A heterotypic synonym of Chroococcales is (order) Prochlorales Lewin, 1977, with type genus "Prochloron".[5] Additional names of the same nature included:
- Division Prochlorophyta Lewin, 1976
- Class Prochlorophyceae Lewin, 1977
- Family Prochloraceae Lewin, 1977
- Chloroxybacteria Margulis & Schwartz, 1982
- Subdivision Prochlorobacteria Jeffrey 1982
- Division Prochlorophycota Shameel 2008
The assignment as a division/subdivision was based on a belief that because this class lack red and blue phycobilin pigments and have stacked thylakoids, they are so distinct from typical cyanobacteria as to warrant a high rank.[6][7]
The four taxa with "Lewin 1977" became validly published names under the ICNP in 1986, as the revised version (ex Lewin 1977) Florenzano et al. 1986, by virtue of being published in Int. J. Syst. Bacteriol. with a description.[8]
They are an important component of photosynthetic picoplankton.[9] These oligotrophic organisms are abundant in nutrient poor tropical waters and use a unique photosynthetic pigment, divinyl-chlorophyll, to absorb light and acquire energy.[9]
This unique group of phytoplankton, with no phycobilin pigments, were initially found in 1975 near the Great Barrier Reef[10] and off the coast of Mexico (Prochloron).[11] Prochlorophyta was soon assigned as a new algal sub-class in 1976 by Ralph A. Lewin of the Scripps Institution of Oceanography.[12][13] Other phytoplankton that lacked phycobilin pigments were later found in freshwater lakes in the Netherlands by Tineke Burger-Wiersma and colleagues[14] and were termed Prochlorothrix (additional reading on Prochlorothrix can be found in a journal article by A.V. Pinevich [15] ). In 1986 Prochlorococcus was found by Sallie W. (Penny) Chisholm and colleagues.[16] Prochlorococcus may be responsible for a significant portion of the global primary production.
Prochlorophytes are very small microbes generally between 0.2 and 2 μm (photosynthetic picoplankton). They morphologically resemble Cyanobacteria (formerly known as Blue Green Algae). Members of Prochlorophyta have been found as coccoid (spherical) (Coccus) shaped, as in Prochlorococcus, and as filaments, as in Prochlorothrix.
