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Rhizamoeba matisi Mrva, 2016

Diagnosis: Uninucleate, binucleate or (rarely) multinucleate cells. Length of the locomotive form 48–176 μm (mean 89.12 μm), breadth 5–17 μm (8.8 μm), length/breadth ratio 5.9–25 (mean 11.7 μm); the cell is elongated, monopodial, Y shaped or polypodial usually with one leading pseudopodium larger than the other pseudopodia; bulbous uroid covered with trailing uroidal filaments. Nucleus flexible, spindle-shaped or elliptical and elongated (length 4–15 μm, breadth 2.5–4 μm), vesicular with a single central nucleolus or with fragments of closely apposed nucleolar material. Floating form with spherical central mass and up to eight blunt-ended pseudopodia. Cysts uninucleate, occasionally binucleate or quadrinucleate with closely apposed nuclei; spherical or ovoid, 12.5–25 μm (mean 16.5 μm) in diameter, with several collar-shaped cyst pores. Habitat: Freshwater and mosses.

Differential diagnosis: Differs from other freshwater species in elongated monopodial locomotive form, its size, and much higher length/breadth ratio, in the absence of broad flattened forms, in the morphology of the floating form, the shape of the nucleus and in the structure of nucleolus. Monopodial forms may resemble Hartmannella or Vermamoeba, but differs from the representatives of both these genera by presence of adhesive uroidal filaments, never noted in both latter species (Page 1983; 1988; Smirnov 1996-97).

Ecology: Type location: Water filled tree-hole from the locality Naháč-Kukovačník, Malé Karpaty Mts., Slovakia.

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