1. Vesicles small, difficult to see on preserved leeches; body weakly or not divided into anterior and posterior parts. Body slim; colorless or scattered pigment cells; 24-26 mm long. . . . . . . . . . . . . . . . . . . . . Myzobdella, 2
Vesicles large, obvious after preservation; body strongly divided into anterior and posterior parts. . . . . . . . . . . . . . . . . . . . . . . Cystobranchus verrilli
2. Uniformly brown, lacking stripes; 12 or 14 annuli per segment; length > 9mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Myzobdella lugubris
Longitudinal stripes and 3 annuli per segment; length 6-8mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . Myzobdella reducta