptophyceae = Cryptomonadea). It is aimed at providing a resource dealing especially with the morphology, ultrastructure, taxonomy, nomenclature, systematics, ecology and biology of this most intriguing group of protists. It is based on the author's own research, supported by the work of a dedicated developer-webmaster.


The specific aims of this website include, but are not limited to:


  • The provision of an annoted list of all described cryptomonad taxa;
  • The provision of user-friendly taxonomic identification aids;
  • The provision of an updatable series of Species Cards for the most commonly cited cryptomonads;
  • The provision of an updatable list of geographic records.

This website welcomes requests for cross-linking of information from related websites.



A word on funding. This website is entirely self-funded. Direct sponsorship proposals from potentially interested third parties working in the scientific, technical, imaging, publishing and scientifically-related communities at large are also welcome.




  • About cryptomonads

Cryptomonads are of great evolutionary importance owing especially to the presence of a nucleomorph, a subcellular structure which has attracted much interest ever since it was first detected using electron microscopy and later recognized as a distinct cell organelle resembling an eukaryotic nucleus. The nucleomorph (now also referred to as "cryptonucleus") is now known to be the vestigial nucleus of a red algal-like photosynthetic endosymbiont from which the present-day cryptomonad chloroplast has evolved.

Molecular methods have made it possible to investigate the phylogenetic relationships of cryptomonads as a group, and the phylogeny of recognised cryptomonad genera and suprageneric taxa. Thanks to the cryptomonads it is now accepted that eukaryotic chloroplast-containing protists have evolved not only through the ingestion and retention of a photosynthetic prokaryote endosymbiont, but also through the establishment of a secondary endosymbiotic association with a photosynthetic eukaryote.

Cryptomonads are also of great ecological significance. It has long been known that they are widely distributed in marine and freshwater ecosystems. They have also been found in terrestrial subsurface or subaerial habitats such as soil, groundwater and snow. In the marine plankton they may often reach very high population densities, and it is especially in this environment that photosynthetic forms may contribute significantly to primary production. In freshwater environments they are often present in constant but relatively low numbers throughout the year, although sudden population increases are also common.


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  • Cryptomonads in the environment

Cryptomonads are widespread and abundant in the sea, particularly in the pelagic environment where photosynthetic forms may be responsible for a large part of primary carbon production, and in coastal areas where they may form nuisance blooms. Unfortunately however, very few ecological surveys of marine plankton have attempted to identify cryptomonads down to the genus or species levels, and therefore it is very difficult to establish a truly representative picture of the diversity of marine cryptomonads and its relationships to environmental variability.

In freshwater environments, about 100 known species (i.e., ca. 50% of the anecdotally accepted number of described species, although the true number of described species is actually much larger) are known to occur, particularly in nutrient-poor lakes, although they also occur in smaller water bodies and rivers especially in the presence of nutrient enrichment or in the vicinity of submerged macrophytes. Some are favoured by low pH values and/or waters rich in organic substances, which may stimulate growth in some species. A few photosynthetic species are also able to grow heterotrophically or even mixotrophically by ingesting bacteria.

Cryptomonads are often present in constant but relatively low numbers throughout the year, although sudden population increases are also common; several are more common during the colder months the year, although in temperate nutrient-poor lakes cryptomonad populations may peak in the summer rather than winter. A number of cryptomonads originally described from marine or brackish environments have also been reported from freshwater. At least in some cases this may be due to taxonomic misidentifications, although some species effectively show a wide tolerance range for a variety of ecological factors, salinity in particular.


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  • Cryptomonad systematics

"Classic" cryptomonad classification schemes (i.e., those based on gross morphological features visible by light microscopy) originate from the schemes proposed by Adolf Pascher in the early 1900's and by E.G. Pringsheim in the 1940's. In the last forty years or so, the traditional systematics and taxonomy of cryptomonads have been revolutionized by new ultrastructural information, to the extent that the most recent formal classification schemes are based almost entirely on ultrastructure, and electron microscopy is now a routine morphological identification tool. An ever increasing amount of molecular genetic information has also become available.

Initially the focus was mostly on the phylogeny of the cryptomonads as a whole but, more recently, molecular sequence data have also been used to investigate the phylogeny of genera and supra-generic groupings, although the situation is still far from resolved. Molecular sequencing data are also contributing to understanding relations between species within some genera.


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