Prymnesiophytes (Class Haptophyceae) are small, biflagellate and often solitary cells characterised by scales on the cell body and the presence of a haptonema, a thread-like or bulbous appendage protruding from near the base of the flagella. The morphology of the scales is the principal feature used in the identification of species. Until recently, many species remained undiscovered owing to their small size and delicate structure.
Cells typically contain 2 saucer-shaped, parietal chloroplasts. Golgi bodies and endoplasmic reticulum can vary between species. Aspects of the taxonomy, life cycle, ultrastructure and ecology of the haptophytes were discussed in detail by Green & Leadbeater (1984). The haptonema, its structure and possible functions were documented by Hibberd (1980) and Inouye & Kawachi (1994). Included here are a number of haptophytes, particularly of the genus Chrysochromulina, which have been rarely reported from Antarctic waters, are of doubtful identity, or are species of which only scales have been observed.
There are 22 species in our key they generally require the use of a scanning or transmission electron microscope (SEM, TEM) to resolve cryptic features and scale structure. A thumbnail image of each species is included as a “first impression” and this, in some cases, can lead directly to a successful identification. Further images can be viewed on the factsheets. Images are sourced from Antarctic Marine Protists (eds. Scott & Marchant, 2005) unless otherwise credited. A glossary to explain specific terms has been integrated into both key and factsheets.
Taxonomic names are those used in ‘AlgaeBase’ (accessed April 2013). The following references and weblinks may be useful to the user:
- Edvardsen, B, Eikren, W, Throndsen, J, Saez, AG, Probert, I, Medlin, LK. 2011. Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of the Prymnesiales (Haptophyta). Eur. J. Phycol. 46(3):202-228.
- Chrysochromulina key, Sorbonne Universites.
- LeRoi, J.-M., Hallegraeff, G.M., Scale-bearing Nanoflagellates: Chrysophytes, Haptophytes (excluding Coccolithophorids) and Prasinophytes, in Hallegraeff et al. Algae of Australia. Phytoplankton of Temperate Coastal Waters (ABRS, Canberra) 293-341 (2010).