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Pelomyxa palustris
Pelomyxa palustris, almost 2 mm in length

Pelomyxa palustris Greeff, 1874

Diagnosis: Cells amoeboid, reaching 5 mm long with a large anterior pseudopod and a posterior uroid. With numerous nuclei. Short cilia have been demonstrated. Cytoplasm contains usually several glycogen bodies, as large as the nuclei (10 µm). Nuclei surrounded by symbiotic bacteria. Symbiotic bacteria present.

Ecology: In sediments of swamped stagnant and low-flow fresh water reservoirs at a depth of 20 – 50 cm. Common.

Remarks: A complex life cycle has been described. However, recent investigations (Frolov et al, 2004, 2005, 2006, 2011) indicate that this complex life cycle doesn’t exist and that the several stages in this life cycle are valid species, as is  Pelomyxa binucleata. The question is whether the name Pelomyxa palustris covers a distinct species or a morphotype-complex.

Pelomyxa palustris
Highly vacuolated cytoplasm with some nuclei and refractive bodies (glucogen?) – Bert Bospad
Pelomyxa palustris
Highly vacuolated cytoplasm with some nuclei (n) and refractive bodies (rb); not all bodies are indicated.
Pelomyxa palustris
Highly vacuolated cytoplasm with some nuclei (n) and refractive bodies (rb). These bodies are surrounded by bacteria (endosymbionts). However nuclei of this specimen didn’t show any adhering bacteria.
Pelomyxa palustris
Pelomyxa palustris
Nucleus, arrows indicate adhering bacteria and bacteria in cross section. Symbiotic bacteria
Pelomyxa palustris
Pelomyxa palustris, 800 µm – Diepveen, Dwingeloo
Pelomyxa palustris
Pelomyxa palustris, pseudopodium with bacteria
Pelomyxa palustris
Pelomyxa palustris, pseudopodium
Pelomyxa palustris
Pelomyxa palustris, about 2 mm in diameter
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