1. Anus close to the posterior sucker; no pedicel. . . . . . . . . . . . . . . . . . . . . . . . 2
Anus between segments XXIII and XXIV with the 16 postanal annuli forming a slender stalk (pedicel) which bears the posterior sucker; no papillae; length 35 mm; typically found on its host Aplodinotus grunniens (freshwater drum). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Placobdella pediculata
2. Margins of posterior sucker denticulate; head expanded and discoid and set off from body by a narrow neck. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Margins of posterior sucker not denticulate; head not distinctly expanded or otherwise set off from body by a narrow neck, but mor or less continuous with body. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Placobdella montifera
3. Dorsum with conspicuous white genital and anal patches, one or more medial white patches and white band in neck region. . . . . . . . . . . . . . . . . . . . . . . . 4
Dorsum without white patches and with or without white band in neck region. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Dorsal papillae in 2-3 rows . . . . . . . . . . . . . . . . . . . . Placobdella ornata
Dorsal papillae in 5-6 rows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Body with ventral stripes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Without ventral stripes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Dorsum with numerous small papillae arranged in five distinct longitudinal rows; length 50mm. . . . . . . . . . . . . . . . . . . . . Placobdella multilineata
Dorsum with 7 longitudinal rows of small white tipped papillae; interupted dorsomedial line; alternating lateral rows of light and dark pigmentatioj; three pair of pre-anal papillae; length 45mm. . . . . . . . . Placobdella papillifera
7. Dorsum brownish-green, variegated with orange with thin dark dorsal medial line and 6-7 rows of white tipped papillae; length 13-25 mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Placobdella picta
Eyes coalesced; head not set off from body; mouth pore in sucker disk. Small posterior sucker; typically with white patches on head, occasionally on mid body, and anal region; adults 5-25 mm; parasitic of primarily amphibians and fish. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Placobdella phalera*
*Now a junior synonym of Placobdella ornata