Mayorella
Typical Mayorella shape

Genus Mayorella Schaeffer, 1926

Diagnosis: Locomotive digitiform subpseudopodia extending from anterior hyaloplasm; floating form often with long pseudopodia, radiating from an irregular body; nucleus usually spherical with a central nucleolus; most species with prominent cytoplasmic crystals, truncated, paired, bipyramidal or clustered with spheroids; cell surface as a cuticle, 200 nm thick.

Ecology: The genus is widespread in freshwater and marine habitats.

Type species: Mayorella bigemma (Schaeffer, 1918).

Remarks: This genus is morphologically identical with  Korotnevella (=Dactylamoeba). Only with TEM methods the surface cuticle of Mayorella can be distinguished from the surface microscales of Korotnevella.
The contractile vacuole, often more than one present, differs so far known from Korotnevella species by the way it empties. The contractile vacuole is replaced by hyaloplasm in Mayorella. According to Page (1988) this phenomenon appears to be one means of distinguishing between Mayorella and Korotnevella without using the electron microscope.
About 30 species have been described.

Mayorella contractile vacuole
Mayorella contractile vacuole
Contractile vacuole of Mayorella: h = hyaloplasm; cv = shrinking contractile vacuole; o = original size of contractile vacuole. Right: the same contractile vacuole, some seconds later, now almost completely replaced by hyaloplasm.
Mayorella
Mayorella
The drawings show some common species.
Mayorella
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