Ochromonadales (e.g., Ochromonas, Pseudokephyrion, Dinobryon) Order Mallomonadales (= Class Synurophyceae, e.g., Mallomonas, Synura) Order Pedinellales (= Class Pedinellophyceae, e.g., Pedinella) Order Chrysamoebidales (e.g., Rhizochrysis, Chrysarachnion) Order Chrysocapsales (e.g., Chrysocapsa, Hydrurus) Order Chrysosphaerales (e.g., Chrysosphaera) Order Phaeothamniales (e.g., Phaeothamnion, Thallochrysis) Preisig (1995) Classification of the class Chrysophyceae and splinter groups according to Preisig (1995): Class Chrysophyceae Order Bicosoecales Order Chromulinales Order Hibberdiales Order Hydrurales Order Sancinochrysidales Order Chrysomioridales Class Dictyochophyceae Order Pedinellales Order Rhizochromulinales Order Dictyochales Class Synurophyceae Order Synurales Guiry and Guiry (2019) According to Guiry and Guiry (2019): Class Chrysophyceae Order Chromulinales Order Hibberdiales Order Hydrurales Order Rhizochrysidales Order Thallochrysidales Chrysophyceae ordo incertae sedis (11 genera) Ecology Chrysophytes live mostly in freshwater, and are important for studies of food web dynamics in oligotrophic freshwater ecosystems, and for assessment of environmental degradation resulting from eutrophication and acid rain. Evolution Chrysophytes contain the pigment fucoxanthin. Because of this, they were once considered to be a specialized form of cyanobacteria. Because many of these organisms had a silica capsule, they have a relatively complete fossil record, allowing modern biologists to confirm that they are, in fact, not derived from cyanobacteria, but rather an ancestor that did not possess the capability to photosynthesize. Many of the chrysophyta precursor fossils entirely lacked any type of photosynthesis-capable pigment. The most primitive stramenopiles are regarded as heterotrophic, such as the ancestors of the Chrysophyceae were likely heterotrophic flagellates that obtained their ability to photosynthesize from an endosymbiotic relationship with fucoxanthin-containing cyanobacteria. References Bibliography Andersen, R. A. 2004. Biology and systematics of heterokont and haptophyte algae. American Journal of Botany 91(10): 1508–1522. 2004. Duff, K.E., B.A. Zeeb & J.P. Smol. 1995. Atlas of Chrysophycean Cysts, Vol. 1., ; 2001, Vol. 2, . Kluwer Academic Publishers, Dordrecht. Jørgen Kristiansen. 2005. Golden algae: a biology of chrysophytes. A.R.G. Gantner Verlag, distributed by Koeltz Scientific Books, Königstein, Germany, vii + 167 pp. . Kristiansen, J. and R.A. Andersen [Eds.]. 1986. Chrysophytes: Aspects and Problems. Cambridge University Press, Cambridge, xiv + 337 pp. Kristiansen, J. and Preisig, H. [Eds.]. 2001. Encyclopedia of chrysophyte genera. Bibliotheca Phycologica, Vol. 110, J. Cramer, Berlin. Medlin, L. K., W. H. C. F. Kooistra, D. Potter, G. W. Saunders, and R. A. Anderson. 1997. Phylogenetic relationships of the “golden algae” (haptophytes, heterokont chromophytes) and their plastids. Plant Systematics and Evolution (Supplement) 11: 187–219. Sandgren, C.D., J.P. Smol, and J. Kristiansen [Eds.]. 1995. Chrysophyte algae: ecology, phylogeny