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2018 Top 10 New Species

Image by Andrew Walmsley

Protist: Aquarium to enigmaESF Top 10 New Species of 2018

  • Ancoracysta twista

    Ancoracysta twista Differential interference contrast microscopy of a cell. Two flagella, the feeding gullet, nucleus and a posterior digestive vacuole are visible.
    Photo credit: Denis V. Tiknonenkov

  • Ancoracysta twista

    Ancoracysta twista Electron microscopy of an ultrathin section through a cell. The central nucleus is positioned between two dark-stained, oval extrusomes ("ancoracysts"), which are involved in prey capture.
    Photo credit: Denis V. Tiknonenkov

map showing location of Protist Origin in wild unknown: Discovered on tropical brain coral in an aquariumGoogle Maps view

About the Protist

Ancoracysta twista

Discovered in an aquarium in San Diego, California, USA, this new single-celled protist has challenged scientists to determine its nearest relatives. It does not fit neatly within any known group and appears to be a previously undiscovered, early lineage of Eukaryota with a uniquely rich mitochondrial genome. Eukaryotes are organisms with cells in which genetic material is organized in a membrane-bound nucleus. Prokaryotes, like bacteria and archaea, lack such an organized nucleus. Eukaryotes include single-celled protists as well as multi-celled organisms we commonly think of as animals, plants and fungi.

Ancoracysta twista is a predatory flagellate that uses its whip-like flagella to propel itself and unusual harpoon-like organelles, called ancoracysts, to immobilize other protists on which it feeds. The geographic origin of the species in the wild is not known. It was found in a tropical aquarium at the Scripps Institution of Oceanography on a brain coral. The unusually large number of genes in its mitochondrial genome opens a window into the early evolution of eukaryotic organisms.

Etymology The species name refers to the twirling motion the protist makes while swimming.

Type locality Origin in wild unknown. Discovered on a tropical brain coral in an aquarium in San Diego, California, USA.

Type Resin-embedded cells deposited in Beaty Biodiversity Museum, University of British Columbia

Description Janouskovec, J., Tikhonenkov, D.V., Burki, F., Howe, A.T., Rohwer, F.L., Mylnikov, P., and P.J. Keeling(2017) A new lineage of Eukaryotes illuminates early mitochondrial genome reduction. Current Biology 27: 1-8

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