Ecology and External Morphology of Lernaea cyprinacea

The external morphology of Lernaea cyprinacea L. in Vigo Co., Indiana, was more variable than has been previously reported. The pregenital prominence was absent in small lernaeids, then de- veloped as a single protuberance, which doubled as the female copepod lengthened and matured. No correlation was found between the location on the host fish and the direction of torsion. Sixteen species of fishes, taken in Vigo Co., were parasitized by L. cyprinacea. They were: Notropis blennius,* N. atherinoides,* N. spilopterus,* N. volucellus,* Semotilus atromaculatus,* Phenacobius mirabilis,* Hybognathus nu- chalis,* Ictiobus niger,* I. cyprinellus,* Lepomis macrochirus, Microp- terus salmoides, Pomoxis annularis,* Catostomus commersoni, Esox americanus,* Moxostoma erythrurum,* and Percina maculata* (asterisk denotes new host records). L. cyprinacea parasitized 0.8% of the fishes examined. Usually there was one parasite per fish, attached near a fin.