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Parachaos zoochlorellae

Parachaos zoochlorellae  (Willumsen, 1982)

Diagnosis: Locomotive forms varying between a monopodium with length : breadth ratio from 4 : 1 to 8 : 1 to a polypodium with up to four sub-cylindrical pseudopodia, which may elongate to a length of four times its breadth with a ratio of the main stem of the amoeba to a pseudopodium of between 1 : 1 to 2 : 1. Hyaline caps on pseudopodia when extended. Posterior end of amoeba often has a villous-bulb uroid. Length in locomotion between 164 and 403 µm: mean 274.5 µm; monopodial forms attain the greatest length. Resting palmate form with about 10 short hemispherical pseudopodia in the periphery of the amoeba. Numbers of nuclei highly variable, depending on the size of the amoeba, but with a maximum of about 50 per amoeba. Nucleus spherical, 5.3 to 12.3 µm in diameter, mean 8.3 µm. Nucleolar material divided between many parietal granules and a central homogeneous nucleolus (only observed in stained preparations) ½ to 1/3 of the nuclear diameter. Zoochlorellae, presumably the green alga, Chlorella sp., a constant and often cytoplasmic inclusion. Plate-like, colorless crystals in large numbers located close to the cytoplasmic membrane. One posteriorly situated contractile vacuole.

Ecology: Type found in a small pond with slowly moving fresh water, Denmark. I found this amoeba in the early spring of 2015 in floating debris in a ditch close to the Naardermeer in the Netherlands. Martin Kreutz reported it from Germany (2021, pers. comm.)

P. zoochlorellae, video: Martin Kreutz
Parachaos zoochlorellae
Parachaos zoochlorellae, Photomicrograph: Niels B. S. Willumsen
Parachaos zoochlorellae
Parachaos zoochlorellae, with stained nuclei. Photomicrograph: Niels B. S. Willumsen
Parachaos zoochlorellae
Parachaos zoochlorellae, Photomicrograph: Niels B. S. Willumsen
Parachaos zoochlorellae
Parachaos zoochlorellae, Photomicrograph: Niels B. S. Willumsen
Parachaos zoochlorellae
Parachaos zoochlorellae, Photomicrograph: Martin Kreutz
Parachaos zoochlorellae
Parachaos zoochlorellae, Photomicrograph: Martin Kreutz
Parachaos zoochlorellae
Parachaos zoochlorellae, Photomicrograph: Martin Kreutz
Parachaos zoochlorellae
Parachaos zoochlorellae, Photomicrograph: Martin Kreutz
Parachaos zoochlorellae
Parachaos zoochlorellae, Photomicrograph: Martin Kreutz
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