Cystidicolidae

Key to genera of CYSTIDICOLIDAE

1 Cuticular ornamentation in form of transverse rings with spines; parasitic in alimentary tract of fishes, generally freshwater.............................................................................................. Spinitectus

- Cuticular ornamentation, if present, never in form of transverse rings with spines; parasitic in alimentary tract or swim bladder of fishes............................................................................................ 2

2 Four pairs of pre-cloacal papillae in male................................................................. 3

- Six or more pairs of pre-cloacal papillae in male............................................................ 5

3 Bidentate plate-like structure arising from antero-lateral wall of buccal cavity present; anterior margin of pseudolabia forming narrow ridge; parasitic in alimentary tract of fishes, mostly sturgeons.................................. Capillospirura

- Bidentate plate-like structure arising from antero-lateral wall of buccal cavity absent; pseudolabia narrow or broad....... 4

4 Pseudolabia very broad and flat; anterior surface of each pseudolabium with small protuberance (pseudolabial protrusion); submedian labia absent........................................................................ Salmonema

- Buccal cavity dilated anteriorly forming buccal capsule divided into ventral and dorsal chambers; parasitic in swim bladder of salmonid fishes.............................................................................. Salvelinema

5 Pseudolabia narrow: anterior extension of each lateral wall of buccal cavity projecting beyond junction with pseudolabium in a two-pronged horn-like structure, prongs of each projection lying on either side of pseudolabium.......... Caballeronema

- P seudolabia narrow: horn-like structures absent; anterior surface of each pseudolabium with a prominent conical protuberance or a blunt knob; four submedian labia present...................................................... Ascarophis

6 Anterior margin of vestibule armed with two rows of denticles; pseudolabia rudimentary, each forming small, conical, anteriorly protruding structure; 12 to 18 pairs of pre-cloacal papillae in male; parasitic in swim bladder of salmonid fishes.................................................................................................... Cystidicola