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Metachaos spec.
Metachaos spec., dark and with large nucleus.

Metachaos spec.

Diagnosis: Locomotive form usually between 75 and 500 µm in length. Pseudopodia cylindrical and smooth with clear hyaline zone. Cytoplasm often very granular with bipyramidal or irregular crystals. Nucleus discoid or spherical, filled with granules of nucleolar material. Uroid often typically elongated, U-shaped, papillate or morulate and temporary. No dorsal folds.

Dimensions: monopodium 350-560 µm; nucleus 33-70 µm (mean 42 µm)

Ecology: Freshwater. I have found this species on several locations in the Netherlands (Baarn, Naardermeer, Roden, Diepveen-Dwingeloo) and in Tirol, Austria. It could easily be cultured with “pond” culture.

Remarks: This species is remarkable because of the density of crystals, which gives it usually a dark and black appearance, though some specimens were observed with the same density of crystals as is normal for Amoeba proteus. Its shape can differ strongly. Between cover slip and slide the amoebae are less slender as in culture dishes.

In 2013 Enrique Lara sequenced this amoeba, from one of my cultures, and its sequence was nearly identical with that of Amoeba leningradensis!

Metachaos spec.
Specimen with fewer crystals as usual.
Metachaos spec.
 
Uroid, right below and uroid, characteristic U-shape
Metachaos spec.
Metachaos spec.
Uroid
Metachaos spec.
Metachaos spec.
Monopodial forms
Metachaos spec.
Monopodial form changing direction
Metachaos spec.
Crystals
Metachaos spec.
Nucleus with some endosymbionts (arrows)
Metachaos kerrii
Characteristic uroid
Metachaos
Metachaos spec., with contractile vacuole and nucleus (in the centre of the image).
Metachaos kerrii
Monopodium 390 µm long; n=nucleus.
Metachaos
Contractile vacuole and nucleus (right)
Metachaos spec.
Metachaos spec.
Nucleus
Metachaos spec.
Metachaos spec.
Two specimens in a culture dish, with long slender pseudopodia
Metachaos spec.
Specimens in a culture dish

The drawings below were made around 1980 from specimens which I found on several locations in the Netherlands.

Amoeba kerrii
Metachaos spec: A: Monopodium; B-C-D: Polypodial shapes; E: Floating form; F-H: Nuclei, lateral view; K: apical view; I: Nucleoli; J: Crystals. (drawing Ferry Siemensma)
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