The bicosoecids, formally Bicosoecida (ICZN) or Bicosoecales/Bicoecea (ICBN), are a small group of unicellular flagellates, included among the heterokonts. The cells are free-living, with no chloroplasts, and in some genera are encased in a lorica.

The name of the type genus Bicosoeca described by James-Clark in 1866 is derived from Greek roots (bikos, vase, bowl, plus oekein, inhabit). The philologically preferable compound would be Bicoeca, as "corrected" by Stein in 1878 and followed by most subsequent authors. However, according to the ICBN and ICZN, the original spelling of the name cannot be considered incorrect and it must be used in its original form.

The group was formerly considered to be related to the Chrysophyceae.[5]

Some authors use the vernacular term "bicosoecid" (or "bicoecid") in a narrower sense, only for Bicosoeca, aplying "bicoeceans" to Bicosoeca and related groups like Cafeteria.[6]

With the advent of using molecular phylogenies to resolve relationships of many eukaryotes the original circumscription of bicosoecids has been greatly expanded upon to include other orders and the rank has changed from an order to a class.[7]


  • Hibberd, D. J. (1986). Ultrastructure of the Chrysophyceae. Colorless forms. p. 29-30 In: Chrysophytes: Aspects and Problems. Kristiansen, J. and R.A. Andersen [Eds.]. Cambridge University Press, Cambridge.


  1. ^ Grassé, P.-P. Contribution à l'étude des flagellés parasites. Archives de zoologie expérimentale et générale, t. 65, 1926, pp. 345-602 [576], disponible at Gallica.
  2. ^ Grassé, P.-P. & Deflandre, G . (1952). Ordre des Bicoecidea. In: Grassé, P.-P. (Ed.). Traité de Zoologie. Vol. 1, fasc. 1. Phylogénie. Protozoaries: Generalités, Flagellés. Masson et Cie, Paris. 599-601.
  3. ^ Kristiansen, Jørgen (1972). "Structure and occurrence of Bicoeca crystallina, with remarks on the taxonomic position of the Bicoecales". British Phycological Journal. 7 (1): 1–12. doi:10.1080/00071617200650011. 
  4. ^ Loeblich III, Alfred R. & Loeblich, Laurel Ann. 1979. Division Chrysophyta, pp. 411-423. In: CRC Handbook of Microbiology, 2nd ed., vol. 2, Fungi, Algae, Protozoa, and Viruses, ed. by A. I.Laskin and H. A. Lechevalier, CRC Press, Inc., West Palm Beach, FL.
  5. ^ Hibberd, David J. (1978). "Bicosoeca accreta sp. nov., a flagellate accumulating extraneous silica fragments". British Phycological Journal. 13 (2): 161–166. doi:10.1080/00071617800650201. 
  6. ^ Cavalier-Smith, T; Chao, E. E. (2006). "Phylogeny and megasystematics of phagotrophic heterokonts (kingdom Chromista)". Journal of Molecular Evolution. 62 (4): 388–420. doi:10.1007/s00239-004-0353-8. PMID 16557340.  Supplementary material [1].
  7. ^ Cavalier-Smith, T; Scoble, J. M. (2013). "Phylogeny of Heterokonta: Incisomonas marina, a uniciliate gliding opalozoan related to Solenicola (Nanomonadea), and evidence that Actinophryida evolved from raphidophytes". European Journal of Protistology. 49 (3): 328–353. doi:10.1016/j.ejop.2012.09.002. 

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