Genus: Body long, rear usually pointed (Illustrated Guide, 1985). Elogate; snout or neck-like prolongation (proboscis) conspicuous; contractile vacuoles two or more (Kudo, 1966). Contractile vacuoles usually lie in a row along the dorsal surface (Carey, 1992). Species: 250-400 (sometimes up to 600) μm long; numerous macronuclei; contractile vacuoles in a row on the aboral surface (Kudo, 1966). 200-600 μm long; small tail region; 200-500 very small macronuclei; contractile vacuoles from anterior to posterior on the dorsal surface (Carey, 1992).

Similar Genus ->> Trachelius; Paradileptus;

200 μm 400 μm 600 μm; x 100 : 100 μm 200 μm 300 μm; x 200

D. anser (Müller, 1786) Dujardin, 1840: 250-400 (sometimes up to 600) μm long; numerous macronuclei; contractile vacuoles in a row on the aboral surface (Kudo, 1966). 200-600 μm long; small tail region; 200-500 very small macronuclei; contractile vacuoles from anterior to posterior on the dorsal surface (Carey, 1992).
D. aculeatus Dragesco, 1960: Elongate; 300 μm long; long sharply pointed tail; 4 large rectangular macronuclei; a row of contractile vacuoles on dorsal surface (Carey, 1992).