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Vacuolamoeba acanthoformis
Vacuolamoeba acanthoformis, after Tyce et al., 2016

Genus Vacuolamoeba Tice , Geisen, & Brown 2016

Diagnosis: Irregular shaped amoebae, pseudopods variable with anterior hyaloplasmic lamellopodial extensions free of inclusions. Acanthopodial extensions can form from all areas of the cell body. Occasionally cells produce uroid with lamellopodial form that includes filose uroidal extensions. Cells most often with 1 vesicular nucleus with a central nucleolus. Cells have 2 nuclei have been observed. Cell body often has many ca. 4-5 vacuoles, sometimes with one or more contractile vacuoles. Cysts round to irregularly shaped with a single wall. Cysts usually form individually rather than in clusters.

Type species: Vacuolamoeba acanthoformis n. sp.

Vacuolamoeba acanthoformis Tice , Geisen, & Brown 2016

Diagnosis: Characteristics of the genus. Mean cell length or breadth is 22.5 μm (standard deviation = 1.4 μm, n = 9). Cells are most often uninucleate with a single round centrally positioned nucleolus. Nucleus diameter ranges from 3.2-5.5 μm (mean = 4.3 μm, standard deviation = 0.8 μm, n = 8). Nucleolus diameter ranges from 1.1-2.2 μm (mean = 1.6 μm, standard deviation = 0.3 μm, n = 8). Mean cyst diameter = 8.0 μm (standard deviation = 1.0 μm, n = 16).

Type habitat: High altitude soil from Tibet.

Differential diagnosis: May upon initial observation resemble both Acanthamoeba spp. and Protacanthamoeba spp. Spore morphology is the easiest way to distinguish this species from any species of Acanthamoeba. Spores of this species are smooth walled and do not exhibit the endocyst/exocyst arrangement typical of most Acanthamoeba spp. Differs from P. bohemica in that the acanthopoida are not nearly as pronounced.

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