Genus Zonomyxa Nüsslin, 1882
Diagnosis: Shell discoid in resting stage, 140 to 160 µm; locomotive form pyriform or oblong, 220 to 250 µm long. Shell chitinoid pellicle, without mucilaginous envelope, flexible, follows the movements of the cell. Surface contains small temporary perforations, allowing thin plasma threads to emerge. Pseudopods single, clear, conical, from slit-like pseudostome. Endoplasm granular, violet-tinted. Up to 32 vesicular nuclei present. Crystalloid bodies, 3 to 5 µm.
Feeding: herbivorous.
Habitat: Sphagnum mosses. Monospecific.
Zonomyxa violacea Nüsslin, 1882
Diagnosis: As for the genus. The description is almost identical as for Amphizonella violacea. According to Meisterfeld (2006) Zonomyxa violacea can be distinguished from A. violacea by the following characters:
– a thinner membrane,
– no external mucus layer,
– and most significantly: numerous nuclei.
Zonomyxa typically has four nuclei (Meisterfeld, 2006), though Penard (1906) reported up to 32. These are smaller (~20 µm) than the single large nucleus of Amphizonella violacea. I found an average of 7 nuclei per cell. However, it remains uncertain whether Zonomyxa is identical to Amphizonella.
Dimensions: my measurements 360-450 µm, nuclei c. 28 µm.
Habitat: in Sphagnum. Tirol, France.
Remarks: I have only found cells containing around seven spherical nuclei. Nuclei are difficult to detect in living specimens. I crushed the cells to force the nuclei out of the cell membrane. My specimens were taken from Sphagnum in Tirol, Austria. I have also found this species in Sphagnum from the Vosges in France.
Compare the above specimen with the original drawing below made by Nüsslin (1884). This drawing shows much better the common shape of this organism as the one which is usually used in textbooks, a drawing made by Penard.
The drawing above was made by Penard (1906) and is usually used in textbooks, adding more confusion than clarity to the identity of this amoeboid. Penards drawing closely resembles the one of Nüsslin in the upper right corner of the drawing below, where it has the shape of a <. Remarkable are the thin ‘hairs’ around the cell. I’ve seen similar ‘hairs’ in specimens of A. violacea, where they were bacteria along wires of mucus.
