Couplet 52

52a:  Antenna with 3 antennomeres; pronotum with antennal pockets anterolaterally above lateral margins; dorsoventrally flattened, louse-like parasites of beavers (Platypsyllus)

Leiodidae   p. 408

52b:  Antenna with 9-11 antennomeres; pronotum without antennal pockets