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Fisculla terrestris
Fisculla terrestris, large specimen with 6 nuclei.

Genus Fisculla Dumack, Mausbach et Bonkowski, 2016

Diagnosis: Filose radially symmetric amoebae. Theca often deformed by ingested food, sometimes wrinkled or folded. Apical ellipsoid or round nucleus, clear or grainy; round nucleolus sometimes visible by light microscopy. One or several contractile vacuoles (hard to see) and food vacuoles, usually basal. Granules vary in amount, sometimes in layers, sometimes spread evenly. Cells creep by filopodia, which may branch or anastomose but lack granules; cell body carried upright. May form floating stages with retracted or expanded filopodia. Cysts formed within the theca, the theca forms a loose envelope around the cyst wall. Cells may aggregate basolaterally in a ring, each retaining its nucleus and individual shape, or apparently partially fuse basally within one multinucleate lobed theca.

Division longitudinal, binary. Sexual reproduction unknown. In contrast to Lecythium: no granules in filopodia, cells form aggregates by fusion, often between the apical end and the nucleus an additional layer of granules which could not be observed in L. hyalinum or L. jennyae.

Type species: F. terrestris

Ecology: Eukaryotic prey (yeasts, algae) caught by filopodia; dragged to thecal opening for ingestion. No bacterial ingestion observed. At least F. terrestris can form a tubular feeding siphon. Freshwater or terrestrial.

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