Discoba
The general plan of Discoba structure is reduced to a dikinetid state (2–3 flagella or many pairs), while usually 3 microtubule roots depart from a pair of kinetosomes. Many taxa are characterized by trans splicing, the formation of a giant unsplitted transcript during RNA processing. Cells are usually large and in different groups are characterized by various particular adaptations, such as paraxial road, kinetoplast, or undulating membrane. Mitochondria, if present, with discoid, rarely tubular cristae, but in some taxa they are reduced to peroxisomes or mitosomes. Most species are phagoheterotrophs, feeding on cytostomes or lobopodia, but there are also osmotrophs and even autotrophic forms with chloroplasts that have a 3-membrane envelope and chlorophylls a and b (euglenoids). In many euglenoids, plastids are secondarily absent, but the ability to phagotrophy has also been lost – such forms feed osmotrophically (Rhabdomonadineae), however, some euglenoids (Peranematida) are phagotrophs and are primarily devoid of plastids. The sexual process is absent.
Jakobea is a sister/basal lineage.
References
Busse I, Preisfeld A. Phylogenetic position of
Rhynchopus sp. and
Diplonema ambulator as indicated by analyses of euglenozoan small subunit ribosomal DNA. Gene. 2002. V. 284(1–2). P. 83–91.
Cavalier-Smith T. Eukaryote kingdoms: seven or nine? BioSystems. 1981. V. 14. P. 461–484.
Cavalier-Smith T. Evolution of prokaryotic and eukaryotic cells. Foundations of medical cell biology Greenwich. 1991. V. 1. P. 217–272.
Cavalier-Smith T. Principles of protein and lipid targeting in secondary symbiogenesis: Euglenoid, dinoflagellate, and sporozoan plastid origins and the eukaryote family tree // The Journal of Eukaryotic Microbiology. 1999. Vol. 46, no. 4. P. 347–366.
https://doi.org/10.1111/j.1550-7408.1999.tb04614.xCavalier-Smith T. Kingdom Protozoa and its 18 phyla. Microbiol. Rev. 1993. V. 57. P. 953–994.
Cavalier-Smith T., Nikolaev S. The zooflagellates Stephanopogon and Percolomonas are a clade (class Percolatea: phylum Percolozoa). J. Eukaryot. Microbiol. 2008. V. 55 (6). P. 501–509.
https://doi.org/10.1111/j.1550-7408.2008.00356.xCavalier-Smith T. Early evolution of eukaryote feeding modes, cell structural diversity, and classification of the protozoan phyla Loukozoa, Sulcozoa, and Choanozoa. Europ. J. Protistol. 2013. V. 49 (2). P. 115–178.
https://doi.org/10.1016/j.ejop.2012.06.001Foissner W., Blatterer H., Foissner I. The Hemimastigopora (Hemimastix amphikineta nov. gen., nov. spec.), a new protistan phylum from Gondwanian soils. Eur. J. Protistol. 1988. V. 23. P. 361–383.
Hampl V., Hug L., Leigh J. W., et al. Phylogenomic analyses support the monophyly of Excavata and resolve relationships among eukaryotic “supergroups”.Proceedings of the National Academy of Sciences U.S.A. 2009. V. 106 (10). P. 3859–3864.
https://doi.org/10.1073/pnas.0807880106Honigberg B.M. A contribution to the systematic of the non pigmented flagellates, a new terminology. Progress in Protozoology. N.Y., 1963, pp. 68–69.
Page F.C., Blanton R.L. The Heterolobosea (Sarcodina: Rhizopoda), a new class uniting the Schizopyrenida and the Acrasidae (Acrasida). Protistologica. 1985. V. 21. P. 121–132.
Pascher A. Systematische Übersicht uber mit Flagellaten in zusammenhaug stehenden Algenreichen und Versuch Einreihung in die Stamme der Pflanzenreiches. Berlin. Bot. Centralbl. 1931. V. 48. P. 317–332.
Patterson D.J.
Jakoba libera (Ruinen, 1938), a heterotrophic flagellate from deep oceanic sediments. J. Marine Biological Association of the United Kingdom. 1990. V. 70. P. 381–393.
Yubuki N., Egcomb V.P., Bernhard J.M. et al. Ultrastructure and molecular phylogeny of
Calkinsia aureus: cellular identity of a novel clade of deep-sea euglenozoans with epibiotic bacteria. BMC Microbiol. 2009. V. 16.
https://doi.org/10/1186/1471-2180-9-16