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Polychaos fasciculatum CCAP 1564/1
Locomotive forms. DIC.

Photo: A.Smirnov

Polychaos fasciculatum CCAP 1564/1
Nucleus, contractile vacuole and uroidal structures.

Photo: A.Smirnov

Polychaos fasciculatum CCAP 1564/1.

1: nucleus (tangential section through the piece of
nucleolar material makes an impression of
large nucleolus, 2: cell coat (filaments coagulated
under fixation, 3: nuclear lamina; 4: mitochondria

TEM: A.Smirnov

Polychaos fasciculatum Penard 1902 CCAP 1564/1

  • Polypodial, "plamate" amoeba with short, parallel pseudopodia and large fasciculate uroid (especially at the beginning of locomotion). Lentgh in locomotion 65-140 mkm (average 110 mkm), monopodial, clavate locomotive forms may appear under low oxygene tension (Page, 1988). Crystals are truncate bipyramids. Floating form of radial type; several thick pseudopodia of unequal lenght radiate from irregular central mass of the granuloplasm.

  • Single spherical nucleus, 11-23 mkm in diameter, with nucleolar material in few narrow peripheral lobes, sometimes - in a single curved band, twisting inside the nucleus.

  • Surface coat consists of very fine filaments, often collupsing under unappropriate fixation.

  • This species may be confused with Polychaos annulatum, 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).

    Culture Collection of Algae and Protozoa, CEH Windermere, UK). It is a "rise" culture with relatively low density of amoebae.

  • Freshwater, Europe. 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.
  • Page F.C. 1986. The genera and possible relationships of the family Amoebidae, with special attention to comparative ultrastructure. Protistologica. 22: 301-316.
  • Page F.C. 1988. A new key to freshwater and soil gymnamoebae. FBA, Ambleside. 122p.
  • Page F.C. 1991. Nackte Rhizopoda. in: Protozoenfauna, b.2. Gustav Fisher, Stuttgart. 3-172.

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