DESCRIPTION OF THE PHYLUM CARPEDIEMONADA (CAVALIER-SMITH 2003)
| EUKARYA> EXCAVATA> EUEXCAVATA> CARPEDIEMONADA |
CARPEDIEMONADA LINKS
| Carpediemonada (kar-pe-de-a-mo-NA-da) comes from three Latin roots that mean seize (carpe); the day (die); and unit (monus). The phylum was named for the single common genus, Carpediemonas. This may not describe the taxon (except the reference to the unit, meaning cell); however, Ekebom et al. (1996) must have felt that they had to “seize the day” when they discovered the strange organism. |
| INTRODUCTION TO THE CARPEDIEMONADA This strange group was first reported from substrate samples taken in the Great Barrier Reef in 1996 (Ekebom et al. 1996), when its excavate (text with tooltip) An excavate is a feeding groove that terminates in a cytostome on the surface of certain taxa within the Excavata. Usually, they are associated with a recurrent or posteriorly-directed flagellum. status was recognized. Unlike other members of this kingdom, the carpediemonads are free-living. Also, the cell does have an excavate feeding groove in which the 3-vaned recurrent flagellum (text with tooltip) Recurrent flagella bend to the posterior end of the cell. Typically, they are identified as recurrent when anteriorly-directed flagella are present. resides. Typical of the other excavates, Carpediemonas does not have mitochondria and lives in anoxic organic-rich mud where it feed on bacteria. This phylum, Carpediemonada, holds uncertain status until its relationships to other excavates can be determined. It is based on a single (maybe a few) species in the genus, Carpediemonas (Figure 1). Ekebom et al. (1996) recognized that although it was an excavate taxon, it was unusual in that it was free-living, had two flagella and three basal bodies. It does not have a functional mitochondrion, but does have a double membrane bound organelle ( hydrogenosome (text with tooltip) Hydrogenosomes are symbiotic bacteria or organelles that generate hydrogen as a kind of anaerobic mitochondrion. ) that likely is an anaerobic mitochondrion. Simpson et al. (2002) supposed that Carpediemonas represented a stage toward the amitochondriate, parasitic lifestyle of taxa like Giardia. Lara et al. (2006) suggest a sister-group relationship with the jakobids (see Figure 2). Clearly, a resolution to the position of this taxon may do much to resolve the unknown relationships within the Kingdom Euexcavatae. |
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| FIGURE 1. (Left) Differential Interference micrograph of Carpediemonas. (Right) An illustration of the same cell showing the flagella and the ventral groove or excavate. Image from http://microscope.mbl.edu/baypaul/microscope/images/ |
 | FIGURE 2. A cladogram showing the relationships between the phyla of the Euexcavatae (taxa in bold). Carpediemonads are in the free-living clade that includes Jakobada. The cladogram is a consensus view from Lara et al. (2006), Kolisko et al. (2008), and Malik et al. (2011). |
| LITERATURE CITED Cavalier-Smith, T. 2003b. The excavate protozoan phyla Metamonada Grasse emend. (Anaeromonadea, Parabasalia, Carpediemonas, Eopharyngia) and Loukozoa emend. (Jakobea, Malawimonas): their evolutionary affinities and new higher taxa. International Journal of Systematic and Evolutionary Microbiology. 53:1741-1758. Ekebom, J., D. J. Patterson, and N. Vors. 1996. Heterotrophic flagellates from coral reef sediments (Great Barrier Reef, Australia). Archiv fur Protisenkunde. 146: 251-272. Kolisko, M., I. Cepicka, V. Hampl, J. Leigh, A. J. Roger, J. Kulda, A. G. B. Simpson, and J. Flegr. 2008. Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA, alpha-tubulin and HSP990 genes: implications for the evolutionary history of the double karyomastigont of diplomonads. BMC Evolutionary Biology. 8: 205 doi: 10.1186/1471-2148-8-205 Lara, E., A. Chatzinotas, and A. G. B. Simpson. 2006. Andalucia (n. gen.) – the deepest branch within jacobids (Jacobida: Excavata), based on morphological and molecular study of a new flagellate from soil. Journal of Eukayotic Microbiology. (53(2): 112-120. Malik, S-B., C. D. Brochu, I. Bilic, J. Yuan, M. Hess, J. M. Logsdon, and J. M. Carlton. 2011. Phylogeny of parasitic Parabasalia and free-living relatives inferred from conventional markers vs. Rpb1, a single-copy gene. PLoS ONE. 6(6): e20774. doi:10.1371/journal.pone.0020774 Patterson, D. J. 1999. The diversity of eukaryotes. American Naturalist. 154 (Suppl.): S96–S124. Simpson, A. G. B., and D. J. Patterson. 2001. On core jakobids and excavate taxa: the ultrastructure of: Jakoba incarcerata. Journal of Eukaryotic Microbiology. 48: 480–492. Simpson, A. G. B., A. J. Roger, J. D. Silberman, D. D. Leipe, V. P. Edgcomb, L. S. Jermiin, D. J. Patterson, and M. L. Sogin. 2002. Evolutionary history of ‘early diverging’ eukaryotes: The excavate taxon Carpediemonas is close relative of Giardia. Mol. Biol. Evol. 19: 1782–1791. |
| By Jack R. Holt. Last revised: 02/17/2014 |
