Two caryophyllaeid tapeworms, lsoglaridacris longus sp. n., and I. folius sp. n., are described from two species of redhorse, namely, Moxostoma macolepidotum and M. erythrurum, respectively. Members of the genus lsoglaridacris appear to be host specific, since the two species mentioned in this study occur in different fish hosts collected from the same rivers.
Both I. longus and I. folius appear to exhibit seasonal periodicity, the smallest populations occurring in late summer. Their presence or absence in fish during the winter months, however, is unknown. Infected fish usually harbor a small number of cestodes, generally only a single worm. The annual per cent of infection is 38% for the northern redhorse and 37% for the golden redhorse. Eggs are operculate and oncospheres show well-defined hooks after 17 days.
A key to the three known species of the genus lsoglaridacris is presented
