Pseudodifflugia siemensmai Zagumyonnaya, Zagumyonnyi et Tikhonenkov, 2026
Diagnosis: Shell pyriform, rigid, not compressed, organic, scarcely or densely agglutinated with xenosomes of various shapes and sizes; aperture circular, somewhat irregular in outline, not encrusted with xenosomes, and without organic rim; nucleus not observed. Filopodia branch but do not anastomose. The length of the filopodia range from three to four times the size of the shell. Shells can be aggregated into “rosette” formations.
Dimensions: Siemensma (www.arcella.nl): Length 15.7 µm, diameter 12 µm (n=1).
Zagumyonnaya et al. (2026): Shell 18.4–26.8 × 14.2–18.9 μm; length-width ratio 1.3–1.5; aperture diameter 4.7-5.9 μm.
Ecology: sediments of peat bog, Bert Bospad, the Netherlands (Siemensma, arcella.nl). Plankton of overgrown litterol zones of Lake Singul, Western Siberia.
