Genus: Oblong; ciliary circle around cytostome; usually one caudal cilium;
with large posterior vesicle containing turbid fluid (Kudo, 1966).
Easily recognizable by the transverse annulations of the body and the presence of a
large protruding vacuole in posterior (Carey, 1992).
Similar to Vasicola, but small and free swimming,
without a lorica (How to know the protozoa, 1979).
M. truncata Cohn, 1866: Elongate; with about twelve furrow rings;
up to 30 μm long (Kudo, 1966).
M. elongata Kahl, 1928: Cylindrical; 60-80 μm long; a single long caudal cilium; lorica not known (Carey, 1992).
M. recurva Penard, 1922: Vermiform or cylindrical, with posterior expanded; up to 68 μm long; body annulated, curved; a rigid, slender and colourless lorica; large posterior vacuole with a single caudal cilium; spherical macronucleus central; contractile posterior (Carey, 1992).