Microcometes paludosa Cienkowski, 1876
Diagnosis: Shell hyaline, usually dark brown, small, with one side fastened to the substrate; outline polygonal, irregular; shell with three to five apertures, with or without short necks. Pseudopodia very thin, granular, branching. Usually with two short flagella. Nucleus globular with a central nucleolus. Three to six contractile vacuoles.
Dimensions: Cienkowski shell 22 µm; De Saedeleer (1934): shell 6.8-17 µm. My measurements: 9.0-11.2 µm.
Ecology: freshwater; bacterivorous. A very common species. I found it in nearly all samples. One has to keep wet-mounts in moist chambers to let specimens (swarmers) come out of the detritus and settle to the glass, because they are hard to spot in the detritus. I found this species in The Netherlands and samples from Germany (Weser) and Peru (Lake Cocococha).
Remarks: The original description of Cienkowski is here. Additional information about Australia is here. Lee et al (2005) notice 4-8 apertures for Australian specimens. I have never seen more than 5. I agree with Lee et al that this is a common species.