Chromista

Chromista is a eukaryotic kingdom, probably polyphyletic. It includes all algae whose chloroplasts contain chlorophylls a and c, as well as various colorless forms that are closely related to them. As it is assumed the last common ancestor already possessed chloroplasts of red algal origin, the non-photosynthetic forms evolved from ancestors able to perform photosynthesis. These chloroplasts are surrounded by four membranes, and are believed to have been acquired from some red algae. Chromista has been defined in different ways at different times. The name Chromista was first introduced by Cavalier-Smith in 1981; the earlier names Chromophyta, Chromobiota and Chromobionta correspond to roughly the same group. It has been described as consisting of three different groups: In 2010, Thomas Cavalier-Smith indicated his desire to move Alveolata, Rhizaria and Heliozoa into Chromista. Some examples of classification of the Chromista and related groups are shown below. The Chromophycées (Chadefaud, 1950), renamed Chromophycota (Chadefaud, 1960), included the current Ochrophyta (autotrophic Stramenopiles), Haptophyta (included in Chrysophyceae until Christensen, 1962), Cryptophyta, Dinophyta, Euglenophyceae and Choanoflagellida (included in Chrysophyceae until Hibberd, 1975). The Chromophyta (Christensen 1962, 1989), defined as algae with chlorophyll c, included the current Ochrophyta (autotrophic Stramenopiles), Haptophyta, Cryptophyta, Dinophyta and Choanoflagellida. The Euglenophyceae were transferred to the Chlorophyta. The Chromophyta (Bourrelly, 1968) included the current Ochrophyta (autotrophic Stramenopiles), Haptophyta and Choanoflagellida. The Cryptophyceae and the Dinophyceae were part of Pyrrhophyta (= Dinophyta).