Schwabia stoutii
Difflugia stoutii, after Lüftenegger and Foissner, 1991

Schwabia stoutii (Ogden, 1983) comb. n.

Diagnosis: Test ovoid or ovoid elongate, in cross-section round or slightly compressed, composed of mainly small, flattish particles of siliceous material, including quartz, diatom frustules and shell plates from smaller testate amoebae. It is extremely fragile. Organic cement is seen only as small threads due to the regular overlapping of the shell components. The aperture is roughly circular, sometimes oval, small and appears to be recessed, but this latter feature may be due to structural fragility. Test brownish.

Dimensions: Ogden: Length 47-59 µm, width 33-36 µm, diameter of aperture 9-12 µm (n=4). Lüftenegger and Foissner, 1991: Length 38-61 µm (n=27), width 22-40 µm, thickness 16-25 µm, diameter of aperture 6-10 µm (n=15).

Ecology: Sphagnum, North Wales (Ogden, 1983), soil, Austria (Lüftenegger and Foissner, 1991).

Remarks: D. stoutii is distinct in having a fragile, elongate ovoid shell composed of flattish particles and a small aperture. It was described by Ogden (1983) as a Difflugia species, but in my opinion it is a Schwabia species. It’s a pity that Ogden didn’t observe living specimens. Until now we assume that Schwabia belongs to the Cercozoa and is related to Pseudodifflugia.

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