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Genus Dictyamoeba Berney, Bass & Geisen, 2015

Diagnosis: Multinucleate, highly branching and reticulate naked amoebae with slender, pointed, sometimes branched pseudopodia. Trophozoites moving too slowly to be seen in light microscopy. The main cell body is multiply branched and anastomosing even in its simplest form, and can grow into gigantic networks (up to several mm) with intersecting segments of varying width and numerous terminal branching areas. Abundant fine pseudopodia are concentrated mostly at the extremity of lateral and terminal branches, especially in complex networks, but can be formed anywhere around the cell body in simpler forms. Numerous contractile vacuoles observed everywhere in the network, but more commonly at intersections of the main branches. Movement of entire cells too slow to be directly observable. Cysts of varying sizes and shapes, the simplest ones rounded, the larger ones irregular inshape.

Type species: Dictyamoeba vorax

Dictyamoeba vorax Berney, Bass & Geisen, 2015

Diagnosis: Non-marine, with morphological characteristics of the genus. Size across between 30-300  µm in young trophozoites. Can survive on bacteria alone, but in that case retains a relatively simple form and medium size. Grows into a gigantic network in presence of yeasts, which are consumed very rapidly; in that case yeasts tend to be collected in clumps at nodes of the network before being consumed. When all food has been consumed, the whole network contracts simultaneously in different areas, leading to the formation the formation of very many cysts of all possible sizes and shapes, the position of which mirrors the original layout of the network.

Ecology: Garden soil sample with moss and lichens, Wales, UK.

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