The present invention relates to novel anthelmintic compounds of formula (IA) below: wherein, Y is selected from the group consisting of —H, aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclyl, alkyl, haloalkyl, and alkoxyalkyl; and Z is selected from the group consisting of aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclyl, alkyl, haloalkyl, and alkoxyalkyl. Variables Ring A, Ring B, Ring C, X1, X6, and X8 are as defined herein. The invention also relates to parasiticidal compositions comprising the compounds, and methods and uses of the compounds for treating and preventing parasitic infections and infestations in animals.