Epithemia

Epithemia is a genus of diatoms belonging to the family Rhopalodiaceae.^[1] The genus has cosmopolitan distribution and are found in freshwater and marine ecosystems.^[2][1] Recent studies have proposed that the genus Rhopalodia should be recategorized to join Epithemia based on phylogenetic evidence,^[3] although this change in nomenclature has been disputed.^[4]

Epithemia
Epithemia sorex
Scientific classification
Domain:	Eukaryota
Clade:	Sar
Clade:	Stramenopiles
Phylum:	Ochrophyta
Clade:	Diatomeae
Class:	Bacillariophyceae
Order:	Rhopalodiales
Family:	Rhopalodiaceae
Genus:	Epithemia F.T.Kützing, 1844

Members of this genus have endosymbionts that fix nitrogen called spheroid bodies, that are derived from cyanobacteria.^[5][6] This endosymbiont is closely related to the nitroplast organelle.^[2][7] Because of this close relationship, Epithemia has been proposed as a model system to study the early stages of organelle evolution.

Because of their nitrogen fixing endosymbionts, they can be a possible indicator of eutrophication, because Epithemia abundance decreased with increased ambient inorganic N concentrations.^[8]

Species

Those marked with a * were previously in the genus Rhopalodia.^[1]

• Epithemia adnata (Kützing) Brébisson, 1838
• Epithemia alpestris Kützing, 1844
• Epithemia alpestris W.Smith, 1853
• Epithemia anasthasiae Pantocsek, 1902
• Epithemia argus (Ehrenberg) Kützing 1844
• Epithemia catenata^[2]
• Epithemia constricta W. Smith (Krammer)*^[9]
• Epithemia gibba Kützing, 1844*
• Epithemia gibberula Kützing, 1844*
• Epithemia musculus Kützing, 1844*
• Epithemia pelagica^[2]
• Epithemia reicheltii Schmidt et al. 1904
• Epithemia smithii Carruthers 1864
• Epithemia sorex Kützing, 1844
• Epithemia turgida Kützing, 1844