A redescription of Amphizonella violacea [Amoebozoa: Arcellinida]

Summary. We redescribe the lobose testate amoeba Amphizonella violacea Greeff, 1866. We have collected this conspicuous but often overlooked species in xerophilic mosses from six localities in Germany. The overall shape is much more variable than hitherto k nown. Non moving cells are usually roundish or oval but can emit pseudopods, moving amoebae adopt a more longish tongue or fan-like shape sometimes non moving amoebae take a stretched form with pseudopods at opposite ends. In contrast to previously published images the outer gelatinelike mucus layer is not always present. After excystation this layer is secreted de novo. Its thickness is variable and can reach up to 23 µm. Normally it contains numerous rod-shaped bacterial exobionts of unknown function. In SEM the outer surface is smooth. The untextured organic shell-wall is flexible and opens in a large not well defined aperture.