D. gigas: About 700 μm long;
macronucleus sausage-shaped; contractile vacuoles line the dorsal surface and extend right to the
tip of the neck region (Illustrated Guide, 1985).
D. monilatus (Stokes, 1886) Kahl, 1931: Elongate;
700 μm long; no separate tail region;
macronucleus moniliform; contractile vacuoles line the dorsal surface and extend right to the
tip of the neck region (Carey, 1992). Proboscis less than 1/4 of the body length.