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Polychaos annulatum original isolate.
1-2: polypodial, 3-4: monopodial locomotive forms,
5: nucleus, Phaco, 6: nucleus, haemotoxylin-stained
(NE-nuclear envelope). Scale bar 50mkm in 1-4 and
10 mkm in 5-6. DIC.
Photo: A.Smirnov

Polychaos annulatum original isolate.
1-2: cell coat, 3: mitochondria and endobionts,
4: dyctyosomes. Scale bar 500 nm
Photo: A.Smirnov

Polychaos annulatum original isolate.

Nucleus (two variants of organisation, with respective
diagrams on the right). Scale bar 500 nm.
TEM: A.Smirnov

Polychaos annulatum (Penard 1902) Smirnov & Goodkov, 1998
  • At the beginning of movement amoebae are always polypodial, "plamate, with short, parallel pseudopodia and very large fasciculate uroid (up to 1/2 of the body). In active locomotion amoebae normally acquire monopodial form and may loose any distinct uroidal structures or to have bulbous uroid. Lentgh in locomotion 220 - 325 mm, breadth was 35 - 43 mm, the Length/Breadth ratio (L/B) about 9. Crystals resemble small bipyramids or have irregular shape. Floating form of radial type, with spherical central mass of the cytoplasm and short thick radiating pseudopodia. Often amoebae flotate without taking the specialized floating form.

  • Single spherical nucleus, 16-25 mkm in diameter, with nucleolar material forming a perforated sphere inside the nucleus.

  • Surface coat consists of very fine filaments,about 330 nm in length, often collupsing under unappropriate fixation.

  • This species may be confused with Polychaos fasculatum, however the latter has very distinct nuclear structure. Careful examination of 3D organisation of the nucleolus always excludes any doubts about the species identification. Comparison of Polychaos fasciculatum-like" amoebae was done by Smirnov & Goodkov (1998).

  • Freshwater, Europe, North-Western Russia. Cultivation: Rise + PJ medium and accompanying small protists. Can be maintained for some time in PJ + Tetrahymena.

Basic references for identification:
  • Smirnov A.V. and GoodkovA.V. 1998. Study of Polychaos annulatum Penard, 1902 comb. nov. (Gymnamoebia, Amoebidae) with taxonomical analysis of Polychaos fasciculatum-like species. Europ. J. Protistol. 34: 1-9.

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