Genus: Cigar- or foot-shaped; a single macronucleus and 1 to several vesicular or compact microuclei (Kudo, 1966). Species: 180-300 μm long; a compact micronucleus; two contractile vacuoles (Kudo, 1966). Cylindrical or cigar-shaped; rounded anteriorly, pointed posteriorly; one large compact micronucleus ("caudatum" group) approximately 8 μm diam.; two contractile vacuoles; 170-290 μm long (Wichterman, 1986). Elongate, rounded anteriorly, pointed posteriorly; caudal cilia present; 180-280 μm long; a single macronucleus with a single micronucleus; two contractile vacuoles (Carey, 1992).

50 μm 100 μm 150 μm; x 400 : 31 μm 63 μm 94 μm; x 640