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Nuclearia simplex
Nuclearia thermophila, flattened specimen

 

Nuclearia thermophila Yoshida, Nakayam and Inouy, 2008

Diagnosis: Cells having two forms: spherical to subspherical; floating forms non-motile, with radial filopodia, and flattened amoeboid forms, often elongated. Filopodia sometimes branching or knobbed. Nucleus central, with spherical nucleolus. Many food vacuoles and lipid droplet-like vacuoles with homogeneous contents. Golgi body perinuclear and mitochondria with flat cristae.  No cell wall or extracellular matrix. Cysts spherical, surrounded by a thick layer of mucus.

Dimensions: floating spherical forms about 20-40 µm; flattened amoeboid forms measuring 30-65 µm in diameter, reaching to 150 µm when elongated. My measurements: spherical form 10-35 µm (mean 25-30 µm), flattened forms c. 46-60 µm, nucleus c. 10.2 µm, cysts 15-22 µm, with mucous layer up to 47 µ.

Ecology: freshwater. This species has been described from a warm water lake, hence the name. I found this Nuclearia-species in peat bogs. It multiplied easily in “pond” cultures with a maize grain; feeding on green algae has been observed.

Remarks: I kept this species in cultures for many months. In wet mounts kept in humidity chambers some specimens encysted after some days. Cysts have not been observed by Yoshida et al (2008).

Nuclearia
Nuclearia thermophila came up in some cultures of material from a peat bog.
Nuclearia simplex
Nuclearia thermophila
Flattened specimens with knobbed filopodia
Nuclearia simplex
When specimens became more or less pressed between cover slip and slide, because of evaporating water, they became very flattened and irregular, with many small vacuoles. Notice the tiny knobs on some filopodia.
Nuclearia thermophila
Five specimens probably feeding on the same prey.
Nuclearia thermophila
Contractile vacuole, sequence
Nuclearia thermophila
Trophozoit (left) and cyst.
Nuclearia thermophila
Cyst
Nuclearia thermophila
Cysts
Nuclearia thermophila
Specimen with two nuclei, which I only observed once.
Nuclearia thermophila
Nuclearia thermophila
Branched filopodia
Nuclearia thermophila
Elongated flattened form, body 60 µm
Nuclearia thermophila
Spherical and flattened specimen. The right one with Diplophrys archeri as food.
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