KEY TO IMPORTANT ADULT HUMAN TREMATODES
1. Dioecious trematodes (one sex per worm)...................... Schistosoma species.
Monoecious trematodes (both sexes per worm)............................................. 2
2. Small flukes: size under 5 mm........................................................................ 3
Large flukes: size range 20 to 45 mm............................................................ 4
Medium flukes: size range 5 to 20 mm........................................................... 5
3. Gonotyl absent; ventral sucker offset to one side;
intestinal ceca straight; testes oval and oblique......... Metagonimus yokogawai
Gonotyl present; ventral sucker central; intestinal
ceca straight; testes oval and para........................... Heterophyes heterophyes
4. Cephalic cone present; intestinal ceca branched;
testes tandem and dendritic.............................................. Faciolopsis hepatica
Cephalic cone absent; intestinal ceca undulating; testes
tandem and dendritic.............................................................. Faciolopsis buski
5. Anterior testes................................................................................................. 6
Posterior testes................................................................................................ 7
6. Intestinal ceca straight; testes oblique and lobate;
wide acetabulum at posterior end; gourd-shaped
body............................................................................ Gastrodiscoides hominis
Intestinal ceca straight; testes oblique and lobate;
Elongated.................................................................. Dicrocoelium dendriticum
7. Circlet of spines around oral sucker; intestinal ceca
straight; testes tandem and lobate................................... Echinostoma species
Intestinal ceca straight; testes oblique and lobate............ Opisthorchis species
Intestinal ceca straight; testes tandem and
highly branched................................................................ Opisthorchis sinensis
Intestinal ceca undulating; testes para and lobate..... Paragonimus westermani
Table 3-1. Key to important adult human trematodes.
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