Cystobranchus meyeri sp. n. (Hirudinea: Piscicolidae) from Catostomus commersoni Lacépède in North America

Cystobranchus meyeri sp. n. (Hirudinea: Piscicolidae) is described from the white sucker, Catostomus commersoni Lacépède (Osteichthyes: Catostomidae) from the Mohawk River drainage of eastern New York. Size, details of internal anatomy, and the presence of 8 ocelli on the posterior sucker distinguish it from the 3 other species in North America. A table compares the members of this genus and a key to the species is included. Problems of classification, host records, and host specificity are discussed.