Microworld

world of amoeboid organisms

Menu
Pelomyxa palustris
Pelomyxa palustris

Genus Pelomyxa Greeff, 1874

Diagnosis: Free-living amoebae from anaerobic or micro-aerophilic habitats, cells amoeboid, reaching 5 mm long with a large anterior pseudopod and a posterior uroid; shell usually spherical to elongated ovoid; one to numerous nuclei; short flagella present in most species; cytoplasm filled contains several glycogen bodies; different types of symbiotic bacteria have been observed; all pelobionts lack mitochondria.

Remarks: Pelobionts are an original group of amoeboid protists inhabiting bottom sediments of freshwater basins under micro aerobic or anaerobic conditions. Earlier investigators described nearly twenty species. Later, the validity of most species was doubted and studies of Chapman-Andresen, (1978, 1982) showed a complex life cycle, and all Pelomyxa species ever described, were considered to be stages of the life cycle of Pelomyxa palustris. This led to the conclusion that Pelomyxa palustris was a polymorphic species.
Since 2004, a series of studies by Frolov et al (2004, 2005, 2006, 2011) changed this view completely. They provided evidence that some original described species are valid species an no part of a complex life cycle of Pelomyxa palustris. Concerning the latter, it is still unclear whether P. palustris is a nominal species or a group of species erroneously united into a single taxon.

Pelomyxa representatives are multinuclear and possess numerous immobile flagella. All pelobionts lack mitochondria and most, with the exception of Mastig­amoeba punctachora and P. palustris, the Golgi apparatus.

Key to Pelomyxa species:

1Usually with two nuclei2
Usually with more than two nuclei3
2Nuclei < 30 µmP. flava
Nuclei > 30 µmP. binucleata
3Cell with numerous conical projectionsP. corona
Cell without such projections4
4Nucleus with central nucleolus5
Nucleus with small peripheral nucleoliP. palustris
5No glycogen bodies presentP. gruberi
Glycogen bodies presentP. stagnalis
Immobile cilia
Recent posts

Penardochlamys arcelloides

P. arcelloides – from Penard, 1904 Penardochlamys arcelloides  (Penard, 1904) Deflandre, 1953 Diagnosis: Colorless or very slightly yellowish envelope, bag or cauldron-shaped, very thin, chitinous,

Read More »

Reticulomyxa hannae

R. hannae, plasmodium – photomicrograph Steffen Clauss Reticulomyxa hannae Völcker and Clauß, 2020 Diagnosis: Trophozoites surrounded by a very thin mucous envelope, with slowly moving plasmodia, variable

Read More »

Velamentofex saxonensis

V. saxonensis, feeding (photomicrograph Steffen Clauss) Velamentofex saxonensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 30-95 μm, granuloreticulopodia up to 1000 μm long. with a hyaline, thin

Read More »

Velamentofex tyrolensis

V. tyrolensis (photomicrograph Steffen Clauss) Velamentofex tyrolensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 98-125 μm, with reticulopodia up to 300 μm long, with a hyaline,

Read More »

Velamentofex berolinensis

V. berolinensis Velamentofex berolinensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 50-300 µm, with a hyaline, extremely flexible, membranous test. Nuclei numerous, 11.6-16.2 µm in diameter,

Read More »

Lieberkuehniidae

 Lieberkuehniidae  Siemensma, Holzmann, Apothéloz-Perret-Gentil, Clauß, Voelcker, Bettighofer, Khanipour Roshan, Walden, Dumack and Pawlowski, 2020 Diagnosis: Multinucleate organic-walled monothalamous foraminifera. Test very flexible, elongated to broadly

Read More »